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  Subjects -> ENGINEERING (Total: 2383 journals)
    - CHEMICAL ENGINEERING (204 journals)
    - CIVIL ENGINEERING (199 journals)
    - ELECTRICAL ENGINEERING (109 journals)
    - ENGINEERING (1248 journals)
    - ENGINEERING MECHANICS AND MATERIALS (396 journals)
    - HYDRAULIC ENGINEERING (56 journals)
    - INDUSTRIAL ENGINEERING (74 journals)
    - MECHANICAL ENGINEERING (97 journals)

ENGINEERING (1248 journals)                  1 2 3 4 5 6 7 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 8)
3D Research     Hybrid Journal   (Followers: 20)
AAPG Bulletin     Hybrid Journal   (Followers: 8)
AASRI Procedia     Open Access   (Followers: 14)
Abstract and Applied Analysis     Open Access   (Followers: 3)
Aceh International Journal of Science and Technology     Open Access   (Followers: 2)
ACS Nano     Full-text available via subscription   (Followers: 277)
Acta Geotechnica     Hybrid Journal   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 7)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 3)
Acta Scientiarum. Technology     Open Access   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Active and Passive Electronic Components     Open Access   (Followers: 7)
Adaptive Behavior     Hybrid Journal   (Followers: 11)
Adıyaman Üniversitesi Mühendislik Bilimleri Dergisi     Open Access  
Adsorption     Hybrid Journal   (Followers: 4)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 7)
Advanced Science     Open Access   (Followers: 5)
Advanced Science Focus     Free   (Followers: 5)
Advanced Science Letters     Full-text available via subscription   (Followers: 10)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 18)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Complex Systems     Hybrid Journal   (Followers: 7)
Advances in Engineering Software     Hybrid Journal   (Followers: 27)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 15)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 13)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 21)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 22)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 29)
Advances in Operations Research     Open Access   (Followers: 12)
Advances in OptoElectronics     Open Access   (Followers: 5)
Advances in Physics Theories and Applications     Open Access   (Followers: 13)
Advances in Polymer Science     Hybrid Journal   (Followers: 43)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Remote Sensing     Open Access   (Followers: 44)
Advances in Science and Research (ASR)     Open Access   (Followers: 5)
Aerobiologia     Hybrid Journal   (Followers: 3)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 6)
AIChE Journal     Hybrid Journal   (Followers: 35)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access   (Followers: 1)
Alexandria Engineering Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 26)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 10)
American Journal of Engineering Education     Open Access   (Followers: 9)
American Journal of Environmental Engineering     Open Access   (Followers: 16)
American Journal of Industrial and Business Management     Open Access   (Followers: 23)
Analele Universitatii Ovidius Constanta - Seria Chimie     Open Access  
Annals of Combinatorics     Hybrid Journal   (Followers: 4)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Regional Science     Hybrid Journal   (Followers: 7)
Annals of Science     Hybrid Journal   (Followers: 7)
Antarctic Science     Hybrid Journal   (Followers: 1)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applicable Analysis: An International Journal     Hybrid Journal   (Followers: 1)
Applied Catalysis A: General     Hybrid Journal   (Followers: 6)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 18)
Applied Clay Science     Hybrid Journal   (Followers: 6)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 11)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 4)
Applied Nanoscience     Open Access   (Followers: 8)
Applied Network Science     Open Access   (Followers: 3)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 5)
Applied Sciences     Open Access   (Followers: 3)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4)
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 5)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 5)
Archives of Foundry Engineering     Open Access  
Archives of Thermodynamics     Open Access   (Followers: 8)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 3)
Asia-Pacific Journal of Science and Technology     Open Access  
Asian Engineering Review     Open Access  
Asian Journal of Applied Science and Engineering     Open Access   (Followers: 1)
Asian Journal of Applied Sciences     Open Access   (Followers: 2)
Asian Journal of Biotechnology     Open Access   (Followers: 8)
Asian Journal of Control     Hybrid Journal  
Asian Journal of Current Engineering & Maths     Open Access  
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 8)
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
ATZagenda     Hybrid Journal  
ATZextra worldwide     Hybrid Journal  
Australasian Physical & Engineering Sciences in Medicine     Hybrid Journal   (Followers: 1)
Australian Journal of Multi-Disciplinary Engineering     Full-text available via subscription   (Followers: 2)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 9)
Avances en Ciencias e Ingeniería     Open Access  
Balkan Region Conference on Engineering and Business Education     Open Access   (Followers: 1)
Bangladesh Journal of Scientific and Industrial Research     Open Access  
Basin Research     Hybrid Journal   (Followers: 5)
Batteries     Open Access   (Followers: 6)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 26)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 4)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 1)
BER : Motor Trade Survey     Full-text available via subscription  
BER : Retail Sector Survey     Full-text available via subscription   (Followers: 1)
BER : Retail Survey : Full Survey     Full-text available via subscription   (Followers: 1)
BER : Survey of Business Conditions in Manufacturing : An Executive Summary     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Retail : An Executive Summary     Full-text available via subscription   (Followers: 3)
Beyond : Undergraduate Research Journal     Open Access  
Bhakti Persada : Jurnal Aplikasi IPTEKS     Open Access  
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Biofuels Engineering     Open Access   (Followers: 1)
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 10)
Biomedical Engineering     Hybrid Journal   (Followers: 15)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 13)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 21)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 37)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 9)
Biomedical Science and Engineering     Open Access   (Followers: 4)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 2)
Biotechnology Progress     Hybrid Journal   (Followers: 39)
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription   (Followers: 1)
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access   (Followers: 2)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 12)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 13)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 14)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 31)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 42)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 6)
Case Studies in Thermal Engineering     Open Access   (Followers: 5)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 7)
Catalysis Science and Technology     Free   (Followers: 8)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 7)
CEAS Space Journal     Hybrid Journal   (Followers: 2)
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 3)
Central European Journal of Engineering     Hybrid Journal  
CFD Letters     Open Access   (Followers: 6)
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 2)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
Chinese Journal of Engineering     Open Access   (Followers: 2)
Chinese Science Bulletin     Open Access   (Followers: 1)
Ciencia e Ingenieria Neogranadina     Open Access  
Ciencia en su PC     Open Access   (Followers: 1)
Ciencias Holguin     Open Access   (Followers: 3)
CienciaUAT     Open Access   (Followers: 1)
Cientifica     Open Access  
CIRP Annals - Manufacturing Technology     Full-text available via subscription   (Followers: 11)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 13)
City, Culture and Society     Hybrid Journal   (Followers: 21)
Clay Minerals     Full-text available via subscription   (Followers: 10)
Clean Air Journal     Full-text available via subscription   (Followers: 1)
Clinical Science     Full-text available via subscription   (Followers: 9)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Coastal Engineering     Hybrid Journal   (Followers: 11)
Coastal Engineering Journal     Hybrid Journal   (Followers: 6)
Coatings     Open Access   (Followers: 4)
Cogent Engineering     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Color Research & Application     Hybrid Journal   (Followers: 2)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 14)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 13)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 2)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 28)
Composite Interfaces     Hybrid Journal   (Followers: 7)
Composite Structures     Hybrid Journal   (Followers: 277)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 213)
Composites Part B : Engineering     Hybrid Journal   (Followers: 248)
Composites Science and Technology     Hybrid Journal   (Followers: 188)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 15)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computational Science and Discovery     Full-text available via subscription   (Followers: 2)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 8)
Computer Science and Engineering     Open Access   (Followers: 19)
Computers & Geosciences     Hybrid Journal   (Followers: 31)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 8)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 5)
Computers and Geotechnics     Hybrid Journal   (Followers: 11)
Computing and Visualization in Science     Hybrid Journal   (Followers: 6)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 33)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 8)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 9)
Control Engineering Practice     Hybrid Journal   (Followers: 43)

        1 2 3 4 5 6 7 | Last

Journal Cover Composites Science and Technology
  [SJR: 1.512]   [H-I: 144]   [188 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0266-3538
   Published by Elsevier Homepage  [3175 journals]
  • High performance proton-conducting composite based on vanadium-substituted
           Dawson-type heteropoly acid for proton exchange membranes
    • Authors: Han Wu; Xuefei Wu; Qingyin Wu; Wenfu Yan
      Pages: 1 - 6
      Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): Han Wu, Xuefei Wu, Qingyin Wu, Wenfu Yan
      Proton exchange membranes (PEMs) are the key parts in proton exchange membrane fuel cells (PEMFCs). In this work, a proton-conducting composite membrane rGO-P2W16V2@SPEEK was synthesized from vanadium-substituted Dawson-type heteropoly acid (H8P2W16V2O62•20H2O, abbreviated as P2W16V2), sulfonated polyether ether ketone (SPEEK) and reduced graphene oxide (rGO). Characterizations proved the integrity of the Dawson-structure heteropoly acids (HPAs) in composites and the uniform inorganic-organic hybrid distribution. The membrane shows excellent proton conductivity of 7.90 × 10−2 S cm−1 at 50 °C and the proton conduction was proved to comply with the Grotthuss mechanism. Up to now, this is the first time that a Dawson-type HPA was reported for the application of PEMs and this work extended the application of polyoxometalate-based materials in the field of fuel cells.

