Subjects -> TEXTILE INDUSTRIES AND FABRICS (Total: 40 journals)


Showing 1 - 16 of 16 Journals sorted alphabetically
AATCC Journal of Research     Full-text available via subscription   (Followers: 13)
AATCC Review     Full-text available via subscription   (Followers: 4) - Revista Eletrônica de Moda     Open Access  
Asian Journal of Textile     Open Access   (Followers: 11)
Autex Research Journal     Open Access   (Followers: 3)
Cerâmica     Open Access   (Followers: 6)
Composites Science and Technology     Hybrid Journal   (Followers: 245)
Fashion and Textiles     Open Access   (Followers: 17)
Fashion Practice : The Journal of Design, Creative Process & the Fashion     Hybrid Journal   (Followers: 13)
Fibers     Open Access   (Followers: 7)
Fibre Chemistry     Hybrid Journal   (Followers: 4)
Focus on Pigments     Full-text available via subscription   (Followers: 4)
Geosynthetics International     Hybrid Journal   (Followers: 5)
Geotextiles and Geomembranes     Hybrid Journal   (Followers: 6)
Indian Journal of Fibre & Textile Research (IJFTR)     Open Access   (Followers: 14)
International Journal of Fashion Design, Technology and Education     Hybrid Journal   (Followers: 17)
International Journal of Textile Science     Open Access   (Followers: 15)
Journal of Engineered Fibers and Fabrics     Open Access   (Followers: 2)
Journal of Fashion Technology & Textile Engineering     Hybrid Journal   (Followers: 10)
Journal of Industrial Textiles     Hybrid Journal   (Followers: 6)
Journal of Leather Science and Engineering     Open Access   (Followers: 1)
Journal of Natural Fibers     Hybrid Journal   (Followers: 6)
Journal of Textile Design Research and Practice     Full-text available via subscription   (Followers: 6)
Journal of Textile Science & Engineering     Open Access   (Followers: 6)
Journal of The Institution of Engineers (India) : Series E     Hybrid Journal   (Followers: 2)
Journal of the Textile Institute     Hybrid Journal   (Followers: 11)
Text and Performance Quarterly     Hybrid Journal   (Followers: 5)
Textile History     Hybrid Journal   (Followers: 20)
Textile Progress     Hybrid Journal   (Followers: 5)
Textile Research Journal     Hybrid Journal   (Followers: 14)
Textiles and Clothing Sustainability     Open Access   (Followers: 3)
Textiles and Light Industrial Science and Technology     Open Access   (Followers: 5)
Third Text     Hybrid Journal   (Followers: 11)
Wearables     Open Access   (Followers: 2)
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Number of Followers: 7  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2079-6439
Published by MDPI Homepage  [233 journals]
  • Fibers, Vol. 9, Pages 1: Numerical Method for Coupled Nonlinear
           Schrödinger Equations in Few-Mode Fiber

    • Authors: Airat Zh. Sakhabutdinov, Vladimir I. Anfinogentov, Oleg G. Morozov, Vladimir A. Burdin, Anton V. Bourdine, Artem A. Kuznetsov, Dmitry V. Ivanov, Vladimir A. Ivanov, Maria I. Ryabova, Vladimir V. Ovchinnikov
      First page: 1
      Abstract: This paper discusses novel approaches to the numerical integration of the coupled nonlinear Schrödinger equations system for few-mode wave propagation. The wave propagation assumes the propagation of up to nine modes of light in an optical fiber. In this case, the light propagation is described by the non-linear coupled Schrödinger equation system, where propagation of each mode is described by own Schrödinger equation with other modes’ interactions. In this case, the coupled nonlinear Schrödinger equation system (CNSES) solving becomes increasingly complex, because each mode affects the propagation of other modes. The suggested solution is based on the direct numerical integration approach, which is based on a finite-difference integration scheme. The well-known explicit finite-difference integration scheme approach fails due to the non-stability of the computing scheme. Owing to this, here we use the combined explicit/implicit finite-difference integration scheme, which is based on the implicit Crank–Nicolson finite-difference scheme. It ensures the stability of the computing scheme. Moreover, this approach allows separating the whole equation system on the independent equation system for each wave mode at each integration step. Additionally, the algorithm of numerical solution refining at each step and the integration method with automatic integration step selection are used. The suggested approach has a higher performance (resolution)—up to three times or more in comparison with the split-step Fourier method—since there is no need to produce direct and inverse Fourier transforms at each integration step. The key advantage of the developed approach is the calculation of any number of modes propagated in the fiber.
      Citation: Fibers
      PubDate: 2021-01-02
      DOI: 10.3390/fib9010001
      Issue No: Vol. 9, No. 1 (2021)
  • Fibers, Vol. 9, Pages 2: The Mechanical Properties of PVC Nanofiber Mats
           Obtained by Electrospinning

    • Authors: Quoc Pham Le, Mayya V. Uspenskaya, Roman O. Olekhnovich, Mikhail A. Baranov
      First page: 2
      Abstract: This paper investigates the mechanical properties of oriented polyvinyl chloride (PVC) nanofiber mats, which, were obtained by electrospinning a PVC solution. PVC was dissolved in a solvent mixture of tetrahydrofuran/dimethylformamide. Electrospinning parameters used in our work were, voltage 20 kV; flow rate 0.5 mL/h; the distance between the syringe tip and collector was 15 cm. The rotating speed of the drum collector was varied from 500 to 2500 rpm with a range of 500 rpm. Nanofiber mats were characterized by scanning electron microscope, thermogravimetric analysis, differential scanning calorimetry methods. The mechanical properties of PVC nanofiber mats, such as tensile strength, Young’s modulus, thermal degradation, and glass transition temperature were also analyzed. It was shown that, by increasing the collector’s rotation speed from 0 (flat plate collector) to 2500 rpm (drum collector), the average diameter of PVC nanofibers decreased from 313 ± 52 to 229 ± 47 nm. At the same time, it was observed that the mechanical properties of the resulting nanofiber mats were improved: tensile strength increased from 2.2 ± 0.2 MPa to 9.1 ± 0.3 MPa, Young’s modulus from 53 ± 14 to 308 ± 19 MPa. Thermogravimetric analysis measurements showed that there was no difference in the process of thermal degradation of nanofiber mats and PVC powders. On the other hand, the glass transition temperature of nanofiber mats and powders did show different values, such values were 77.5 °C and 83.2 °C, respectively.
      Citation: Fibers
      PubDate: 2021-01-05
      DOI: 10.3390/fib9010002
      Issue No: Vol. 9, No. 1 (2021)
  • Fibers, Vol. 9, Pages 3: New Textile for Personal Protective
           Equipment—Plasma Chitosan/Silver Nanoparticles Nylon Fabric

    • Authors: Cláudia M. Botelho, Margarida M. Fernandes, Jefferson M. Souza, Nicolina Dias, Ana M. Sousa, José A. Teixeira, Raul Fangueiro, Andrea Zille
      First page: 3
      Abstract: Fabric structures are prone to contamination with microorganisms, as their morphology and ability to retain moisture creates a proper environment for their growth. In this work, a novel, easily processed and cheap coating for a nylon fabric with antimicrobial characteristics was developed. After plasma treatment, made to render the fabric surface more reactive sites, the fabric was impregnated with chitosan and silver nanoparticles by simply dipping it into a mixture of different concentrations of both components. Silver nanoparticles were previously synthesized using the Lee–Meisel method, and their successful obtention was proven by UV–Vis, showing the presence of the surface plasmon resonance band at 410 nm. Nanoparticles with 25 nm average diameter observed by STEM were stable, mainly in the presence of chitosan, which acted as a surfactant for silver nanoparticles, avoiding their aggregation. The impregnated fabric possessed bactericidal activity higher for Gram-positive Staphylococcus aureus than for Gram-negative Pseudomonas aeruginosa bacteria for all combinations. The percentage of live S. aureus and P. aeruginosa CFU was reduced to less than 20% and 60%, respectively, when exposed to each of the coating combinations. The effect was more pronounced when both chitosan and silver were present in the coating, suggesting an effective synergy between these components. After a washing process, the antimicrobial effect was highly reduced, suggesting that the coating is unstable after washing, being almost completely removed from the fabric. Nevertheless, the new-coated fabric can be successfully used in single-use face masks. To our knowledge, the coating of nylon fabrics intended for face-mask material with both agents has never been reported.
      Citation: Fibers
      PubDate: 2021-01-06
      DOI: 10.3390/fib9010003
      Issue No: Vol. 9, No. 1 (2021)
  • Fibers, Vol. 9, Pages 4: Mechanical and Dielectric Properties of Aligned
           Electrospun Fibers

