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  Subjects -> SCIENCES: COMPREHENSIVE WORKS (Total: 426 journals)
Showing 1 - 200 of 265 Journals sorted alphabetically
AAS Open Research     Open Access   (Followers: 2)
ABC Journal of Advanced Research     Open Access  
Academic Voices : A Multidisciplinary Journal     Open Access   (Followers: 2)
Accountability in Research: Policies and Quality Assurance     Hybrid Journal   (Followers: 20)
Acta Materialia Transilvanica     Open Access  
Acta Nova     Open Access   (Followers: 1)
Acta Scientifica Malaysia     Open Access   (Followers: 1)
Acta Scientifica Naturalis     Open Access   (Followers: 3)
Adıyaman University Journal of Science     Open Access  
Advanced Science     Open Access   (Followers: 13)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 10)
Advanced Theory and Simulations     Hybrid Journal   (Followers: 5)
Advances in Research     Open Access  
Advances in Science and Technology     Full-text available via subscription   (Followers: 17)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 8)
Afrique Science : Revue Internationale des Sciences et Technologie     Open Access   (Followers: 2)
AFRREV STECH : An International Journal of Science and Technology     Open Access   (Followers: 4)
American Academic & Scholarly Research Journal     Open Access   (Followers: 6)
American Journal of Applied Sciences     Open Access   (Followers: 27)
American Journal of Humanities and Social Sciences     Open Access   (Followers: 14)
ANALES de la Universidad Central del Ecuador     Open Access   (Followers: 3)
Anales del Instituto de la Patagonia     Open Access  
Applied Mathematics and Nonlinear Sciences     Open Access   (Followers: 1)
Apuntes de Ciencia & Sociedad     Open Access  
Arab Journal of Basic and Applied Sciences     Open Access  
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 5)
Archives Internationales d'Histoire des Sciences     Partially Free   (Followers: 6)
Archives of Current Research International     Open Access  
ARO. The Scientific Journal of Koya University     Open Access  
ARPHA Conference Abstracts     Open Access   (Followers: 6)
ARPHA Proceedings     Open Access   (Followers: 4)
ArtefaCToS : Revista de estudios sobre la ciencia y la tecnología     Open Access   (Followers: 1)
Asia-Pacific Journal of Science and Technology     Open Access  
Asian Journal of Advanced Research and Reports     Open Access   (Followers: 2)
Asian Journal of Applied Science and Engineering     Open Access   (Followers: 2)
Asian Journal of Scientific Research     Open Access   (Followers: 3)
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 7)
Australian Field Ornithology     Full-text available via subscription   (Followers: 4)
Australian Journal of Social Issues     Hybrid Journal   (Followers: 7)
Avances en Ciencias e Ingeniería     Open Access  
AZimuth     Full-text available via subscription   (Followers: 2)
Bangladesh Journal of Scientific Research     Open Access   (Followers: 1)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 3)
Berichte Zur Wissenschaftsgeschichte     Hybrid Journal   (Followers: 10)
Berkeley Scientific Journal     Full-text available via subscription  
BIBECHANA     Open Access   (Followers: 2)
BibNum     Open Access  
Bilge International Journal of Science and Technology Research     Open Access   (Followers: 1)
Bioethics Research Notes     Full-text available via subscription   (Followers: 16)
Bistua : Revista de la Facultad de Ciencias Básicas     Open Access  
BJHS Themes     Open Access  
Black Sea Journal of Engineering and Science     Open Access  
Borneo Journal of Resource Science and Technology     Open Access  
Brazilian Journal of Science and Technology     Open Access   (Followers: 2)
Bulletin de la Société Royale des Sciences de Liège     Open Access  
Bulletin of the National Research Centre     Open Access  
Butlletí de la Institució Catalana d'Història Natural     Open Access  
Central European Journal of Clinical Research     Open Access  
Chain Reaction     Full-text available via subscription  
Ciencia & Natura     Open Access   (Followers: 1)
Ciencia Amazónica (Iquitos)     Open Access   (Followers: 1)
Ciencia en Desarrollo     Open Access   (Followers: 2)
Ciencia en su PC     Open Access   (Followers: 1)
Ciencia Ergo Sum     Open Access  
Ciência ET Praxis     Open Access  
Ciencia y Tecnología     Open Access  
Ciencia, Docencia y Tecnología     Open Access  
Ciencias Holguin     Open Access   (Followers: 2)
CienciaUAT     Open Access   (Followers: 1)
Citizen Science : Theory and Practice     Open Access   (Followers: 2)
Communications Faculty of Sciences University of Ankara Series A2-A3 Physical Sciences and Engineering     Open Access  
Communications in Applied Sciences     Open Access  
Comprehensive Therapy     Hybrid Journal   (Followers: 3)
Comunicata Scientiae     Open Access   (Followers: 1)
ConCiencia     Open Access  
Conference Papers in Science     Open Access   (Followers: 2)
Configurations     Full-text available via subscription   (Followers: 10)
COSMOS     Hybrid Journal  
Crea Ciencia Revista Científica     Open Access   (Followers: 2)
Cuadernos de Investigación UNED     Open Access  
Current Issues in Criminal Justice     Hybrid Journal   (Followers: 15)
Current Research in Geoscience     Open Access   (Followers: 8)
Dalat University Journal of Science     Open Access  
Data     Open Access   (Followers: 3)
Data Curation Profiles Directory     Open Access   (Followers: 4)
Dhaka University Journal of Science     Open Access  
Dharmakarya     Open Access  
Diálogos Interdisciplinares     Open Access  
Digithum     Open Access   (Followers: 2)
Discover Sustainability     Open Access   (Followers: 3)
Einstein (São Paulo)     Open Access  
Ekaia : EHUko Zientzia eta Teknologia aldizkaria     Open Access  
Elkawnie : Journal of Islamic Science and Technology     Open Access  
Emergent Scientist     Open Access  
Enhancing Learning in the Social Sciences     Open Access   (Followers: 9)
Enseñanza de las Ciencias : Revista de Investigación y Experiencias Didácticas     Open Access  
Entramado     Open Access  
Entre Ciencia e Ingeniería     Open Access   (Followers: 1)
Epiphany     Open Access   (Followers: 4)
Episteme Transversalis     Open Access  
Ergo     Open Access  
Estação Científica (UNIFAP)     Open Access   (Followers: 1)
Ethiopian Journal of Education and Sciences     Open Access   (Followers: 6)
Ethiopian Journal of Science and Technology     Open Access  
Ethiopian Journal of Sciences and Sustainable Development     Open Access   (Followers: 6)
European Online Journal of Natural and Social Sciences     Open Access   (Followers: 12)
European Scientific Journal     Open Access   (Followers: 10)
Evidência - Ciência e Biotecnologia - Interdisciplinar     Open Access  
Exchanges : the Warwick Research Journal     Open Access   (Followers: 2)
Experimental Results     Open Access  
Extensionismo, Innovación y Transferencia Tecnológica     Open Access   (Followers: 3)
Facets     Open Access  
Fides et Ratio : Revista de Difusión Cultural y Científica     Open Access   (Followers: 1)
Fırat University Turkish Journal of Science & Technology     Open Access  
Fontanus     Open Access  
Forensic Science Policy & Management: An International Journal     Hybrid Journal   (Followers: 372)
Frontiers for Young Minds     Open Access  
Frontiers in Climate     Open Access   (Followers: 3)
Frontiers in Science     Open Access   (Followers: 1)
Futures & Foresight Science     Hybrid Journal   (Followers: 4)
Gaudium Sciendi     Open Access   (Followers: 1)
Gazi University Journal of Science     Open Access  
Ghana Studies     Full-text available via subscription   (Followers: 15)
Global Journal of Pure and Applied Sciences     Full-text available via subscription  
Global Journal of Science Frontier Research     Open Access   (Followers: 2)
Globe, The     Full-text available via subscription   (Followers: 4)
HardwareX     Open Access  
Heidelberger Jahrbücher Online     Open Access  
Heliyon     Open Access  
Himalayan Journal of Science and Technology     Open Access   (Followers: 1)
History of Science and Technology     Open Access  
Hoosier Science Teacher     Open Access  
Iberoamerican Journal of Science Measurement and Communication     Open Access  
Impact     Open Access   (Followers: 2)
Indian Journal of History of Science     Hybrid Journal  
Indonesian Journal of Fundamental Sciences     Open Access  
Indonesian Journal of Science and Mathematics Education     Open Access   (Followers: 4)
Indonesian Journal of Science and Technology     Open Access  
Ingenieria y Ciencia     Open Access   (Followers: 1)
Innovare : Revista de ciencia y tecnología     Open Access  
Instruments     Open Access  
Integrated Research Advances     Open Access  
Interciencia     Open Access   (Followers: 1)
Interface Focus     Full-text available via subscription  
International Annals of Science     Open Access  
International Archives of Science and Technology     Open Access  
International Journal of Academic Research in Business, Arts & Science     Open Access   (Followers: 2)
International Journal of Advanced Multidisciplinary Research and Review     Open Access  
International Journal of Advancement in Education and Social Sciences     Open Access   (Followers: 1)
International Journal of Advances in Engineering, Science and Technology     Open Access   (Followers: 3)
International Journal of Applied Science     Open Access  
International Journal of Basic and Applied Sciences     Open Access   (Followers: 4)
International Journal of Computational and Experimental Science and Engineering (IJCESEN)     Open Access  
International Journal of Culture and Modernity     Open Access  
International Journal of Engineering, Science and Technology     Open Access  
International Journal of Innovation and Applied Studies     Open Access   (Followers: 12)
International Journal of Innovative Research and Scientific Studies     Open Access   (Followers: 6)
International Journal of Innovative Research in Social and Natural Sciences     Open Access   (Followers: 2)
International Journal of Network Science     Hybrid Journal   (Followers: 3)
International Journal of Recent Contributions from Engineering, Science & IT     Open Access   (Followers: 1)
International Journal of Research in Science     Open Access   (Followers: 2)
International Journal of Science & Emerging Technologies     Open Access   (Followers: 1)
International Journal of Sciences : Basic and Applied Research     Open Access  
International Journal of Social Sciences and Management     Open Access   (Followers: 3)
International Journal of Technology Policy and Law     Hybrid Journal   (Followers: 7)
International Letters of Social and Humanistic Sciences     Open Access   (Followers: 1)
International Review of Applied Sciences     Open Access  
InterSciencePlace     Open Access   (Followers: 1)
Investiga : TEC     Open Access  
Investigación Joven     Open Access  
Investigación Valdizana     Open Access  
Investigacion y Ciencia     Open Access   (Followers: 1)
Iranian Journal of Science and Technology, Transactions A : Science     Hybrid Journal  
iScience     Open Access   (Followers: 1)
Issues in Science & Technology     Free   (Followers: 7)
Istituto Lombardo - Accademia di Scienze e Lettere - Rendiconti di Scienze     Open Access  
Ithaca : Viaggio nella Scienza     Open Access  
J : Multidisciplinary Scientific Journal     Open Access  
Jaunujų mokslininkų darbai     Open Access  
Journal de la Recherche Scientifique de l'Universite de Lome     Full-text available via subscription   (Followers: 2)
Journal for New Generation Sciences     Open Access   (Followers: 3)
Journal of Chromatography & Separation Techniques     Open Access   (Followers: 12)
Journal of Advanced Research     Open Access   (Followers: 3)
Journal of Al-Qadisiyah for Pure Science     Open Access   (Followers: 1)
Journal of Alasmarya University     Open Access  
Journal of Analytical Science & Technology     Open Access   (Followers: 6)
Journal of Applied Science and Technology     Full-text available via subscription   (Followers: 1)
Journal of Applied Sciences and Environmental Management     Open Access   (Followers: 3)
Journal of Big History     Open Access   (Followers: 3)
Journal of Composites Science     Open Access   (Followers: 3)
Journal of Critical Thought and Praxis     Open Access   (Followers: 2)
Journal of Deliberative Mechanisms in Science     Open Access  
Journal of Diversity Management     Open Access   (Followers: 6)
Journal of Indian Council of Philosophical Research     Hybrid Journal  
Journal of Institute of Science and Technology     Open Access  
Journal of Integrated Science and Technology     Open Access  
Journal of Interaction Science     Open Access   (Followers: 1)
Journal of Kerbala University     Open Access   (Followers: 1)
Journal of King Saud University - Science     Open Access   (Followers: 1)
Journal of Law, Information and Science     Full-text available via subscription   (Followers: 20)

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Journal of Composites Science
Number of Followers: 3  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2504-477X
Published by MDPI Homepage  [233 journals]
  • J. Compos. Sci., Vol. 5, Pages 140: Controlled Magnetic Isolation and
           Decoupling of Perpendicular FePt Films by Capping Ultrathin Cu(002)
           Nano-Islands

    • Authors: Da-Hua Wei, Ji-Hong Chang, Chi-Chun Hsu, Cheng-Jie Yang, Yuan-Chang Liang, Chung-Li Dong, Yeong-Der Yao
      First page: 140
      Abstract: This study investigated the ultrathin Cu(002) capping nano-island effects on the magnetic characterizations and microstructure of epitaxial FePt(001) films directly fabricated on MgO(001) substrates at the relatively low temperature of 300 °C via electron-beam deposition. The enhancement of the coercivity is attributed to the lowered exchange coupling of FePt magnetic grains that begun from Cu atom behavior of spreading in many directions mainly along grain boundaries due to its lower surface energy than that of pure Fe or Pt. The measurement of angular-dependent coercivity shows a tendency of a domain-wall motion shift toward the rotation of the reverse-domain type upon the thickness of the Cu capping nano-island layer atop the FePt films. The intergranular interaction was clarified by the Kelly–Henkel plot, which indicated that there was strong exchange coupling (positive δM) between neighboring grains in the FePt continuous films without Cu capping nano-islands. On the other hand, a negative δM value was gained when the FePt films were capped with a Cu(002) single layer, indicating that the Cu capping layer can be used to control the strength of intergrain exchange coupling between the adjacent FePt grains and thicker Cu(002) capping nano-islands toward magnetic isolation; thus, there was an existence of dipole interaction in our designed Cu/FePt composite structure of stacked films.
      Citation: Journal of Composites Science
      PubDate: 2021-05-21
      DOI: 10.3390/jcs5060140
      Issue No: Vol. 5, No. 6 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 141: Dielectric Properties of Wood-Polymer
           Composites: Effects of Frequency, Fiber Nature, Proportion, and Chemical
           Composition

    • Authors: Imen Elloumi, Ahmed Koubaa, Wassim Kharrat, Chedly Bradai, Ahmed Elloumi
      First page: 141
      Abstract: The characterization of the dielectric properties of wood–polymer composites (WPCs) is essential to understand their interaction with electromagnetic fields and evaluate their potential use for new applications. Thus, dielectric spectroscopy monitored the evolution of the dielectric properties of WPCs over a wide frequency range of 1 MHz to 1 GHz. WPCs were prepared using mixtures of different proportions (40%, 50%, and 60%) of wood and bark fibers from various species, high-density polyethylene, and maleated polyethylene (3%) by a two-step process, extrusion and compression molding. Results indicated that wood fibers modify the resistivity of polyethylene at low frequencies but have no effect at microwave frequencies. Increasing the fiber content increases the composites’ dielectric properties. The fibers’ cellulose content explains the variation in the dielectric properties of composites reinforced with fibers from different wood species. Indeed, composites with high cellulose content show higher dielectric constants.
      Citation: Journal of Composites Science
      PubDate: 2021-05-24
      DOI: 10.3390/jcs5060141
      Issue No: Vol. 5, No. 6 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 142: Physico-Mechanical Study of
           CMC/BFO/PoPD Nanocomposite Films Reinforced with Cellulose Nanocrystals
           (CNCMCC) for Effective Photocatalytic Removal of Methyl Orange

    • Authors: Nurul Hidayu Nazri, Yogesh Kumar, Mohd Amirul Ramlan, Mohammad Haafiz Mohammad Kassim, Md. Sohrab Hossain, Noor Haida Mohd Kaus
      First page: 142
      Abstract: The present study was conducted to develop a nanocomposite film of carboxymethyl cellulose (CMC) reinforced with cellulose nanocrystals isolated from microcrystalline cellulose (CNCMCC) in the presence of bismuth ferrite (BFO)/poly-o-phenylenediamine (PoPD). The physicochemical properties, the mechanical and thermal stability, and its photocatalytic activity towards the removal of methyl orange (MO) were determined. Results show that the integration of CNCMCC into the CMC matrix enhanced the mechanical strength of the film. The tensile strength (TS) of the nanocomposite film increased from 0.205 to 0.244 MPa, while elongation at break (EB) decreased from 201.44 to 168.78% in the presence of 20 wt.% of CNCMCC. The incorporation of CNCMCC in the CMC matrix substantially enhanced the nanocomposite’s thermal stability from 181.16 to 185.59 °C and decreased the degradation residue from 72.64 to 63.16%. The determination of the photocatalytic activity of the CMC/CNCMCC/BFO/PoPD composite film revealed the removal of methyl orange (MO) of 93.64% with high structural integrity after 3 h of treatment. Thus, the isolated CNCMCC-reinforced CMC/BFO/PoPD composite film can be used as a photocatalyst for the removal of organic pollutants from wastewater, including the methyl orange.
      Citation: Journal of Composites Science
      PubDate: 2021-05-25
      DOI: 10.3390/jcs5060142
      Issue No: Vol. 5, No. 6 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 143: Practical Rubber Pre-Treatment Approch
           for Concrete Use—An Experimental Study

    • Authors: Rajeev Roychand, Rebecca J. Gravina, Yan Zhuge, Xing Ma, Julie E. Mills, Osama Youssf
      First page: 143
      Abstract: There is a lot of ongoing active research all over the world looking for various applications of used tyre rubber, to increase its utilisation rate. One of the common research applications is to incorporate rubber into concrete as a partial replacement for conventional aggregates. However, due to its poor bonding performance with cement paste, the utilisation of rubber in concrete has been hindered to date. A cost-effective and time-saving rubber pre-treatment method is of great interest, especially for the concrete industry. Out of all the various pre-treatment methods, soaking rubber particles in water is the most cost-effective and least complex method. In addition, sodium sulphate accelerates the hydration reaction of the cement composites. This study looks at the effect of soaking crumb rubber in tap water for short (2 h) and long (24 h) durations, and the optimised duration was then compared with soaking the crumb rubber in a 5% concentration of sodium sulphate solution. Compressive strength, bond behaviour, and rubber/cement interfacial transition zone (ITZ) were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. The results demonstrate that a soaking duration of 2 h provides much better performance in both the strength and bond properties compared to 24-h soaking. A further improvement in the 7-day strength was achieved with the rubber soaked in 5% sodium sulphate solution for 2 h, providing a more practical and economical rubber pre-treatment method for concrete industry use.
      Citation: Journal of Composites Science
      PubDate: 2021-05-26
      DOI: 10.3390/jcs5060143
      Issue No: Vol. 5, No. 6 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 144: The Performance of
           Filava-Polysiloxane, Silres® H62C Composite in High Temperature
           Application