      PubDate: 2018-04-23T14:34:31Z
      DOI: 10.1016/j.compscitech.2018.04.018
      Issue No: Vol. 162 (2018)
       
  • Synergetic enhancement of thermal conductivity by constructing hybrid
           conductive network in the segregated polymer composites
    • Authors: Zhi-Guo Wang; Feng Gong; Wan-Cheng Yu; Yan-Fei Huang; Lei Zhu; Jun Lei; Jia-Zhuang Xu; Zhong-Ming Li
      Pages: 7 - 13
      Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): Zhi-Guo Wang, Feng Gong, Wan-Cheng Yu, Yan-Fei Huang, Lei Zhu, Jun Lei, Jia-Zhuang Xu, Zhong-Ming Li
      Effectively thermal conduction pathways are essential for the thermal conductivity of polymer-based composites. In this contribution, we proposed a facile and feasible strategy to improve the thermal conductivity of polymer composites through constructing a segregated structure and hybrid conductive network. Boron nitride (BN) and aluminium nitride (AlN) were mechanically wrapped upon ultrahigh-molecular-weight polyethylene (UHMWPE) granules and then high-pressure consolidated. Morphology observation revealed that in the typical segregated pathways, polyhedral AlNs were in tandem with adjacent BN plates. A significantly synergistic enhancement in the thermal conductivity was achieved by the hybrid conductive network. At the total filler content of 50 wt%, the BN/AlN/UHMWPE composite with a filler ratio of 6:1 showed the thermal conductivity of 7.1 Wm-1 K−1, outperforming BN/UHMWPE and AlN/UHMWPE composites by 35.1% and 613%, respectively. Infrared thermal images further demonstrated that the composites with hybrid segregated structure had strongest capability to dissipate the heat against the counterparts with single segregated structure. Based on the percolation effect with an effective medium approach, the theoretical calculation suggested that AlN played a bridge role to interconnect the BN platelets in the segregated conductive pathways, leading to the formation of the more effective thermally conductive pathways. The obtained results offer valuable fundamentals to design and fabricate the highly thermal-conductive polymer composites as advanced thermal management materials.

      PubDate: 2018-04-23T14:34:31Z
      DOI: 10.1016/j.compscitech.2018.03.016
      Issue No: Vol. 162 (2018)
       
  • Synthesis of highly-stretchable graphene – poly(glycerol sebacate)
           elastomeric nanocomposites piezoresistive sensors for human motion
           detection applications
    • Authors: Yi Yan; Michael Potts; Zhengyi Jiang; Vitor Sencadas
      Pages: 14 - 22
      Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): Yi Yan, Michael Potts, Zhengyi Jiang, Vitor Sencadas
      Strain sensors capable of monitoring human motion are highly desirable not only to monitor in real time complex body parts movement but also to assess the patients' health condition. In this work, highly stretchable elastomeric nanocomposite strain sensors were developed by synthesis of poly(glycerol sebacate) (PGS) prepolymer, followed by incorporation of the graphene flakes (fG) during the curing procedure of the PGS elastomeric matrix. The PGS had Young's modulus ( E ) of 69 ± 6 kPa, while the sample with 10 wt% fG had a E of 501 ± 28 kPa, which is as soft as human skin. Moreover, the incorporation of the fG filler led to an increase of the matrix cross-linking density, from 8.0 ± 0.6 mol/m3, up to 35.5 ± 1.4 mol/m3, recorded for the pure matrix and for the sample with 10 wt% fG, respectively. The electromechanical behavior of the nanocomposite samples showed that the resistance changes linearly with the applied strain, until a maximum strain of 50%, and is independent of the stroke speed or applied strain. The nanocomposite sensor sensibility was calculated through the gauge Factor (GF), and a value of ∼2 was obtained for all the processed strain gauges. Furthermore, the developed sensors showed a remarkable capability to monitor the bending movement of the finger. Finally, the performance revealed by the synthetized piezoresistive sensors will contribute to the next generation of highly stretchable smart materials for sensing and control human motion with minimum discomfort.

      PubDate: 2018-04-23T14:34:31Z
      DOI: 10.1016/j.compscitech.2018.04.010
      Issue No: Vol. 162 (2018)
       
  • Improving thermal, electrical and mechanical properties of
           fluoroelastomer/amino-functionalized multi-walled carbon nanotube
           composites by constructing dual crosslinking networks
    • Authors: Wei Gao; Jianhua Guo; Junbin Xiong; Andrew T. Smith; Luyi Sun
      Pages: 49 - 57
      Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): Wei Gao, Jianhua Guo, Junbin Xiong, Andrew T. Smith, Luyi Sun
      Carboxylic functionalized multi-walled carbon nanotubes (MWCNTs-COOH) were modified by using ethylenediamine (EDA) to prepare amino-functionalized multi-walled carbon nanotubes (MWCNTs-A). MWCNTs-A were characterized by Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Fluoroelastomer (FKM) was reinforced by incorporation of MWCNTs-COOH and MWCNTs-A, respectively. The thermal, electrical and mechanical properties of the FKM/MWCNT composites were studied. The results indicated that a more homogeneous dispersion of nanotubes and a stronger interfacial interaction in FKM/MWCNTs-A composites were achieved than in FKM/MWCNTs-COOH ones. As a result, the thermal, electrical and mechanical properties of the FKM/MWCNTs-A composites were higher than that of the FKM/MWCNTs-COOH composites due to the participation of MWCNTs-A in the crosslinking process to form dual crosslinking networks in the FKM matrix.

      PubDate: 2018-04-23T14:34:31Z
      DOI: 10.1016/j.compscitech.2018.04.022
      Issue No: Vol. 162 (2018)
       
  • Hybrid core-shell nanofibers as moisture sensors for human breath
           monitoring
    • Authors: Ruihua Lv; Shuai Li; Tianxiang Jin; Bing Na; Haiying Zhou; Hesheng Liu
      Pages: 58 - 63
      Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): Ruihua Lv, Shuai Li, Tianxiang Jin, Bing Na, Haiying Zhou, Hesheng Liu
      This study reports moisture sensors for monitoring human breath process. The sensors are assembled from hybrid core-shell nanofibers with electrospun poly (acrylonitrile) nanofibers as the mechanical core and thin polyaniline shells as the moisture sensing material, respectively. The polyaniline shells are coated on the electrospun nanofibers via in situ polymerization. The sensors are sensitive to moisture breathed out from both mouth and nose; and their response is determined by the loading and morphology of polyaniline as well as the amount of moisture. In combination with high porosity and mechanical flexibility, the sensors can be readily integrated with textiles to fabricate wearable electronics.

      PubDate: 2018-04-23T14:34:31Z
      DOI: 10.1016/j.compscitech.2018.04.021
      Issue No: Vol. 162 (2018)
       
  • A review of flammability of natural fibre reinforced polymeric composites
    • Authors: N.K. Kim; S. Dutta; D. Bhattacharyya
      Pages: 64 - 78
      Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): N.K. Kim, S. Dutta, D. Bhattacharyya
      Susceptibility to damage from heat and flame is one of the major issues for utilisation of natural fibre reinforced polymeric composites in practical applications. Thus, the knowledge of thermal decomposition and flammability of the bio-based fibres, polymers and their composites is highly required for the materials selection and the development of composite products. Moreover, suitable flame retardant treatments on these composites have shown to effectively enhance their thermal stability and fire resistance. This article provides a review of research on thermal behaviour and flammability of natural fibres, such as cellulose and protein based fibres, and polymers along with composites filled with these materials. Furthermore, eco-friendly flame retardant treatments to overcome the environmental impact of conventional flame retardants are introduced with the combined effects of natural fibres on composites' fire performance. In addition, a review of studies on the predictive models regarding thermal response and structural damages of composites in fire is also included with their advantages and limitations.

      PubDate: 2018-04-30T15:00:04Z
      DOI: 10.1016/j.compscitech.2018.04.016
      Issue No: Vol. 162 (2018)
       
  • Extension of Puck's inter fibre fracture (IFF) criteria for UD composites
    • Authors: Jiefei Gu; Puhui Chen
      Pages: 79 - 85
      Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): Jiefei Gu, Puhui Chen
      Puck's action plane failure criteria have already proven their capability in the first and second world-wide failure exercises (WWFE-I and WWFE-II). However, Puck and his co-workers have only recommended inclination parameters for GFRP/Epoxy and CFRP/Epoxy. These UD composites generally have high transverse compressive-to-tensile strength ratios Y C /Y T , and are regarded by them as intrinsically brittle materials. Therefore, Puck's inter fibre fracture (IFF) criteria might not be directly applied to other types of UD composites with low Y C /Y T ratios. In particular, Puck's original IFF criteria will result in unrealistic predictions if Y C /Y T is extremely low. In the present study, Puck's original IFF criteria are extended to all types of UD composite materials to solve the problem. Composites are divided into three categories, namely semi-brittle materials, brittle materials, and intrinsically brittle materials. Depending on the material category, three different algorithms are proposed for determination of the two parameters in Puck's IFF criteria, namely the resistance of the action plane against transverse tensile stressing, R ⊥ A t , as well as the inclination parameter of contour lines of the fracture body, p ⊥ ⊥ . The present criteria are theoretically evaluated for composites with low Y C /Y T ratios, while the predictions of the present criteria are compared with the test results of composites with high Y C /Y T ratios such as thermoset GFRP and CFRP. Theoretical and experimental assessment demonstrates the reasonableness of the extension of Puck's IFF criteria.

      PubDate: 2018-04-30T15:00:04Z
      DOI: 10.1016/j.compscitech.2018.04.019
      Issue No: Vol. 162 (2018)
       
  • In situ experimental investigation on the out-plane damage evolution of 3D
           woven carbon-fiber reinforced composites
    • Authors: Zhixing Li; Licheng Guo; Li Zhang; Qimei Wang
      Pages: 101 - 109
      Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): Zhixing Li, Licheng Guo, Li Zhang, Qimei Wang
      The damage evolution study on 3D woven carbon-fiber reinforced composites has always been a challenge to the research community. In this paper, a new in situ experimental method is proposed to realize the non-destructive observation of the failure process of 3D woven carbon-fiber reinforced composites. Synchrotron radiation computer tomography (SRCT), an in situ load frame and new-style specimens are integrated. With the method, the 3D crack initiation and propagation can be continuously recorded by the SRCT scanner. Through analyzing the experimental results, the out-plane failure mechanism under tension and shear loads is found. Particularly, it is shown that the interface property is the leading factor affecting out-plane strengths. Moreover, the effect of braiding angle on the out-plane strengths in different directions is discussed. According to the failure modes, it can be concluded that with the increasing of the braiding angle, the out-plane tension strength will increase but the out-plane shear strength will decrease. The proposed in situ experimental method and the above findings are significant to calibration of failure prediction model and the novel design of woven composites.