    • Authors: Blesson Isaac, Robert M. Taylor, Kenneth Reifsnider
      First page: 4
      Abstract: This review paper examines the current state-of-the-art in fabrication of aligned fibers via electrospinning techniques and the effects of these techniques on the mechanical and dielectric properties of electrospun fibers. Molecular orientation, system configuration to align fibers, and post-drawing treatment, like hot/cold drawing process, contribute to better specific strength and specific stiffness properties of nanofibers. The authors suggest that these improved, aligned nanofibers, when applied in composites, have better mechanical and dielectric properties for many structural and multifunctional applications, including advanced aerospace applications and energy storage devices. For these applications, most fiber alignment electrospinning research has focused on either mechanical property improvement or dielectric property improvement alone, but not both simultaneously. Relative to many other nanofiber formation techniques, the electrospinning technique exhibits superior nanofiber formation when considering cost and manufacturing complexity for many situations. Even though the dielectric property of pure nanofiber mat may not be of general interest, the analysis of the combined effect of mechanical and dielectric properties is relevant to the present analysis of improved and aligned nanofibers. A plethora of nanofibers, in particular, polyacrylonitrile (PAN) electrospun nanofibers, are discussed for their mechanical and dielectric properties. In addition, other types of electrospun nanofibers are explored for their mechanical and dielectric properties. An exploratory study by the author demonstrates the relationship between mechanical and dielectric properties for specimens obtained from a rotating mandrel horizontal setup.
      Citation: Fibers
      PubDate: 2021-01-06
      DOI: 10.3390/fib9010004
      Issue No: Vol. 9, No. 1 (2021)
  • Fibers, Vol. 9, Pages 5: Cellulose Dissolution in Ionic Liquid under Mild
           Conditions: Effect of Hydrolysis and Temperature

    • Authors: Sanjit Acharya, Yang Hu, Noureddine Abidi
      First page: 5
      Abstract: This study investigated the effect of acid hydrolysis of cellulose on its dissolution under mild conditions in ionic liquid, 1-butyl-3-methylimidazolium acetate/N,N-dimethylacetamide (BMIMAc/DMAc). Acid hydrolysis of high molecular weight (MW) cotton cellulose (DP > 4000) was carried out to produce hydrolyzed cotton (HC) samples for dissolution. The HC samples were characterized using gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA), and the dissolution process was monitored using polarized light microscopy (PLM). It was found that the drastic decrease of the MW of cellulose did not result in improvement of its dissolution at room temperature. As compared to original cotton cellulose, the high amount of undissolved fibers in HC solutions led to unstable rheological behavior of HC solutions. Agglomeration and inhomogeneous dispersion of HC, and increased crystallinity, in this case, likely made the diffusion of BMIMAc/DMAc more difficult to the inside of the polymeric network of cellulose at ambient temperature, thereby hindering the dissolution. However, increasing the temperature from room temperature to 35 °C and 55 °C, led to a significant improvement in cellulose dissolution. This phenomenon implies that reducing the MW of cellulose might not be able to improve its dissolution under certain conditions. During the dissolution process, the physical properties of cellulose including fiber aggregation status, solvent diffusivity, and cellulose crystallinity may play a critical role compared to the MW, while the MW may not be an important factor. This finding may help further understand the mechanism of cellulose dissolution and seek better strategies to dissolve cellulose under mild conditions for industrial applications.
      Citation: Fibers
      PubDate: 2021-01-06
      DOI: 10.3390/fib9010005
      Issue No: Vol. 9, No. 1 (2021)
  • Fibers, Vol. 9, Pages 6: Techniques for Modelling and Optimizing the
           Mechanical Properties of Natural Fiber Composites: A Review

    • Authors: Timothy K. Mulenga, Albert U. Ude, Chinnasamy Vivekanandhan
      First page: 6
      Abstract: The study of natural fiber-based composites through the use of computational techniques for modelling and optimizing their properties has emerged as a fast-growing approach in recent years. Ecological concerns associated with synthetic fibers have made the utilisation of natural fibers as a reinforcing material in composites a popular approach. Computational techniques have become an important tool in the hands of many researchers to model and analyze the characteristics that influence the mechanical properties of natural fiber composites. This recent trend has led to the development of many advanced computational techniques and software for a profound understanding of the characteristics and performance behavior of composite materials reinforced with natural fibers. The large variations in the characteristics of natural fiber-based composites present a great challenge, which has led to the development of many computational techniques for composite materials analysis. This review seeks to infer, from conventional to contemporary sources, the computational techniques used in modelling, analyzing, and optimizing the mechanical characteristics of natural fiber reinforced composite materials.
      Citation: Fibers
      PubDate: 2021-01-14
      DOI: 10.3390/fib9010006
      Issue No: Vol. 9, No. 1 (2021)
  • Fibers, Vol. 8, Pages 53: 3D-Printed Pseudo Ductile Fiber-Reinforced
           Polymer (FRP) Composite Using Discrete Fiber Orientations

    • Authors: Shreya Vemuganti, Eslam Soliman, Mahmoud Reda Taha
      First page: 53
      Abstract: The use of fiber-reinforced polymer (FRP) composite materials are continuously growing in civil infrastructure due to their high strength, low weight, and manufacturing flexibility. However, FRP is characterized by sudden failure and lacks ductility. When used in construction, gradual failure of FRP components is desired to avoid catastrophic structural collapse. Due to its mechanical orthotropy, the behavior of FRP relies significantly on fiber orientation and stacking sequence. In this paper, a novel multi-angled glass fiber reinforced polymer (GFRP) composite laminate showing pseudo ductile behavior is produced using 3D-printing. This is accomplished by varying fiber orientation angles, stacking sequence, and thickness of lamina. Single-angled GFRP composite specimens were 3D-printed with different fiber orientation angles of 0°, 12°, 24°, 30°, 45°, and 90° using continuous and fused filament techniques. The tension test results of the single-angled specimens were then used to aid the design of multi-angled laminate for potential progressive failure behavior. A 3D finite element (FE) model was developed to predict the response of the experimental results and to provide insight into the failure mechanism of the multi-angled laminate. The experimental observations and the FE simulations show the possibility of producing pseudo ductile FRP-by-design composite using 3D-printing technology, which leads the way to fabricate next-generation composites for civil infrastructure.
      Citation: Fibers
      PubDate: 2020-08-20
      DOI: 10.3390/fib8090053
      Issue No: Vol. 8, No. 9 (2020)
  • Fibers, Vol. 8, Pages 54: Modeling the Influence of Knots on Douglas-Fir
           Veneer Fiber Orientation

    • Authors: Rémy Frayssinhes, Stéphane Girardon, Louis Denaud, Robert Collet
      First page: 54
      Abstract: This study presents a method for predicting the local fiber orientation of veneers made from peeled Douglas-fir logs based on the knowledge of the tree branch characteristics (location, radius, insertion angle, azimuth angle, and living branch ratio). This model is based on the Rankine oval theory approach and focuses on the local deviation of the fiber orientation in the vicinity of knots. The local fiber orientation was measured online during the peeling process with an in-house-developed scanner based on the tracheid effect. Two logs from the same tree were peeled, and their ribbons were scanned. The knot locations and fiber orientation were deduced from the scanner data. The first objective was to compare the fiber orientation model with measurements to enhance and validate the model for French Douglas-fir. The second objective was to link data measurable on logs to veneer quality.
      Citation: Fibers
      PubDate: 2020-08-21
      DOI: 10.3390/fib8090054
      Issue No: Vol. 8, No. 9 (2020)
  • Fibers, Vol. 8, Pages 55: Stabilization and Incipient Carbonization of
           Electrospun Polyacrylonitrile Nanofibers Fixated on Aluminum Substrates

    • Authors: Jan Lukas Storck, Timo Grothe, Khorolsuren Tuvshinbayar, Elise Diestelhorst, Daria Wehlage, Bennet Brockhagen, Martin Wortmann, Natalie Frese, Andrea Ehrmann
      First page: 55
      Abstract: Polyacrylonitrile (PAN) nanofibers, prepared by electrospinning, are often used as a precursor for carbon nanofibers. The thermal carbonization process necessitates a preceding oxidative stabilization, which is usually performed thermally, i.e., by carefully heating the electrospun nanofibers in an oven. One of the typical problems occurring during this process is a strong deformation of the fiber morphologies—the fibers become thicker and shorter, and show partly undesired conglutinations. This problem can be solved by stretching the nanofiber mat during thermal treatment, which, on the other hand, can lead to breakage of the nanofiber mat. In a previous study, we have shown that the electrospinning of PAN on aluminum foils and the subsequent stabilization of this substrate is a simple method for retaining the fiber morphology without breaking the nanofiber mat. Here, we report on the impact of different aluminum foils on the physical and chemical properties of stabilized PAN nanofibers mats, and on the following incipient carbonization process at a temperature of max. 600 °C, i.e., below the melting temperature of aluminum.
      Citation: Fibers
      PubDate: 2020-08-21
      DOI: 10.3390/fib8090055
      Issue No: Vol. 8, No. 9 (2020)
  • Fibers, Vol. 8, Pages 56: Meso-Scale Formulation of a Cracked-Hinge Model
           for Hybrid Fiber-Reinforced Cement Composites