    • Authors: Klaudio Bari, Thozhuvur Govindaraman Loganathan
      First page: 144
      Abstract: The research aim is to investigate the performance of novel enriched mineral fibres (Filava) in polysiloxane SLIRES H62 resin. Specimens were manufactured using a vacuum bagging process and oven cured at 250 °C. Specimens were prepared for flexural testing according to BS EN ISO 14125:1998 to obtain flexural strength, modulus, and elongation. The mechanical strength was compared to similar composites, with the aim of determining composite performance index. The flexural modulus (9.7 GPa), flexural strength (83 MPa), and flexural strain (2.9%) were obtained from a three-point bending test. In addition, the study investigates the thermal properties of the composite using a state-of-art Zwick Roell high temperature tensile rig. The results showed Filava/Polysiloxane Composites had an ultimate tensile strength 400 MPa, Young’s modulus 16 GPa and strain 2.5% at 1000 °C, and no smoke and ash were observed during pyrolysis. Ongoing research is currently taking place to use Filava-H62 in fire-retardant enclosure for lithium-ferro-phosphate Batteries used in electric trucks.
      Citation: Journal of Composites Science
      PubDate: 2021-05-27
      DOI: 10.3390/jcs5060144
      Issue No: Vol. 5, No. 6 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 145: Artificial Intelligence Application in
           Solid State Mg-Based Hydrogen Energy Storage

    • Authors: Song-Jeng Huang, Matoke Peter Mose, Sathiyalingam Kannaiyan
      First page: 145
      Abstract: The use of Mg-based compounds in solid-state hydrogen energy storage has a very high prospect due to its high potential, low-cost, and ease of availability. Today, solid-state hydrogen storage science is concerned with understanding the material behavior of different compositions and structure when interacting with hydrogen. Finding a suitable material has remained an elusive idea, and therefore, this review summarizes works by various groups, the milestones they have achieved, and the roadmap to be taken on the study of hydrogen storage using low-cost magnesium composites. Mg-based compounds are further examined from the perspective of artificial intelligence studies, which helps to improve prediction of their properties and hydrogen storage performance. There exist several techniques to improve the performance of Mg-based compounds: microstructure modification, use of catalytic additives, and composition regulation. Microstructure modification is usually achieved by employing different synthetic techniques like severe plastic deformation, high energy ball milling, and cold rolling, among others. These synthetic approaches are discussed herein. In this review, a discussion of key parameters and operating conditions are highlighted in a view to finding high storage capacity and faster kinetics. Furthermore, recent approaches like machine learning have found application in guiding the experimental design. Hence, this review paper also explores how machine learning techniques have been utilized to fasten the materials research. It is however noted that this study is not exhaustive in itself.
      Citation: Journal of Composites Science
      PubDate: 2021-05-29
      DOI: 10.3390/jcs5060145
      Issue No: Vol. 5, No. 6 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 115: Ballistic Impact and Virtual Testing
           of Woven FRP Laminates

    • Authors: Ioannis K. Giannopoulos, Mehdi Yasaee, Nikolaos Maropakis
      First page: 115
      Abstract: The aim of the work was to investigate the numerical simulations correlation with the experimental behaviour of steel ball high velocity impact onto a 2 × 2 twill woven carbon composite laminate. The experimental set up consisted of a pressurised gas-gun able to shot steel ball projectiles onto two different composite plate layup configurations of plates made of the same composite material fabric. Subsequently, the experiments were replicated using the LSDYNA explicit finite element analysis software package. Progressive failure numerical models of two different fidelity levels were constructed. The higher fidelity model was simulating each of the plys of the composite panels separately, tied together using cohesive zone modelling properties. The lower fidelity model consisted of a single layer plate with artificial integration points for each ply. The simulation results came out to be in satisfactory agreement with the experimental ones. While the delamination extent was moderately under predicted by the higher fidelity model, the general behaviour was complying with the experimental results. The lower fidelity model was consistent in representing the damage of the panel during the impact and better predicted the impactor residual velocities due to the better matching of the pane stiffness. Despite the competency of the higher fidelity model to capture the damage of the laminate in a more detailed level, the computational cost was 80% higher than the lower fidelity case, which rendered that model impractical against the lower fidelity one, to use in larger models representing more substantial or more complex structures.
      Citation: Journal of Composites Science
      PubDate: 2021-04-22
      DOI: 10.3390/jcs5050115
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 116: Numerical Buckling Analysis of Hybrid
           Honeycomb Cores for Advanced Helmholtz Resonator Liners

    • Authors: Moritz Neubauer, Martin Dannemann, Michael Kucher, Niklas Bleil, Tino Wollmann, Niels Modler
      First page: 116
      Abstract: In order to realize novel acoustic liners, honeycomb core structures specially adapted to these applications are required. For this purpose, various design concepts were developed to create a hybrid cell core by combining flexible wall areas based on thermoplastic elastomer films and rigid honeycomb areas made of fiber-reinforced thermoplastics. Within the scope of the presented study, a numerical approach was introduced to analyze the global compressive failure of the hybrid composite core structure, considering local buckling and composite failure according to Puck and Cuntze. Therefore, different geometrical configurations of fiber-reinforced tapes were compared with respect to their deformation as well as their resulting failure behavior by means of a finite element analysis. The resulting compression strength obtained by a linear buckling analysis agrees largely with calculated strengths of the more elaborate application of the failure criteria according to Puck and Cuntze, which were implemented in the framework of a nonlinear buckling analysis. The findings of this study serve as a starting point for the realization of the manufacturing concept, for the design of experimental tests of hybrid composite honeycomb core structures, and for further numerical investigations considering manufacturing as well as material specific aspects.
      Citation: Journal of Composites Science
      PubDate: 2021-04-23
      DOI: 10.3390/jcs5050116
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 117: Optimization of Operating Conditions
           for Electrochemical Decolorization of Methylene Blue with
           Ti/α-PbO2/β-PbO2 Composite Electrode

    • Authors: Md. Ashraful Islam Molla, Genta Yanagi, Mai Furukawa, Ikki Tateishi, Hideyuki Katsumata, Satoshi Kaneco
      First page: 117
      Abstract: α-PbO2 was introduced into the intermediate layer of an electrode to prevent the separation of the electrodeposited layer and maintain oxidizing power. The resulting Ti/α-PbO2/β-PbO2 composite electrode was applied to the electrochemical decolorization of methylene blue (MB) and the operating conditions for MB decolorization with the Ti/α-PbO2/β-PbO2 electrode were optimized. The morphology, structure, composition, and electrochemical performance of Ti/α-PbO2 and Ti/α-PbO2/β-PbO2 anode were evaluated using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The optimum operating parameters for the electrochemical decolorization of MB at Ti/α-PbO2/β-PbO2 composites were as follows: Na2SO4 electrolyte 0.05 g L−1, initial concentration of MB 9 mg L−1, cell voltage 20 V, current density 0.05–0.10 A cm−2, and pH 6.0. MB dye could be completely decolorized with Ti/α-PbO2/β-PbO2 for the treatment time of less than one hour, and the dye decolorization efficiency with Ti/α-PbO2/β-PbO2 was about 5 times better, compared with those obtained with Ti/α-PbO2.
      Citation: Journal of Composites Science
      PubDate: 2021-04-27
      DOI: 10.3390/jcs5050117
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 118: Structural Optimization of Locally
           Continuous Fiber-Reinforcements for Short Fiber-Reinforced Plastics

    • Authors: Konstantin Mehl, Sebastian Schmeer, Nicole Motsch-Eichmann, Philipp Bauer, Ingolf Müller, Joachim Hausmann
      First page: 118
      Abstract: The integration of continuous fiber-reinforced structures into short or long fiber-reinforced plastics allows a significant increase in stiffness and strength. In order to make the best possible use of the high stiffness and strength of continuous fiber-reinforcements, they must be placed in the direction of load in the most stressed areas. A frequently used tool for identifying the most heavily loaded areas is topology optimization. Commercial topology optimization programs usually do not take into account the material properties associated with continuous fiber-reinforced hybrid structures. The anisotropy of the reinforcing material and the stiffness of the base material surrounding the reinforcement are not considered during topology optimization, but only in subsequent steps. Therefore in this publication, existing optimization methods for hybrid and anisotropic materials are combined to a new approach, which takes into account both the anisotropy of the continuous fiber-reinforcement and the stiffness of the base material. The results of the example calculations not only show an increased stiffness at the same material input but also a simplification of the resulting reinforcement structures, which allows more economical manufacturing.
      Citation: Journal of Composites Science
      PubDate: 2021-04-27
      DOI: 10.3390/jcs5050118
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 119: Additive Manufacturing for Effective
           Smart Structures: The Idea of 6D Printing

    • Authors: Stelios K. Georgantzinos, Georgios I. Giannopoulos, Panteleimon A. Bakalis
      First page: 119
      Abstract: This paper aims to establish six-dimensional (6D) printing as a new branch of additive manufacturing investigating its benefits, advantages as well as possible limitations concerning the design and manufacturing of effective smart structures. The concept of 6D printing, to the authors’ best knowledge, is introduced for the first time. The new method combines the four-dimensional (4D) and five-dimensional (5D) printing techniques. This means that the printing process is going to use five degrees of freedom for creating the final object while the final produced material component will be a smart/intelligent one (i.e., will be capable of changing its shape or properties due to its interaction with an environmental stimulus). A 6D printed structure can be stronger and more effective than a corresponding 4D printed structure, can be manufactured using less material, can perform movements by being exposed to an external stimulus through an interaction mechanism, and it may learn how to reconfigure itself suitably, based on predictions via mathematical modeling and simulations.
      Citation: Journal of Composites Science
      PubDate: 2021-05-01
      DOI: 10.3390/jcs5050119
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 120: Development of a Pultrusion Die for
           the Production of Thermoplastic Composite Filaments to Be Used in Additive
           Manufacture

    • Authors: Filipe Ferreira, Pedro Fernandes, Nuno Correia, António Torres Marques
      First page: 120
      Abstract: The use of 3D printing has proven to have significant benefits to manufacture components with complex geometries with several types of materials and reinforcements for a wide variety of uses including structural applications. The focus of this study is to develop and implement a thermoplastic pultrusion process that can obtain a carbon fiber/polypropylene (CF/PP) filament for a 3D printing process. This development process included the design and finite element analysis of the die used to conform the filament, considering the adaptation of a filament-winding setup to achieve adequate production conditions. The finite element model tried to achieve homogeneous heating of the die with the use of a series of resistors controlled by PID controllers monitoring several thermocouples strategically positioned while the use of water circulating channels was responsible for the cooling effect. The die-heating environment is optimized for different scenarios with different initial temperatures, cooling temperatures, and pulling speeds. A series of experiments were performed under different conditions, such as different heating temperatures and pulling speeds to analyze the quality of the filament produced. The obtained filaments presented an average diameter of 1.94 mm, fiber volume fraction of 43.76%, and void content of 6.97%.
      Citation: Journal of Composites Science
      PubDate: 2021-05-01
      DOI: 10.3390/jcs5050120
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 121: 3D X-ray Microscopy as a Tool for in
           Depth Analysis of the Interfacial Interaction between a Single Carbon
           Fiber and an Epoxy Matrix after Mechanical Loading

    • Authors: Vogtmann, Klingler, Rief, Gurka
      First page: 121
      Abstract: The benefit of fiber-reinforced composites originates from the interaction between the fiber reinforcement and the matrix. This interplay controls many of its mechanical properties and is of utmost importance to enable its unique performance as a lightweight material. However, measuring the fiber−matrix interphase strength with micromechanical tests, like the Broutman test, is challenging, due to the many, often unknown boundary conditions. Therefore, this study uses state-of-the-art, high-resolution X-ray computed microtomography (XRM) as a tool to investigate post mortem the failure mechanisms of single carbon fibers within an epoxy matrix. This was conducted at the example of single carbon fiber Broutman test specimens. The capabilities of today’s XRM analysis were shown in comparison to classically obtained light microscopy. A simple finite element model was used to enhance the understanding of the observed fracture patterns. In total, this research reveals the possibilities and limitations of XRM to visualize and assess compression-induced single fiber fracture patterns. Furthermore, comparing two different matrix systems with each other illustrates that the failure mechanisms originate from differences in the fiber−matrix interphases. The carbon fiber seems to fail due to brittleness under compression stress. Observation of the fiber slippage and deformed small fracture pieces between the fragments suggests a nonzero stress state at the fragment ends after fiber failure. Even more, these results demonstrate the usefulness of XRM as an additional tool for the characterization of the fiber−matrix interphase.
      Citation: Journal of Composites Science
      PubDate: 2021-05-04
      DOI: 10.3390/jcs5050121
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 122: Self-Healing Potential and
           Post-Cracking Tensile Behavior of Polypropylene Fiber-Reinforced
           Cementitious Composites

    • Authors: Mohit Garg, Pejman Azarsa, Rishi Gupta
      First page: 122
      Abstract: The use of synthetic fibers as reinforcement in fiber-reinforced cementitious composites (FRCC) demonstrates a combination of better ductile response vis-à-vis metallic ones, enhanced durability in a high pH environment, and resistance to corrosion as well as self-healing capabilities. This study explores the effect of macro- and micro-scale polypropylene (PP) fibers on post-crack energy, ductility, and the self-healing potential of FRCC. Laboratory results indicate a significant change in fracture response, i.e., loss in ductility as curing time increases. PP fiber samples cured for 2 days demonstrated ductile fracture behavior, controllable crack growth during tensile testing, post-cracking behavior, and a regain in strength owing to FRCC’s self-healing mechanism. Different mixes of FRCC suggest an economical mixing methodology, where the strong bond between the PP fibers and cementitious matrix plays a key role in improving the tensile strength of the mortar. Additionally, the micro PP fiber samples demonstrate resistance to micro-crack propagation, observed as an increase in peak load value and shape deformation during compression and tensile tests. Notably, low volume fraction of macro-scale PP fibers in FRCC revealed higher post-crack energy than the higher dosage of micro-scale PP fibers. Lastly, few samples with a crack of < 0.5 mm exhibited a self-healing mechanism, and upon testing, the healed specimens illustrated higher strain values.
      Citation: Journal of Composites Science
      PubDate: 2021-05-07
      DOI: 10.3390/jcs5050122
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 123: The Biomimetic Evolution of Composite
           

    • Authors: Gad Marom
      First page: 123
      Abstract: Advanced polymer-based composite materials have revolutionized the structural material arena since their appearance some 60 years ago. Yet, despite their relatively short existence, they seem to be taken for granted as if they have always been there. One of the reasons for this state of affairs is that composite materials of various types have accompanied human history for thousands years, and their emergence in the modern era could be considered a natural evolutionary process. Nevertheless, the continuous line that leads from early days of composites in human history to current structural materials has exhibited a number of notable steps, each generating an abrupt advance toward the contemporary new science of composite materials. In this paper, I review and discuss the history of composites with emphasis on the main steps of their development.
      Citation: Journal of Composites Science
      PubDate: 2021-05-07
      DOI: 10.3390/jcs5050123
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 124: Kinetic Analysis on the Stabilization
           Effects of Substituted POSS Powders Embedded in γ-Radiolyzed
           Polypropylene

    • Authors: Traian Zaharescu, Ignazio Blanco, Tunde Borbath, Istvan Borbath, Marius Mariș
      First page: 124
      Abstract: The present paper proposes a reliable alternative for the increasing stability of polypropylene (PP) by modified polyhedral oligomeric silsesquioxanes (POSS). The chemiluminescence measurements and FTIR records point complementarily out the determinant influence of substituents on the progress of oxidation during the accelerated degradation caused by γ-irradiation. The main kinetic approach of oxidation acting in radiation-induced aging recommends some of the studied structures of modified POSS as appropriate compounds for improving stability of polypropylene at low additive concentration. The analysis of the present results is based on the implication of substituted POSS, whose contribution to the limitation of oxidation is conditioned by the influence of substituents. The delay of the oxidative degradation in studied γ-irradiated polypropylene is the consequence of the interaction between molecular PP fragments and the silanol moieties generated during radiolysis, which are the most vulnerable points of POSS structure.
      Citation: Journal of Composites Science
      PubDate: 2021-05-09
      DOI: 10.3390/jcs5050124
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 125: A Green Composite Based on
           Gelatin/Agarose/Zeolite as a Potential Scaffold for Tissue Engineering
           Applications

    • Authors: Mohamadreza Youssefi Azarfam, Mojtaba Nasirinezhad, Haleh Naeim, Payam Zarrintaj, Mohammadreza Saeb
      First page: 125
      Abstract: Designing a novel platform capable of providing a proper tissue regeneration environment is a key factor in tissue engineering. Herein, a green composite based on gelatin/agarose/zeolite with pomegranate peel extract was fabricated as an innovative platform for tissue engineering. Gelatin/agarose was loaded with pomegranate peel extract-loaded zeolite to evaluate its swelling behavior, porosity, release rate, and cell viability performance. The composite characteristics were evaluated using XRD and DSC. The hydrogel performance can be adjusted for the desired aim by zeolite content manipulation, such as controlled release. It was shown that the green nanocomposite exhibited proper cellular activity along with a controlled release rate. Moreover, the hydrogel composite’s swelling ratio was decreased by adding zeolite. This study suggested a fully natural composite as a potential biomaterial for tissue engineering, which opens new ways to design versatile hydrogels for the regeneration of damaged tissues. The hydrogel performance can be adjusted specifically by zeolite content manipulation for controlled release.
      Citation: Journal of Composites Science
      PubDate: 2021-05-09
      DOI: 10.3390/jcs5050125
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 126: Study of the Surface and Dimensional
           Quality of the AlSi10Mg Thin-Wall Components Manufactured by Selective
           Laser Melting

    • Authors: Muhammad Waqas, Dingyong He, Hassan Elahi, Saleem Riaz, Marco Eugeni, Paolo Gaudenzi
      First page: 126
      Abstract: Additive manufacturing (AM), a 3D printing technique that manufactures components by sequential addition of powder, has massively reshaped the manufacturing and engineering sectors from batch production to manufacturing customized, innovative, state-of-the-art, and sustainable products. Additive manufacturing of aluminum alloys by selective laser melting (SLM) is one of the latest research trends in this field due to the fact of its advantages and vast applications in manufacturing industries such as automobiles and aerospace. This paper investigated the surface and dimensional quality of SLM-built AlSi10Mg parts using a response surface method (RSM) and found the influence of the wall thickness and process parameters (i.e., laser power, scanning speed, hatch distance) on the pieces. Thin-walled test specimens of AlSi10Mg alloy were manufactured with different combinations of process parameters at three wall thicknesses: 1.0 mm, 2.0 mm, and 3.0 mm. The Minitab DOE module was used to create 27 different configurations of wall thickness and process parameters. The samples’ surface roughness and dimensional accuracy were investigated, and the findings were evaluated using the ANOVA technique. The regression model and the ANOVA technique showed high precision and had a particular reference value for practical engineering applications.
      Citation: Journal of Composites Science
      PubDate: 2021-05-09
      DOI: 10.3390/jcs5050126
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 127: Compounding of Short Fiber Reinforced
           Phenolic Resin by Using Specific Mechanical Energy Input as a Process
           Control Parameter