      PubDate: 2018-04-30T15:00:04Z
      DOI: 10.1016/j.compscitech.2018.04.024
      Issue No: Vol. 162 (2018)
       
  • Advanced Green composites using liquid crystalline cellulose fibers and
           waxy maize starch based resin
    • Authors: Muhammad M. Rahman; Anil N. Netravali
      Pages: 110 - 116
      Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): Muhammad M. Rahman, Anil N. Netravali
      Advanced green composites have been fabricated by using modified liquid crystalline cellulose (M-LCC) fibers and micro-fibrillated cellulose (MFC) modified waxy maize starch (M-WMS) based resin. LCC fibers, as a reinforcement, were modified in terms of tensile properties by a combination of chemical and heat treatment, under a predetermined tension. The surface topography, crystallinity, molecular alignment, and mechanical properties of M-LCC fibers were investigated to determine the effects of combination modification process on the fibers. M-WMS, as a resin, was prepared by two steps. In the first step, an environment-friendly cross-linker, 1,2,3,4-butane tetracarboxylic acid (BTCA), was used to improve the water resistance and tensile properties of the resin. In the second step, ‘MFC’, as reinforcing agent, was dispersed in the cross-linked resin to obtain substantial improvements in its tensile properties. Unidirectional advanced green composites consisting of M-LCC fibers and M-WMS were fabricated using hand lay-up followed by a compression molding process. The results showed that the M-LCC fibers had strength close to 2 GPa and the composites had strength close to 800 MPa. These advanced green composites could be used in structural applications.

      PubDate: 2018-04-30T15:00:04Z
      DOI: 10.1016/j.compscitech.2018.04.023
      Issue No: Vol. 162 (2018)
       
  • Microwave nondestructive detection and quantitative evaluation of kissing
           defects in GFRP laminates
    • Authors: Peiyu Wang; Zhencheng Li; Licheng Zhou; Yongmao Pei
      Pages: 117 - 122
      Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): Peiyu Wang, Zhencheng Li, Licheng Zhou, Yongmao Pei
      Kissing defects remain difficult to detect due to insufficient contrast. Herein we proposed a microwave equiphase frequency truncation method (EFTM) to detect and evaluate the thickness of kissing defects in GFRP laminates. It is found that the frequency difference varies linearly with the kissing defect thickness under the assumption of single reflection, and the linear slope is approximately in inverse proportion to the product of the thickness and permittivity term of the specimen. Theoretical calculation, simulation and experimental detection results of GFRP laminates and Teflon specimens all showed a fine linearity relationship between the frequency difference and the thickness of kissing defect. Besides, the experimental linear slopes were in good agreement with theoretical predictions for both GFRP and Teflon specimens, which indicates the applicability of this method for different dielectric materials. The experimental results clearly showed that kissing defects of 2.92 μm was successfully detected and quantified. In summary, this method is feasible and effective in detecting and evaluating kissing defects in dielectric laminates.

      PubDate: 2018-04-30T15:00:04Z
      DOI: 10.1016/j.compscitech.2018.04.029
      Issue No: Vol. 162 (2018)
       
  • Estimation of interfacial toughness using bilayer fiber bundle compact
           tension (BFBCT) specimens
    • Authors: Guocheng Qi; Boming Zhang; Shanyi Du
      Pages: 1 - 7
      Abstract: Publication date: 16 June 2018
      Source:Composites Science and Technology, Volume 161
      Author(s): Guocheng Qi, Boming Zhang, Shanyi Du
      This work aims at characterizing the interfacial toughness based on the mode I interlayer fracture toughness of bilayer fiber bundle compact tension (BFBCT) specimens. Extensive fiber/matrix interfacial deboning was found along the crack propagation path in mode I delamination test of BFBCT specimens. The apparent G Ic values could distinguish interfacial toughness properties of different carbon and aramid fiber/matrix systems. The transverse fiber bundle tension (TFBT) test for evaluating interfacial bonding strength was also performed as a comparison. It was found that the interface between T800H carbon fiber and epoxy was both the strongest and the toughest among all tested carbon fiber/epoxy interfaces. Compared with carbon fibers, aramid fibers possessed a higher interfacial toughness but a lower interfacial strength. The mode I delamination test of BFBCT specimens is a simple and reliable method for evaluating interfacial toughness in composites. BFBCT test as well as TFBT test can be used to comprehensively characterize the strength and toughness properties for fiber/matrix interface based on fiber bundle specimens.

      PubDate: 2018-04-15T16:20:50Z
      DOI: 10.1016/j.compscitech.2018.03.029
      Issue No: Vol. 161 (2018)
       
  • Self-bonding sandwiched membranes from PDMS and cellulose nanocrystals by
           engineering strategy of layer-by-layer curing
    • Authors: Tao Xia; Hongjuan Yuwen; Ning Lin
      Pages: 8 - 15
      Abstract: Publication date: 16 June 2018
      Source:Composites Science and Technology, Volume 161
      Author(s): Tao Xia, Hongjuan Yuwen, Ning Lin
      Multilayer materials attracted intense scientific interests in view of their special interlayer structure and potential application in diverse fields. Different from the conventional approach of layer-by-layer assembly, in this study we proposed an engineering approach of layer-by-layer curing from polydimethylsiloxane (PDMS) elastomer and rigid cellulose nanocrystals (CNC). The covalent-bonding from the crosslinking curing reaction as the driving force ensured the strong interlayers adhesion, and meanwhile the nanoreinforcing effect from silylated CNC in the composite layers provided the tailor-made physicochemical properties for the fabricated multilayer membranes. The multilayer structures indicating the good interlayers' adhesion and structural integrity of the di- and tri-layer membranes were observed from the microscopy characterization. In comparison with the monolayer PDMS membrane, the developed CPC trilayer membrane (possessing the sandwiched structure of two composite layers and one neat layer) exhibited the advancement on the storage modulus, special optical scattering and hazing, dielectric permittivity and barrier performance, derived from the nanoscaled reinforcing and obstruction effects of rod-like natural nanoparticles (SiCNC).

      PubDate: 2018-04-15T16:20:50Z
      DOI: 10.1016/j.compscitech.2018.03.038
      Issue No: Vol. 161 (2018)
       
  • Polymer composites with lychee-like core covered by segregated conducting
           and flexible networks: unique morphology, high flexibility, stretchability
           and thermoelectric performance
    • Authors: Chuanghong Xiao; Yufeng Xue; Minhuan Liu; Xiubin Xu; Xu Wu; Zhengping Wang; Yan Xu; Guangming Chen
      Pages: 16 - 21
      Abstract: Publication date: 16 June 2018
      Source:Composites Science and Technology, Volume 161
      Author(s): Chuanghong Xiao, Yufeng Xue, Minhuan Liu, Xiubin Xu, Xu Wu, Zhengping Wang, Yan Xu, Guangming Chen
      Polymer nanocomposites show great potential as platforms for the development of organic synthetic devices and systems, while a rational structural design of the matrix and the precursors are still urgently needed to ensure the viable development of these composite materials. Here, we report the controlled preparation of the novel composites with lychee-like polymer core covered by carbon nanotube/polyurethane segregated conducting and flexible networks. The composites were fabricated using a simple aqueous coating strategy. The resultant self-supporting films showed outstanding flexibility and stretchability with the minimum bending radius of less than 1 mm and an elongation at break of 3.8%. In addition, the composite films exhibited excellent thermoelectric function with the electrical conductivity, Seebeck coefficient, and power factor of 109.3 ± 4.3 S cm−1, 24.0 ± 0.2 μV K−1, and 6.28 ± 0.52 μW m−1 K−2, respectively.

      PubDate: 2018-04-15T16:20:50Z
      DOI: 10.1016/j.compscitech.2018.03.039
      Issue No: Vol. 161 (2018)
       
  • Stitched shape memory alloy wires enhance damage recovery in self-healing
           fibre-reinforced polymer composites
    • Authors: Amaël Cohades; Nathan Hostettler; Malvina Pauchard; Christopher J.G. Plummer; Véronique Michaud
      Pages: 22 - 31
      Abstract: Publication date: 16 June 2018
      Source:Composites Science and Technology, Volume 161
      Author(s): Amaël Cohades, Nathan Hostettler, Malvina Pauchard, Christopher J.G. Plummer, Véronique Michaud
      A major issue in composite technology is matrix micro-cracking due to low-velocity impact damage, which may severely limit service lifetimes of composite parts. In a novel approach, remarkable levels of healing of impact damage are obtained using shape memory alloy (SMA) wires to close longitudinal cracks in woven glass fibre-reinforced polymer plates with an epoxy-polycaprolactone (EP-PCL) matrix that shows dual-phase continuity. Thermal actuation of SMA wires stitched through the thickness of the stacked glass fibre plies introduces compressive loads to the cracks thanks to anchoring of the SMA loops at the fabric surfaces and debonding of the intervening threads, which prevents local deformation of the SMA, so that crack closure by about 200 μm is achievable. Concomitant expansion of the vascular network formed by the molten PCL fills the compressed cracks, resulting in highly effective healing on cooling, as demonstrated by C-scan images. Specimens stitched with SMA wires hence show almost complete healing, i.e. damage area recovery of 85%, after low-velocity impact at up to 17 J followed by heat treatment at 150 °C. This represents a 55% improvement over previous results for unstitched EP-PCL composites, and hence significantly greater degrees of healing than so far reported for this range of impact energies and this type of system.

      PubDate: 2018-04-15T16:20:50Z
      DOI: 10.1016/j.compscitech.2018.03.040
      Issue No: Vol. 161 (2018)
       
  • Structures and properties of alkanethiol-modified graphene
           oxide/solution-polymerized styrene butadiene rubber composites: Click
           chemistry and molecular dynamics simulation
    • Authors: Yanlong Luo; Youping Wu; Kaiqiang Luo; Fei Cai; Tianshu Zhai; Sizhu Wu
      Pages: 32 - 38
      Abstract: Publication date: 16 June 2018
      Source:Composites Science and Technology, Volume 161
      Author(s): Yanlong Luo, Youping Wu, Kaiqiang Luo, Fei Cai, Tianshu Zhai, Sizhu Wu
      Alkanethiol-modified graphene oxides (GOs) containing alkanethiol (C x GO) molecules with varying chain lengths were synthesized through click chemistry. Then, C x GO/solution-polymerized styrene butadiene rubber (C x GO/SSBR) composites with different C x GO loadings were prepared by a solution-mixing method. By combining experiment and molecular dynamics (MD) simulation, we investigated the relationship between the microstructures and properties of the C x GO/SSBR composites. Results showed that the 1-heptanethiol-modified GO (C7GO)/SSBR composite had the smallest fractional free volume and the least mobility of the polymer chains. Moreover, the 1-octadecanethiol-modified GO (C18GO)/SSBR composite displayed the largest binding energy (E binding ). Thermal stability, gas barrier, dynamic, and static mechanical properties were improved by introducing C x GO. The long chain length of C x GO indicated that the composites had good performance. We believe that these results provide a basis for the design and fabrication of high-performance GO/SSBR composites.