    • Authors: Enzo Martinelli, Marco Pepe, Fernando Fraternali
      First page: 56
      Abstract: This study presents a non-linear cracked-hinge model for the post-cracking response of fiber-reinforced cementitious composites loaded in bending. The proposed displacement-based model follows a meso-mechanical approach, which makes it possible to consider explicitly the random distribution and orientation of the reinforcing fibers. Moreover, the model allows for considering two different fiber typologies whereas the cement matrix is modelled as a homogeneous material. The proposed mechanical model combines a fracture-based, stress-crack opening relationship for the cementitious matrix with generalized laws aimed to capture the crack-bridging effect played by the reinforcing fibers. These laws are derived by considering both the fiber-to-matrix bond mechanism and fiber anchoring action possibly due to hooked ends. The paper includes a numerical implementation of the proposed theory, which is validated against experimental results dealing with fiber-reinforced cement composites reinforced with different short fibers. The excellent theory vs. experiment matching demonstrates the high technical potential of the presented model, obtained at a reasonable computational cost.
      Citation: Fibers
      PubDate: 2020-09-01
      DOI: 10.3390/fib8090056
      Issue No: Vol. 8, No. 9 (2020)
  • Fibers, Vol. 8, Pages 57: Wettability and Anti-Corrosion Performances of
           Carbon Nanotube-Silane Composite Coatings

    • Authors: Luigi Calabrese, Amani Khaskoussi, Edoardo Proverbio
      First page: 57
      Abstract: In this paper, a sol-gel N-propyl-trimethoxy-silane coating filled with different amount of multi-wall carbon nanotubes (MWCNTs) was investigated in order to improve the aluminum corrosion resistance. The nanocomposite coating was applied, by drop casting, on AA6061 aluminum alloy substrate. The morphological analysis highlighted that a uniform sol-gel coating was obtained with 0.4 wt.% CNT. Lower or higher nanotube contents lead to the formation of heterogeneities or agglomeration in the coating, respectively. Furthermore, all nanocomposite coatings exhibited effective adhesion to the substrate. In particular, the pull-off strength ranged in 0.82–1.17 MPa. Corrosion protection of the aluminum alloy in NaCl 3.5 wt.% electrolyte (seawater) was significantly improved after CNT addition to the base coating. The stability in electrochemical impedance was observed during three days of immersion in the sodium chloride solution. AS3-CNT2 and AS3-CNT4 batches showed advanced electrochemical stability during immersion tests. Furthermore, interesting results were evidenced in potentiodynamic polarization curves where a decrease of the corrosion current of at least two order of magnitude was observed. Moreover, the breakdown potential was shifted toward noble values. Best results were observed on AS3-CNT6 specimen which exhibited a passivation current density of approximately 1.0 × 10−5 mA/cm2 and a breaking potential of 0.620 V/AgAgClsat.
      Citation: Fibers
      PubDate: 2020-09-10
      DOI: 10.3390/fib8090057
      Issue No: Vol. 8, No. 9 (2020)
  • Fibers, Vol. 8, Pages 58: Influence of Gamma Radiation on Mechanical
           Properties of Jute Fabric-Reinforced Polymer Composites

    • Authors: K.Z.M. Abdul Motaleb, Rimvydas Milašius, Abdul Ahad
      First page: 58
      Abstract: Woven jute fabric was used as a reinforcing material for making two types of composite, named Jute/PR and Jute/Epoxy, with two different matrixes of polyester resin and epoxy, respectively, by hand layup techniques. Five different doses of gamma radiation from 100 to 500 krad were used to investigate the effects of the mechanical properties of the composites and the jute fabrics. Though gamma radiation improved the mechanical properties, such as the tensile strength (TS) and Young’s modulus (Y), and decreased the elongation at break % (Eb%) of the composites, it deteriorated all these properties for jute fabrics. The highest values of TS and Y and the lowest value of Eb% were found to be 39.44 Mpa, 1218.33 Mpa, and 7.68% for the Jute/PR; and 48.83 Mpa, 1459.67 Mpa, and 3.68% for the Jute/Epoxy composites, respectively, at a 300 krad gamma radiation dose. A further increase in dose altered all these properties; thus, 300 krad was found to be the optimum dose for both of the composites. Between the two composites, gamma radiation influenced the Jute/PR composite more than the Jute/Epoxy composite.
      Citation: Fibers
      PubDate: 2020-09-13
      DOI: 10.3390/fib8090058
      Issue No: Vol. 8, No. 9 (2020)
  • Fibers, Vol. 8, Pages 59: Determination of Optimum Twist Equation for the
           Long Staple Combed Cotton Ring-Spun Yarn

    • Authors: Dunja Šajn Gorjanc, Neža Sukič
      First page: 59
      Abstract: The aim of this research was to determine the optimum twist equation for ring-spun yarns. The yarn twist can be calculated by different equations. With the research, we tried to find the appropriate equation to determine the yarn twist, which is determined by the values of yarn strength and hairiness. In the research, yarns from long staple combed cotton rovings and of different fineness (10 tex, 11.8 tex, 20 tex and 29.4 tex) were analyzed. The yarn twist was calculated using the equations of Koechlin and Laetsch. The analyzed yarns were produced in the spinning mill on the laboratory ring spinning machine Spinntester. In the second part of the investigation, yarn strength and hairiness were analyzed as a function of yarn twist. The results showed that Laetsch’s equation is suitable for determining the twist for yarns with a fineness of 10 tex, 11.8 tex, 20 tex and 29.4 tex, since, in this case, the calculated number of yarn threads is higher and thus the strength and elongation at break are also higher. The yarn hairiness is higher in analyzed samples for yarns with the twist calculated according to the Koechlin’s equation.
      Citation: Fibers
      PubDate: 2020-09-21
      DOI: 10.3390/fib8090059
      Issue No: Vol. 8, No. 9 (2020)
  • Fibers, Vol. 8, Pages 60: A Novel Method of Spectra Processing for
           Brillouin Optical Time Domain Reflectometry

    • Authors: Fedor L. Barkov, Yuri A. Konstantinov, Anton I. Krivosheev
      First page: 60
      Abstract: A new method of Brillouin spectra post-processing, which could be applied in modern distributed optical sensors: Brillouin optical time domain analyzers/reflectometers (BOTDA/BOTDR), has been demonstrated. It operates by means of the correlation analysis performed with special technique («backward-correlation»). It does not need any additional data for time or space averaging and operates with the single spectrum only. We have simulated the method accuracy dependence on signal-to-noise ratio (SNR) and other parameters. It is shown that the new method produces better results at low SNRs than conventional technique, based on finding of Brillouin spectrum maximum, do. These results are in a good agreement with the experiment. Finally, we have estimated the performance of the new method for its application in polarization-BOTDA set-up for a polarization maintaining (PM) fiber modal birefringence distributed study.
      Citation: Fibers
      PubDate: 2020-09-22
      DOI: 10.3390/fib8090060
      Issue No: Vol. 8, No. 9 (2020)
  • Fibers, Vol. 8, Pages 48: Effect of Silane Coupling Treatment on the
           Adhesion between Polyamide and Epoxy Based Composites Reinforced with
           Carbon Fibers

    • Authors: Vincenzo Fiore, Vincenzo Orlando, Carmelo Sanfilippo, Dionisio Badagliacco, Antonino Valenza
      First page: 48
      Abstract: The increasing efforts aimed to design structures with reduced weight and better mechanical performances has led in recent years to a growing use of fiber reinforced polymer materials in several fields such as marine. However, these materials can be composed of chemically very different elements and, hence, may be difficult to joint. This research aims to improve the adhesion between a thermoplastic matrix of polyamide reinforced with short carbon fibers (PA12-CR) and a carbon fiber reinforced epoxy matrix (CFRP). Two different silane coupling agents, (3-Aminopropyl)trimethoxysilane (AM) and (3-Glycidyloxypropyl)trimethoxysilane (EP), were applied, through the spray deposition method, on the PA12-CR substrate to create a reactive layer between the adherents. Different deposition methods and coupling agents curing conditions were also investigated. The wettability of the PA12-CR surface as well as the chemical modifications induced by silane treatments were investigated through contact angle and Fourier Transform Infrared spectroscopy (FTIR) analyses. Furthermore, the interfacial adhesion between PA12-CR and CFRP substrates was evaluated through Mode I delamination tests (DCB). The effectiveness of the most promising treatment was finally verified on sandwich structures, having PA12-CR printed as internal core and CFRP laminates as external skins, through quasi-static three-point bending mechanical tests. Overall, the epoxy-based silane (EP) allowed significantly better resistance to the delamination up until the tensile failure of the CFRP substrate.
      Citation: Fibers
      PubDate: 2020-07-28
      DOI: 10.3390/fib8080048
      Issue No: Vol. 8, No. 8 (2020)
  • Fibers, Vol. 8, Pages 49: A New Fabric Reinforced Geopolymer Mortar (FRGM)
           with Mechanical and Energy Benefits