    • Authors: Robert Maertens, Wilfried V. Liebig, Peter Elsner, Kay A. Weidenmann
      First page: 127
      Abstract: For a newly developed thermoset injection molding process, glass fiber-reinforced phenolic molding compounds with fiber contents between 0 wt% and 60 wt% were compounded. To achieve a comparable remaining heat of the reaction in all compound formulations, the specific mechanical energy input (SME) during the twin-screw extruder compounding process was used as a control parameter. By adjusting the extruder screw speed and the material throughput, a constant SME into the resin was targeted. Validation measurements using differential scanning calorimetry showed that the remaining heat of the reaction was higher for the molding compounds with low glass fiber contents. It was concluded that the SME was not the only influencing factor on the resin crosslinking progress during the compounding. The material temperature and the residence time changed with the screw speed and throughput, and most likely influenced the curing. However, the SME was one of the major influence factors, and can serve as an at-line control parameter for reactive compounding processes. The mechanical characterization of the test specimens revealed a linear improvement in tensile strength up to a fiber content of 40–50 wt%. The unnotched Charpy impact strength at a 0° orientation reached a plateau at fiber fractions of approximately 45 wt%.
      Citation: Journal of Composites Science
      PubDate: 2021-05-11
      DOI: 10.3390/jcs5050127
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 128: Parametric Optimization of Isotropic
           and Composite Axially Symmetric Shells Subjected to External Pressure and
           Twisting

    • Authors: Marek Barski, Paweł J. Romanowicz, Małgorzata Chwał, Adam Stawiarski
      First page: 128
      Abstract: The present paper is devoted to the problem of the optimal design of thin-walled composite axially symmetric shells with respect to buckling resistance. The optimization problem is formulated with the following constraints: namely, all analyzed shells have identical capacity and volume of material. The optimization procedure consists of four steps. In the first step, the initial calculations are made for cylindrical shells with non-optimal orientation of layers and these results are used as the reference for optimization. Next, the optimal orientations of layers for cylindrical shapes are determined. In the third step, the optimal geometrical shape of a middle surface with a constant thickness is determined for isotropic material. Finally, for the assumed shape of the middle surface, the optimal fiber orientation angle θ of the composite shell is appointed. Such studies were carried for three cases: pure external pressure, pure twisting, and combined external pressure with twisting. In the case of shells made of isotropic material the obtained results are compared with the optimal structure of uniform stability, where the analytical Shirshov’s local stability condition is utilized. In the case of structures made of composite materials, the computations are carried out for two different materials, where the ratio of E1/E2 is equal to 17.573 and 3.415. The obtained benefit from optimization, measured as the ratio of critical load multiplier computed for reference shell and optimal structure, is significant. Finally, the optimal geometrical shapes and orientations of the layers for the assumed loadings is proposed.
      Citation: Journal of Composites Science
      PubDate: 2021-05-12
      DOI: 10.3390/jcs5050128
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 129: A Hierarchical Architecture of
           Functionalized Polyaniline/Manganese Dioxide Composite with
           Stable-Enhanced Electrochemical Performance

    • Authors: Yapeng Wang, Yanxiang Wang, Chengjuan Wang, Yongbo Wang
      First page: 129
      Abstract: As one of the most outstanding high-efficiency and environmentally friendly energy storage devices, the supercapacitor has received extensive attention across the world. As a member of transition metal oxides widely used in electrode materials, manganese dioxide (MnO2) has a huge development potential due to its excellent theoretical capacitance value and large electrochemical window. In this paper, MnO2 was prepared at different temperatures by a liquid phase precipitation method, and polyaniline/manganese dioxide (PANI/MnO2) composite materials were further prepared in a MnO2 suspension. MnO2 and PANI/MnO2 synthesized at a temperature of 40 °C exhibit the best electrochemical performance. The specific capacitance of the sample MnO2-40 is 254.9 F/g at a scanning speed of 5 mV/s and the specific capacitance is 241.6 F/g at a current density of 1 A/g. The specific capacitance value of the sample PANI/MnO2-40 is 323.7 F/g at a scanning speed of 5 mV/s, and the specific capacitance is 291.7 F/g at a current density of 1 A/g, and both of them are higher than the specific capacitance value of MnO2. This is because the δ-MnO2 synthesized at 40 °C has a layered structure, which has a large specific surface area and can accommodate enough electrolyte ions to participate the electrochemical reaction, thus providing sufficient specific capacitance.
      Citation: Journal of Composites Science
      PubDate: 2021-05-13
      DOI: 10.3390/jcs5050129
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 130: A Review on Mechanical Properties of
           Natural Fibre Reinforced Polymer Composites under Various Strain Rates

    • Authors: Tan Ke Khieng, Sujan Debnath, Ernest Ting Chaw Liang, Mahmood Anwar, Alokesh Pramanik, Animesh Kumar Basak
      First page: 130
      Abstract: With the lightning speed of technological evolution, the demand for high performance yet sustainable natural fibres reinforced polymer composites (NFPCs) are rising. Especially a mechanically competent NFPCs under various loading conditions are growing day by day. However, the polymers mechanical properties are strain-rate dependent due to their viscoelastic nature. Especially for natural fibre reinforced polymer composites (NFPCs) which the involvement of filler has caused rather complex failure mechanisms under different strain rates. Moreover, some uneven micro-sized natural fibres such as bagasse, coir and wood were found often resulting in micro-cracks and voids formation in composites. This paper provides an overview of recent research on the mechanical properties of NFPCs under various loading conditions-different form (tensile, compression, bending) and different strain rates. The literature on characterisation techniques toward different strain rates, composite failure behaviours and current challenges are summarised which have led to the notion of future study trend. The strength of NFPCs is generally found grow proportionally with the strain rate up to a certain degree depending on the fibre-matrix stress-transfer efficiency. The failure modes such as embrittlement and fibre-matrix debonding were often encountered at higher strain rates. The natural filler properties, amount, sizes and polymer matrix types are found to be few key factors affecting the performances of composites under various strain rates whereby optimally adjust these factors could maximise the fibre-matrix stress-transfer efficiency and led to performance increases under various loading strain rates.
      Citation: Journal of Composites Science
      PubDate: 2021-05-13
      DOI: 10.3390/jcs5050130
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 131: Cohesive Zone Modeling of the
           Elastoplastic and Failure Behavior of Polymer Nanoclay Composites

    • Authors: Uraching Chowdhury, Xiang-Fa Wu
      First page: 131
      Abstract: Cohesive zone model (CZM) is commonly used to deal with the nonlinear zone ahead of crack tips in materials with elastoplastic deformation behavior. This model is capable of predicting the behavior of crack initiation and growth. In this paper, CZM-based finite element analysis (FEA) is performed to examine the effects of processing parameters (i.e., the clay nanoparticle volume fraction and aspect ratio) in the mechanical behaviors of a polymeric matrix reinforced with aligned clay nanoparticles. The polymeric matrix is treated as an ideal elastoplastic solid with isotropic hardening behavior, whereas the clay nanoparticles are simplified as stiff, linearly elastic platelets. Representative volume elements (RVEs) of the resulting polymer nanoclay composites (PNCs) are adopted for FEA with the clay nanoparticle distributions to follow both stack and stagger configurations, respectively. In the study, four volume fractions (Vf = 2.5%, 5%, 7.5% and 10%) and four aspect ratios (ρ = 5, 7.5, 10, and 20) of the clay nanoparticles in the PNCs are considered. Detailed computational results show that either increasing volume fraction or aspect ratio of the clay nanoparticles enhances the effective tensile strength and stiffness of the PNCs. The progressive debonding process of the clay nanoparticles in the polymeric resin was predicted, and the debonding was initiated in the linearly elastic loading range. The numerical results also show that PNCs with stagger nanoparticle configuration demonstrate slightly higher values of the engineering stress than those based on the stack nanoparticle configuration at both varying volume fractions and aspect ratios of the clay nanoparticles. In addition, CZM-based FEA predicts a slightly lower stress field around the clay particles in PNCs than that without integration of CZM. The present computational studies are applicable for processing PNCs with controllable mechanical properties, especially the control of the key processing parameters of PNCs, i.e., the volume fraction and aspect ratio of the clay nanoparticles.
      Citation: Journal of Composites Science
      PubDate: 2021-05-14
      DOI: 10.3390/jcs5050131
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 132: Thermal and Mechanical Properties of
           Green Insulation Composites Made from Cannabis and Bark Residues

    • Authors: Konstantinos Ninikas, Andromachi Mitani, Dimitrios Koutsianitis, George Ntalos, Hamid R. Taghiyari, Antonios N. Papadopoulos
      First page: 132
      Abstract: The objective of this paper was to investigate the technical feasibility of manufacturing low density insulation particleboards that were made from two renewable resources, namely hemp fibers (Cannabis sativa) and pine tree bark, which were bonded with a non-toxic methyl cellulose glue, as a binder. Four types of panels were made, which consisted of varying mixtures of tree bark and hemp fibers (tree bark to hemp fibers percentages of 90:10, 80:20, 70:30, and 60:40). An additional set of panels was made, consisting only of bark. The results showed that addition of hemp fibers to furnish improved mechanical properties of boards to reach an acceptable level. The thermal conductivity unfavorably increased as hemp content increased, though all values were still within the acceptable range. Based on cluster analysis, board type 70:30 (with 30% hemp content) produced the highest mechanical properties as well as the optimal thermal conductivity value. It is concluded that low density insulation boards can be successfully produced using these waste raw materials.
      Citation: Journal of Composites Science
      PubDate: 2021-05-17
      DOI: 10.3390/jcs5050132
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 133: Experimental Design of Solid Particle
           Wear Behavior of Ni-Based Composite Coatings

    • Authors: Pragyan Senapati, Harekrushna Sutar, Rabiranjan Murmu, Shubhra Bajpai
      First page: 133
      Abstract: The composition of nickel-based metal matrix NiCrBSi was varied with 5%, 10% and 15% of Al2O3 particles to obtain high wear resistant coatings by means of a high-velocity oxy fuel (HVOF) thermal spraying process. The coating was characterized by optical microscope, scanning electron microscope (SEM) and X-ray diffractometer (XRD). The physical properties of coatings such as porosity, thickness, surface roughness, surface hardness, fracture toughness, bond strength and density were measured and compared. The experimental design of Taguchi L27 orthogonal array was employed to study and compare the effect of parameters such as impingement angle, impact velocity and alumina per cent in the coating on erosion. The coating containing 15 wt.% of Al2O3 and erodent speed of 33 m/s striking at inclination angle of 30° proved to be the best arrangement in preventing volume loss to a minimum of 0.00015 cc due to low-impact energy, high bond strength and high surface hardness. Analysis of variance (ANOVA) supported the assertion that the impact angle (A) of erodent and composition (C) were the factors contributing most to the volumetric loss as indicated by their combined effect A × C leading to the highest combined factor of 7.34. The scanning electron microscopy (SEM) images of the eroded coatings reveal that the mechanisms of erosion were the fracturing of splats, development of craters, micro cutting and ploughing action.
      Citation: Journal of Composites Science
      PubDate: 2021-05-17
      DOI: 10.3390/jcs5050133
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 134: Preliminary Experimental and Numerical
           Study of Metal Element with Notches Reinforced by Composite Materials

    • Authors: Paweł J. Romanowicz, Bogdan Szybiński, Mateusz Wygoda
      First page: 134
      Abstract: The presented study is related to the application of the composite overlays used in order to decrease the effect of the stress concentrations around the cut-outs in structural metal elements. The proposed approach with the application of the digital image correlation extends the recently presented studies. Such structural elements with openings of various shapes have been accommodated for a wide range of industrial applications. These structures exhibit certain stress concentrations which decrease their durability and strength. To restore their strength, various reinforcing overlays can be used. In the present paper, the flat panel structure without and with the composite overlays made of HEXCEL TVR 380 M12/26%/R-glass/epoxy is under the experimental and the numerical study. Particular attention is paid to the investigation of the samples with the rectangular holes, which for smooth rounded corners offer a higher durability than the samples with the circular hole of the same size. The experimental results are obtained for the bare element and are reinforced with composite overlay samples. The experimental results are obtained with the use of the Digital Image Correlation method, while the numerical results are the product of the Finite Element Analysis. In the numerical analysis, the study of the shape, size and fiber orientation in applied overlays is done. The reduction of the stress concentration observed in opening notches has confirmed the effectiveness of the overlay application. In the investigated example, the application of the square composite overlay increased the structure strength even by 25%.
      Citation: Journal of Composites Science
      PubDate: 2021-05-18
      DOI: 10.3390/jcs5050134
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 135: Multiscale Toughening of Composites
           with Carbon Nanotubes—Continuous Multiscale Reinforcement New Concept

    • Authors: Monssef Drissi-Habti, Yassine El Assami, Venkadesh Raman
      First page: 135
      Abstract: Strengthening composite structures for advanced industries such as offshore wind generation is a real issue. Due to the huge dimensions expected for next generation wind-blades, composites based on glass fibers can no longer be used due to the lack of stiffness, whereas composites based on carbon fibers are expensive. Therefore, switching to alternative structural solutions is highly needed. This might be achieved by appropriate use of carbon nanotubes (CNTs) either as fillers of epoxy matrices, especially in inter-plies, or as fillers of epoxy glues used in structural bonding joints. As an example, trailing edges of offshore wind-blades are addressed in the current article, where monolithic bonding holds together the two structural halves and where the risk of sudden and brittle separation of edges while wind-turbines are in service is quite high. This can lead to tedious and very expensive maintenance, especially when keeping in mind the huge dimensions of new generation wind turbine blades that exceed lengths of 100 m. Bond joints and composites inter-plies of the final CNT-reinforced structures will exhibit stiffness and toughness high enough to face the severe offshore environment. In this article, multiscale Finite Element (FE) modeling is carried out to evaluate mechanical properties following the addition of CNTs. To achieve an optimal reinforcement, the effect of inclination of CNTs vs. mechanical loading axis is studied. Two innovations are suggested through this numerical study: The first consists of using homogenization in order to evaluate the effects of CNT reinforcement macroscopically. The second innovation lies in this forward-looking idea to envisage how we can benefit from CNTs in continuous fiber composites, as part of a deep theoretical rethinking of the reinforcement mechanisms operating at different scales and their triggering kinetics. The presented work is purely numerical and should be viewed as a “scenario” of structural composite materials of the future, which can be used both in the offshore industry and in other advanced industries. More broadly and through what is proposed, we humbly wish to stimulate scientific discussions about how we can better improve the performances of structural composite materials.
      Citation: Journal of Composites Science
      PubDate: 2021-05-18
      DOI: 10.3390/jcs5050135
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 136: Maximizing the Performance of 3D
           Printed Fiber-Reinforced Composites

    • Authors: S M Fijul Kabir, Kavita Mathur, Abdel-Fattah M. Seyam
      First page: 136
      Abstract: Fiber-reinforced 3D printing technology offers significant improvement in the mechanical properties of the resulting composites relative to 3D printed (3DP) polymer-based composites. However, 3DP fiber-reinforced composite structures suffer from low fiber content compared to the traditional composite, such as 3D orthogonal woven preforms solidified with vacuum assisted resin transfer molding (VARTM) that impedes their high-performance applications such as in aerospace, automobile, marine and building industries. The present research included fabrication of 3DP fiberglass-reinforced nylon composites, with maximum possible fiber content dictated by the current 3D printing technology at varying fiber orientations (such as 0/0, 0/90, ±45 and 0/45/90/−45) and characterizing their microstructural and performance properties, such as tensile and impact resistance (Drop-weight, Izod and Charpy). Results indicated that fiber orientation with maximum fiber content have tremendous effect on the improvement of the performance of the 3DP composites, even though they inherently contain structural defects in terms of voids resulting in premature failure of the composites. Benchmarking the results with VARTM 3D orthogonal woven (3DOW) composites revealed that 3DP composites had slightly lower tensile strength due to poor matrix infusion and voids between adjacent fiber layers/raster, and delamination due to lack of through-thickness reinforcement, but excellent impact strength (224% more strong) due to favorable effect of structural voids and having a laminated structure developed in layer-by-layer fashion.
      Citation: Journal of Composites Science
      PubDate: 2021-05-18
      DOI: 10.3390/jcs5050136
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 137: Temperature Study during the Edge
           Trimming of Carbon Fiber-Reinforced Plastic [0]8/Ti6Al4V Stack Material

    • Authors: Arquimedes Castillo-Morales, Xavier Rimpault, Jean-François Chatelain, Gilbert Lebrun
      First page: 137
      Abstract: Carbon Fiber-Reinforced Plastic (CFRP) and Titanium alloy (Ti6Al4V) stacks are used extensively in the modern aerospace industry thanks to their outstanding mechanical properties and resistance to thermal load applications. Machining the CFRP/Ti6Al4V stack is a challenge and is complicated by the differences in each constituent materials’ machinability. The difficulty arises from the matrix degradation of the CFRP material caused by the heat generated during the machining process, which is a consequence of the low thermal conductivity of Ti6Al4V material. In most cases, CFRP and Ti6Al4V materials are stacked and secured together using rivets or bolts. This results in extra weight, while the drilling process required for such an assembly may damage the CFRP material. To overcome these issues, some applications employ an assembly that is free of bolts or rivets, and which uses adhesives or an adapted curing process to bond both materials together. The present research analyzes a thermal distribution and its effect on quality during the edge trimming process of a CFRP/Ti6Al4V stack assembly. Different types of tools and cutting parameters are compared using thermocouples embedded within the material and others on the tool cutting edge. In contrast to previous studies, the feed rate was the most significant factor affecting the cutting temperature and quality of the workpiece, while the cutting speed had no significant impact. The temperature in the workpiece increases as the feed per tooth decreases.
      Citation: Journal of Composites Science
      PubDate: 2021-05-19
      DOI: 10.3390/jcs5050137
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 138: Recent Advances in Multi-Scale
           Experimental Analysis to Assess the Role of Compatibilizers in Cellulosic
           Filler-Reinforced Plastic Composites

    • Authors: Yoshikuni Teramoto
      First page: 138
      Abstract: Adding acid-modified resin compatibilizers is essential for plastic composites reinforced with carbon-neutral cellulosic filler. Researchers have measured the efficacy of adding a compatibilizer in the context of mechanics. However, it is necessary to microscopically clarify how the compatibilizer actually works for quality control and further expansion of applications. In this review, the author first describes the situation of cellulosic composites and presents issues regarding how one assesses the role of the compatibilizer. The author then reviews recent multi-scale experimental approaches to the detection of covalent bonds between the cellulosic filler and compatibilizer, estimation of nanoscale interphases, and the micron-scale dispersibility of the fillers. With accumulation of such experimental facts, appropriate parameter settings can be expected for the structural analysis such as the finite-element method, as well as the potential to provide appropriate explanatory variables for material/process informatics.
      Citation: Journal of Composites Science
      PubDate: 2021-05-20
      DOI: 10.3390/jcs5050138
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 139: Demagnetization Effect on the
           Magnetoelectric Response of Composite Multiferroic Cylinders

    • Authors: Somer Nacy, George Youssef
      First page: 139
      Abstract: Strain-mediated multiferroic composite structures are gaining scientific and technological attention because of the promise of low power consumption and greater flexibility in material and geometry choices. In this study, the direct magnetoelectric coupling coefficient (DME) of composite multiferroic cylinders, consisting of two mechanically bonded concentric cylinders, was analytically modeled under the influence of a radially emanating magnetic field. The analysis framework emphasized the effect of demagnetization on the overall performance. The demagnetization effect was thoroughly considered as a function of the imposed mechanical boundary conditions, the geometrical dimensions of the composite cylinder, and the introduction of a thin elastic layer at the interface between the inner piezomagnetic and outer piezoelectric cylinders. The results indicate that the demagnetization effect adversely impacted the DME coefficient. In a trial to compensate for the reduction in peak DME coefficient due to demagnetization, a non-dimensional geometrical analysis was carried out to identify the geometrical attributes corresponding to the maximum DME. It was observed that the peak DME coefficient was nearly unaffected by varying the inner radius of the composite cylinder, while it approached its maximum value when the thickness of the piezoelectric cylinder was almost 60% of the total thickness of the composite cylinder. The latter conclusion was true for all of the considered boundary conditions.
      Citation: Journal of Composites Science
      PubDate: 2021-05-20
      DOI: 10.3390/jcs5050139
      Issue No: Vol. 5, No. 5 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 92: Multi-Objective Optimization of
           Functionally Graded Beams Using a Genetic Algorithm with Non-Dominated
           Sorting