      PubDate: 2018-04-15T16:20:50Z
      DOI: 10.1016/j.compscitech.2018.03.036
      Issue No: Vol. 161 (2018)
       
  • Functionalized MWCNTs modified flame retardant PLA nanocomposites and cold
           rolling process for improving mechanical properties
    • Authors: Liqiang Gu; Jianhui Qiu; Youwei Yao; Eiichi Sakai; Liting Yang
      Pages: 39 - 49
      Abstract: Publication date: 16 June 2018
      Source:Composites Science and Technology, Volume 161
      Author(s): Liqiang Gu, Jianhui Qiu, Youwei Yao, Eiichi Sakai, Liting Yang
      10-hydroxy-9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-OH) has been successfully covalently grafted onto the surfaces of multi-walled carbon nanotubes (MWCNTs) to obtain DOPO-functionalized MWCNTs (MWCNT-DOPO-OH) by a three-step process. The resultant core-shell nanostructured MWCNT-DOPO-OH was introduced into aluminum hypophosphite/poly(lactic acid) (AHP/PLA) flame retardant systems via melt blending to improve both flame retardancy and mechanical properties. AHP/PLA/MWCNT-DOPO-OH nanocomposites with synergistic effect of 1 wt.% MWCNT-DOPO-OH and 14 wt.% AHP were shown to be effective in improving flame retardancy with UL 94 V-0 rating and limiting oxygen index (LOI) value of 28.6. And these flame-retardant nanocomposites show a usable T g higher than 57.8 °C and much higher char yield for preventing the anti-dropping. Moreover, a cold rolling process was performed for AHP/PLA/MWCNT-DOPO-OH nanocomposites to further improve the mechanical properties for secondary processing. For 1 wt.% MWCNT-DOPO-OH loading PLA nanocomposites, the tensile strength increased from 69.5 MPa to 77.9 MPa and 82.0 MPa, and the fracture strain increased from 17.9% to 27.5% and 120%, at rolling ratios of 30% and 50%, respectively, indicating that MWCNT-DOPO-OH modified PLA was homogenized plastic deformation during the rolling process.

      PubDate: 2018-04-15T16:20:50Z
      DOI: 10.1016/j.compscitech.2018.03.033
      Issue No: Vol. 161 (2018)
       
  • Simultaneous enhancement of electrical conductivity and mechanical
           properties in buckypaper-reinforced polydivinylbenzene(doped polyaniline)
           composites
    • Authors: Xiuyan Cheng; Tomohiro Yokozeki; Haopeng Wang; Lixin Wu; Qing-Fu Sun
      Pages: 50 - 56
      Abstract: Publication date: 16 June 2018
      Source:Composites Science and Technology, Volume 161
      Author(s): Xiuyan Cheng, Tomohiro Yokozeki, Haopeng Wang, Lixin Wu, Qing-Fu Sun
      The key barrier to design conductive polymer composites with maintained mechanical performance is to increase the content of conductive nanofillers with well-dispersity in the polymer matrix. Here we report new buckypaper (BP) reinforced polydivinylbenzene (PDVB)/doped polyaniline (DPANI) composites with significant improvement in both electrical and mechanical properties. The composites have been fabricated through a positive-pressure filtration method which features high loading of well-dispersed oxidized MWCNTs. The electrical conductivity and the elastic modulus of the BP reinforced composites were found to be 11.56 and 6.88-times improved, respectively, compared to the native PDVB(DPANI). The enhancement mechanism is explained by the formation of electrical transport pathways and an extensive molecular-level interaction between BP and DPANI. The enhancement effect has also been confirmed by comparing the experiment result with theoretical calculations following the Tandon-Weng model. The fabrication strategy and the analysis method presented herein can be used for the design of new functional polymer composites with both high electrical conductivity and high modulus.

      PubDate: 2018-04-15T16:20:50Z
      DOI: 10.1016/j.compscitech.2018.03.042
      Issue No: Vol. 161 (2018)
       
  • Enhancement of mechanical, thermal and morphological properties of
           compatibilized graphene reinforced dynamically vulcanized thermoplastic
           elastomer vulcanizates based on polyethylene and reclaimed rubber
    • Authors: S.M.R. Paran; G. Naderi; M.H.R. Ghoreishy; A. Heydari
      Pages: 57 - 65
      Abstract: Publication date: 16 June 2018
      Source:Composites Science and Technology, Volume 161
      Author(s): S.M.R. Paran, G. Naderi, M.H.R. Ghoreishy, A. Heydari
      The effect of graphene nanoplatelets (GnPs) introduction into the compatibilized multiphase polymer systems such as dynamically vulcanized thermoplastic elastomers (TPVs) based on linear low density polyethylene (LLDPE) and reclaimed rubber (RR) was explored through using the experimental and theoretical analysis. The nanocomposites were prepared by using traditional melt mixing method and characterized by various experimental measurements including transmission electron microscopy (TEM), scanning electron microscopy (SEM), differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), Dynamic mechanical thermal analysis (DMTA), tensile test and rheological measurements. The morphological investigations of prepared TPV nanocomposites show the considerable effect of GnPs on the size reduction of rubber droplets. The DSC measurements indicated the role of GnPs as an effective nucleating agent in the TPV nanocomposites. The results of TGA measurements show that the GnPs can cause a higher thermal stability in LLDPE/RR TPVs especially in the presence of a maleated polyethylene (MA-PE) as a compatibilizer. The mechanical properties exploration of TPV nanocomposites represents the considerable effect of GnPs on the increasing of Young's modulus. The analytical stiffness analysis through using Christensen-Lo model with emphasizing the effect of interphase region could precisely predict the effect of various GnPs loading on the Young's modulus. Fabrication of an industrial applicable TPV nanocomposites with enhanced mechanical, thermal and morphological properties could be achieved by using both the proper loadings of GnPs and compatibilizer.

      PubDate: 2018-04-15T16:20:50Z
      DOI: 10.1016/j.compscitech.2018.04.006
      Issue No: Vol. 161 (2018)
       
  • Plasma poly(acrylic acid) compatibilized hydroxyapatite-polylactide
           biocomposites for their use as body-absorbable osteosynthesis devices
    • Authors: S. Petisco-Ferrero; L. Pérez Álvarez; L. Ruiz-Rubio; J.L. Vilas Vilela; J.R. Sarasua
      Pages: 66 - 73
      Abstract: Publication date: 16 June 2018
      Source:Composites Science and Technology, Volume 161
      Author(s): S. Petisco-Ferrero, L. Pérez Álvarez, L. Ruiz-Rubio, J.L. Vilas Vilela, J.R. Sarasua
      The nanoscale interface between hydroxyapatite (HA) particles and PLLA matrix appears to be the determining factor for poor mechanical performance of this family of biocomposites in load-bearing applications. It has been demonstrated that when these biocomposites are loaded, the physical adsorption between inorganic particles and polymeric matrix does not allow for load transfer and additional free surfaces that act as crack nucleators are created. To overcome this limitation, we propose plasma polymerization of poly (acrylic acid) (PAA) on HA particles as an effective method to produce strong interactions with the polylactide (PLLA) matrix. In this work, evidences of an intimate bonding between HAPAA particles and PLLA are given. Based on the thermodegradation behaviour of the composites it was found that the plasma deposited layer arrested free hydroxyl groups of PLLA chains, hindering the transesterification reactions that cause the thermal degradation of PLLA. As a result, thermal degradation of the composites was retarded and followed the chain scission route producing acetaldehyde, CO and CO2. From the mechanical characterization it became clear that load transfer was developed by means of the PAA compatibilized interface resulting in the observed enhancement of the elasticity and damping behaviour of the biocomposites.

      PubDate: 2018-04-15T16:20:50Z
      DOI: 10.1016/j.compscitech.2018.04.001
      Issue No: Vol. 161 (2018)
       
  • Analyzing effects of interfaces on recovery rates of shape memory
           composites from the perspective of molecular motions
    • Abstract: Publication date: 28 July 2018
      Source:Composites Science and Technology, Volume 163
      Author(s): Hairong Chen, Hong Xia, Yiping Qiu, Qing-Qing Ni
      Over recent years, researchers have noticed that recovery rates of shape memory composites (SMCs) would vary due to the addition of fillers. So far, although several superficial reasons are discussed, a thorough analysis has not been presented yet probably due to the absence of a microscopic mechanism of SMCs. Here, a molecular mechanism of SMCs is clarified by identifying the differences lying in molecular motions of shape memory polymers and SMCs. On the basis of the molecular mechanism of SMCs, both a positive effect and a negative effect of fillers on recovery rates are revealed. Because interfaces between fillers and matrices play a decisive role in the two effects of fillers, several experiments are designed to verify the role of interfaces. The experimental results prove that the interfaces are benefit and harmful for recovery rates at the same time. Moreover, the results are able to qualitatively predict that the recovery rates of SMCs would increase or decrease with more addition of fillers.