    • Authors: Fabio Longo, Alessio Cascardi, Paola Lassandro, Maria Antonietta Aiello
      First page: 49
      Abstract: A large part of the European building Heritage is dated back over centuries. Consequently, its structural and thermal performances are often inadequate. Commonly, different interventions are proposed for solving these issues separately. However, reasonable drawbacks arise when the structural retrofitting requires a direct contact with the target-member while the insulation layer is potentially interposed in between. In this scenario, the present research proposes a novel and unique system able to guarantee both the energetic and the structural retrofitting. Inorganic Matrix Composites (IMCs) are a promising solution in this sense. Among them, the Fabric Reinforced Cementitous Matrix (FRCM) is one of the most used; or rather a composite made of a fabric (open grid or mesh) within an inorganic matrix (lime or cement based). Even if the inorganic matrix has a relevant thickness (if compared with the one of the fabric), its thermal resistance is insufficient. The novelty of this work consists in assessing a new geo-polymeric FRCM-system by combining fly-ash binder (reused material) and expanded glass aggregate (recycled material). Direct tensile tests, for measuring the tensile strength, ultimate strain and elastic modulus, were performed in addition to thermal conductivity tests. The results were compared with those of traditional FRCM (commercially available). The potentiality of the proposal for structural and energy retrofitting is discussed and examples of its possible application are also reported.
      Citation: Fibers
      PubDate: 2020-07-30
      DOI: 10.3390/fib8080049
      Issue No: Vol. 8, No. 8 (2020)
  • Fibers, Vol. 8, Pages 50: Bonding Wood Veneer with Biobased Poly(Lactic
           Acid) Thermoplastic Polyesters: Potential Applications for Consolidated
           Wood Veneer and Overlay Products

    • Authors: Warren J. Grigsby, Arpit Puri, Marc Gaugler, Jan Lüedtke, Andreas Krause
      First page: 50
      Abstract: This study reports on the use of poly(lactic acid) (PLA) as a renewable thermoplastic adhesive for laminated panels using birch, spruce, and pine veneers. Consolidated panels were prepared from veneer and PLA foils by hot-pressing from 140 to 180 °C to achieve minimum bondline temperatures. Evaluation of panel properties revealed that the PLA-bonded panels met minimum tensile strength and internal bond strength performance criteria. However, the adhesion interface which developed within individual bondlines varied with distinctions between hardwood and softwood species and PLA grades. Birch samples developed greater bondline strength with a higher pressing temperature using semi-crystalline PLA, whereas higher temperatures produced a poorer performance with the use of amorphous PLA. Panels formed with spruce or pine veneers had lower bondline performance and were also similarly distinguished by their pressing temperature and PLA grade. Furthermore, the potential for PLA-bonded laminated panels was demonstrated by cold water soak testing. Samples exhibiting relatively greater bondline adhesion had wet tensile strength values comparable to those tested in dry state. Our study outcomes suggest the potential for PLA bonding of veneers and panel overlays with the added benefits of being renewable and a no added formaldehyde system.
      Citation: Fibers
      PubDate: 2020-07-31
      DOI: 10.3390/fib8080050
      Issue No: Vol. 8, No. 8 (2020)
  • Fibers, Vol. 8, Pages 51: Activated Carbons as Methanol Adsorbents for a
           New Cycle “Heat from Cold”

    • Authors: Ilya Girnik, Alexandra Grekova, Larisa Gordeeva, Yuri Aristov
      First page: 51
      Abstract: Activated carbons are widely used for sustainable technology of adsorptive transformation and storage of heat. Here, we analyze the applicability of twelve commercial carbons and an innovative carbonaceous composite “LiCl confined to multi-wall carbon nanotubes” (LiCl/MWCNT) for a new cycle “Heat from Cold” (HeCol). It has recently been proposed for amplification of low- temperature ambient heat in cold countries. The analysis is made in terms of the methanol mass exchanged and the useful heat generated per cycle; the latter is the main performance indicator of HeCol cycles. The maximum specific useful heat, reaching 990 and 1750 J/g, can be obtained by using carbon Maxsorb III and the composite, respectively. For these materials, methanol adsorption dynamics under typical HeCol conditions are experimentally studied by the large pressure jump method. Before making this analysis, the fine carbon powder is consolidated by either using a binder or just pressing to obtain larger particles (ca. 2 mm). The methanol desorption from the consolidated samples of Maxsorb III at T = 2 °C is faster than for LiCl/MWCNT, and the maximum (initial) useful power reaches (2.5–4.0) kW/kg sorbent. It is very promising for designing compact HeCol units utilizing the carbon Maxsorb III.
      Citation: Fibers
      PubDate: 2020-08-08
      DOI: 10.3390/fib8080051
      Issue No: Vol. 8, No. 8 (2020)
  • Fibers, Vol. 8, Pages 52: Finite Element Analysis of Beams Reinforced with
           Banana Fiber Bars (BFB)

    • Authors: Amgad Elbehiry, Marwan Mostafa
      First page: 52
      Abstract: One of the challenges of the century is to reach compatibility between the required resistance and the usage of lightweight building materials that may negatively affect the mechanical properties. Natural fibers nowadays are used as enhancers in the industrial field. Hence, the fibers contribute by giving an ideal solution to improve mechanical proprieties of the structural elements such as tensile and impact strength. In previous studies, the use of natural fibers as reinforcement in construction materials has increased. Natural fibers have a lot of characteristics such as being strong, lightweight, inexpensive, and eco-friendly. This paper aims to investigate the performance of banana fiber bars (BFB) as reinforced material. Through this study, the development and characterization of natural fibers-based composite beams were observed. After the beams were designed, several types of finite element analysis were conducted using ‘ANSYS’ nonlinear finite element program under one-point loading. Results show good correlations between experimental and predicted results.
      Citation: Fibers
      PubDate: 2020-08-14
      DOI: 10.3390/fib8080052
      Issue No: Vol. 8, No. 8 (2020)
  • Fibers, Vol. 8, Pages 44: Characterization of Wear and Physical Properties
           of Pawpaw–Glass Fiber Hybrid Reinforced Epoxy Composites for Structural

    • Authors: Isiaka Oluwole Oladele, Oluwaseun Temilola Ayanleye, Adeolu Adesoji Adediran, Baraka Abiodun Makinde-Isola, Anuoluwapo Samuel Taiwo, Esther Titilayo Akinlabi
      First page: 44
      Abstract: In this study, wear resistance and some selected physical properties of pawpaw–glass fiber hybrid reinforced epoxy composites were investigated. Two different layers of pawpaw stem—linear and network structures—were extracted and chemically modified. Hybrid reinforced composites were developed comparatively from the two fiber structures and glass fiber using hand lay-up in an open mold production process. The wear resistance was studied via the use of a Taber Abrasion Tester while selected physical properties were also investigated. The influence of the fiber structure on the properties examined revealed that network structured pawpaw fiber was the best as reinforcement compared to the linearly structured fiber. The addition of these vegetable fibers to epoxy resin brought about improved thermal conductivity and increased the curing rate while the wear resistance of the corresponding developed composites were enhanced by 3 wt% and 15 wt% of fibers from linear and network pawpaw fibers. It was noticed that linearly structured pawpaw fiber had its best result at 3 wt% while network structured pawpaw fiber had its best result at 15 wt%.
      Citation: Fibers
      PubDate: 2020-07-03
      DOI: 10.3390/fib8070044
      Issue No: Vol. 8, No. 7 (2020)
  • Fibers, Vol. 8, Pages 45: Carbon Nanotubes-Filled Siloxane Composite Foams
           for Oil Recovery Application: Compression Properties

    • Authors: Elpida Piperopoulos, Luigi Calabrese, Emanuela Mastronardo, Edoardo Proverbio, Candida Milone
      First page: 45
      Abstract: This paper studies the correlation between oil recovery usability and mechanical behavior under compression loads of an innovative oil recovery material. The examined composites are silicone foams filled with carbon nanotubes (CNT). Here, the reutilization of oil recovery processes of the newly developed composite foams is evaluated. In this regard, static and cyclic compressive tests are carried out. Samples filled with pristine and functionalized CNT are tested to evaluate the influence of the filler’s characteristics on the composite foam’s mechanical behavior. The results show that the presence of CNT (CNT-0) increases the elastic modulus (0.030 MPa) and collapse stress (0.010 MPa) of the siloxane matrix. On the contrary, as the CNT functionalization degree increases, a worsening of the composite’s mechanical performance is observed. CNT-0 foam evidences, also, the optimal mechanical stability to cyclic compressive loads, maintaining high stress values until 30 cycles. Furthermore, a correlation between the absorption capacity, elastic modulus, and cyclability is reported, highlighting a simplified approach to tailor the high absorption durability performance of filled CNT silicone foams. The promising results confirm the possible reuse of these new composite foams as absorbent materials for oil spill recovery applications.
      Citation: Fibers
      PubDate: 2020-07-10
      DOI: 10.3390/fib8070045
      Issue No: Vol. 8, No. 7 (2020)
  • Fibers, Vol. 8, Pages 46: Effects of Flat-Shaped Face Layer Particles and
           Core Layer Particles of Intentionally Greater Thickness on the Properties
           of Wood-Reduced Particleboard