    • Authors: Chih-Ping Wu, Kuan-Wei Li
      First page: 92
      Abstract: A mixed layer-wise (LW) higher-order shear deformation theory (HSDT) is developed for the thermal buckling analysis of simply-supported, functionally graded (FG) beams subjected to a uniform temperature change. The material properties of the FG beam are assumed to be dependent on the thickness and temperature variables, and the effective material properties are estimated using either the rule of mixtures or the Mori–Tanaka scheme. The results shown in the numerical examples indicate the mixed LW HSDT solutions for critical temperature change parameters are in excellent agreement with the accurate solutions available in the literature. A multi-objective optimization of FG beams is presented to maximize the critical temperature change parameters and to minimize their total mass using a non-dominated sorting-based genetic algorithm. Some specific forms for the volume fractions of the constituents of the FG beam are assumed in advance, such as the one- and three-parameter power-law functions. The former is used in the thermal buckling analysis of the FG beams for comparison purposes, and the latter is used in their optimal design.
      Citation: Journal of Composites Science
      PubDate: 2021-03-30
      DOI: 10.3390/jcs5040092
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 93: Development of a Shape Replicating
           Draping Unit for Continuous Layup of Unidirectional Non-Crimp Fabrics on
           Complex Surface Geometries

    • Authors: Berend Denkena, Carsten Schmidt, Simon Werner, Dietmar Schwittay
      First page: 93
      Abstract: The manufacturing of large-scale structural components is still dominated by manual labor in many sectors of the modern composite industry. Efforts are being made to establish an automated layup technology for complex structural elements. Processing dry non-crimp fiber fabrics (NCF) offers great cost opportunities and high deposition rates, compared to prepreg-based technologies like automated fiber placement (AFP). Here, the fabric architecture is considered during the draping of the plane textile on curved surfaces. In this paper, the development of a draping unit for balancing fabric tension and consolidating continuously across the layup width is presented. We introduce a geometrical process model to achieve a fabric-friendly draping of the used unidirectional NCF. The shape of the resulting draping front depends on the surface geometry, the shearing of the previously laid-up textile, and the positioning of the material feed. To consolidate the fabric at the altering draping front in an automated layup process, the shape of the continuous consolidation element can be controlled by the elongation of serial soft actuators, manipulated by parallel robot kinematics. The shape replication ability of the draping unit is promising for the implementation of a continuous, fabric-friendly draping process for complex surface geometries.
      Citation: Journal of Composites Science
      PubDate: 2021-04-01
      DOI: 10.3390/jcs5040093
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 94: Flexural Characteristics of
           Functionally Graded Fiber-Reinforced Cementitious Composite with Polyvinyl
           Alcohol Fiber

    • Authors: Toshiyuki Kanakubo, Takumi Koba, Kohei Yamada
      First page: 94
      Abstract: The objective of this study is to investigate the flexural characteristics of functionally graded fiber-reinforced cementitious composite (FG-FRCC) concerning the fiber volume fraction (Vf) varying in layers and the layered effect in bending specimens. The FG-FRCC specimens, in which Vf increases from 0% in the compression zone to 2% in the tensile zone, are three-layered specimens using polyvinyl alcohol (PVA) FRCC that are fabricated and tested by a four-point bending test. The maximum load of the FG-FRCC specimens exhibits almost twice that of homogeneous specimens, even when the average of the fiber volume fraction in the whole specimen is 1%. The result of the section analysis, in which the stress–strain models based on the bridging law (tensile stress–crack width relationship owned by the fibers) consider the fiber orientation effect, shows a good adaptability with the experiment result.
      Citation: Journal of Composites Science
      PubDate: 2021-04-01
      DOI: 10.3390/jcs5040094
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 95: Assessment of Replacement of Metal
           Parts by BFRP Composites into a Highly Efficient Electrical Prototype

    • Authors: Rosa Marat-Mendes, Diogo Ribeira, Luís Reis
      First page: 95
      Abstract: This work intends to evaluate the use of epoxy composite materials reinforced with basalt fibers as replacement to metallic mechanical parts of a highly efficient electrical prototype. The analysis of the behavior of the original metallic bracket was made and an optimization process was carried out in order to achieve the most suitable geometry and stacking sequence if produced in composite material. Finite element analysis using Siemens NX12 and experimental tests to the produced composite part were performed in order to access it. It was verified that the total weight of the composite part shows a 45% reduction. The composite part shows a higher deformation than the metallic one due to basalt fiber’s higher flexibility. However, the advantages added by the new component largely compensate for the disadvantages that may have been added without compromising its performance. Obtained results show that the use of basalt fiber reinforced composites as the material of mechanical parts of a highly efficient electrical prototype that is a good alternative.
      Citation: Journal of Composites Science
      PubDate: 2021-04-01
      DOI: 10.3390/jcs5040095
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 96: A Review on the Usage of Continuous
           Carbon Fibers for Piezoresistive Self Strain Sensing Fiber Reinforced
           Plastics

    • Authors: Patrick Scholle, Michael Sinapius
      First page: 96
      Abstract: This literature review examines the application of carbon fibers and their reinforced plastics for Self-Strain-Sensing structures and gives an up-to-date overview of the existing research. First, relevant basic experimental approaches that can be found in the literature are presented and discussed. Next, we propose to cluster the available articles into 5 categories based on specimen size and ranging from experiments on bare carbon fiber via impregnated fiber rovings to carbon fiber laminates. Each category is analyzed individually and the potential differences between them are discussed based on experimental evidence found in the past. The overview shows, that the choice of carbon fiber and the specific experimental setup both significantly influence the piezoresistive properties measured in Self-Strain-Sensing carbon fiber reinforced plastics. Conclusively, based on the conclusions drawn from the literature review, we propose a small number of measurements that have proven to be important for the analysis of Self-Strain-Sensing carbon fiber structures.
      Citation: Journal of Composites Science
      PubDate: 2021-04-02
      DOI: 10.3390/jcs5040096
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 97: DMSO Deintercalation in
           Kaolinite–DMSO Intercalate: Influence of Solution Polarity on Removal

    • Authors: Berenger ZOGO MFEGUE, Jean Aimé MBEY, Sandotin Lassina COULIBALY, Vincent Laurent ONANA, Paul-Désiré NDJIGUI
      First page: 97
      Abstract: This study focused on the deintercalation of dimethyl sulfoxide (DMSO) from a kaolinite–DMSO complex in various solvents. The use of kaolinite as filler in polymer–clay composite generally faced the difficulty of kaolinite dispersion due to its high cohesion. For improved dispersion of kaolinite within a given matrix, previous intercalation of small polar molecules is usually done prior to its displacement during composite-making. The influence of the solvent polarity on the deintercalation in analyzed here to understand its role during the deintercalation process. The intercalation of the DMSO was done by solution-mixing and its displacement was done in distilled water, ethyl acetate, and acetone. The products of deintercalation were analyzed using Fourier transform infra-red (FTIR), powder X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The weakening of the kaolinite cohesion after DMSO intercalation is demonstrated through the broadening of the diffraction peak associated with the kaolinite on XRD patterns. From FTIR spectra, the weakening is associated with the displacement to low wavenumbers of the Si–O or Al–O vibration bands within the kaolinite–DMSO complex. The kaolinite dehydroxylation temperatures from DSC show that the rate of DMSO displacement affects the ordering of the recovered kaolinite. The crystallite size of the kaolinite is reduced from the raw to the recovered kaolinite after DMSO displacement, indicating an exfoliation of the kaolinite. From these results, it is found that the removal of the DMSO from the kaolinite–DMSO complex is influenced by solvent polarity. The higher the polarity, the greater the removal of the DMSO from the complex. Solvent polarity affects the rate of DMSO displacement, which influences the ordering of the recovered kaolinite. It is suggested that solvent polarity can be used to control the removal rate of DMSO, which may be key to the dispersion of the kaolinite platelets.
      Citation: Journal of Composites Science
      PubDate: 2021-04-02
      DOI: 10.3390/jcs5040097
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 98: In Vivo Effects of Two In-Office Vital
           Tooth Bleaching Systems on Enamel Permeability

    • Authors: Angelica Bertacci, Gianfranco Ulian, Daniele Moro, Stefano Chersoni, Giovanni Valdrè
      First page: 98
      Abstract: Tooth bleaching is a common treatment for the amelioration of the aesthetic of discoloured teeth. In this context, there are two common approaches that employ concentrated solutions (30–40 wt.%) of either hydrogen peroxide or carbamide peroxide as bleaching agents. However, there is an ongoing debate on the possible adverse effects of these different treatments on tooth health, such as variation of the enamel structure, surface morphology, and chemistry, which also affect tooth sensitivity. In the present work, a study on the effect of the two bleaching agents, a 35 wt.% solution of hydrogen peroxide and a 30 wt.% solution of carbamide peroxide, on the permeability and surface morphology of enamel is reported. The investigation was carried out on replicas of incisors obtained after different treatment times and for several patients, employing scanning electron microscopy to study the morphological features of the treated teeth. The significance of the analytical study was corroborated by a statistical analysis of the results. The collected data suggest that hydrogen peroxide treatment increases the enamel permeability, and this could be related with tooth sensitivity, whereas the carbamide peroxide solution increases the formation of precipitates on the tooth enamel.
      Citation: Journal of Composites Science
      PubDate: 2021-04-04
      DOI: 10.3390/jcs5040098
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 99: SEM Evaluation of Endosequence BC
           Sealer Hiflow in Different Environmental Conditions

    • Authors: Orlando Donfrancesco, Andrea Del Giudice, Alessio Zanza, Michela Relucenti, Stefano Petracchiola, Gianluca Gambarini, Luca Testarelli, Marco Seracchiani
      First page: 99
      Abstract: The aim of the present study is to evaluate the setting and sealant ability of two different bioceramic sealers in two different environmental conditions: humid and wet environment. Ex vivo root canal treatment was performed on 24 freshly extracted teeth. Irrigation was performed with Niclor NaOCl 5% and EDTA 17%, then obturated with a bioceramic sealer in the two different environmental conditions listed above. Furthermore, scanning electron microscope (SEM) investigation was performed to verify the presence of gaps and the setting ability of the two sealers in two different environmental conditions was evaluated. While presence of gaps was found mainly in the wet specimens, on the other hand, regarding the setting ability, there is no statistically significant difference between the two different samples. Therefore, even if humid conditions represent the gold standard in terms of lower gaps dimension, since there is no methodology standardizing the drying procedure of the root canal, it is compulsory to investigate the sealing ability of the bioceramic sealers, even in wet conditions. Thanks to the findings shown in the present study, it is demonstrated that even in wet conditions the ability of the sealer to set does not change and such clinical situation could affect the bioceramic sealer protocol.
      Citation: Journal of Composites Science
      PubDate: 2021-04-04
      DOI: 10.3390/jcs5040099
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 100: Improvement of Performance Profile of
           Acrylic Based Polyester Bio-Composites by Bast/Basalt Fibers Hybridization
           for Automotive Applications

    • Authors: Anjum Saleem, Luisa Medina, Mikael Skrifvars
      First page: 100
      Abstract: New technologies in the automotive industry require lightweight, environment-friendly, and mechanically strong materials. Bast fibers such as kenaf, flax, and hemp reinforced polymers are frequently used composites in semi-structural applications in industry. However, the low mechanical properties of bast fibers limit the applications of these composites in structural applications. The work presented here aims to enhance the mechanical property profile of bast fiber reinforced acrylic-based polyester resin composites by hybridization with basalt fibers. The hybridization was studied in three resin forms, solution, dispersion, and a mixture of solution and dispersion resin forms. The composites were prepared by established processing methods such as carding, resin impregnation, and compression molding. The composites were characterized for their mechanical (tensile, flexural, and Charpy impact strength), thermal, and morphological properties. The mechanical performance of hybrid bast/basalt fiber composites was significantly improved compared to their respective bast fiber composites. For hybrid composites, the specific flexural modulus and strength were on an average about 21 and 19% higher, specific tensile modulus and strength about 31 and 16% higher, respectively, and the specific impact energy was 13% higher than bast fiber reinforced composites. The statistical significance of the results was analyzed using one-way analysis of variance.
      Citation: Journal of Composites Science
      PubDate: 2021-04-04
      DOI: 10.3390/jcs5040100
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 101: Metal-Organic Framework-Based
           Stimuli-Responsive Polymers

    • Authors: Menglian Wei, Yu Wan, Xueji Zhang
      First page: 101
      Abstract: Metal-organic framework (MOF) based stimuli-responsive polymers (coordination polymers) exhibit reversible phase-transition behavior and demonstrate attractive properties that are capable of altering physical and/or chemical properties upon exposure to external stimuli, including pH, temperature, ions, etc., in a dynamic fashion. Thus, their conformational change can be imitated by the adsorption/desorption of target analytes (guest molecules), temperature or pressure changes, and electromagnetic field manipulation. MOF-based stimuli responsive polymers have received great attention due to their advanced optical properties and variety of applications. Herein, we summarized some recent progress on MOF-based stimuli-responsive polymers (SRPs) classified by physical and chemical responsiveness, including temperature, pressure, electricity, pH, metal ions, gases, alcohol and multi-targets.
      Citation: Journal of Composites Science
      PubDate: 2021-04-07
      DOI: 10.3390/jcs5040101
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 102: Isosteric Enthalpy Behavior of CO2
           Adsorption on Micro-Mesoporous Materials: Carbon Microfibers (CMFs),
           SBA-15, and Amine-Functionalized SBA-15

    • Authors: Reyna Ojeda-López, Armando Domínguez-Ortiz, Carlos Felipe, A. Cervantes-Uribe, Isaac J. Pérez-Hermosillo, J. Marcos Esparza-Schulz
      First page: 102
      Abstract: The isosteric enthalpy of adsorption (Δadsh˙) of CO2 in three different micro and mesoporous materials was evaluated in this work. These materials were a microporous material with functional groups of nitrogen and oxygen (CMFs, carbon microfibers), a mesoporous material with silanol groups (SBA-15, Santa Barbara Amorphous), and a mesoporous material with amine groups (SBA-15_APTES, SBA-15 amine-functionalized with (3-Aminopropyl)-triethoxysilane). The temperature interval explored was between 263 K and 303 K, with a separation of 5 K between each one, so a total of nine CO2 isotherms were obtained. Using the nine isotherms and the Clausius–Clapeyron equation, the reference value for Δadsh˙ was found. The reference value was compared with those Δadsh˙ obtained, considering some arrangement of three or five CO2 isotherms. Finally, it was found that at 298 K and 1 bar, the total amount of CO2 adsorbed is 2.32, 0.53, and 1.37 mmol g−1 for CMF, SBA-15, and SBA-15_APTES, respectively. However, at a coverage of 0.38 mmol g−1, Δadsh˙ is worth 38, 30, and 29 KJ mol−1 for SBA-15_APTES, CMFs, and SBA-15, respectively. So, physisorption predominates in the case of CMF and SBA-15 materials, and the Δadsh˙ values significantly coincide regardless of whether the isotherms arrangement used was three or five. Meanwhile, in SBA-15_APTES, chemisorption predominates as a consequence of the arrangements used to obtain Δadsh˙. This happens in such a way that the use of low temperatures (263–283 K) tends to produce higher Δadsh˙ values, while the use of high temperatures (283–303 K) decreases the Δadsh˙ values.
      Citation: Journal of Composites Science
      PubDate: 2021-04-08
      DOI: 10.3390/jcs5040102
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 103: Investigating the Hall-Petch Constants
           for As-Cast and Aged AZ61/CNTs Metal Matrix Composites and Their Role on
           Superposition Law Exponent

    • Authors: Aqeel Abbas, Song-Jeng Huang
      First page: 103
      Abstract: AZ61/carbon nanotubes (CNTs) (0, 0.1, 0.5, and 1 wt.%) composites were successfully fabricated by using the stir-casting method. Hall–Petch relationship and superposition of different strengthening mechanisms were analyzed for aged and as-cast AZ61/CNTs composites. Aged composites showed higher frictional stress (108.81 MPa) than that of as-cast (31.56 Mpa) composites when the grain size was fitted directly against the experimentally measured yield strength. In contrast, considering the superposition of all contributing strengthening mechanisms, the Hall–Petch constants contributed by only grain-size strengthening were found (σ0 = 100.06 Mpa and Kf = 0.3048 Mpa m1/2) for as-cast and (σ0 = 87.154 Mpa and Kf = 0.3407 Mpa m1/2) for aged composites when superposition law exponent is unity. The dislocation density for the as-cast composites was maximum (8.3239 × 1013 m−2) in the case of the AZ61/0.5 wt.%CNT composite, and for aged composites, it increased with the increase in CNTs concentration and reached the maximum value (1.0518 × 1014 m−2) in the case of the AZ61/1 wt.%CNT composite.
      Citation: Journal of Composites Science
      PubDate: 2021-04-09
      DOI: 10.3390/jcs5040103
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 104: Development of a Reactive Polyurethane
           Foam System for the Direct Sandwich Composite Molding (D-SCM) Process

    • Authors: Felix Behnisch, Viktoria Lichtner, Frank Henning, Philipp Rosenberg
      First page: 104
      Abstract: Sandwich structures utilize the geometric stiffening effect by increasing the area moment of inertia. This reduces carbon fiber (CF) material within CF-reinforced plastic (CFRP) components, and thus, the CO2 footprint. A suitable material combination for lightweight design is the use of continuous fiber-reinforced face sheets with a light foam core. CFRP sandwich structures with foam core are manufactured by combining a prefabricated foam core with fiber-reinforced cover layers in a two-step press process. Besides the reduction of the used CFRP material, more efficient manufacturing processes are needed. The aim of this paper is to develop a novel polyurethane foam system to enable the direct sandwich composite molding (D‑SCM) process for the production of CFRP sandwich structures by utilizing the resulting foaming pressure during the reactive polyurethane (PUR) foam system expansion for the impregnation of the CF reinforced face sheets. The developed formulation enables D-SCM structures with 150–250 kg/m3 foam density and 44–47.5% fiber volume content, based on a preliminary evaluation.
      Citation: Journal of Composites Science
      PubDate: 2021-04-11
      DOI: 10.3390/jcs5040104
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 105: Effect of Hydrogels Containing
           Nanosilica on the Properties of Cement Pastes

    • Authors: Babak Vafaei, Khashayar Farzanian, Ali Ghahremaninezhad
      First page: 105
      Abstract: The effect of hydrogels containing nanosilica (NSi) on the autogenous shrinkage, mechanical strength, and electrical resistivity of cement pastes was studied. The interaction between the hydrogels and the surrounding cementitious matrix was examined using thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The addition of hydrogels decreased autogenous shrinkage in the cement pastes and this reduction showed a dependence on the concentration of NSi in the hydrogels. Compressive strength and electrical resistivity were reduced in the cement pastes with hydrogels and this reduction was decreased with increased concentration of NSi in the hydrogel. A change in the phase composition of the cement paste in the region close to the hydrogel was noted, compared to the region away from the hydrogel. In a lime solution with increased pH and temperature, Ca(OH)2 and CaCO3 were found to form within the hydrogels; evidence of calcium-silicate-hydrate (C-S-H) formation in the hydrogels with NSi was obtained, indicating the possible pozzolanic potential of the hydrogels with NSi.
      Citation: Journal of Composites Science
      PubDate: 2021-04-12
      DOI: 10.3390/jcs5040105
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 106: Color Stability of CAD/CAM Interim
           Material for Long-Term Fixed Dental Prostheses vs. Conventional Materials
           after Immersion in Different Staining Solutions