      PubDate: 2018-05-18T02:44:01Z
       
  • Effect of functional groups on the agglomeration of graphene in
           nanocomposites
    • Abstract: Publication date: 28 July 2018
      Source:Composites Science and Technology, Volume 163
      Author(s): Zheling Li, Jingwen Chu, Cheng Yang, Sijia Hao, Mark A. Bissett, Ian A. Kinloch, Robert J. Young
      A base wash procedure was used to partially remove the oxygen functional groups from the graphene oxide (GO) flakes to prepare the base-washed GO (BwGO). It is found that the base wash treatment does not alter the physical properties (size, thickness etc.) of the GO significantly but the chemical composition is changed. Nanocomposites were prepared by incorporating the BwGO flakes obtained in a poly(vinyl alcohol) (PVA) matrix. It was found the storage modulus of the nanocomposites is enhanced from 4.4 GPa to 6.5 GPa with 5 wt% of BwGO. This is in agreement with the micromechanical estimation obtained by using Raman spectroscopy that follows the interfacial stress transfer from the matrix to the BwGO fillers. The lower effective modulus of BwGO than GO as calculated using the classical ‘rule of mixtures’ is due to the loss of functional groups on GO that serve as a surfactant to prevent the flakes from re-agglomerating. An agglomeration factor η a is therefore proposed and a concept of ‘effective volume fraction’ is introduced to quantify and evaluate the level of agglomeration of fillers in nanocomposites, which can be otherwise difficult to visualize optically. It is found that the removal of the functional groups causes the flakes to re-agglomerate, and reduces the ‘effective volume fraction’ by about 10–20%.

      PubDate: 2018-05-18T02:44:01Z
       
  • Smart composites of piezoelectric particles and shape memory polymers for
           actuation and nanopositioning
    • Abstract: Publication date: 28 July 2018
      Source:Composites Science and Technology, Volume 163
      Author(s): Hairong Chen, Hong Xia, Yiping Qiu, Zhenzhen Xu, Qing-Qing Ni
      To combine the piezoelectric effect and shape memory effect, various kinds of smart composites are developed through compounding lead zirconate titanate (PZT) particles with average diameters of 400 nm and shape memory polyurethane (SMPU) matrices. Compared with pristine SMPU, the resulting composites are enhanced by more than 133% in the maximum recovery stresses. Additionally, the film actuators made from these composites can generate 1 nm resolution displacements without any control method in a common laboratory environment when the step voltage signals are applied to them. This feature partly profits from the softness of SMPU matrices which, to some extent, protects PZT particles from ambient noise. Moreover, taking the advantage of shape memory effect easily deforms the film actuators into a variety of designed shapes. As a consequence, the shaped actuators are able to produce many more displacements while the positioning errors remain the same. The displacements of the “U” type actuator and the “Z” type actuator are respectively 18 nm (about 4.7 times displacement of the corresponding film actuator) at 840 V and 75 nm (about 13.3 times displacement of the corresponding film actuator) at 600 V. The proposed smart composites strongly show the potential to lower the requirements of nanopositioning and reduce costs.
      Graphical abstract image

      PubDate: 2018-05-18T02:44:01Z
       
  • Cellulose-carbon nanotube composite aerogels as novel thermoelectric
           materials
    • Abstract: Publication date: 28 July 2018
      Source:Composites Science and Technology, Volume 163
      Author(s): Minoj Gnanaseelan, Yian Chen, Jinji Luo, Beate Krause, Jürgen Pionteck, Petra Pötschke, Haisong Qi
      Thermoelectric materials based on cellulose/carbon nanotube (CNT) nanocomposites have been developed by a facile approach and the effects of amount (2–10 wt%) and types of CNTs (single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs)) on the morphology (films and aerogels) and the thermoelectric properties of the nanocomposites have been investigated. Composite films based on SWCNTs showed significantly higher electrical conductivity (5 S/cm at 10 wt%) and Seebeck coefficient (47.2 μV/K at 10 wt%) compared to those based on MWCNTs (0.9 S/cm and 11 μV/K, respectively). Lyophilization, leading to development of aerogels with sub-micron sized pores, decreased the electrical conductivity for both types by one order of magnitude, but did not affect the Seebeck coefficient of MWCNT based nanocomposites. For SWCNT containing aerogels, higher Seebeck coefficients than for films were measured at 3 and 4 wt% but significantly lower values at higher loadings. CNT addition increased the thermal conductivity from 0.06 to 0.12 W/(m∙K) in the films, whereas the lyophilization significantly reduced it towards values between 0.01 and 0.09 W/(m∙K) for the aerogels. The maximum Seebeck coefficient, power factor, and ZT observed in this study are 49 μV/K for aerogels with 3 wt% SWCNTs, 1.1 μW/(m∙K2) for composite films with 10 wt% SWCNTs, and 7.4 × 10−4 for films with 8 wt% SWCNTs, respectively.

      PubDate: 2018-05-18T02:44:01Z
       
  • Mechanical properties of polypropylene composites reinforced by hydrolyzed
           and microfibrillated Kevlar fibers
    • Abstract: Publication date: 28 July 2018
      Source:Composites Science and Technology, Volume 163
      Author(s): Sirui Fu, Bowen Yu, Wei Tang, Mao Fan, Feng Chen, Qiang Fu
      As a traditional general plastic, polypropylene (PP) has been widely used in daily life. Glass fibers are often used to further reinforce the properties of PP for its application in engineering area. However, there are still some drawbacks existing for glass fibers filled polypropylene composites, such as high filler content, easy fracture of glass fibers and damage to the machines during processing. Therefore, organic fibers are considered as an ideal candidate to replace glass fibers. In this work, short Kevlar fibers (KFs) modified by ball milling in phosphoric acid and surface hydrolyzation were introduced to PP matrix to improve the interfacial interaction and mechanical properties. It is found that KFs were exfoliated into several flaky microfibers and then broken into pieces during the ball milling process. With the aid of phosphoric acid, the KFs can be split further thereby increasing specific surface area greatly. Then the original and milled KFs were hydrolyzed by NaOH aqueous solution in order to introduce OH group on the surface of KFs. The dispersion and mechanical properties of PP reinforced with various KFs, including original, ball milled, and hydrolyzed, were investigated and compared. It was found that the combination of ball milling in phosphoric acid and surface hydrolyzation is the most effective way for enhancement of interfacial reaction and mechanical properties. Adding 10 wt. % of KFs could lead to an increase of tensile strength of PP from 30 MPa to 47 MPa, which only can be achieved by adding at least of 25 wt. % of glass fibers. The tensile test shows that hydrolyze of KFs surface are a more important factor to promote the interfacial interaction between fibers and matrix. Our work demonstrates that PP can be enhanced efficiently by the introduction of hydrolyzed and microfibrillated KFs. Although KFs are expensive compared with glass fiber at this moment, their high reinforcement efficiency and toughness could make them competitive as reinforcing filler for the preparation of advanced polymer composites with excellent mechanical and processing properties.

      PubDate: 2018-05-18T02:44:01Z
       
  • Synchrotron X-ray scattering and IR-mapping studies of wet-spun
           lignin-derived carbon fibre precursor
    • Abstract: Publication date: 28 July 2018
      Source:Composites Science and Technology, Volume 163
      Author(s): Azam Oroumei, Peter Lynch, Mark Tobin, Minoo Naebe
      Lignin in a blend with polyacrylonitrile (PAN) was wet-spun in various processing conditions with the aim of identifying the most influential wet-spinning parameters on the properties of lignin/PAN fibres. Morphological, chemical, and structural properties of wet-spun lignin/PAN fibres were investigated by Scanning Electron Microscopy (SEM), synchrotron Infrared Microspectroscopy (IR-mapping), and synchrotron Wide-Angle X-ray Scattering (WAXS). Although the highest concentration of the coagulation bath (65%) was found favourable for fibre cross-section circularity, it led to a significant lignin loss in the wet-spun lignin/PAN fibres. This was confirmed by IR-mapping studies that showed strong CN traces but negligible aromatic ring traces within the lignin/PAN fibres wet-spun from coagulation bath concentrations of above 50%. The axial preferred orientation of the constituting structural units of wet-spun lignin/PAN fibres showed the highest sensitivity to lignin concentration of spinning dopes as compared to the other two process variables, namely feed rate and coagulation bath concentration. A reduction in the axial preferred orientation of wet-spun fibres from 0.71 to 0.27 was observed upon increasing the lignin content from 23% to 40%. This was correlated to variations in mechanical properties of the wet-spun lignin/PAN fibres.

      PubDate: 2018-05-18T02:44:01Z
       
  • Smart-fabric sensor composed of single-walled carbon nanotubes containing
           binary polymer composites for health monitoring
    • Abstract: Publication date: 28 July 2018
      Source:Composites Science and Technology, Volume 163
      Author(s): Shahid Aziz, Seung-Hwan Chang
      A smart-fabric sensor for health monitoring has been fabricated using composite of single-walled carbon nanotubes (SWCNTs)-filled binary polymer of poly vinylidene fluoride/poly (3,4-ethylenedioxythiophene)-poly (styrenesulfonate) (PVDF/PEDOT:PSS). The response curves and working principle were investigated, and sensors were fabricated to achieve a highly linear and stable response for a wide range of temperatures (25–100 °C) and bending angles. The sensors show a stable and nearly linear response of impedance change by varying temperatures in the range of 25–100 °C. The impedance of the sensors changed from 5.8 MΩ to 2.95 MΩ for temperature change in the range of 25–100 °C with a sensitivity of 38 kΩ/°C. The bending movement sensitivity of the sensors was found to be 90 kΩ per degree angle, and the response of the sensor was very stable in the range of 0–120°.

      PubDate: 2018-05-17T02:39:25Z
       
  • Controlling the structure of arborescent carbon nanotube networks for
           advanced rubber composites
    • Abstract: Publication date: 28 July 2018
      Source:Composites Science and Technology, Volume 163
      Author(s): Kazufumi Kobashi, Seisuke Ata, Takeo Yamada, Don N. Futaba, Kenji Hata
      We propose a method for controlling the arborescent structure of long carbon nanotubes (CNTs) to harness their intrinsic properties in advanced rubber composites. Our method of structural control was based on a wet-jet mill to vary the shear forces (20–150 MPa) applied to aligned single-wall CNTs in solution. As the pressure of jet mill increased, the resulting suspended CNTs changed from agglomerates of bundled “trunk”-like structures to a CNT “mesh”-like structure with a high degree of disentanglement and absence of the “trunk”-like structures. The sizes of the CNT agglomerates became small and the number increased with the pressure of jet mill, indicating that smaller “mesh”-like CNT structures were formed with shortening of CNTs. This knowledge was used to increase the electrical conductivity of a CNT-rubber composite, highlighting the need to optimize the disentanglement state of the CNTs for application towards composite materials. Thus we successfully fabricated a CNT rubber with higher electrical conductivity (1.4 × 10−2 S/cm) by balancing the disentanglement and shortening of the CNTs at the jet mill pressure of 120 MPa. On the other hand, the higher pressure of 150 MPa resulted in the lowest conductivity (7.5 × 10−4 S/cm) due to more extensive shortening of CNTs.