    • Authors: Jan T. Benthien, Martin Ohlmeyer
      First page: 46
      Abstract: Against the background of the intention to reduce the amount of wood used in the production of particleboard for economic reasons, the associated reduction in panel density and consequently the panel properties, the influence of the alternative use of flat-shaped face layer particles and core layer particles of intentionally greater thickness on the panel properties was investigated. Appropriate particles were made for this purpose, panels with typical (650 kg/m3) and reduced wood usage (500 kg/m3) were produced, and e.g., their bending properties and internal bond strength were determined. Particle size characterization was done with sieve analysis, image analysis (length and width measurement), and manual thickness gauging. It was found that the alternative use of the flat-shaped particle significantly increased the bending properties and thus the level of the reference can be achieved despite the reduced use of wood. The reason for the increased bending properties was assumed to be the higher strength of the particles themselves and the more effective adhesive bond between the particles. The increase in internal bond strength when using alternative particles could be attributed solely the different production history (e.g., use of fresh cutting blades and laboratory scale production).
      Citation: Fibers
      PubDate: 2020-07-13
      DOI: 10.3390/fib8070046
      Issue No: Vol. 8, No. 7 (2020)
  • Fibers, Vol. 8, Pages 47: Specific Dimensional Change Behavior of
           Laminated Beech Veneer Lumber (BauBuche) in Terms of Moisture Absorption
           and Desorption

    • Authors: Jan T. Benthien, Martin Riegler, Nick Engehausen, Martin Nopens
      First page: 47
      Abstract: Replacing greenhouse gas-intensive building materials with wood products from sustainable forestry contributes to the implementation of current climate conventions such as the Paris Agreement. Hardwood products, such as laminated veneer lumber made of beech (e.g., BauBuche), are an alternative to conventional building materials. For the application of wood products in the construction sector, a precise knowledge of the mechanical and physical properties is essential. Therefore, the aim of the present study was to investigate the sorption behavior and associated dimensional changes of the product BauBuche. This was done by applying a manual testing procedure (climatic chamber, balance and caliper) as well as a dynamic vapor sorption analyzer equipped with a camera. During initial moistening after production, due to the irreversible spring back (approximately 2 mm at 50 mm; i.e., 4%), Baubuche shows an extremely strong swelling in the radial direction. Once the maximum spring back is reached, Baubuche shows sorption behavior in the radial and tangential direction, which is comparable to that of solid beech wood in the radial direction. Consequently, the dimensional changes caused by moisture changes must be taken into account in the dimensioning of Baubuche components in order to avoid damage to building structures.
      Citation: Fibers
      PubDate: 2020-07-16
      DOI: 10.3390/fib8070047
      Issue No: Vol. 8, No. 7 (2020)
  • Fibers, Vol. 8, Pages 33: Impact of Alternative Stabilization Strategies
           for the Production of PAN-Based Carbon Fibers with High Performance

    • Authors: Soulis, Konstantopoulos, Koumoulos, Charitidis
      First page: 33
      Abstract: The aim of this work is to review a possible correlation of composition, thermal processing, and recent alternative stabilization technologies to the mechanical properties. The chemical microstructure of polyacrylonitrile (PAN) is discussed in detail to understand the influence in thermomechanical properties during stabilization by observing transformation from thermoplastic to ladder polymer. In addition, relevant literature data are used to understand the comonomer composition effect on mechanical properties. Technologies of direct fiber heating by irradiation have been recently involved and hold promise to enhance performance, reduce processing time and energy consumption. Carbon fiber manufacturing can provide benefits by using higher comonomer ratios, similar to textile grade or melt-spun PAN, in order to cut costs derived from an acrylonitrile precursor, without suffering in regard to mechanical properties. Energy intensive processes of stabilization and carbonization remain a challenging field of research in order to reduce both environmental impact and cost of the wide commercialization of carbon fibers (CFs) to enable their broad application.
      Citation: Fibers
      PubDate: 2020-05-26
      DOI: 10.3390/fib8060033
      Issue No: Vol. 8, No. 6 (2020)
  • Fibers, Vol. 8, Pages 34: Original Solution of Coupled Nonlinear
           Schrödinger Equations for Simulation of Ultrashort Optical Pulse
           Propagation in a Birefringent Fiber

    • Authors: Airat Zhavdatovich Sakhabutdinov, Vladimir Ivanovich Anfinogentov, Oleg Gennadievich Morozov, Vladimir Alexandrovich Burdin, Anton Vladimirovich Bourdine, Ildaris Mudarrisovoch Gabdulkhakov, Artem Anatolievich Kuznetsov
      First page: 34
      Abstract: This paper discusses approaches to the numerical integration of the coupled nonlinear Schrödinger equations system, different from the generally accepted approach based on the method of splitting according to physical processes. A combined explicit/implicit finite-difference integration scheme based on the implicit Crank–Nicolson finite-difference scheme is proposed and substantiated. It allows the integration of a nonlinear system of equations with a choice of nonlinear terms from the previous integration step. The main advantages of the proposed method are: its absolute stability through the use of an implicit finite-difference integration scheme and an integrated mechanism for refining the numerical solution at each step; integration with automatic step selection; performance gains (or resolutions) up to three or more orders of magnitude due to the fact that there is no need to produce direct and inverse Fourier transforms at each integration step, as is required in the method of splitting according to physical processes. An additional advantage of the proposed method is the ability to calculate the interaction with an arbitrary number of propagation modes in the fiber.
      Citation: Fibers
      PubDate: 2020-06-03
      DOI: 10.3390/fib8060034
      Issue No: Vol. 8, No. 6 (2020)
  • Fibers, Vol. 8, Pages 35: A Comparative Study of the Performance of

    • Authors: Safaa Qays Abdualrahman, Alaa Hussein Al-Zuhairi
      First page: 35
      Abstract: Most reinforced concrete (RC) structures are constructed with square/rectangular columns. The cross-section size of these types of columns is much larger than the thickness of their partitions. Therefore, parts of these columns are protruded out of the partitions. The emergence of columns edges out of the walls has some disadvantages. This limitation is difficult to be overcome with square or rectangular columns. To solve this problem, new types of RC columns called specially shaped reinforced concrete (SSRC) columns have been used as hidden columns. Besides, the use of SSRC columns provides many structural and architectural advantages as compared with rectangular columns. Therefore, this study was conducted to explain the structural performance of slender SSRC columns experimentally and numerically via nonlinear finite element analysis. The study is based on nine RC specimens tested up to failure, as well as eighteen finite element (FE) models analyzed by Abaqus soft wear program. The use of SSRC columns led to increase strength by about 12% and reduce deformations, especially with slenderness ratio more than 40 as compared with equivalent square-shaped columns. Two design formulas were proposed to determine the compressive strength of SSRC columns under concentric loading. The results obtained indicate a good structural performance of SSRC columns when compared with equivalent square-shaped columns.
      Citation: Fibers
      PubDate: 2020-06-04
      DOI: 10.3390/fib8060035
      Issue No: Vol. 8, No. 6 (2020)
  • Fibers, Vol. 8, Pages 36: Influence of Milled Glass Fiber Fillers on Mode
           I & Mode II Interlaminar Fracture Toughness of Epoxy Resin for
           Fabrication of Glass/Epoxy Composites

    • Authors: Saravanakumar, Arumugam, Souhith, Santulli
      First page: 36
      Abstract: The present work is focused on improving mode I and mode II delamination resistance of glass/epoxy composite laminates (50 wt.% of glass fibers) with milled glass fibers, added in various amounts (2.5, 5, 7.5 and 10% of the epoxy weight). Including fillers in the interlayer enhances the delamination resistance by providing a bridging effect, therefore demanding additional energy to initiate the crack in the interlaminar domain, which results in turn in enhanced fracture toughness. The maximal increase of mode I and mode II fracture toughness and of flexural strength was obtained by the addition of 5% milled glass fiber. The mechanism observed suggests that crack propagation is stabilized even leading to its arrest/deflection, as a considerable amount of milled glass fiber filler was oriented transverse to the crack path. In contrast, at higher filler loading, tendency towards stress concentration grows due to local agglomeration and improper dispersion of excess fillers in inter/intralaminar resin channel, causing poor adhesion to the matrix, which leads to reduction in fracture toughness, strength and strain to failure. Fractured surfaces analyzed using scanning electron microscopy (SEM) revealed a number of mechanisms, such as crack deflection, individual debonding and filler/matrix interlocking, all contributing in various ways to improve fracture toughness.
      Citation: Fibers
      PubDate: 2020-06-11
      DOI: 10.3390/fib8060036
      Issue No: Vol. 8, No. 6 (2020)
  • Fibers, Vol. 8, Pages 37: Determination and Review of Physical and
           Mechanical Properties of Raw and Treated Coconut Fibers for Their
           Recycling in Construction Materials