    • Authors: Lissethe Peñate, Montse Mercade, María Arregui, Miguel Roig, Juan Basilio, Rosario Cedeño
      First page: 106
      Abstract: The color stability of interim computer-aided design and computer-assisted manufacturing (CAD/CAM) materials has not been exhaustively investigated. The aim of this study was to compare the translucency (TP) and contrast ratio (CR) of CAD/CAM blocks and conventional interim materials, as well as the effects of varnish application and tooth-brushing on color stability after immersion in different staining solutions. Four hundred and eighty specimens were fabricated with four different interim materials (n = 120) and were divided into three experimental, and one control group (n = 30). The color measurements were taken at the initial time (T0), 24 h (T1), 7 days (T2), and 30 days (T3) after immersion in different solutions. CIEDE2000 (ΔE00) values were analyzed with ANOVA and Fischer’s LSD test with a 95% confidence interval. The relationship between TP and CR was analyzed with a Pearson correlation. All interim materials showed a significant difference (p < 0.05) in color change after 30 days. Results showed that polyethyl methacrylate resins (PEMA) had the highest stability over time. The TP and CR were statistically significant (p < 0.05). It was observed that brushing improved the color stability but the ΔE00 were the highest when the varnish alone or varnish and brushing were used, except in the bis-acryl group, in which varnish and brushing decreased the color stainability.
      Citation: Journal of Composites Science
      PubDate: 2021-04-13
      DOI: 10.3390/jcs5040106
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 107: Assessment of Analytical Orientation
           Prediction Models for Suspensions Containing Fibers and Spheres

    • Authors: Bastien Dietemann, Fatih Bosna, Harald Kruggel-Emden, Torsten Kraft, Claas Bierwisch
      First page: 107
      Abstract: Analytical orientation models like the Folgar Tucker (FT) model are widely applied to predict the orientation of suspended non-spherical particles. The accuracy of these models depends on empirical model parameters. In this work, we assess how well analytical orientation models can predict the orientation of suspensions not only consisting of fibers but also of an additional second particle type in the shape of disks, which are varied in size and filling fraction. We mainly focus on the FT model, and we also compare its accuracy to more complex models like Reduced-Strain Closure model (RSC), Moldflow Rotational Diffusion model (MRD), and Anisotropic Rotary Diffusion model (ARD). In our work, we address the following questions. First, can the FT model predict the orientation of suspensions despite the additional particle phase affecting the rotation of the fibers' Second, is it possible to formulate an expression for the sole Folgar Tucker model parameter that is based on the suspension composition' Third, is there an advantage to choose more complex orientation prediction models that require the adjustment of additional model parameters'
      Citation: Journal of Composites Science
      PubDate: 2021-04-13
      DOI: 10.3390/jcs5040107
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 108: Fabrication of Porous Carbon Films and
           Their Impact on Carbon/Polypropylene Interfacial Bonding

    • Authors: Yucheng Peng, Ruslan Burtovyy, Rajendra Bordia, Igor Luzinov
      First page: 108
      Abstract: Porous carbon films were generated by thermal treatment of polymer films made from poly(acrylonitrile-co-methyl acrylate)/polyethylene terephthalate (PAN/PET) blend. The precursor films were fabricated by a dip-coating process using PAN/PET solutions in hexafluoro-2-propanol (HFIP). A two-step process, including stabilization and carbonization, was employed to produce the carbon films. PET functioned as a pore former. Specifically, porous carbon films with thicknesses from 0.38–1.83 μm and pore diameters between 0.1–10 μm were obtained. The higher concentrations of PET in the PAN/PET mixture and the higher withdrawal speed during dip-coating caused the formation of larger pores. The thickness of the carbon films can be regulated using the withdrawal speed used in the dip-coating deposition. We determined that the deposition of the porous carbon film on graphite substrate significantly increases the value of the interfacial shear strength between graphite plates and thermoplastic PP. This study has shown the feasibility of fabrication of 3D porous carbon structure on the surface of carbon materials for increasing the interfacial strength. We expect that this approach can be employed for the fabrication of high-performance carbon fiber-thermoplastic composites.
      Citation: Journal of Composites Science
      PubDate: 2021-04-14
      DOI: 10.3390/jcs5040108
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 109: Recent Advances in Geopolymer
           Technology. A Potential Eco-Friendly Solution in the Construction
           Materials Industry: A Review

    • Authors: Matteo Sambucci, Abbas Sibai, Marco Valente
      First page: 109
      Abstract: In the last ten years, the Portland cement industry has received wide criticism due to its related high embodied energy and carbon dioxide footprint. Recently, numerous “clean” strategies and solutions were developed. Among these, geopolymer technology is gaining growing interest as a functional way to design more eco-friendly construction materials and for waste management issues suffered by various industries. Previous research has highlighted the attractive engineering properties of geopolymeric materials, especially in terms of mechanical properties and durability, resulting in even higher performance than ordinary concrete. This review provides a comprehensive analysis of current state-of-the-art and implementations on geopolymer concrete materials, investigating how the key process factors (such as raw materials, synthesis regime, alkali concentration, water dosage, and reinforcement fillers) affect the rheological, microstructural, durability, and mechanical properties. Finally, the paper elucidates some noteworthy aspects for future research development: innovative geopolymer-based formulations (including alkali-activated blends for additive manufacturing and thermo-acoustic insulating cellular compounds), concrete applications successfully scaled in the civil-architectural fields, and the perspective directions of geopolymer technology in terms of commercialization and large-scale diffusion.
      Citation: Journal of Composites Science
      PubDate: 2021-04-17
      DOI: 10.3390/jcs5040109
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 110: Composite Material of PDMS with
           Interchangeable Transmittance: Study of Optical, Mechanical Properties and
           Wettability

    • Authors: Flaminio Sales, Andrews Souza, Ronaldo Ariati, Verônica Noronha, Elder Giovanetti, Rui Lima, João Ribeiro
      First page: 110
      Abstract: Polydimethylsiloxane (PDMS) is a polymer that has attracted the attention of researchers due to its unique properties such as transparency, biocompatibility, high flexibility, and physical and chemical stability. In addition, PDMS modification and combination with other materials can expand its range of applications. For instance, the ability to perform superhydrophobic coating allows for the manufacture of lenses. However, many of these processes are complex and expensive. One of the most promising modifications, which consists of the development of an interchangeable coating, capable of changing its optical characteristics according to some stimuli, has been underexplored. Thus, we report an experimental study of the mechanical and optical properties and wettability of pure PDMS and of two PDMS composites with the addition of 1% paraffin or beeswax using a gravity casting process. The composites’ tensile strength and hardness were lower when compared with pure PDMS. However, the contact angle was increased, reaching the highest values when using the paraffin additive. Additionally, these composites have shown interesting results for the spectrophotometry tests, i.e., the material changed its optical characteristics when heated, going from opaque at room temperature to transparent, with transmittance around 75%, at 70 °C. As a result, these materials have great potential for use in smart devices, such as sensors, due to its ability to change its transparency at high temperatures.
      Citation: Journal of Composites Science
      PubDate: 2021-04-17
      DOI: 10.3390/jcs5040110
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 111: Optimization of Process Conditions for
           Continuous Growth of CNTs on the Surface of Carbon Fibers

    • Authors: Chengjuan Wang, Yanxiang Wang, Shunsheng Su
      First page: 111
      Abstract: Grafting carbon nanotubes (CNTs) is one of the most commonly used methods for modifying carbon fiber surface, during which complex device is usually needed and the growth of CNTs is difficult to control. Herein, we provide an implementable and continuous chemical vapor deposition (CVD) process, by which the novel multiscale reinforcement of carbon nanotube (CNT)-grafted carbon fiber is prepared. After exploring the effects of the moving speed and growth atmosphere on the morphology and mechanical properties of carbon nanotubes/carbon fiber (CNTs/CF) reinforcement, the optimal CVD process conditions are determined. The results show that low moving speeds of carbon fibers passing through the reactor can prolong the growth time of CNTs, increasing the thickness and density of the CNTs layer. When the moving speed is 3 cm/min or 4 cm/min, the surface graphitization degree and tensile strength of CNTs/CF almost simultaneously reach the highest value. It is also found that H2 in the growth atmosphere can inhibit the cracking of C2H2 and has a certain effect on prolonging the life of the catalyst. Meanwhile, the graphitization degree is promoted gradually with the increase in H2 flow rate from 0 to 0.9 L/min, which is beneficial to CNTs/CF tensile properties.
      Citation: Journal of Composites Science
      PubDate: 2021-04-17
      DOI: 10.3390/jcs5040111
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 112: Effect of Defects Part II: Multiscale
           Effect of Microvoids, Orientation of Rivet Holes on the Damage
           Propagation, and Ultimate Failure Strength of Composites

    • Authors: Vahid Tavaf, Mohammadsadegh Saadatzi, Sourav Banerjee
      First page: 112
      Abstract: Material properties at the vicinity of the cut-outs in composites are not entirely defect-free. The nteraction of multiple cutouts like rivet holes, the repercussion of their configuration on crack propagation, and ultimate strength were predicted using Peridynamic method and the results are reported in this article. The effect of microscale defects at the vicinity of the cutouts on macroscale damage propagation were shown to have quantifiable manifestation. This study focused on two to four holes in unidirectional composite plates with 0°, 45°, and 90° fiber directions, while the vicinity of a hole was considered degraded. Numerical results were validated using quantitative ultrasonic image correlation (QUIC) and the tensile test. Both the experimental and numerical results confirmed that the strength of the horizontal configuration is higher than the vertical in the plates with two holes. Furthermore, the square configuration was found to be stronger than the diamond configuration with four holes. When the effect of microscale defects was considered, the prediction of ultimate strength was better compared to the experimental results. The predictive model could be reliably used for progressive damage analysis.
      Citation: Journal of Composites Science
      PubDate: 2021-04-17
      DOI: 10.3390/jcs5040112
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 113: Development of Ultra-Lightweight and
           High Strength Engineered Cementitious Composites

    • Authors: Zhitao Chen, Junxia Li, En-Hua Yang
      First page: 113
      Abstract: In this study, ultra-lightweight and high strength Engineered Cementitious Composites (ULHS-ECCs) are developed via lightweight filler incorporation and matrix composition tailoring. The mechanical, physical, and micromechanical properties of the resulting ULHS-ECCs are investigated and discussed. ULHS-ECCs with a density below 1300 kg/m3, a compressive strength beyond 60 MPa, a tensile strain capacity above 1%, and a thermal conductivity below 0.5 w/mK are developed. The inclusion of lightweight fillers and the variation in proportioning of the ternary binder can lead to a change in micromechanical properties, including the matrix fracture toughness and the fiber/matrix interface properties. As a result, the tensile strain-hardening performance of the ULHS-ECCs can be altered.
      Citation: Journal of Composites Science
      PubDate: 2021-04-18
      DOI: 10.3390/jcs5040113
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 114: Experimental Investigation of
           Instabilities on Different Scales in Compressive Fatigue Testing of
           Composites

    • Authors: Andreas Baumann, Joachim Hausmann
      First page: 114
      Abstract: Compression testing of continuous fiber reinforced materials is challenging, because a great number of competing failure modes and instabilities on different length scales have to be considered. In comparison to tensile testing, the results are more affected by the chosen test set-up. Effects introduced by the test set-up as well as the type of damage in continuous fiber reinforced materials are mainly investigated for quasi-static loading. This is not the case for cyclic compression loading. Neither standardized methods nor a great deal of literature for reference exists. The aim of this work is to increase the understanding by analyzing the potential effects the set-up in fatigue loading might have on the damage for two common testing strategies by fatigue tests, load increase creep tests and supplementary analytical models. The results show that damage modes can be altered by the testing strategy for the investigated woven glass fiber reinforced polyamide 6. The tools both experimentally and analytically provide the basis to choose the correct set-up in future investigations.
      Citation: Journal of Composites Science
      PubDate: 2021-04-20
      DOI: 10.3390/jcs5040114
      Issue No: Vol. 5, No. 4 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 64: The Influence of Pressure-Induced-Flow
           Processing on the Morphology, Thermal and Mechanical Properties of
           Polypropylene Blends

    • Authors: Pengfei Li, Yanpei Fei, Shilun Ruan, Jianjiang Yang, Feng Chen, Yangfu Jin
      First page: 64
      Abstract: The pressure-induced-flow (PIF) processing can effectively prepare high-performance polymer materials. This paper studies the influence of pressure-induced-flow processing on the morphology, thermodynamic and mechanical properties of polypropylene (PP)/polyamide 6 (PA6) blends, PP/polyolefin elastomer (POE) blends and PP/thermoplastic urethane (TPU) blends. The results show that pressure-induced-flow processing can significantly improve the thermodynamic and mechanical properties of the blends by regulating internal structure. Research shows that the pressure-induced-flow processing can increase the strength and the toughness of the blends, particularly in PP/TPU blends.
      Citation: Journal of Composites Science
      PubDate: 2021-02-24
      DOI: 10.3390/jcs5030064
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 65: Modeling and Simulations of the Sulfur
           Infiltration in Activated Carbon Fabrics during Composite Cathode
           Fabrication for Lithium-Sulfur Batteries

    • Authors: Kyriakos Lasetta, Joseph Paul Baboo, Constantina Lekakou
      First page: 65
      Abstract: During the manufacture of a composite cathode for lithium-sulfur (Li-S) batteries it is important to realize homogeneous infiltration of a specified amount of sulfur, targeted to be at least 5 mg cm−2 to achieve good battery performance in terms of high energy density. A model of the sulfur infiltration is presented in this study, taking into account the pore size distribution of the porous cathode host, phase transitions in sulfur, and formation of different sulfur allotropes, depending on pore size, formation energy and available thermal energy. Simulations of sulfur infiltration into an activated carbon fabric at a hot-plate temperature of 175 °C for two hours predicted a composite cathode with 41 wt% sulfur (8.3 mg cm−2), in excellent agreement with the experiment. The pore size distribution of the porous carbon host proved critical for both the extent and form of retained sulfur, where pores below 0.4 nm could not accommodate any sulfur, pores between 0.4 and 0.7 nm retained S4 and S6 allotropes, and pores between 0.7 and 1.5 nm contained S8.
      Citation: Journal of Composites Science
      PubDate: 2021-02-25
      DOI: 10.3390/jcs5030065
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 66: The Effect of Modifications of
           Activated Carbon Materials on the Capacitive Performance: Surface,
           Microstructure, and Wettability

    • Authors: Kouao Dujearic-Stephane, Meenal Gupta, Ashwani Kumar, Vijay Sharma, Soumya Pandit, Patrizia Bocchetta, Yogesh Kumar
      First page: 66
      Abstract: In this review, the efforts done by different research groups to enhance the performance of the electric double-layer capacitors (EDLCs), regarding the effect of the modification of activated carbon structures on the electrochemical properties, are summarized. Activated carbon materials with various porous textures, surface chemistry, and microstructure have been synthesized using several different techniques by different researchers. Micro-, meso-, and macroporous textures can be obtained through the activation/carbonization process using various activating agents. The surface chemistry of activated carbon materials can be modified via: (i) the carbonization of heteroatom-enriched compounds, (ii) post-treatment of carbon materials with reactive heteroatom sources, and (iii) activated carbon combined both with metal oxide materials dan conducting polymers to obtain composites. Intending to improve the EDLCs performance, the introduction of heteroatoms into an activated carbon matrix and composited activated carbon with either metal oxide materials or conducting polymers introduced a pseudo-capacitance effect, which is an additional contribution to the dominant double-layer capacitance. Such tricks offer high capacitance due to the presence of both electrical double layer charge storage mechanism and faradic charge transfer. The surface modification by attaching suitable heteroatoms such as phosphorus species increases the cell operating voltage, thereby improving the cell performance. To establish a detailed understanding of how one can modify the activated carbon structure regarding its porous textures, the surface chemistry, the wettability, and microstructure enable to enhance the performance of the EDLCs is discussed here in detail. This review discusses the basic key parameters which are considered to evaluate the performance of EDLCs such as cell capacitance, operating voltage, equivalent series resistance, power density, and energy density, and how these are affected by the modification of the activated carbon framework.
      Citation: Journal of Composites Science
      PubDate: 2021-02-26
      DOI: 10.3390/jcs5030066
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 67: Static Fatigue of SiC/SiC
           Minicomposites at High Temperatures Up to 1200 °C in Air: Multiscale
           Approach

    • Authors: Jacques Lamon, Adrien Laforêt
      First page: 67
      Abstract: The present paper investigates the static fatigue behavior of Hi-Nicalon fiber-reinforced SiC–SiC minicomposites at high temperatures in the 900–1200 °C range, and under tensile stresses above the proportional limit. The stress–rupture time relation was analyzed with respect to subcritical crack growth in filaments and fiber tow fracture. Slow crack growth from flaws located at the surface of filaments is driven by the oxidation of free carbon at the grain boundaries. Lifetime of the reinforcing tows depends on the statistical distribution of filament strength and on structural factors, which are enhanced by temperature increase. The rupture time data were plotted in terms of initial stresses on reinforcing filaments. The effect of temperature and load on the stress–rupture time relation for minicomposites was investigated using results of fractography and predictions of minicomposite lifetime using a model of subcritical growth for critical filaments. The critical filament is the one whose failure by slow crack-growth triggers unstable fracture of the minicomposite. This is identified by the strength–probability relation provided by the cumulative distribution function for filament strength at room temperature. The results were compared to the fatigue behavior of dry tows. The influence of various factors related to oxidation, including multiple failures, load sharing, and variability, was analyzed.
      Citation: Journal of Composites Science
      PubDate: 2021-02-28
      DOI: 10.3390/jcs5030067
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 68: On the Use of Mechano-Chemically
           Modified Ground Tire Rubber (GTR) as Recycled and Sustainable Filler in
           Styrene-Butadiene Rubber (SBR) Composites

    • Authors: Javier Araujo-Morera, Reyes Verdugo-Manzanares, Sergio González, Raquel Verdejo, Miguel Angel Lopez-Manchado, Marianella Hernández Santana
      First page: 68
      Abstract: The management of end-of-life tires (ELTs) is one of the main environmental issues that society faces nowadays. Recycling of ELTs appears as one feasible option for tackling the problem, although their incorporation as ground tire rubber (GTR) in other rubber matrices is limited due to poor compatibility. In this research, we report a successful combination of a cryo-grinding process with a chemical treatment for modifying the surface of GTR. Various cryo-grinding protocols were studied until a particle size of 100–150 µm was achieved. Chemical treatments with different acids were also analyzed, resulting in the optimal modification with sulfuric acid (H2SO4). Modified GTR was added to a styrene-butadiene rubber (SBR) matrix. The incorporation of 10 phr of this filler resulted in a composite with improved mechanical performance, with increments of 115% and 761% in tensile strength and elongation at break, respectively. These results validate the use of a recycled material from tire waste as sustainable filler in rubber composites.
      Citation: Journal of Composites Science
      PubDate: 2021-03-03
      DOI: 10.3390/jcs5030068
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 69: Synthesis and Electrochemical
           Performance of Mesoporous NiMn2O4 Nanoparticles as an Anode for
           Lithium-Ion Battery