      PubDate: 2018-05-17T02:39:25Z
       
  • Bridging the segregated structure in conductive polypropylene composites:
           An effective strategy to balance the sensitivity and stability of strain
           sensing performances
    • Abstract: Publication date: 28 July 2018
      Source:Composites Science and Technology, Volume 163
      Author(s): Shuaiguo Zhao, Dandan Lou, Guojie Li, Yanjun Zheng, Guoqiang Zheng, Kun Dai, Chuntai Liu, Yuanli Jiang, Changyu Shen
      Conductive polymer composites (CPCs) based strain sensors have been studied intensively recently. For a desirable strain sensor, a high sensitivity, a nice recoverability together with a good stability are required synchronously. In this study, the design of a segregated carbon black (CB) conductive network was demonstrated to be crucial for preparing polypropylene (PP)-based strain sensors with fine recoverability and stability, but a low sensitivity. The incorporation of carbon fibers (CFs) with large aspect ratio into the segregated CB/PP was utilized to build a bridged-segregated structure, leading to a synergistic conductive network. As a result, an improved sensitivity as well as a good stability was both achieved for the CF/CB/PP composite. The origin of these results was further explained on the basis of the tunneling model proposed by Simmons and the synergetic effect. This work provides a strategy for improving the performance of strain sensor with balanced sensitivity and stability by introducing a bridged-segregated structure.

      PubDate: 2018-05-17T02:39:25Z
       
  • Enhanced interfacial and mechanical properties of high-modulus carbon
           fiber composites: Establishing modulus intermediate layer between fiber
           and matrix based on tailored-modulus epoxy
    • Abstract: Publication date: 28 July 2018
      Source:Composites Science and Technology, Volume 163
      Author(s): Peng Xu, Yunhua Yu, Dawei Liu, Mei He, Gang Li, Xiaoping Yang
      Tailored-modulus epoxy matrix was designed on basis of surface analysis of high-modulus carbon fibers (HMCF), and the effects of modulus intermediate layer on interfacial and mechanical properties of HMCF composites were investigated. Narrow grooves and active functional groups were detected on HMCF surface. The modulus of epoxy was tuned by stiff organic molecular structure of cycloaliphatic epoxy (CE) and amide acid (AA). Modulus intermediate layer was established along with modulus gap shrinkage and interphase extension between HMCF and high-modulus epoxy, causing remarkable improvements in interfacial properties of composites. Schematic model of interphase reinforcing mechanism was proposed, and modulus intermediate layer with a platform in the composites with high modulus epoxy matrix could facilitate the shift in stress concentration and suppress initiation and propagation of cracks, which resulted in improved mechanical properties of HMCF composites by enhancement of interfacial bonding and stress transfer capability between fiber and matrix.

      PubDate: 2018-05-17T02:39:25Z
       
  • Effects of degree of chemical interaction between carbon fibers and
           surface sizing on interfacial properties of epoxy composites
    • Abstract: Publication date: 28 July 2018
      Source:Composites Science and Technology, Volume 163
      Author(s): Qing Wu, Ruyi Zhao, Quansheng Ma, Jianfeng Zhu
      This paper offers a simple approach to increase the interfacial bonding strength of carbon fiber/epoxy composites by optimizing the degree of chemical interaction among functional groups of fiber surface, sizing agent and resin via heat treatments on carbon fibers. 130 °C treatment on CF1 and 150 °C treatment on CF2 results respectively 71.1% and 15.1% improvements on interfacial shear strength (IFSS), as compared with untreated CF1 and CF2 composites. Variations of IFSS for heat treated carbon fibers correspond well to dispersion component to polar component (γd/γp) tendency of desized heat treated fibers. The work of adhesion between heat treated fibers and resin matrix only reveals close correlation with IFSS trend for CF1/epoxy composites, while not applicable for CF2/epoxy composites. With increasing heat treatment temperature, the decreasing γd/γp of desized fibers indicates increasing degree of chemical interaction between fibers and surface sizing, which was also proven by the results of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. High degree of chemical interaction between fibers and surface sizing is adverse to the interaction between sizing and resin matrix, and thus lower the IFSS.

      PubDate: 2018-05-17T02:39:25Z
       
  • Methodology for macro-modeling of bio-based composites with inelastic
           constituents
    • Abstract: Publication date: 28 July 2018
      Source:Composites Science and Technology, Volume 163
      Author(s): Liva Pupure, Janis Varna, Roberts Joffe
      Methodology for development of a macro-scale model (with strain as an input) for Regenerated Cellulose fiber (RCF) composites with highly non-linear (viscoelastic (VE) and viscoplastic (VP)) constituents is presented and demonstrated. The VE is described by Schapery's models and Zapas' model is used for VP. For a purely VE constituent the model can be identified from stress relaxation in constant strain tests. In the presence of VP the constant strain test does not render VE stress relaxation functions, because part of the applied strain is VP and the VE strain is changing. As an alternative creep and strain recovery tests are suggested to find the plasticity law and also the nonlinear creep compliances to identify the VE model where stress is an input. The incremental form of this model is then inverted and used to simulate the VE relaxation tests and the simulated relaxation functions are used to identify the VE model with VE strain as an input. Models for constituents are used in micromechanics simulations of the composite behavior in arbitrary ramps including the composite VE relaxation test. Using the latter, a macro-model is developed and its validity and accuracy are demonstrated.

      PubDate: 2018-05-17T02:39:25Z
       
  • Synergistic effect of flame retardants and carbon nanotubes on flame
           retarding and electromagnetic shielding properties of thermoplastic
           polyurethane
    • Abstract: Publication date: 28 July 2018
      Source:Composites Science and Technology, Volume 163
      Author(s): Xiaoying Ji, Dayong Chen, Qingwen Wang, Jiabin Shen, Shaoyun Guo
      Thermoplastic polyurethane (TPU)-based composites filled with carbon nanotubes (CNTs) and intumescent flame retardants (IFRs) were fabricated through melt compounding method. For comparison, TPU/IFR and TPU/CNT composites with different filling proportions were prepared, respectively. The results presented that the addition of 1 wt% CNTs and 10 wt% IFRs into TPU could achieve good flame retarding and electromagnetic interference (EMI) shielding properties simultaneously. With regard to flame retardancy, the compounding of CNTs and IFRs effectively suppressed the heat release rate and the UL-94 rating was upgraded to V-0 accompanied with prompt self-extinguishment and disappeared melt-dripping, which was equivalent to incorporate 20 wt% IFRs alone. However, the flame retardancy became deteriorated by loading more CNTs. It was revealed that the addition of CNTs could strengthen the carbonization effect of IFRs, but suppress their intumescent effect. Hence, a right amount of CNT loading was of critical importance to achieve synergistic effect with IFRs. Moreover, compared with the TPU/CNT system, the TPU/IFR/CNT system possessing the same CNT contents had a lower percolation threshold. When 1 wt% CNTs were introduced, the electrical conductivity was increased about two orders of magnitude and EMI shielding effectiveness was doubled in the presence of IFRs. The morphological observation and rheological analysis demonstrated that mixing with IFRs not only improved the dispersion of CNTs through particle collisions, but also benefited for establishing the continuous conductive pathways among the IFR particles. Accordingly, this work provided a promising and facile route to fabricate EMI shielding polymeric composites with excellent flame retardancy.

      PubDate: 2018-05-17T02:39:25Z
       
  • Dielectric response of nano aluminium tri-hydrate filled silicone rubber
    • Abstract: Publication date: 28 July 2018
      Source:Composites Science and Technology, Volume 163
      Author(s): Chao Wu, Xidong Liang, Leonard A. Dissado, Nikola M. Chalashkanov, Stephen J. Dodd, Yanfeng Gao, Sen Xu
      The dielectric response of a nano-ATH (Aluminium Tri-hydrate) filled silicone rubber is investigated over the frequency range 10−4 to 103 Hz and compared with that of the micro-ATH composite. An equivalent circuit has been used to decompose the dielectric response into: a loss peak process, a quasi-dc (Q-DC) process, a dc-conductance and constant high frequency capacitance. It was found that the Q-DC and loss peak were a result of the ATH filler with the loss peak more clearly resolved in the nano-ATH filled material than in the micro-ATH material where it is weaker and partly obscured by the Q-DC process. In contrast to the micro-ATH material the characteristic frequencies of all the dielectric responses in the nano-ATH filled samples have the same activation energy. The physical mechanisms of the Q-DC process and loss peak are discussed in terms of long range transport between nano-ATH clusters and the dipolar behaviour of isolated clusters respectively.

      PubDate: 2018-05-17T02:39:25Z
       
  • Styrenic block copolymer/sulfonated graphene oxide composite membranes for
           highly bendable ionic polymer actuators with large ion concentration
           gradient
    • Abstract: Publication date: 28 July 2018
      Source:Composites Science and Technology, Volume 163
      Author(s): Jang-Woo Lee, Taehoon Kwon, Youngjong Kang, Tae Hee Han, Chang Gi Cho, Soon Man Hong, Suk-Won Hwang, Chong Min Koo
      In this study, sulfonated graphene oxide (sGO) with a large enhanced sulfonation degree of 1.65 mmol g−1 was simultaneously introduced as a highly ion conduction-activating carbonaceous filler for ionic polymer–metal composite (IPMC) actuator. The nanostructured styrenic block copolymer/sGO/ionic liquid (IL) composite membrane actuators revealed much larger actuation performance than top-ranked polyelectrolyte/IL actuators ever reported so far in terms of bending strain (0.88% under 2 V dc), initial strain rate (0.312% min−1), and charge-specific displacement (276.4 mm C−1). Moreover, SSPB/sGO/IL actuators exhibited excellent actuation performance without drawbacks of conventional IPMCs, such as back-relaxation and early loss of inner solvent. In addition, via tracking the movement of the IL's anion through energy-dispersive X-ray spectroscopy (EDS) analysis, not only the transporting behaviour of IL but also the pumping effect with solvated ion complexes inside the actuator are confirmed for the first time.