    • Authors: Bui, Sebaibi, Boutouil, Levacher
      First page: 37
      Abstract: In order to reduce the dependency on conventional materials and negative environmental impacts, one of the main responsibilities of the construction field is to find new eco-friendly resources to replace the traditional materials partially. Natural fibers were known as potential candidates for the reinforcement of structures in civil engineering by virtue of their advantages. Among the different kinds of vegetable fibers, coconut fiber has been exploited in a limited way over the past few years. This paper aims at evaluating the different properties of local coconut fibers (Vietnam). Several laboratory tests provide geometrical, physical, mechanical properties and durability properties that are compared with literature results obtained from similar natural fibers. The local coconut fibers tested demonstrated properties suitable for reinforced mortars. With adequate control of their preparation, they could be reused in the manufacture of mortars in the construction.
      Citation: Fibers
      PubDate: 2020-06-12
      DOI: 10.3390/fib8060037
      Issue No: Vol. 8, No. 6 (2020)
  • Fibers, Vol. 8, Pages 38: MESO-Scale Modeling of CFRP-Confined Concrete:
           Microplane-Based Approach

    • Authors: Gambarelli, Ožbolt
      First page: 38
      Abstract: The present paper shows the results of three-dimensional (3D) meso-scale numerical simulations that were performed on unconfined and Carbon Fibre Reinforced Polymer (CFRP)-confined concrete specimens under uniaxial compression. The numerical results are compared with available experimental data. The meso-scale structure of concrete is composed by two phases, namely: the coarse aggregate and the mortar matrix. The presence of Interfacial Transition Zone (ITZ) is neglected. A simple generation procedure is used to randomly place the coarse aggregate inside the concrete specimens. The finite element code MASA is used to perform the three-dimensional (3D) Finite Element meso-scale simulations. The constitutive laws for mortar and epoxy resin are based on the microplane model, while an elastic-brittle behavior is assumed for the fibers. Aggregate in concrete is considered to be linear elastic. The adopted meso-scale model for concrete can realistically reproduce the mechanical behavior of both unconfined and CFRP-confined specimens. However, in the case of small corner radius, the effect of confinement predicted by the model is overestimated with respect to the experimental results. This is partially related to the simplifications introduced in the model in terms of aggregate volumetric fraction (10%) and aggregate size distribution. It is shown that a more detailed meso-scale model, which is characterized by 30% of the coarse aggregate and realistic aggregate size distribution, can better capture the interaction between the concrete heterogeneity and the confining effect provided by CFRP.
      Citation: Fibers
      PubDate: 2020-06-13
      DOI: 10.3390/fib8060038
      Issue No: Vol. 8, No. 6 (2020)
  • Fibers, Vol. 8, Pages 39: Cyclic Performance of RC Columns with Inadequate
           Lap Splices Strengthened with CFRP Jackets

    • Authors: George Kalogeropoulos, Alexander-Dimitrios Tsonos
      First page: 39
      Abstract: The cyclic performance of non-seismically designed reinforced concrete (RC) columns, strengthened with carbon fiber reinforced polymer (CFRP) jackets, was analytically and experimentally investigated herein. Three cantilever column specimens were constructed, incorporating design parameters of the period 1950s–1970s, namely with concrete of a low compressive strength, plain steel bars, widely-spaced ties and inadequate lap splices of reinforcement. The specimens were strengthened using CFRP jackets and were subsequently subjected to cyclic inelastic lateral displacements. The main parameters examined were the length of the lap splices, the acceptable relative bar slipping value and the width of the jackets. The hysteresis behaviors of the enhanced columns were compared, while also being evaluated with respect to those of two original columns and to the seismic performance of a control specimen with continuous reinforcement, tested in a previous work. An analytical formulation was proposed for accurately predicting the seismic responses of the column specimens, comparing the actual shear stress value with the ultimate shear capacity of the concrete in the lap splice region. The test results verified the predictions of the analytical model, regarding the seismic performance of the strengthened columns. Moreover, the influences of the examined parameters in securing the ductile hysteresis performance were evaluated.
      Citation: Fibers
      PubDate: 2020-06-13
      DOI: 10.3390/fib8060039
      Issue No: Vol. 8, No. 6 (2020)
  • Fibers, Vol. 8, Pages 40: Experimental Study on the Effectiveness of
           Inorganic Bonding Materials for Near-Surface Mounting Shear Strengthening
           of Prestressed Concrete Beams

    • Authors: Vikas Singh Kuntal, M. Chellapandian, S. Suriya Prakash, Akanshu Sharma
      First page: 40
      Abstract: Use of organic resins such as epoxy and vinyl esters as bonding materials in fibre reinforced polymer (FRP) strengthening of concrete members is widely accepted. However, the performance of organic resins is compromised when exposed to high temperature and extreme weather conditions leading to reduced durability of the strengthened systems. The present study attempts to evaluate the effectiveness of inorganic (cement mortar and geopolymer mortar) bonding materials for shear strengthening of prestressed concrete (PSC) beams using the near-surface mounting (NSM) technique. Different types of bonding materials are used in this study for NSM shear strengthening including: (i) epoxy resin, (ii) high strength cement grout (HSCG) and (iii) geopolymer mortar. Bond tests were first conducted to evaluate the pull-out/bond strength of different bonding materials. Bond tests revealed that epoxy resin had the highest bond strength followed by geopolymer mortar and HSCG. Sixteen full-scale PSC beams were cast with and without stirrups. The beams were strengthened using NSM CFRP laminates oriented at 45-degree configuration and then tested under a three-point bending configuration. Experimental results revealed that the performance of high strength cement grout and geopolymer mortar was similar but with a lesser efficiency compared to the epoxy resin.
      Citation: Fibers
      PubDate: 2020-06-17
      DOI: 10.3390/fib8060040
      Issue No: Vol. 8, No. 6 (2020)
  • Fibers, Vol. 8, Pages 41: Flexural Strengthening of RC Continuous T-Beams
           Using CFRP

    • Authors: Ayssar Al-Khafaji, Hani Salim
      First page: 41
      Abstract: In this paper, experimental investigations for strengthening reinforced concrete (RC) continuous beams were performed. Eighteen T-beams were cast, twelve of which were inverted T-beams where the flange portion of the T-beam was subjected to positive flexure to represent the support region of a continuous beam. Six of the T-beams were non-inverted where the web is subjected to positive flexure. Carbon fiber reinforced polymer (CFRP) sheets with different widths were considered, and different strengthening configurations with the same area of CFRP were investigated. The use of one-layer, multiple layers, or multiple strips of CFRP were evaluated to investigate the effect of these configurations on the ultimate capacity and ductility of the strengthened beams. From the experimental observation of the non-inverted beams, it was found that the ultimate load capacities of the CFRP-strengthened beams were enhanced by 4% to 90% compared to the control beam. Using multiple layers of CFRP sheets enhanced the stiffness of the beams by 4% to 46%, depending on the CFRP area and configurations. The debonding of CFRP before the ultimate failure provided additional ductility to the tested beams. For the strengthening of the inverted beams, it was found that the addition of CFRP strips did not increase the strength of the beams when the width of CFRP to beam width ratio was less than 0.25, but the ductility of the beam was enhanced slightly. The use of multiple strips was found to be a more effective way for the strengthening of the negative moment region than using multiple layers. This can also provide more desirable modes of failure than when applying CFRP in multiple layers. Ductility was found to be lower if multiple layers were used compared to other configurations. Moreover, it was observed that as the compressive strength of concrete increased the addition of the CFRP improved the beams ductility.
      Citation: Fibers
      PubDate: 2020-06-20
      DOI: 10.3390/fib8060041
      Issue No: Vol. 8, No. 6 (2020)
  • Fibers, Vol. 8, Pages 42: A Moving Interface Finite Element Formulation to
           Predict Dynamic Edge Debonding in FRP-Strengthened Concrete Beams in
           Service Conditions