    • Authors: Swapnil J. Rajoba, Rajendra D. Kale, Sachin B. Kulkarni, Vinayak G. Parale, Rohan Patil, Håkan Olin, Hyung-Ho Park, Rushikesh P. Dhavale, Manisha Phadatare
      First page: 69
      Abstract: NiMn2O4 (NMO) is a good alternative anode material for lithium-ion battery (LIB) application, due to its superior electrochemical activity. Current research shows that synthesis of NMO via citric acid-based combustion method envisaged application in the LIB, due to its good reversibility and rate performance. Phase purity and crystallinity of the material is controlled by calcination at different temperatures, and its structural properties are investigated by X-ray diffraction (XRD). Composition and oxidation state of NMO are further investigated by X-ray photoelectron spectroscopy (XPS). For LIB application, lithiation delithiation potential and phase transformation of NMO are studied by cyclic voltammetry curve. As an anode material, initially, the average discharge capacity delivered by NMO is 983 mA·h/g at 0.1 A/g. In addition, the NMO electrode delivers an average discharge capacity of 223 mA·h/g after cell cycled at various current densities up to 10 A/g. These results show the potential applications of NMO electrodes for LIBs.
      Citation: Journal of Composites Science
      PubDate: 2021-03-04
      DOI: 10.3390/jcs5030069
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 70: A Self-Healing System Based on Ester
           Crosslinks for Carbon Black-Filled Rubber Compounds

    • Authors: Bashir Algaily, Wisut Kaewsakul, Siti Salina Sarkawi, Ekwipoo Kalkornsurapranee
      First page: 70
      Abstract: Carbon black-reinforced rubber compounds based on the blends of natural rubber (NR) and butadiene rubber (BR) for tire sidewall applications were formulated to investigate the self-healing efficacy of a modifier called EMZ. This modifier is based on epoxidized natural rubber (ENR) modified with hydrolyzed maleic anhydride (HMA) as the ester crosslinking agent plus zinc acetate dihydrate (ZAD) as the transesterification catalyst. The influence of EMZ modifier content in sidewall compounds on processing characteristics, reinforcement, mechanical and fatigue properties, as well as property retentions, was investigated. Increasing the content of EMZ, the dump temperatures and Mooney viscosities of the compounds slightly increase, attributed to the presence of extra polymer networks and filler–rubber interactions. The bound rubber content and Payne effect show a good correction that essentially supports that the EMZ modifier gives enhanced filler–rubber interaction and reduced filler–filler interaction, reflecting the improved homogeneity of the composites. This is the key contribution to a better flex cracking resistance and a high fatigue-to-failure resistance when utilizing the EMZ modifier. To validate the property retentions, molecular damages were introduced to vulcanizates using a tensile stress–strain cyclic test following the Mullins effect concept. The property retentions are significantly enhanced with increasing EMZ content because the EMZ self-healing modifier provides reversible or dynamic ester linkages that potentially enable a bond-interchange mechanism of the crosslinks, leading to the intermolecular reparation of the rubber network.
      Citation: Journal of Composites Science
      PubDate: 2021-03-04
      DOI: 10.3390/jcs5030070
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 71: Editorial for the Special Issue on
           Discontinuous Fiber Composites, Volume II

    • Authors: Christoph Kuhn, Tim A. Osswald
      First page: 71
      Abstract: This Special Issue on discontinuous fiber composites and its published papers, like its predecessor, give the polymer engineer and scientist an insight into challenges and research topics in the field of discontinuous fiber-reinforced composites [...]
      Citation: Journal of Composites Science
      PubDate: 2021-03-05
      DOI: 10.3390/jcs5030071
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 72: Damage by Improvised Incendiary Devices
           on Carbon Fiber-Reinforced Polymer Matrix Composites

    • Authors: Sebastian Eibl
      First page: 72
      Abstract: This study focuses on short-term thermal degradation of polymer matrix composites by one-sided impact of improvised incendiary devices (IID). Specimens of two commercial composites HexPly® 8552/IM7 and M18-1/G939 with various thicknesses (1–8 mm) are systematically investigated as well as sandwich structures thereof, applying various amounts of fire accelerant predominantly in laboratory scale fire tests. Results of preceding large-scale fire tests with IIDs justify the chosen conditions for the laboratory-scale fire tests. The aim is to correlate the amount of fire accelerant with heat damage and residual mechanical strength. Thermal damage is characterized visually and by ultrasonic testing, infrared spectroscopy, and residual interlaminar shear strength. Matrix degradation and combustion only contribute to the overall amount of released heat by the fire accelerant for thin and especially vertically aligned panels as tested by a cone calorimeter (without electrical heating), but not for horizontally orientated and thicker panels. Degradation processes are discussed in detail. Protective effects are observed for typical coatings, a copper mesh applied for protection against lightning strike, combinations thereof as well as an intumescent coating. Especially sandwich structures are prone to severe damage by assaults with IID, such as Molotov cocktails.
      Citation: Journal of Composites Science
      PubDate: 2021-03-05
      DOI: 10.3390/jcs5030072
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 73: Consolidation and Tow Spreading of
           Digitally Manufactured Continuous Fiber Reinforced Composites from
           Thermoplastic Commingled Tow Using a Five-Axis Extrusion System

    • Authors: Mark E. Bourgeois, Donald W. Radford
      First page: 73
      Abstract: During the development of digitally manufactured, commingled tow continuous fiber reinforced composites, consolidation force was controlled using a controlled spring force that yielded a repeatable tow width. However, the use of the extruder face to consolidate the material requires that the extruder remain perpendicular to the placement surface throughout the process. When considering more complex tool contours including sloped surfaces, more than three axes of motion are necessary to maintain the perpendicularity of the extruder tip to the surface. In this effort, a five-axis system is developed and used to demonstrate the ability to consolidate over complex contours. In addition, the nozzle face temperatures required for good consolidation and wetout result in poor tow path fidelity when complex paths are introduced. The implementation of an automated, computer-controlled localized cooling system enables both good wetout and consolidation while also enabling more accurate changes in tow path due to improvements in local tow tack. With the development of the five-axis system it is also shown that the tow width can be adjusted by rotating the existing placement nozzle to angles not equal to 90°. Thus, through a combination of controlled localized cooling and real-time control of the nozzle angle, a possible approach to control of tow width, independent of the tow placement angle and radius of curvature during tow steering, is described.
      Citation: Journal of Composites Science
      PubDate: 2021-03-05
      DOI: 10.3390/jcs5030073
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 74: Analytical Solution for Static and
           Dynamic Analysis of Graphene-Based Hybrid Flexoelectric Nanostructures

    • Authors: Kishor Balasaheb Shingare, Susmita Naskar
      First page: 74
      Abstract: Owing to their applications in devices such as in electromechanical sensors, actuators and nanogenerators, the consideration of size-dependent properties in the electromechanical response of composites is of great importance. In this study, a closed-form solution based on the linear piezoelectricity, Kirchhoff’s plate theory and Navier’s solution was developed, to envisage the electromechanical behaviors of hybrid graphene-reinforced piezoelectric composite (GRPC) plates, considering the flexoelectric effect. The governing equations and respective boundary conditions were obtained, using Hamilton’s variational principle for achieving static deflection and resonant frequency. Moreover, the different parameters considering aspect ratio, thickness of plate, different loadings (inline, point, uniformly distributed load (UDL), uniformly varying load (UVL)), the combination of different volume fraction of graphene and piezoelectric lead zirconate titanate are considered to attain the desired bending deflection and frequency response of GRPC. Different mode shapes and flexoelectric coefficients are also considered and the results reveal that the proper addition of graphene percentage and flexoelectric effect on the static and dynamic responses of GRPC plate is substantial. The obtained results expose that the flexoelectric effect on the piezoelastic response of the bending of nanocomposite plates are worth paying attention to, in order to develop a nanoelectromechanical system (NEMS). Our fundamental study sheds the possibility of evolving lightweight and high-performance NEMS applications over the existing piezoelectric materials.
      Citation: Journal of Composites Science
      PubDate: 2021-03-06
      DOI: 10.3390/jcs5030074
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 75: A Brief Overview of Recent Progress in
           Porous Silica as Catalyst Supports

    • Authors: Preeti S. Shinde, Pradnya S. Suryawanshi, Kanchan K. Patil, Vedika M. Belekar, Sandeep A. Sankpal, Sagar D. Delekar, Sushilkumar A. Jadhav
      First page: 75
      Abstract: Porous silica particles have shown applications in various technological fields including their use as catalyst supports in heterogeneous catalysis. The mesoporous silica particles have ordered porosity, high surface area, and good chemical stability. These interesting structural or textural properties make porous silica an attractive material for use as catalyst supports in various heterogeneous catalysis reactions. The colloidal nature of the porous silica particles is highly useful in catalytic applications as it guarantees better mass transfer properties and uniform distribution of the various metal or metal oxide nanocatalysts in solution. The catalysts show high activity, low degree of metal leaching, and ease in recycling when supported or immobilized on porous silica-based materials. In this overview, we have pointed out the importance of porous silica as catalyst supports. A variety of chemical reactions catalyzed by different catalysts loaded or embedded in porous silica supports are studied. The latest reports from the literature about the use of porous silica-based materials as catalyst supports are listed and analyzed. The new and continued trends are discussed with examples.
      Citation: Journal of Composites Science
      PubDate: 2021-03-06
      DOI: 10.3390/jcs5030075
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 76: S-N Curve Characterisation for
           Composite Materials and Prediction of Remaining Fatigue Life Using Damage
           Function

    • Authors: Ho Sung Kim, Saijie Huang
      First page: 76
      Abstract: S-N curve characterisation and prediction of remaining fatigue life are studied using polyethylene terephthalate glycol-modified (PETG). A new simple method for finding a data point at the lowest number of cycles for the Kim and Zhang S-N curve model is proposed to avoid the arbitrary choice of loading rate for tensile testing. It was demonstrated that the arbitrary choice of loading rate may likely lead to an erroneous characterisation for the prediction of the remaining fatigue life. The previously proposed theoretical method for predicting the remaining fatigue life of composite materials involving the damage function was verified at a stress ratio of 0.4 for the first time. Both high to low and low to high loadings were conducted for predicting the remaining fatigue lives and a good agreement between predictions and experimental results was found. Fatigue damage consisting of cracks and whitening is described.
      Citation: Journal of Composites Science
      PubDate: 2021-03-07
      DOI: 10.3390/jcs5030076
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 77: Design of a Lightweight Multifunctional
           Composite Railway Axle Utilising Coaxial Skins

    • Authors: Preetum J. Mistry, Michael S. Johnson, Charles A. McRobie, Ivor A. Jones
      First page: 77
      Abstract: The rising economic and environmental pressures associated with the generation and consumption of energy necessitates the need for lightweighting of railway vehicles. The railway axle is a prime candidate for lightweighting of the unsprung mass. The reduction of unsprung mass correlates to reduced track damage, energy consumption and total operating costs. This paper presents the design of a lightweight multifunctional hybrid metallic-composite railway axle utilising coaxial skins. The lightweight axle assembly comprises a carbon fibre reinforced polymer composite tube with steel stub axles bonded into either end. The structural hybrid metallic-composite railway axle is surrounded by coaxial skins each performing a specific function to meet the secondary requirements. A parametric sizing study is conducted to explore the sensitivity of the design parameters of the composite tube and the stub axle interaction through the adhesive joint. The optimised design parameters of the axle consist of a; composite tube outer diameter of 225 mm, composite tube thickness of 7 mm, steel stub axle extension thickness of 10 mm and a bond overlap length of 100 mm. The optimised hybrid metallic-composite railway axle design concept has a mass of 200 kg representing a reduction of 50% over the solid steel version.
      Citation: Journal of Composites Science
      PubDate: 2021-03-07
      DOI: 10.3390/jcs5030077
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 78: Materials and Manufacturing Techniques
           for Polymeric and Ceramic Scaffolds Used in Implant Dentistry

    • Authors: Mutlu Özcan, Dachamir Hotza, Márcio Celso Fredel, Ariadne Cruz, Claudia Angela Maziero Volpato
      First page: 78
      Abstract: Preventive and regenerative techniques have been suggested to minimize the aesthetic and functional effects caused by intraoral bone defects, enabling the installation of dental implants. Among them, porous three-dimensional structures (scaffolds) composed mainly of bioabsorbable ceramics, such as hydroxyapatite (HAp) and β-tricalcium phosphate (β-TCP) stand out for reducing the use of autogenous, homogeneous, and xenogenous bone grafts and their unwanted effects. In order to stimulate bone formation, biodegradable polymers such as cellulose, collagen, glycosaminoglycans, polylactic acid (PLA), polyvinyl alcohol (PVA), poly-ε-caprolactone (PCL), polyglycolic acid (PGA), polyhydroxylbutyrate (PHB), polypropylenofumarate (PPF), polylactic-co-glycolic acid (PLGA), and poly L-co-D, L lactic acid (PLDLA) have also been studied. More recently, hybrid scaffolds can combine the tunable macro/microporosity and osteoinductive properties of ceramic materials with the chemical/physical properties of biodegradable polymers. Various methods are suggested for the manufacture of scaffolds with adequate porosity, such as conventional and additive manufacturing techniques and, more recently, 3D and 4D printing. The purpose of this manuscript is to review features concerning biomaterials, scaffolds macro and microstructure, fabrication techniques, as well as the potential interaction of the scaffolds with the human body.
      Citation: Journal of Composites Science
      PubDate: 2021-03-11
      DOI: 10.3390/jcs5030078
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 79: Impact Damage Ascertainment in
           Composite Plates Using In-Situ Acoustic Emission Signal Signature
           Identification

    • Authors: Robin James, Roshan Prakash Joseph, Victor Giurgiutiu
      First page: 79
      Abstract: Barely visible impact damage (BVID) due to low velocity impact events in composite aircraft structures are becoming prevalent. BVID can have an adverse effect on the strength and safety of the structure. During aircraft inspections it can be extremely difficult to visually detect BVID. Moreover, it is also a challenge to ascertain if the BVID has in-fact caused internal damage to the structure or not. This paper describes a method to ascertain whether or not internal damage happened during the impact event by analyzing the high-frequency information contained in the recorded acoustic emission signal signature. Multiple 2 mm quasi-isotropic carbon fiber reinforced polymer (CFRP) composite coupons were impacted using the ASTM D7136 standard in a drop weight impact testing machine to determine the mass, height and energy parameters to obtain approximately 1” impact damage size in the coupons iteratively. For subsequent impact tests, four piezoelectric wafer active sensors (PWAS) were bonded at specific locations on each coupon to record the acoustic emission (AE) signals during the impact event using the MISTRAS micro-II digital AE system. Impact tests were conducted on these instrumented 2 mm coupons using previously calculated energies that would create either no damage or 1” impact damage in the coupons. The obtained AE waveforms and their frequency spectrums were analyzed to distinguish between different AE signatures. From the analysis of the recorded AE signals, it was verified if the structure had indeed been damaged due to the impact event or not. Using our proposed structural health monitoring technique, it could be possible to rapidly identify impact events that cause damage to the structure in real-time and distinguish them from impact events that do not cause damage to the structure. An invention disclosure describing our acoustic emission structural health monitoring technique has been filed and is in the process of becoming a provisional patent.
      Citation: Journal of Composites Science
      PubDate: 2021-03-12
      DOI: 10.3390/jcs5030079
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 80: Multiscale Characterization of
           E-Glass/Epoxy Composite Exposed to Extreme Environmental Conditions

    • Authors: George Youssef, Scott Newacheck, Nha Uyen Huynh, Carlos Gamez
      First page: 80
      Abstract: Fiber-reinforced polymer matrix composites continue to attract scientific and industrial interest since they offer superior strength-, stiffness-, and toughness-to-weight ratios. The research herein characterizes two sets of E-Glass/Epoxy composite skins: stressed and unstressed. The stressed samples were previously installed in an underground power distribution vault and were exposed to fire while the unstressed composite skins were newly fabricated and never-deployed samples. The mechanical, morphological, and elemental composition of the samples were methodically studied using a dynamic mechanical analyzer, a scanning electron microscope (SEM), and an x-ray diffractometer, respectively. Sandwich composite panels consisting of E-glass/Epoxy skin and balsa wood core were originally received, and the balsa wood was removed before any further investigations. Skin-only specimens with dimensions of ~12.5 mm wide, ~70 mm long, and ~6 mm thick were tested in a Dynamic Mechanical Analyzer in a dual-cantilever beam configuration at 5 Hz and 10 Hz from room temperature to 210 °C. Micrographic analysis using the SEM indicated a slight change in morphology due to the fire event but confirmed the effectiveness of the fire-retardant agents in quickly suppressing the fire. Accompanying Fourier transform infrared and energy dispersive X-ray spectroscopy studies corroborated the mechanical and morphological results. Finally, X-ray diffraction showed that the fire event consumed the surface level fire-retardant and the structural attributes of the E-Glass/Epoxy remained mainly intact. The results suggest the panels can continue field deployment, even after short fire incident.
      Citation: Journal of Composites Science
      PubDate: 2021-03-12
      DOI: 10.3390/jcs5030080
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 81: Analysis and Modeling of Wrinkling in
           Composite Forming

    • Authors: Philippe Boisse, Jin Huang, Eduardo Guzman-Maldonado
      First page: 81
      Abstract: Different approaches for the simulation of wrinkling during forming of textile reinforcements are presented. It is shown that 3D finite element modeling requires the consideration of an additional bending stiffness of the fibers. In shell-type modeling, the bending stiffness is important because it conditions the size of the wrinkles. Different methods to take into account the bending stiffness independently of the tensile stiffness are presented. The onset and development of wrinkles during forming is a global problem that concerns all deformation modes. It is shown in examples that the shear locking angle is not sufficient to conclude about the development of wrinkles. This article highlights the two points common to the different cases of wrinkling of continuous fiber textile reinforcements: the quasi-inextensibility of the fibers and the possible slippage between the fibers. It presents and compares different approaches to consider these two aspects. The simulation of the simultaneous forming of multilayered textile reinforcements makes it possible to see the influence of the orientation of different plies which is an important factor with regard to wrinkling.
      Citation: Journal of Composites Science
      PubDate: 2021-03-13
      DOI: 10.3390/jcs5030081
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 82: Transition Metal Oxides and Their
           Composites for Photocatalytic Dye Degradation

    • Authors: Preety Ahuja, Sanjeev Kumar Ujjain, Rajni Kanojia, Pankaj Attri
      First page: 82
      Abstract: Transition metal oxides (TMO) and their carbon composites have become a glittering upcoming material science candidate. Their interesting properties, such as their meticulous morphology, plentiful availability, flexible surface chemistry along with outstanding mechanical, thermal, and optical properties make them ideal for efficient photocatalytic dye degradation. An extensive range of TMO, and their carbon composites are reviewed highlighting the progression and opportunities for the photocatalytic degradation of dyes. Here, we concisely describe the numerous techniques to extend the optical absorption of these TMOs involving dye sensitization, metal doping, etc. Besides this, an overview of all aspects of dye degradation along with the prevailing challenges for future utilization and development of such nanocomposites towards highly efficient dye degradation system are also reported.
      Citation: Journal of Composites Science
      PubDate: 2021-03-15
      DOI: 10.3390/jcs5030082
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 83: On the Large Amplitude Forced Vibration
           Analysis of Composite Sectorial Plates