      PubDate: 2018-05-17T02:39:25Z
       
  • Largely enhanced dielectric and thermal conductive properties of novel
           ternary composites with small amount of nanofillers
    • Abstract: Publication date: 28 July 2018
      Source:Composites Science and Technology, Volume 163
      Author(s): Weiyan Li, Zhongqian Song, Jing Qian, Zhongyang Tan, Huiying Chu, Xianyou Wu, Wei Nie
      Polymer-based composites with excellent dielectric and thermal conductive properties attract ever-increasing attentions from researchers due to the irreplaceable role in energy storage system and electrical devices. Herein, poly(vinylidene fluoride) (PVDF)-based ternary composites were fabricated by adding small amount of poly(dopamine) coated boron nitride (DBN) and electrochemical exfoliated graphene (EEG) into PVDF matrix. Due to the high degree of π-conjugation and good dispersity of EEG, high dielectric constant could be achieved with a very small addition. Meanwhile, after a small amount of DBN was introduced into the EEG/PVDF system, high dielectric constant, low dielectric loss and excellent thermal conductivity were integrated into the EEG/DBN/PVDF ternary composites due to the synergistic effect of DBN and EEG. Compared with the dielectric constant of 591 and loss of 1.21 for EEG(2.0%)/PVDF, the dielectric constant of the DBN(3.1%)/EEG(2.0%)/PVDF can reach up to 6655 and the dielectric loss can be suppressed below 0.83 at 102 Hz. In addition, the thermal conductivity of the ternary composite film can reach up to 1.33 W m-1 K-1, which is 5.68 times more than that of pure PVDF (0.234 W m-1 K-1). This work provides a simple and efficient strategy to exploit novel polymer based composites with excellent dielectric and thermal conductive properties for extensive applications in electronics and energy storage systems.

      PubDate: 2018-05-17T02:39:25Z
       
  • Electrospun nanofibres as a tool for controlling the gas bubble size
           distribution in fibre/thermoset-matrix composites
    • Abstract: Publication date: 28 July 2018
      Source:Composites Science and Technology, Volume 163
      Author(s): R. Polanský, P. Prosr, M. Zemanová, J. Pihera, T. Džugan, J. Chvojka
      The influence of electrospun nanofibres made from polyamide 6 (PA6) on the gas bubble size distribution by volume in fibre/thermoset-matrix systems cured without a vacuum was comprehensively studied via various methods. An analysis of the microstructural, thermal and dielectric properties proved that the unique structure of PA6 electrospun nanofibres can withstand the curing conditions required for fibre/thermoset-matrix systems and that the overall dielectric behaviour of manufactured composites is not negatively influenced by the addition of nanofibres. Visual and numerical analyses of the tomograms obtained via X-ray computed microtomography (micro-CT) suggested that a nanofibrous structure can act as a solid grid limiting the growth of large gas bubbles or their random agglomeration during curing. The initial observations were independently supported by partial discharge analysis (PDA), which confirmed that the addition of nanofibrous layers leads to the presence of bubbles with generally smaller dimensions and that the nanofibrous layers significantly suppress the partial discharge (PD) activity inside a composite structure.

      PubDate: 2018-05-17T02:39:25Z
       
  • Natural rubber particle modified fabrics with catalytic activity and
           hydrophobicity
    • Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): Jinlong Tao, Bin Tang, Puwang Li, Dongning He, Lusheng Liao, Zheng Peng, Xungai Wang
      We report a novel and facile approach to fabricate functional fabrics using environment-friendly waterborne natural rubber latex (NRL) containing in-situ synthesized gold nanoparticles (AuNPs). AuNPs were prepared and decorated on the surface of the natural rubber particles (NRPs) by heating, forming a dual-scale hierarchical architecture. The hybrid particles of NRPs and AuNPs (AuNP@NRP) were coated on cotton and hydrophilic polyester fabric surfaces, endowing the fabrics with catalytic and hydrophobic features. The treated fabrics with low loadings of AuNP@NRP exhibited high catalytic activity for the reduction of 4-nitrophenol (4-NP) by NaBH4 and could be reused, after easy separation from the catalytic reaction system, with excellent durability. In addition, the hydrophobicity of fabrics increased as coating cycles increased. The obtained hydrophobic fabrics were used for oil/water separation, showing high separation efficiency (>96%).

      PubDate: 2018-05-17T02:39:25Z
       
  • Self-assembled montmorillonite–carbon nanotube for epoxy composites with
           superior mechanical and thermal properties
    • Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): Shaohua Zeng, Mingxia Shen, Lu Yang, Yijiao Xue, Fengling Lu, Shangneng Chen
      A hybrid nanostructure consisting of montmorillonite−multi-walled carbon nanotube (Mt−MWCNT) was designed and assembled, and further used as reinforcing nanofillers for preparing epoxy-based composites. It was found that Mt could efficiently resist microcrack extension and hinder thermal transfer while MWCNTs anchored on the Mt nanosheets could facilitate the stress and heat transfers and provide mechanical interlocking with the epoxy matrix. Making use of the synergistic effect of Mt and MWCNT, considerable enhancement in thermal and mechanical properties was achieved in the composites. With addition of just 0.5 wt% Mt−MWCNT (Mt:MWCNTs = 10:1, w/w), the tensile strength and modulus of epoxy-based composites were improved by 42.0% and 20.3%, respectively, compared with pure epoxy. Furthermore, the storage modulus in the glassy region increased by 21.2%. Moreover, the glass-transition and onset decomposition temperatures were also significantly enhanced, implying the superior thermal stability of these composites.

      PubDate: 2018-05-17T02:39:25Z
       
  • Synergistic effect of chitin nanocrystals and orientations induced by
           solid-state drawing on PLA-based nanocomposite tapes
    • Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): Anshu Anjali Singh, Jiayuan Wei, Natalia Herrera, Shiyu Geng, Kristiina Oksman
      Uniaxial solid-state drawing was used to orientate plasticized polylactic acid (PLA) and its nanocomposite tapes with 1 and 5 wt% chitin nanocrystals (ChNC). Microscopy studies confirmed the orientation and formation of a ‘shish-kebab’ morphology in the drawn tapes. The mechanical properties demonstrated that the drawing led to stronger and tougher nanocomposites compared to plasticized PLA. The tensile strength increased from 41 MPa to 71 MPa, and the elongation at break increased from 5% to 60% for the nanocomposite with 5 wt% ChNC and a draw ratio of 3. The ChNC had a positive effect on the thermomechanical properties; the tan delta peak shifted to a higher temperature with an increasing ChNC content. These improvements in the mechanical and thermal properties are expected synergistic effects of both the ChNC in the nanocomposite and the alignment of the ChNC together with the polymer chains induced by the solid-state drawing.

      PubDate: 2018-05-17T02:39:25Z
       
  • Identifying interphase properties in polymer nanocomposites using adaptive
           optimization
    • Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): Yixing Wang, Yichi Zhang, He Zhao, Xiaolin Li, Yanhui Huang, Linda S. Schadler, Wei Chen, L. Catherine Brinson
      To predict the properties of nanocomposites, computational models have demonstrated that the interphase behavior can be expressed using the matrix properties with a modified (shifted) frequency. The amount of the shift necessary for a given sample data set can be determined by achieving the best fit between the predicted curve from a computation model and the experimental data through trial-and-error. However, with the complexity of experimental data and expensive computational costs, a manual process to solve this inverse problem is impractical to handle many experimental data sets. This difficulty hinders investigation of the underlying principles behind nanocomposite interphase. In this work, we present an adaptive optimization approach that accelerates the search for interphase properties in polymer nanocomposite data sets by solving the inverse problem using global optimization. The objective is to minimize the difference between the predicted bulk property of a nanocomposite with that from the experiment data. A Gaussian Process (GP) model is built as a surrogate of the objective function with quantification of prediction uncertainty. An adaptive sampling strategy is applied to effectively navigate the complex search space by iteratively selecting the next sampling point based on an expected improvement function. The surrogate model and the optimal solution evolve until the desired objective is achieved. The approach is tested on both the simulations of dielectric and viscoelastic properties in nanocomposites. Our work provides insight into identifying the interphase properties for polymer nanocomposites using adaptive optimization and demonstrates the potential of data-driven approach for achieving a deeper understanding of the interphase properties and its origins.

      PubDate: 2018-05-17T02:39:25Z
       
  • Dispersion of graphene in chlorosulfonated polyethylene by slurry
           compounding
    • Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): Zhijun Yang, Zongchao Xu, Liqun Zhang, Baochun Guo
      It remains a huge challenge to realize the homogeneous graphene dispersion in elastomer matrix by a simple and general compounding method. Herein, we develop a straightforward slurry compounding method for preparation of rubber/graphene composites with well-dispersed graphene. Specifically, TPG (tea polyphenol reduced graphene)/ethanol slurry was first collected by solvent exchange after the reduction of graphene oxide by tea polyphenol and then directly melt compounded with chlorosulfonated polyethylene (CSM) in a two-roll mill to produce the composites. As revealed by the XRD and morphological studies, TPG homogeneously dispersed in CSM matrix, which together with the strong interfacial interaction between TPG and CSM contribute to the remarkable improvement in mechanical properties of the resulted composites. We envision that the present work offers a straightforward yet effective methodology for preparing high-performance elastomer/graphene composites via conventional melt compounding.