    • Authors: Funari, Spadea, Fabbrocino, Luciano
      First page: 42
      Abstract: A new methodology to predict interfacial debonding phenomena in fibre-reinforced polymer (FRP) concrete beams in the serviceability load condition is proposed. The numerical model, formulated in a bi-dimensional context, incorporates moving mesh modelling of cohesive interfaces in order to simulate crack initiation and propagation between concrete and FRP strengthening. Interface elements are used to predict debonding mechanisms. The concrete beams, as well as the FRP strengthening, follow a one-dimensional model based on Timoshenko beam kinematics theory, whereas the adhesive layer is simulated by using a 2D plane stress formulation. The implementation, which is developed in the framework of a finite element (FE) formulation, as well as the solution scheme and a numerical case study are presented.
      Citation: Fibers
      PubDate: 2020-06-24
      DOI: 10.3390/fib8060042
      Issue No: Vol. 8, No. 6 (2020)
  • Fibers, Vol. 8, Pages 43: The Effect of Alcohol Precipitants on Structural
           and Morphological Features and Thermal Properties of Lyocell Fibers

    • Authors: Igor S. Makarov, Lyudmila K. Golova, Markel I. Vinogradov, Ivan S. Levin, Georgiy A. Shandryuk, Natalia A. Arkharova, Yaroslav V. Golubev, Anna K. Berkovich, Timofei V. Eremin, Elena D. Obraztsova
      First page: 43
      Abstract: This research examines the possibilities of regulating the structure of cellulose precursor fibers spun from solutions in N-methylmorpholine-N-oxide when replacing aqueous coagulation baths with thermodynamically softer alcohol baths at different temperatures. The fibers were spun by the dry jet–wet method in isobutanol coagulation baths with a temperature of 25 °C and 70 °C. The study of the phase state of the solvent–coagulant system using viscometry and point cloud methods revealed the temperature-concentration regions of the single-phase and two-phase states of the system. Using elemental analysis, DSC (differential scanning calorimetry) and XRD (X-ray diffraction) methods, it was shown that just spun fibers, due to the presence of a residual amount of solvent and coagulant in them, regardless of the temperature of the precipitator, have an amorphous structure. Additional washing with water completely washed away the solvent and coagulant as well, however, the structure of cellulose changes slightly, turning into a defective amorphous-crystalline one. A relationship was found between the phase composition, structure, and properties of just spun fibers and precursors washed with water. Thus, the loss of structural ordering of both just spun and washed cellulose fibers leads to a decrease in strength characteristics and an increase in deformation. The thermal behavior of the fibers is determined by their phase composition. Fibers just spun into hot alcohol containing a coagulant and traces of solvent acquire thermal stability up to 330 °C. During the pyrolysis of the obtained precursors up to 1000 °C, the value of the carbon yield doubles. The amorphized structure of the obtained fibers allows us to consider it as a model when analyzing the transformation of the structure of precursors during thermolysis.
      Citation: Fibers
      PubDate: 2020-06-26
      DOI: 10.3390/fib8060043
      Issue No: Vol. 8, No. 6 (2020)
  • Fibers, Vol. 8, Pages 26: Tensile Properties and Microstructure of
           Single-Cellulosic Bamboo Fiber Strips after Alkali Treatment

    • Authors: Abeer Adel Salih, Rozli Zulkifli, Che Husna Azhari
      First page: 26
      Abstract: The study systematically explored the effect of alkali concentration and soaking time on the microstructure and tensile properties of single-cellulosic Buluh Semantan. Scanning electron microscopy and tensile tests were conducted to determine the effects of different alkali treatments on the properties of the single-cellulosic bamboo fibers. In particular, the effects of NaOH concentration and soaking time on the tensile properties of the single-cellulosic bamboo fiber were investigated. The single-cellulosic bamboo fiber was immersed in 2, 4, 6, and 8 wt.% aqueous NaOH solutions for soaking times of 1, 3, 6, 12, 18, and 24 h. The tensile properties of the fiber increased after each alkali treatment. The alkali concentration and soaking time significantly affected the fiber properties. The ultimate tensile strength of the single-cellulosic Buluh Semantan treated with 2 wt.% NaOH for 12 h decreased to 214 MPa relative to the fibers that experienced water retting. The highest tensile strength herein was 356.8 MPa for the single-cellulosic fiber that was soaked for 12 h in 4 wt.% NaOH. Comparatively, the tensile strength of the single-cellulosic bamboo fiber that was soaked for 12 h in 8 wt.% NaOH was 234.8 MPa. The tensile modulus of the single-cellulosic fiber was 12.06 GPa after soaking in 8 wt.% NaOH for 18 h, indicating that a strong alkali treatment negatively affected the stiffness and suitability for use of the fibers in applications. The topography of the fiber surface became much rougher after the alkali treatments due to the removal of hemicellulose and other surface impurities. The alkali treatments substantially changed the morphology of the fiber surface, suggesting an increase in wettability.
      Citation: Fibers
      PubDate: 2020-04-28
      DOI: 10.3390/fib8050026
      Issue No: Vol. 8, No. 5 (2020)
  • Fibers, Vol. 8, Pages 27: A Novel Method for Electrospinning Nanofibrous
           3-D Structures

    • Authors: Daniela Lubasova, Anil N. Netravali
      First page: 27
      Abstract: The fast and precise fabrication of three-dimensional (3-D) structures made of nanofibers is an important development trend in the electrospinning technique. This paper describes a new and facile method of electrospinning to fabricate nanofibrous 3-D structures. The nanofibrous 3-D structures can be engineered to have the desired layer thicknesses, where the fiber spacing, density (i.e., fiber volume/unit volume), as well as shape of the structure may be controlled. While innumerable structural variations are possible with this method, this paper discusses, as proof-of-concept, a few cases that illustrate how 3-D nanofiber webs can be made for filtration application. Computerized automation of the method will make it possible to build almost any 3-D web structure suitable for a myriad of applications including ultra-light-weight insulation and scaffolds for hydrogel preparation and tissue.
      Citation: Fibers
      PubDate: 2020-04-30
      DOI: 10.3390/fib8050027
      Issue No: Vol. 8, No. 5 (2020)
  • Fibers, Vol. 8, Pages 28: Loading Dynamics of Cold Atoms into a
           Hollow-Core Photonic Crystal Fiber

    • Authors: Yu Wang, Shijie Chai, Mingjie Xin, Wui Seng Leong, Zilong Chen, Shau-Yu Lan
      First page: 28
      Abstract: Cold atoms trapped and guided in hollow-core photonic crystal fibers provide a scalable diffraction-free setting for atom–light interactions for quantum technologies. However, due to the mismatch of the depth and spatial extension of the trapping potential from free space to the fiber, the number of cold atoms in the fiber is mainly determined by the loading process from free space to waveguide confinement. Here, we provide a numerical study of the loading dynamics of cold atoms into a hollow-core photonic crystal fiber. We use the Monte Carlo method to simulate the trajectories of an ensemble of cold atoms from free space trapping potential to optical potential inside a hollow-core fiber and calculate the temperature, loading efficiency, and geometry of the ensemble. We also study the noise sources that cause heating and a loss of atoms during the process. Our result could be used to design and optimize the loading process of cold atoms into a hollow-core fiber for cold atom experiments.
      Citation: Fibers
      PubDate: 2020-05-01
      DOI: 10.3390/fib8050028
      Issue No: Vol. 8, No. 5 (2020)
  • Fibers, Vol. 8, Pages 29: Surface and Morphological Investigation of
           Synthesized Nanostructured Ridges from Electrospun Polyvinyl
           Alcohol-Albumin Blend—A Taguchi Design of Experiment Approach

    • Authors: Ramis, Pajarito, Natividad, Ocampo, Tugade, Santos, Delfin
      First page: 29
      Abstract: We report the synthesis of presumably a “nanoridge” from the electrospinning of a hydrophilic polymer–protein blend. The material exhibits vertical elevation from the substrate, distinct from the morphologies seen in electrospinning. It is hypothesized that the formation of the nanostructured ridges is due to the migration of the charged protein to the apex through a highly polarized electric field in electrospinning conditions. In this study, we assessed the polyvinyl alcohol–egg albumin (PVA–EA) system in a solvent comprising of water, formic and acetic acid, together with the tip-to-collector distance (TCD) and solution flowrate. To quantify the factor effects in the surface properties of the material, a Taguchi design of experiment was used. The ridge heights observed ranged from 84.8–639.9 nm, and the material height is predominantly affected by the PVA–EA ratio and solution flow rate. The root mean square roughness was influenced by the TCD and flow rate, which has values ranging from 11.37–57.56 nm. In evaluating the sharpness of the ridge, we used the radius of curvature, where the TCD highly affects the apex sharpness. The work offers not just a likely new class of morphology, but a new perspective on the surface characterization of an electrospun material which could affect the performance of such a use in biological and physical systems.
      Citation: Fibers
      PubDate: 2020-05-02
      DOI: 10.3390/fib8050029
      Issue No: Vol. 8, No. 5 (2020)
  • Fibers, Vol. 8, Pages 30: Laser Sources Based on Rare-Earth Ion Doped
           Tellurite Glass Fibers and Microspheres