    • Authors: Ahmad Saood, Zain A. Khan, Mohd T. Parvez, Arshad H. Khan
      First page: 83
      Abstract: The nonlinear steady state large amplitude forced vibration response of a laminated composite annular sector plate is presented. The nonlinear governing equation of motion of the laminated composite annular sector plate has been obtained using kinematics of first-order shear deformation theory (FSDT) and employing Hamilton’s principle. The governing equations of motion have been solved in a time domain using a modified shooting method and arc-length/pseudo-arc length continuation technique. The influence of the boundary condition, sector angle, and annularity ratio on the linear as well as nonlinear steady state forced vibration response has been investigated. The strain/stress variation across the thickness of the annular sector plate is presented to explain the reason for a decrease/increase in hardening nonlinear behaviour. The periodic variation of the non-linear steady state stress has also been obtained to throw light into the factors influencing the unequal stress half cycles and multiple cyclic stress reversals, which is detrimental to the fatigue design of laminated composite annular sectorial plates. The frequency spectra of the steady state stress reveals large even and odd higher harmonic contributions for different cases due to changes in the restoring force dynamics. The modal interaction/exchange during a cycle is demonstrated using a deformed configuration of the laminated annular sector plate.
      Citation: Journal of Composites Science
      PubDate: 2021-03-15
      DOI: 10.3390/jcs5030083
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 84: Comparison of Specimen Geometries for
           Measuring Through-Thickness Tensile Mechanical Properties of
           Fibre-Reinforced Polymer Composites

    • Authors: Rory Pemberton, Louise Crocker, Matthew Poole, Richard Shaw, Michael Gower
      First page: 84
      Abstract: Engineering design of fibre-reinforced polymer (FRP) composite components requires reliable methods for measuring out-of-plane mechanical properties in the through-thickness (T-T) material direction. Within this work, existing indirect and direct test methods and geometries for measuring T-T tensile properties have been evaluated through experimental testing and finite element analysis (FEA). Experimental testing showed variations, particularly in failure properties, for both indirect (failure strengths from 10–94 MPa) and direct (failure strengths from 48–62 MPa) geometries. Results were shown to be in good agreement with FEA, which also confirmed stress concentration factors. A linear relationship between the magnitude of stress concentration factors and experimentally determined T-T tensile failure strengths was observed for all but one of the direct geometries evaluated. Improved knowledge of stress concentration factors from this work should help instil confidence for industry to use T-T tensile properties determined from these methods.
      Citation: Journal of Composites Science
      PubDate: 2021-03-16
      DOI: 10.3390/jcs5030084
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 85: Determination of Quantum Capacitance of
           Niobium Nitrides Nb2N and Nb4N3 for Supercapacitor Applications

    • Authors: Bharti, Gulzar Ahmed, Yogesh Kumar, Patrizia Bocchetta, Shatendra Sharma
      First page: 85
      Abstract: The density of states and quantum capacitance of pure and doped Nb2N and Nb4N3 single-layer and multi-layer bulk structures are investigated using density functional theory calculations. The calculated value of quantum capacitance is quite high for pristine Nb2N and decent for Nb4N3 structures. However for cobalt-doped unpolarized structures, significant increase in quantum capacitance at Fermi level is observed in the case of Nb4N3 as compared to minor increase in case of Nb2N. These results show that pristine and doped Nb2N and Nb4N3 can be preferred over graphene as the electrode material for supercapacitors. The spin and temperature dependences of quantum capacitance for these structures are also investigated.
      Citation: Journal of Composites Science
      PubDate: 2021-03-20
      DOI: 10.3390/jcs5030085
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 86: Development of Carbon Fiber-Reinforced
           Thermoplastics for Mass-Produced Automotive Applications in Japan

    • Authors: Yi Wan, Jun Takahashi
      First page: 86
      Abstract: The application of carbon fiber-reinforced thermoplastics (CFRTPs) for automotive mass production is attracting increasing attention from researchers and engineers in related fields. This article presents recent developments in CFRTPs focusing on the systematic development of lightweight CFRTP applications for automotive mass production. Additionally, a related national project of Japan conducted at the University of Tokyo is also introduced. The basic development demands, the specific requirements of CFRTPs for lightweight applications in automotive mass production, and the current development status and basic scientific outputs are discussed. The development of high-performance CFRTPs (chopped carbon fiber tape-reinforced thermoplastics (CTTs)) and functional CFRTPs (carbon fiber mat-reinforced thermoplastics (CMTs)) is also introduced. The fabrication process control of CTTs is evaluated, which demonstrates the extreme importance of the mechanical performance. The ultralight lattice, toughened structures, and orientation designable components of CMTs provide a flexible multi-material solution for the proposed applications. Moreover, highly efficient carbon fiber recycling technology is discussed, with recycled carbon fibers exhibiting outstanding compatibility with CFRTPs. A cost sensitivity analysis of carbon fiber and CFRTPs is conducted to guarantee the feasibility and affordability of their application. This article also discusses the trends and sustainability of carbon fiber and CFRTPs usage. The importance of the object-oriented optimal development of CFRTPs is emphasized to efficiently exploit their advantages.
      Citation: Journal of Composites Science
      PubDate: 2021-03-22
      DOI: 10.3390/jcs5030086
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 87: Laser Spot Welding and Electric Contact
           Points Using Copper/Single-Walled Carbon Nanotube Nanocomposite
           Synthesized by Laser Surface Implanting

    • Authors: Jay F. Tu, Nilesh Rajule, Sang Don Mun
      First page: 87
      Abstract: In our previous studies, we have developed a wet process, denoted as laser surface implanting (LSI), to synthesize a copper/single-walled carbon nanotube (Cu–SWCNT) metal nanocomposite. The nanostructure of this Cu–SWCNT composite was shown to contain discernable SWCNT clusters in nanosizes inside the copper matrix. Its hardness could achieve up to three times that of pure copper, verified by micro-hardness and nano-hardness tests. A focus ion beam bombardment test and a plane strain compression test show 2.5 times toughness improvement for the Cu-SWCNT composite. Based on these strength improvements, two potential applications for the Cu-SWCNT nanocomposite are proposed and their feasibilities are verified using specially design test rigs. The first application is related to creating long lasting electric contacts. The result shows that the Cu-SWCNT nanocomposite is highly wear-resistant. The contact area of the simulated electric contacts increases after repeated impact loading, which potentially could lower the contact resistance. The second application is to use the Cu-SWCNT implants as high strength spot weld for joining copper foils. A smaller weld with a higher strength reduces the power requirement of the laser and, consequently, the thermal distortion for higher-dimensional precision. The specially designed test rig for the weld strength characterization is a new contribution, providing a new testing capability for small and non-homogeneous samples not suitable for a standard tensile test machine.
      Citation: Journal of Composites Science
      PubDate: 2021-03-22
      DOI: 10.3390/jcs5030087
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 88: Influence of a Dynamic Consolidation
           Force on In Situ Consolidation Quality of Thermoplastic Composite Laminate
           

    • Authors: Berend Denkena, Carsten Schmidt, Maximilian Kaczemirzk, Max Schwinn
      First page: 88
      Abstract: For achieving high quality of in situ consolidation in thermoplastic Automated Fiber Placement, an approach is presented in this research work. The approach deals with the combination of material pre-heating and sub-ultrasonic vibration treatment. Therefore, this research work investigates the influence of frequency dependent consolidation pressure on the consolidation quality. A simplified experimental setup was developed that uses resistance electrical heating instead of the laser to establish the thermal consolidation condition in a universal testing machine. Consolidation experiments with frequencies up to 1 kHz were conducted. The manufactured specimens are examined using laser scanning microscopy to evaluate the bonding interface and differential scanning calorimetry to evaluate the degree of crystallinity. Additionally, the vibration-assisted specimens were compared to specimens manufactured with static consolidation pressure only. As a result of the experimental study, the interlaminar pore fraction and degree of compaction show a positive dependency to higher frequencies. The porosity decreases from 0.60% to 0.13% while the degree of compaction increases from 8.64% to 12.49% when increasing the vibration frequency up to 1 kHz. The differential scanning calorimetry experiments show that the crystallinity of the matrix is not affected by vibration-assisted consolidation.
      Citation: Journal of Composites Science
      PubDate: 2021-03-22
      DOI: 10.3390/jcs5030088
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 89: Comparative Study of the Reinforcement
           Type Effect on the Thermomechanical Properties and Burning of Epoxy-Based
           Composites

    • Authors: Kamila Salasinska, Mateusz Barczewski, Joanna Aniśko, Aleksander Hejna, Maciej Celiński
      First page: 89
      Abstract: Aramid (AF), glass (GF), carbon (CF), basalt (BF), and flax (FF) fibers in the form of fabrics were used to produce the composites by hand-lay up method. The use of fabrics of similar grammage for composites’ manufacturing allowed for a comprehensive comparison of the properties of the final products. The most important task was to prepare a complex setup of mechanical and thermomechanical properties, supplemented by fire behavior analysis, and discuss both characteristics in their application range. The mechanical properties were investigated using tensile and flexural tests, as well as impact strength measurement. The investigation was improved by assessing thermomechanical properties under dynamic deformation conditions (dynamic mechanical–thermal analysis (DMTA)). All products were subjected to a fire test carried out using a cone calorimeter (CC).
      Citation: Journal of Composites Science
      PubDate: 2021-03-23
      DOI: 10.3390/jcs5030089
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 90: Structural Changes and Their
           Implications in Foamed Flexible Polyurethane Composites Filled with
           Rapeseed Oil-Treated Ground Tire Rubber

    • Authors: Paulina Kosmela, Adam Olszewski, Łukasz Zedler, Paulina Burger, Krzysztof Formela, Aleksander Hejna
      First page: 90
      Abstract: The utilization of post-consumer car tires is an essential issue from an ecological and economic point of view. One of the simplest and the least harmful methods is their material recycling resulting in ground tire rubber (GTR), which can be further applied as fillers for polymer-based composites. Nevertheless, insufficient interfacial interactions implicate the necessity of GTR modification before introduction into polymer matrices. In this study, we investigated the influence of rapeseed oil-assisted thermo-mechanical treatment of GTR using a reactive extrusion process on the processing, structure, and performance of flexible polyurethane/GTR composite foams. Applied modifications affected the processing of polyurethane systems. They caused a noticeable reduction in the average cell size of foams, which was attributed to the potential nucleating activity of solid particles and changes in surface tension caused by the presence of oil. Such an effect was especially pronounced for the waste rapeseed oil, which resulted in the highest content of closed cells. Structural changes caused by GTR modification implicated the enhancement of foams’ strength. Mechanical performance was significantly affected by the applied modifications due to the changes in glass transition temperature. Moreover, the incorporation of waste GTR particles into the polyurethane matrix noticeably improved its thermal stability.
      Citation: Journal of Composites Science
      PubDate: 2021-03-23
      DOI: 10.3390/jcs5030090
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 91: Effect of Graphene Oxide as a
           Reinforcement in a Bio-Epoxy Composite

    • Authors: Anthony Loeffen, Duncan E. Cree, Mina Sabzevari, Lee D. Wilson
      First page: 91
      Abstract: Graphene oxide (GO) has gained interest within the materials research community. The presence of functional groups on GO offers exceptional bonding capabilities and improved performance in lightweight polymer composites. A literature review on the tensile and flexural mechanical properties of synthetic epoxy/GO composites was conducted that showed differences from one study to another, which may be attributed to the oxidation level of the prepared GO. Herein, GO was synthesized from oxidation of graphite flakes using the modified Hummers method, while bio-epoxy/GO composites (0.1, 0.2, 0.3 and 0.6 wt.% GO) were prepared using a solution mixing route. The GO was characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscope (TEM) analysis. The thermal properties of composites were assessed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). FTIR results confirmed oxidation of graphite was successful. SEM showed differences in fractured surfaces, which implies that GO modified the bio-epoxy polymer to some extent. Addition of 0.3 wt.% GO filler was determined to be an optimum amount as it enhanced the tensile strength, tensile modulus, flexural strength and flexural modulus by 23, 35, 17 and 31%, respectively, compared to pure bio-epoxy. Improvements in strength were achieved with considerably lower loadings than traditional fillers. Compared to the bio-epoxy, the 0.6 wt.% GO composite had the highest thermal stability and a slightly higher (positive) glass transition temperature (Tg) was increased by 3.5 °C, relative to the pristine bio-epoxy (0 wt.% GO).
      Citation: Journal of Composites Science
      PubDate: 2021-03-23
      DOI: 10.3390/jcs5030091
      Issue No: Vol. 5, No. 3 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 46: Removal of Pb(II) Ions from Aqueous
           Solution Using Modified Starch

    • Authors: O. H. P. Gunawardene, C. A. Gunathilake, A. P. S. M. Amaraweera, N. M. L. Fernando, A. Manipura, W. A. Manamperi, K. M. A. K. Kulatunga, S. M. Rajapaksha, A. Gamage, R. S. Dassanayake, B. G. N. D. Weerasekara, P. N. K. Fernando, C. A. N. Fernando, J. A. S. C. Jayasinghe
      First page: 46
      Abstract: In this study, two types of modified cassava starch samples (MCS and MWS) prepared from commercially available native cassava starch (NCS) and native cassava starch extracted using the wet method (NWS) were investigated for the removal of Pb(II) ions from aqueous solutions. MCS and MWS samples were synthesized under acidic conditions using Pluronic 123 as the structure-directing agent and tetraethylorthosilicate (TEOS) as the chemical modifying agent. Modified starch samples were characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray Diffraction (XRD), and a nitrogen (N2) gas adsorption–desorption analyser. MCS and MWS showed enhanced thermal stabilities upon acid hydrolysis and chemical modification. The effects of contact time and initial Pb(II) concentration were studied through batch adsorption experiments. Adsorption kinetics followed the pseudo-second-order kinetic model. The equilibrium adsorption data were analysed and compared by the Langmuir and Freundlich adsorption models. The coefficient correlation (R2) was employed as a measure of the fit. The Langmuir model fitted well with equilibrium adsorption data, giving a maximum Pb(II) adsorption capacity of 370.37 and 294.12 mg/g for MWS and MCS, respectively. Modified samples exhibited a higher desorption efficiency of over 97%. This study demonstrated that modified starch could be utilized for Pb(II) removal from industrial wastewater.
      Citation: Journal of Composites Science
      PubDate: 2021-02-03
      DOI: 10.3390/jcs5020046
      Issue No: Vol. 5, No. 2 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 47: Editorial for the Special Issue on
           Characterization and Modelling of Composites

    • Authors: Stelios Georgantzinos
      First page: 47
      Abstract: The papers published in this Special Issue of the Journal of Composites Science will give the composite engineer and scientist insight into what the existing challenges are in the characterization and modelling for the composites field, and how these challenges are being addressed by the research community [...]
      Citation: Journal of Composites Science
      PubDate: 2021-02-03
      DOI: 10.3390/jcs5020047
      Issue No: Vol. 5, No. 2 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 48: Study of the Preparation and Properties
           of TPS/PBSA/PLA Biodegradable Composites

    • Authors: Yuxuan Wang, Yuke Zhong, Qifeng Shi, Sen Guo
      First page: 48
      Abstract: Thermoplastic starch/butyl glycol ester copolymer/polylactic acid (TPS/PBSA/PLA) biodegradable composites were prepared by melt-mixing. The structure, microstructure, mechanical properties and heat resistance of the TPS/PBSA/PLA composites were studied by Fourier-transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), tensile test and thermogravimetry tests, respectively. The results showed that PBSA or PLA could bind to TPS by hydrogen bonding. SEM analysis showed that the composite represents an excellent dispersion and satisfied two-phase compatibility when the PLA, TPS and PBSA blended by a mass ration of 10, 30, and 60. The mechanical properties and the heat resistance of TPS/PBSA/PLA composite were improved by adding PLA with content less than 10%, according to the testing results.
      Citation: Journal of Composites Science
      PubDate: 2021-02-04
      DOI: 10.3390/jcs5020048
      Issue No: Vol. 5, No. 2 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 49: Enhancement in Interply Toughness of
           BMI Composites Using Micro-Thin Films

    • Authors: Eldho Mathew, Sunil Chandrakant Joshi, Periyasamy Manikandan
      First page: 49
      Abstract: Nowadays, laminated composites are widely used in the aerospace sector. All laminates have interply/interlaminar interfaces even if they are made using automated processes. The interfaces act as the areas of weaknesses and the potential crack initiation regions. Hence, any enhancement in the crack initiation and propagation resistance is always sought after. Usage of polymeric thin films is one of the promising and viable ways to achieve this. It is also easy to incorporate micro-thin films into any automation process. In the present study, different customized thin films that are compatible with Glass/BMI composites are fabricated. Fracture toughness tests in Mode I (opening mode), Mode II (sliding mode) and Mixed Mode I/II are conducted respectively using Double Cantilever Beam (DCB), End Notch Flexure (ENF) and Mixed Mode Bending (MMB) test specimens. This paper discusses the manufacturing of compatible micro-thin films. The various challenges faced during the manufacturing and incorporation of thin films are presented. The results of the various fracture toughness tests are examined. Mechanisms through which the different films help in resisting the crack initiation and propagation are deliberated and discussed. The incorporation of this technique in Automated Fiber Placement (AFP) is also discussed.
      Citation: Journal of Composites Science
      PubDate: 2021-02-04
      DOI: 10.3390/jcs5020049
      Issue No: Vol. 5, No. 2 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 50: Study of Monitoring Method and Melt
           Flow Behavior in Compression Molding Process Using Thermoplastic Sheets
           Reinforced with Discontinuous Long-Fibers

    • Authors: Masatoshi Kobayashi
      First page: 50
      Abstract: In compression molding using glass-fiber-mat-reinforced thermoplastic (GMT) sheets, a slightly longer compression waiting time from sheet placement on a lower mold to the start of sheet compression by an upper mold can cause incomplete filling due to a decrease in the sheet temperature. However, precise measurement techniques for compression waiting time have not been sufficiently established. A monitoring system was produced that includes pressure—temperature sensors mounted in a compression mold that can simultaneously measure the pressure and temperature of one local surface. Two types of distance sensors were also used to measure upper mold motion widely and precisely. Determination of compression waiting time was attempted by measuring the moment when the lower mold temperature slightly increases in response to contact with the melted GMT sheet and the moment when the melt pressure increases in response to compression by an upper mold. The results showed that compression waiting time could be precisely calculated using the profile data obtained. Moreover, it was also possible to observe the melt pressure overshoot that occurs depending on sheet stacking patterns and mold cavity shape, although in some cases, the overshoot was not observed. In conclusion, this study has demonstrated that the system is effective in monitoring the compression molding process widely and precisely.
      Citation: Journal of Composites Science
      PubDate: 2021-02-06
      DOI: 10.3390/jcs5020050
      Issue No: Vol. 5, No. 2 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 51: The Working Principles of a
           Multifunctional Bondline with Disbond Stopping and Health Monitoring
           Features for Composite Structures