      PubDate: 2018-05-17T02:39:25Z
       
  • Novel carbon-poly(silacetylene) composites as advanced thermal protection
           material in aerospace applications
    • Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): Lei Kong, Xiaobiao Zuo, Shipeng Zhu, Zhongping Li, Jianjun Shi, Long Li, Zhihai Feng, Dahai Zhang, Daiying Deng, Jijun Yu
      In the present work, a new class of 2.5D woven carbon-poly(silacetylene) composites derived from three novel poly(silacetylene) resins has been developed by VARTM process and evaluated to determine the potential for serving as advanced thermal protection material. TG analysis, PGC-MS analysis, Ar arc plasma ablation test, microstructural analysis and a ATCM have been employed to investigate the effects of chemical structures and thermal stability of poly(silacetylene) matrices on the ablation performance of their carbon fiber composites. The incorporation of rigid phenyl groups into poly(silacetylene) matrices can significantly improve the ablation-resistant performance of their carbon fiber composites, which may be ascribed to decreased pyrolysis gaseous volatiles and decreased pyrolysis residue of SiC for the poly(silacetylene) matrices during ablation, resulting in a remarkable enhancement in the mechanical spallation resistance. All the developed carbon- poly(silacetylene) composites exhibit excellent ablation-resistant performance with a recession rate ranging from 0.31 mm s−1 to 0.40 mm s−1, which would make them good candidates for advanced thermal protection materials in aerospace applications.

      PubDate: 2018-05-17T02:39:25Z
       
  • Magnet-induced aligning magnetorheological elastomer based on ultra-soft
           matrix
    • Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): Junru Yao, Youyi Sun, Yan Wang, Qiang Fu, Zhiyuan Xiong, Yaqing Liu
      A novel magnet-induced aligning magnetorheological elastomer (MIMRE) based on ultra-soft polymeric matrix was prepared through an innovative synthetic approach, enables the magnetic particles to mobile and align in elastomer matrix under magnetic field at room temperature. The effect of polymeric matrix modulus on the formation of MIMRE was investigated in detail. It was found that the MIMRE showed excellent magnetorheological (MR) effect, and the absolute and relative MR effect was of 3.61 MPa and 17,286%, respectively. The relative MR effect of magnetorheological elastomer was almost 100 times higher than that of elastomers reported in previous literature. In addition, the application of MIMRE in actuators and self-healing materials was evaluated. The present MIMRE thus opens up a new avenue for the improvement of MR effect of magnetorheological elastomer, while avoiding the use of conventional plasticizer (e.g. silicon oil).

      PubDate: 2018-05-17T02:39:25Z
       
  • BaTiO3@carbon/silicon carbide/poly(vinylidene
           fluoride-hexafluoropropylene) three-component nanocomposites with high
           dielectric constant and high thermal conductivity
    • Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): Xianhong Zhang, Cheng Tan, Yuhong Ma, Fang Wang, Wantai Yang
      This work reports a new three-component composite which is consisted of dielectric carbon coated barium titanate hybrid particles (BT@C), thermal conductive silicon carbide nanoparticles (SiC NPs), and flexible poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP). The BT@C is synthesized via hydrothermal reaction of BT nanoparticles with glucose and further carbonized at 800 °C. The TEM images and Raman spectra reveal that the structure of carbon coating layer is high ordering graphitic carbon. Compared with the two-component BT@C/PVDF-HFP and SiC/PVDF-HFP composites, the three-component BT@C/SiC/PVDF-HFP composites show a positive synergistic effect of the two fillers in enhancing not only thermal conductivity but also dielectric constant. The results show that with the addition of 5.5 wt% and 10 wt% SiC NPs into BT@C-2(50 wt%)/PVDF-HFP composite, the thermal conductivity increases to 0.69 W m−1k−1 and 0.92 W m−1k−1 respectively (0.61 W m−1k−1 as control). For dielectric performance, the dielectric constant of BT@C-2(50 wt%)/PVDF-HFP increases from 80 to 1394 at 1 kHz with addition of 7.8 wt% SiC NPs. The dielectric constant is almost 158 times greater than that of pure PVDF-HFP (8.8, measured) and the dielectric loss tanδ is 0.9. These results show a good balance of dielectric performance. This method offers us a potential for the design and fabrication of polymeric dielectric composites which could be applied in electronic devices.
      Graphical abstract image

      PubDate: 2018-05-17T02:39:25Z
       
  • Nonlinear viscoelasticity of pre-compressed layered polymeric composite
           under oscillatory compression
    • Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): Yangguang Xu, Ran Tao, Gilles Lubineau
      Describing nonlinear viscoelastic properties of polymeric composites when subjected to dynamic loading is essential for development of practical applications of such materials. An efficient and easy method to analyze nonlinear viscoelasticity remains elusive because the dynamic moduli (storage modulus and loss modulus) are not very convenient when the material falls into nonlinear viscoelastic range. In this study, we utilize two methods, Fourier transform and geometrical nonlinear analysis, to quantitatively characterize the nonlinear viscoelasticity of a pre-compressed layered polymeric composite under oscillatory compression. We discuss the influences of pre-compression, dynamic loading, and the inner structure of polymeric composite on the nonlinear viscoelasticity. Furthermore, we reveal the nonlinear viscoelastic mechanism by combining with other experimental results from quasi-static compressive tests and microstructural analysis. From a methodology standpoint, it is proved that both Fourier transform and geometrical nonlinear analysis are efficient tools for analyzing the nonlinear viscoelasticity of a layered polymeric composite. From a material standpoint, we consequently posit that the dynamic nonlinear viscoelasticity of polymeric composites with complicated inner structures can also be well characterized using these methods.

      PubDate: 2018-05-17T02:39:25Z
       
  • Self-reinforced biodegradable Mg-2Zn alloy wires/polylactic acid composite
           for orthopedic implants
    • Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): Hong Cai, Yue Zhang, Xuan Li, Jiao Meng, Feng Xue, Chenglin Chu, Li Tao, Jing Bai
      Biodegradable composite rods with polylactic acid as matrix and Mg-2Zn wires as the reinforcement body were prepared by hot press and hot drawn method in this article. The main purpose is to improve the mechanical properties based on the strengthen and toughness effect of the directionally distributed Mg-2Zn wires in PLA matrix and the improved interfacial bonding strength by MAO treated Mg-2Zn wires as well as the self-reinforcement effect of PLA after hot drawn process. The effect of hot drawn on the orientation, crystallinity and melting temperature changes of PLA were investigated by XRD and DSC method. The relationship between the bending strength and the volume content of Mg-2Zn wires in the composite rods as well as the influence of hot drawn on the mechanical properties were compared and analyzed theoretically. The regularly arrangement of PLA chains after hot drawn is benefit to increase the crystallinity, the elastic modulus as well as the mechanical strength in essence. Theoretical calculation results could provide a reference value and guide us to adjust the Mg-2Zn wires content and prepare the composite rods according to the actual application requirements.

      PubDate: 2018-05-17T02:39:25Z
       
  • Multi-scale design of electromagnetic composite metamaterials for
           broadband microwave absorption
    • Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): Yixing Huang, Wei-Li Song, Changxian Wang, Yuannan Xu, Weiyi Wei, Mingji Chen, Liqun Tang, Daining Fang
      The microwave absorbing composites embedded with magnetic-dielectric lossy components including spherical carbonyl iron (CI) and multi-wall carbon nanotubes (MWCNT) were fabricated by a two-step molding method. By manipulating the content of CI and MWCNT for adjusting complex permittivity and permeability, the as-prepared composites were used to optimize the electromagnetic composite metamaterials (ECMs) for broadband absorption. The multi-scale ECMs achieved −8 dB absorption in 2–40 GHz and −10 dB absorption within the 30 GHz bandwidth, where the minimum reflectivity of −55 dB was found at 14.8 GHz. It is found that the magnetic and dielectric loss materials are responsible for attenuating the electromagnetic energy, while the structure of the metamaterials are mainly linked with the broadband absorption via impedance match improvement and electromagnetic field manipulation. The results suggest that multi-scale design for ECMs is an attractive avenue to enhance microwave absorption performance via utilizing ternary composites and tailoring geometrical sizes for absorption resonance.

      PubDate: 2018-05-17T02:39:25Z
       
  • The use of a pilot-scale continuous paper process for fire retardant
           cellulose-kaolinite nanocomposites
    • Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): D.O. Castro, Z. Karim, L. Medina, J.-O. Häggström, F. Carosio, A. Svedberg, L. Wågberg, D. Söderberg, L.A. Berglund
      Nanostructured materials are difficult to prepare rapidly and at large scale. Melt-processed polymer-clay nanocomposites are an exception, but the clay content is typically below 5 wt%. An approach for manufacturing of microfibrillated cellulose (MFC)/kaolinite nanocomposites is here demonstrated in pilot-scale by continuous production of hybrid nanopaper structures with thickness of around 100 μm. The colloidal nature of MFC suspensions disintegrated from chemical wood fiber pulp offers the possibility to add kaolinite clay platelet particles of nanoscale thickness. For initial lab scale optimization purposes, nanocomposite processing (dewatering, small particle retention etc) and characterization (mechanical properties, density etc) were investigated using a sheet former (Rapid Köthen). This was followed by a continuous fabrication of composite paper structures using a pilot-scale web former. Nanocomposite morphology was assessed by scanning electron microscopy (SEM). Mechanical properties were measured in uniaxial tension. The fire retardancy was evaluated by cone calorimetry. Inorganic hybrid composites with high content of in-plane oriented nanocellulose, nanoclay and wood fibers were successfully produced at pilot scale. Potential applications include fire retardant paperboard for semi structural applications and as reinforcement mats in molded thermoset biocomposites.

      PubDate: 2018-05-17T02:39:25Z
       
  • Modelling the electrical resistance change in a multidirectional laminate
           with a delamination
    • Abstract: Publication date: 7 July 2018
      Source:Composites Science and Technology, Volume 162
      Author(s): Francesco Panozzo, Michele Zappalorto, Lucio Maragoni, Stefan Klaus Nothdurfter, Axel Rullo, Marino Quaresimin
      In this work, the electrical response of a multidirectional symmetric composite laminate with a delamination is studied analytically, numerically and experimentally. An analytical model is initially developed to predict the electrical resistance of the composite laminate as a function of the delamination extent. The model was first validated against the results of a bulk of finite element analyses, considering different lay-ups and electrical resistivity. The model predictions were then compared to experimental data obtained through a dedicated experimental campaign performed on unidirectional and multidirectional Double Cantilever Beam (DCB) specimens. A satisfactory agreement was found in all the cases, thus supporting the accuracy of the analytical model.

      PubDate: 2018-05-17T02:39:25Z
       
 
 
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