    • Authors: Julian Steinmetz, Thomas Löbel, Oliver Völkerink, Christian Hühne, Michael Sinapius, Chresten von der Heide, Andreas Dietzel
      First page: 51
      Abstract: In comparison to bolted joints, structural bonds are the desirable joining method for light-weight composite structures. To achieve a broad implementation of this technology in safety critical structures, the issues of structural bonds due to their complex and often unpredictable failure mechanisms have to be overcome. The proposed multifunctional bondline approach aims at solving this by adding two safety mechanisms to structural bondlines. These are a design feature for limiting damages to a certain size and a structural health monitoring system for damage detection. The key question is whether or not the implementation of both safety features without deteriorating the strength in comparison to a healthy conventional bondline is possible. In previous studies on the hybrid bondline, a design feature for damage limitations in bondlines by means of disbond stopping features was already developed. Thus, the approach to evolve the hybrid bondline to a multifunctional one is followed. A thorough analysis of the shear stress and tensile strain distribution within the hybrid bondline demonstrates the feasibility to access the status of the bondline by monitoring either of these quantities. Moreover, the results indicate that it is sufficient to place sensors within the disbond stopping feature only and not throughout the entire bondline. Based on these findings, the three main working principles of the multifunctional are stated. Finally, two initial concepts for a novel multifunctional disbond arrest feature are derived for testing the fundamental hypothesis that the integration of micro sensors into the disbond stopping feature only enables the crack arrest and the health monitoring functions, while reaching the mechanical strength of a conventional healthy epoxy bondline. This work therefore provides the fundamentals for future investigations in the scope of the multifunctional bondline.
      Citation: Journal of Composites Science
      PubDate: 2021-02-07
      DOI: 10.3390/jcs5020051
      Issue No: Vol. 5, No. 2 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 52: Dielectric Constant Enhancement with
           Low Dielectric Loss Growth in Graphene Oxide/Mica/Polypropylene Composites
           

    • Authors: Chao-Yu Lee, Chia-Wei Chang
      First page: 52
      Abstract: Polypropylene has been widely used as dielectric material in organic thin-film capacitors due to their high breakdown strength, low dielectric loss and self-healing capability. However, polypropylene’s energy density is relatively low. Increasing the energy density of polypropylene by adding materials with a high dielectric constant is commonly used. Still, it often leads to an increase in dielectric loss, lower dielectric strength and other shortcomings. In this study, a thin 2D platelet of mica/graphene oxide composite material was made from exfoliated mica as a substrate and attached by graphene oxide. The mica/graphene oxide platelets were added to polypropylene to make a plastic dielectric composite. The non-conductive flat inorganic additive can increase the dielectric constant and dielectric strength of the composite without increasing dielectric loss. The tiny mica/graphene oxide platelets can significantly improve the dielectric properties of polypropylene. The results show that by adding a small amount (less than 1 wt%) mica/graphene oxide, the relative dielectric constant of polypropylene can increase to more than 3.7 without causing an increase in dielectric loss and the dielectric strength of polypropylene can also enhance.
      Citation: Journal of Composites Science
      PubDate: 2021-02-08
      DOI: 10.3390/jcs5020052
      Issue No: Vol. 5, No. 2 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 53: A Lamination Model for
           Pressure-Assisted Sintering of Multilayered Porous Structures

    • Authors: Zhi-He Jin, Corson L. Cramer
      First page: 53
      Abstract: This work describes a lamination model for pressure-assisted sintering of thin, multilayered, and porous structures based on the linear viscous constitutive theory of sintering and the classical laminated plate theory of continuum mechanics. A constant out-of-plane normal stress is assumed in the constitutive relation. The lamination relations between the force/moment resultants and the strain/curvature rates are presented. Numerical simulations were performed for a symmetric tri-layer laminate consisting of a 10% gadolinia doped ceria (Ce0.9Gd0.1O1.95-δ) composite structure, where porous layers were adhered to the top and bottom of a denser layer under uniaxially-applied pressures and the sinter forging conditions. The numerical results show that, compared with free sintering, the applied pressure can significantly reduce the sintering time required to achieve given layer thicknesses and porosities. Unlike free sintering, which results in a monotonic decrease of the laminate in-plane dimension, pressure-assisted sintering may produce an in-plane dimension increase or decrease, depending on the applied pressure and sintering time. Finally, the individual layers in the laminate exhibit different stress characteristics under pressure-assisted sintering.
      Citation: Journal of Composites Science
      PubDate: 2021-02-09
      DOI: 10.3390/jcs5020053
      Issue No: Vol. 5, No. 2 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 54: Fatigue Life Prediction for Carbon-SMC
           and Carbon-FRP by Considering Elastic Modulus Degradation

    • Authors: Yeong Cheol Im, Dong Yeop Kim, Sang Won Lim, Sang Jae Yoon, Chi Hoon Choi, Myung Hyun Kim
      First page: 54
      Abstract: In the automotive industry, being lightweight has become an important design factor with the enhancement of environmental regulations. As a result, many studies on the application of composite materials are in progress. Among them, interest in carbon materials, such as carbon sheet molding compound (C-SMC) and carbon-fiber-reinforced plastic (CFRP), which have excellent strength and stiffness, is increasing. However, CFRP is a material that makes it difficult to secure economic feasibility due to its relatively high manufacturing costs and limited mass production, despite its excellent mechanical strength and durability. As a result, many studies have been conducted on C-SMC as an alternative carbon composite material that can be easily mass-produced. In this regard, this study intended to conduct a study on evaluating the fatigue strength of C-SMC and CFRP among mechanical properties due to the lack of clear failure criteria for fatigue design. We investigated the tensile and fatigue strengths of C-SMC and CFRP, respectively. In the case of C-SMC, the mechanical strength tests were conducted for two different width conditions to evaluate the cutting effect and the machining methods to assess the effects of the edge conditions. To evaluate the fatigue failure assessment criteria, the stiffness drop and elastic modulus degradation criteria were applied for each fatigue test result from the C-SMC and CFRP. The results confirmed that the rationality of the failure criteria in terms of the stiffness drop and the application of the fatigue life prediction of C-SMC based on elastic modulus degradation demonstrated promising results.
      Citation: Journal of Composites Science
      PubDate: 2021-02-10
      DOI: 10.3390/jcs5020054
      Issue No: Vol. 5, No. 2 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 55: On the Use of Molecular Dynamics
           Simulations for Elucidating Fine Structural, Physico-Chemical and
           Thermomechanical Properties of Lignocellulosic Systems: Historical and
           Future Perspectives

    • Authors: Krishnamurthy Prasad, Mostafa Nikzad, Shammi Sultana Nisha, Igor Sbarski
      First page: 55
      Abstract: The use of Molecular Dynamics (MD) simulations for predicting subtle structural, thermomechanical and related characteristics of lignocellulosic systems is studied. A historical perspective and the current state of the art are discussed. The use of parameterised MD force fields, scaling up simulations via high performance computing and intrinsic molecular mechanisms influencing the mechanical, thermal and chemical characteristics of lignocellulosic systems and how these can be predicted and modelled using MD is shown. Individual discussions on the MD simulations of the lignin, cellulose, lignin-carbohydrate complex (LCC) and how MD can elucidate the role of water on the surface and microstructural characteristics of these lignocellulosic systems is shown. In addition, the use of MD for unearthing molecular mechanisms behind lignin-enzyme interactions during precipitation processes and the deforming/structure weakening brought about by cellulosic interactions in some lignocellulosic systems is both predicted and quantified. MD results from relatively smaller systems comprised of several hundred to a few thousand atoms and massive multi-million atom systems are both discussed. The versatility and effectiveness of MD based on its ability to provide viable predictions from both smaller and massive starting systems is presented in detail.
      Citation: Journal of Composites Science
      PubDate: 2021-02-10
      DOI: 10.3390/jcs5020055
      Issue No: Vol. 5, No. 2 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 56: Numerical Analysis of Filament Wound
           Cylindrical Composite Pressure Vessels Accounting for Variable Dome
           Contour

    • Authors: Kumar C. Jois, Marcus Welsh, Thomas Gries, Johannes Sackmann
      First page: 56
      Abstract: In this work, the stress distribution along cylindrical composite pressure vessels with different dome geometries is investigated. The dome contours are generated through an integral method based on shell stresses. Here, the influence of each dome contour on the stress distribution at the interface of the dome-cylinder is evaluated. At first, the integral formulation for dome curve generation is presented and solved for the different dome contours. An analytical approach for the calculation of the secondary stresses in a cylindrical pressure vessel is introduced. For the analysis, three different cases were investigated: (i) a polymer liner; (ii) a single layer of carbon-epoxy composite wrapped on a polymer liner; and (iii) multilayer carbon-epoxy pressure vessel. Accounting for nonlinear geometry is seen to have an effect on the stress distribution on the pressure vessel, also on the isotropic liner. Significant secondary stresses were observed at the dome-cylinder interface and they reach a maximum at a specific distance from the interface. A discussion on the trend in these stresses is presented. The numerical results are compared with the experimental results of the multilayer pressure vessel. It is observed that the secondary stresses present in the vicinity of the dome-cylinder interface has a significant effect on the failure mechanism, especially for thick walled cylindrical composite pressure vessel. It is critical that these secondary stresses are directly accounted for in the initial design phase.
      Citation: Journal of Composites Science
      PubDate: 2021-02-11
      DOI: 10.3390/jcs5020056
      Issue No: Vol. 5, No. 2 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 57: Studies on the Geometrical Design of
           Spider Webs for Reinforced Composite Structures

    • Authors: Yohannes Regassa, Hirpa G. Lemu, Belete Sirabizuh, Samuel Rahimeto
      First page: 57
      Abstract: Spider silk is an astonishingly tough biomaterial that consists almost entirely of large proteins. Studying the secrets behind the high strength nature of spider webs is very challenging due to their miniature size. In spite of their complex nature, researchers have always been inspired to mimic Nature for developing new products or enhancing the performance of existing technologies. Accordingly, the spider web can be taken as a model for optimal fiber orientation for composite materials to be used in critical structural applications. In this study an attempt is made to analyze the geometrical characteristics of the web construction building units such as spirals and radials. As a measurement tool, we have used a developed MATLAB algorithm code for measuring the node to node of rings and radials angle of orientation. Spider web image samples were collected randomly from an ecological niche with black background sample collection tools. The study shows that the radial angle of orientation is 12.7 degrees with 5 mm distance for the spirals’ mesh size. The extracted geometrical numeric values from the spider web show moderately skewed statistical data. The study sheds light on spider web utilization to develop an optimized fiber orientation reinforced composite structure for constructing, for instance, shell structures, pressure vessels and fuselage cones for the aviation industry.
      Citation: Journal of Composites Science
      PubDate: 2021-02-14
      DOI: 10.3390/jcs5020057
      Issue No: Vol. 5, No. 2 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 58: Mechanical and FEA-Assisted
           Characterization of Fused Filament Fabricated Triply Periodic Minimal
           Surface Structures

    • Authors: Nikolaos Kladovasilakis, Konstantinos Tsongas, Dimitrios Tzetzis
      First page: 58
      Abstract: This paper investigates the mechanical behavior of additive manufactured Triply Periodic Minimal Surface (TPMS) structures, such as Gyroid, Schwarz Diamond and Schwarz Primitive. Fused Filament Fabrication (FFF) technique was utilized in order to fabricate lattice structures with different relative densities, at 10%, 20% and 30%, using Polylactic acid (PLA). The test specimens were formed by structural TPMS unit cells and they were tested under quasi-static compression. A finite element analysis (FEA) was performed in order to predict their stress-strain behavior and compare with the experimental results. The results revealed that each architecture influences the mechanical properties of the structure differently depending on the impact of size effect. The structures were designed as sandwich structures (with a top and bottom plate) to avoid significant deterioration of the mechanical behavior, due to the size effect and this was achieved at high relative densities. The Schwarz Diamond structure demonstrated the highest mechanical strength compared with the other architectures, while the Gyroid structure also revealed a similar mechanical performance. In addition, Schwarz Primitive structure showed increased energy absorption especially during plastic deformation. The overall results revealed that the integrity of the mechanical properties of the studied TPMS FFF printed structures deteriorates, as the relative density of the structures decreases.
      Citation: Journal of Composites Science
      PubDate: 2021-02-17
      DOI: 10.3390/jcs5020058
      Issue No: Vol. 5, No. 2 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 59: Optimizing Precursors and Reagents for
           the Development of Alkali-Activated Binders in Ambient Curing Conditions

    • Authors: Dhruv Sood, Khandaker M. Anwar Hossain
      First page: 59
      Abstract: Alkali-activated binders (AABs) are developed through the activation of aluminosilicate-rich materials using alkaline reagents. The characteristics of AABs developed using a novel dry-mixing technique incorporating powder-based reagents/activators are extensively explored. A total of forty-four binder mixes are assessed in terms of their fresh and hardened state properties. The influence of mono/binary/ternary combinations of supplementary cementitious materials (SCMs)/precursors and different types/combinations/dosages of powder-based reagents on the strength and workability properties of different binder mixes are assessed to determine the optimum composition of precursors and the reagents. The binary (55% fly ash class C and 45% ground granulated blast furnace slag) and ternary (25% fly ash class C, 35% fly ash class F and 40% ground granulated blast furnace slag) binders with reagent-2 (calcium hydroxide and sodium sulfate = 2.5:1) exhibited desired workability and 28-day compressive strengths of 56 and 52 MPa, respectively. Microstructural analyses (in terms of SEM/EDS and XRD) revealed the formation of additional calcium aluminosilicate hydrate with sodium or mixed Ca/Na compounds in binary and ternary binders incorporating reagent-2, resulting in higher compressive strength. This research confirms the potential of producing powder-based cement-free green AABs incorporating binary/ternary combinations of SCMs having the desired fresh and hardened state properties under ambient curing conditions.
      Citation: Journal of Composites Science
      PubDate: 2021-02-20
      DOI: 10.3390/jcs5020059
      Issue No: Vol. 5, No. 2 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 60: Strain Mapping and Damage Tracking in
           Carbon Fiber Reinforced Epoxy Composites during Dynamic Bending Until
           Fracture with Quantum Resistive Sensors in Array

    • Authors: Antoine Lemartinel, Mickaël Castro, Olivier Fouché, Julio-César De Luca, Jean-François Feller
      First page: 60
      Abstract: The sustained development of wind energies requires a dramatic rising of turbine blade size especially for their off-shore implantation, which requires as well composite materials with higher performances. In this context, the monitoring of the health of these structures appears essential to decrease maintenance costs, and produce a cheaper kwh. Thus, the input of quantum resistive sensors (QRS) arrays, to monitor the strain gradient in area of interest and anticipate damage in the core of composite structures, without compromising their mechanical properties, sounds promising. QRS are nanostructured strain and damage sensors, transducing strain at the nanoscale into a macroscopic resistive signal for a consumption of only some µW. QRS can be positioned on the surface or in the core of the composite material between plies, and this homogeneously as they are made of the same resin as the composite. The embedded QRS had a gauge factor of 3, which was found more than enough to follow the strain from 0.01% to 1.4% at the final failure. The spatial deployment of four QRS in array made possible for the first time the experimental visualization of a strain field comparable to the numerical simulation. QRS proved also to be able to memorize damage accumulation within the sample and thus could be used to attest the mechanical history of composites.
      Citation: Journal of Composites Science
      PubDate: 2021-02-20
      DOI: 10.3390/jcs5020060
      Issue No: Vol. 5, No. 2 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 61: Thermomechanical Multifunctionality in
           3D-Printed Polystyrene-Boron Nitride Nanotubes (BNNT) Composites

    • Authors: Tawakalt Mayowa Akintola, Phong Tran, Rebekah Downes Sweat, Tarik Dickens
      First page: 61
      Abstract: In this work, polystyrene (PS) and boron nitrides nanotubes (BNNT) composites were fabricated, prepared, and characterized using modified direct mixing and sonication processes. The polymer composites were extruded into filaments (BNNTs at 10 wt. %) for 3D printing, utilizing the fused deposition modeling (FDM) technique to fabricate parts for mechanical and thermal applications. Using a direct mixing process, we found that the thermal conductivity and the mechanical strength of the PS-BNNT composite were respectively four times and two times higher compared to the sonication method. The thermal stability and glass transition temperatures were positively affected. A 2D microstructural mechanical entanglement model captured the exact geometry of the nanotubes using the MultiMechanics software, and the performance of the additive manufactured (AM) PS-BNNT composites part for thermomechanical application was simulated in COMSOL. The modified direct mixing process for PS-BNNT, which affects morphology, proved to be effective in achieving better interfacial bonding, indicating that BNNTs are promising fillers for improving thermal and mechanical properties, and are applicable for thermal management and electronic packaging.
      Citation: Journal of Composites Science
      PubDate: 2021-02-20
      DOI: 10.3390/jcs5020061
      Issue No: Vol. 5, No. 2 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 62: 3D Printed Hierarchical Honeycombs with
           Carbon Fiber and Carbon Nanotube Reinforced Acrylonitrile Butadiene
           Styrene

    • Authors: Michel Theodor Mansour, Konstantinos Tsongas, Dimitrios Tzetzis
      First page: 62
      Abstract: The mechanical properties of Fused Filament Fabrication (FFF) 3D printed specimens of acrylonitrile butadiene styrene (ABS), ABS reinforced with carbon fibers (ABS/CFs) and ABS reinforced with carbon nanotubes (ABS/CNTs) are investigated in this paper using various experimental tests. In particular, the mechanical performance of the fabricated specimens was determined by conducting compression and cyclic compression testing, as well as nanoindentation tests. In addition, the design and the manufacturing of hierarchical honeycomb structures are presented using the materials under study. The 3D printed honeycomb structures were examined by uniaxial compressive tests to review the mechanical behavior of such cellular structures. The compressive performance of the hierarchical honeycomb structures was also evaluated with finite element analysis (FEA) in order to extract the stress-strain response of these structures. The results revealed that the 2nd order hierarchy displayed increased stiffness and strength as compared with the 0th and the 1st hierarchies. Furthermore, the addition of carbon fibers in the ABS matrix improved the stiffness, the strength and the hardness of the FFF printed specimens as well as the compression performance of the honeycomb structures.
      Citation: Journal of Composites Science
      PubDate: 2021-02-21
      DOI: 10.3390/jcs5020062
      Issue No: Vol. 5, No. 2 (2021)
       
  • J. Compos. Sci., Vol. 5, Pages 63: Analysis of Composite Structures in
           Curing Process for Shape Deformations and Shear Stress: Basis for Advanced
           Optimization

    • Authors: Niraj Kumbhare, Reza Moheimani, Hamid Dalir
      First page: 63
      Abstract: Identifying residual stresses and the distortions in composite structures during the curing process plays a vital role in coming up with necessary compensations in the dimensions of mold or prototypes and having precise and optimized parts for the manufacturing and assembly of composite structures. This paper presents an investigation into process-induced shape deformations in composite parts and structures, as well as a comparison of the analysis results to finalize design parameters with a minimum of deformation. A Latin hypercube sampling (LHS) method was used to generate the required random points of the input variables. These variables were then executed with the Ansys Composite Cure Simulation (ACCS) tool, which is an advanced tool used to find stress and distortion values using a three-step analysis, including Ansys Composite PrepPost, transient thermal analysis, and static structural analysis. The deformation results were further utilized to find an optimum design to manufacture a complex composite structure with the compensated dimensions. The simulation results of the ACCS tool are expected to be used by common optimization techniques to finalize a prototype design so that it can reduce common manufacturing errors like warpage, spring-in, and distortion.
      Citation: Journal of Composites Science
      PubDate: 2021-02-23
      DOI: 10.3390/jcs5020063
      Issue No: Vol. 5, No. 2 (2021)
       
 
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