    • Authors: Elena A. Anashkina
      First page: 30
      Abstract: In recent years, huge progress has been made in the development of rare-earth ion doped tellurite glass laser sources, ranging from watt- and multiwatt-level fiber lasers to nanowatt level microsphere lasers. Significant success has been achieved in extending the spectral range of tellurite fiber lasers generating at wavelengths beyond 2 μm as well as in theoretical understanding. This review is aimed at discussing the state of the art of neodymium-, erbium-, thulium-, and holmium-doped tellurite glass fiber and microsphere lasers.
      Citation: Fibers
      PubDate: 2020-05-11
      DOI: 10.3390/fib8050030
      Issue No: Vol. 8, No. 5 (2020)
  • Fibers, Vol. 8, Pages 31: Measurement of Flexural Rigidity of Multi-Walled
           Carbon Nanotubes by Dynamic Scanning Electron Microscopy

    • Authors: Renata Fortini, Asmus Meyer-Plath, Dominic Kehren, Ulrich Gernert, Leonardo Agudo Jácome, Heinz Sturm
      First page: 31
      Abstract: In this work the flexural rigidity of individual large diameter multi-walled carbon nanotubes (MWCNTs) was investigated. The bending modulus were obtained by detecting the resonance frequencies of mechanically excited cantilevered carbon nanotubes using the so-called dynamic scanning electron microscopy technique, and applying the Euler–Bernoulli beam theory. For the nanotubes studied, we determined a modulus of up to 160 GPa. This agrees with values reported by other authors for MWCNTs produced by catalytic chemical vapor deposition, however, it is 6-8 times smaller than values reported for single and multi-walled carbon nanotubes produced by arc-discharge synthesis. Toxicological studies with carbon nanotubes have been showing that inhaled airborne nanofibers that reach the deep airways of the respiratory system may lead to serious, asbestos-like lung diseases. These studies suggested that their toxicity critically depends on the fiber flexural rigidity, with high rigidity causing cell lesions. To complement the correlation between observed toxicological effects and fiber rigidities, reliable and routinely applicable measurement techniques for the flexural rigidity of nanofibers are required.
      Citation: Fibers
      PubDate: 2020-05-12
      DOI: 10.3390/fib8050031
      Issue No: Vol. 8, No. 5 (2020)
  • Fibers, Vol. 8, Pages 32: Accelerated Thermal Aging of Bio-Based Composite
           Wood Panels

    • Authors: Brent Tisserat, Nicholas Montesdeoca, Veera M. Boddu
      First page: 32
      Abstract: Bio-based adhesives and resins are sought as alternatives to synthetics in order to fabricate all-biobased composite wood panels (CWPs), which provide environmentally friendly building products for indoor use. Very little information exists as to how these bio-based CWPs would perform long-term in non-temperature controlled structures such as warehouses and storage units where extreme temperatures occur depending on the season. In this study, novel all-bio-based CWPs were fabricated using a matrix of 50% distiller’s dried grains with solubles (DDGS) and 50% soybean flour ProsanteTM (PRO) mixed with wood particles. Bio-based CWPs were subjected to accelerated thermal aging for a 10-year period resembling outdoor temperatures in Peoria, IL USA. Four seasonal periods (Winter, Spring, Summer, and Fall) were simulated varying from −26–40 °C and 36–76% relative humidity (RH). The bio-based adhesive employed consisted of 50% distiller’s dried grains with solubles (DDGS) and 50% soybean flour ProsanteTM (PRO). CWPs consisted of 15 or 50% DDGS/PRO with 85% or 50% pine wood. CWPs were evaluated for 5, 7.5, and 10-years for their physical, flexural, dimensional stability, surface roughness, FTIR, TGA, and spectral properties. The changes in the CWP properties were notable during the initial 5 years, and later aged samples showed less change.
      Citation: Fibers
      PubDate: 2020-05-21
      DOI: 10.3390/fib8050032
      Issue No: Vol. 8, No. 5 (2020)
  • Fibers, Vol. 8, Pages 20: The Influence of SBS, Viatop Premium and FRP on
           the Improvement of Stone Mastic Asphalt Performance

    • Authors: Sepehr Saedi, Seref Oruc
      First page: 20
      Abstract: The current study investigates the effects of Fiber Reinforce Polymer (FRP) additive on the performance of Stone Mastic Asphalt (SMA) mixtures with SBS and Viatop Premium additives. The asphalt mixture used in the current study included SBS (Styrene-Butadiene-Styrene) additive modified at the rate of 5% according to the necessary preliminary studies, and some SMA mixture modified by adding FRP (Fiber Reinforced Polymers) additive prepared in dimensions of 5 cm in different proportions (0.3%, 0.5%, 0.7% and 0.9%). The mechanical properties of the mixtures were investigated, and the findings revealed that the SMA mixture; prepared by adding FRP additive, SBS modified bitumen, and Viatop Premium additive; increased the rutting, aging resistance and elasticity of SMAs. Moreover, load spread ability and fatigue life revealed an increase, whereas high temperature sensitivity and tendency to crack at low temperatures decreased throughout the study. The FRP contribution rate that improves the performance characteristics of the SMA mixture to the highest level was found to be 0.7%.
      Citation: Fibers
      PubDate: 2020-03-27
      DOI: 10.3390/fib8040020
      Issue No: Vol. 8, No. 4 (2020)
  • Fibers, Vol. 8, Pages 21: Cellulose Nanocrystals Versus Microcrystalline
           Cellulose as Reinforcement of Lignopolyurethane Matrix

    • Authors: Ramires, Megiatto, Dufresne, Frollini
      First page: 21
      Abstract: Cellulose nanocrystals (CNC) exhibit remarkable properties such as being lightweight, renewability, nanoscale dimension, raw material availability, and a unique morphology. They have been widely used in film-forming composites, but the literature is scarce concerning bulky-composites (i.e., non-filmogenic). Microcrystalline cellulose (MCC) is widely available and has emerged as an important material for the reinforcement of composites. This investigation focuses on the preparation of non-filmogenic composites prepared from a polyurethane-type matrix, based on modified lignosulfonate and castor oil, reinforced with CNC or MCC, aiming to compare their reinforcing capacity. CNC was obtained through the acid hydrolysis of MCC. Sodium lignosulfonate was chemically modified using glutaraldehyde to increase its reactivity towards isocyanate groups in the synthesis of lignopolyurethane. The results show that adding CNC or MCC led to materials with improved impact strength, flexural properties, and storage modulus compared to pristine lignopolyurethane. With the exception of the flexural modulus, which was higher for the CNC-reinforced composite compared to the MCC-reinforced composite, all other properties were similar. The set of results indicates that CNC and MCC are promising for the reinforcement of polyurethane-type matrices. Bulky materials with good properties and prepared from high renewable raw material contents were obtained, meeting current expectations concerning sustainable development.
      Citation: Fibers
      PubDate: 2020-03-29
      DOI: 10.3390/fib8040021
      Issue No: Vol. 8, No. 4 (2020)
  • Fibers, Vol. 8, Pages 22: Transmission of Orbital Angular Momentum and
           Cylindrical Vector Beams in a Large-Bandwidth Annular Core Photonic
           Crystal Fiber

    • Authors: Sharma, Amirkhan, Mishra, Sengupta, Messaddeq, Blanchard, Ung
      First page: 22
      Abstract: The stable propagation of orbital angular momentum and cylindrical vector beams in a newly designed annular core photonic crystal fiber (AC-PCF) tailored for the broadband single-radial order beam transmission (within the so-called “endlessly mono-radial” guiding regime) is demonstrated for the first time. It is shown that the vector-vortex beams can maintain high mode purities above 18 dB after propagation in the fiber under test over all of the wavelength range from 805 to 845 nm (over 17 THz bandwidth) investigated with the help of a tunable laser and an S-plate for the generation of singular beams in free space. Our results confirm that the AC-PCF is a promising design for the broadband transmission of vector-vortex beams that have potential applications in space-division multiplexing, quantum communications, optical sensing and trapping.
      Citation: Fibers
      PubDate: 2020-04-04
      DOI: 10.3390/fib8040022
      Issue No: Vol. 8, No. 4 (2020)
  • Fibers, Vol. 8, Pages 23: Flexural Behavior of High Strength
           Self-Compacted Concrete Slabs Containing Treated and Untreated Geogrid

    • Authors: Abd El-Rahman Fares, Hassan Hassan, Mohammed Arab
      First page: 23
      Abstract: Geogrid is as one of the component materials classified under the geosynthetics used for soil stabilizing and reinforcement. Due to its higher strength-to-weight ratio, ease of handling, and comparatively low costs, geogrid has been gradually explored for possible use in concrete reinforcement. This research aims to assess the feasibility of using geogrids as a possible reinforcement for high-strength self-compacted concrete slabs to provide additional tensile strength and ductility. To enhance the bond between geogrid layers and the cement matrix, two types of geogrid surface modification methods are introduced. Gluing sand to the geogrid surface as a physical surface modification method and immersion in polycarboxylate as a chemical surface modification method are investigated. The effect of geogrid type (uniaxial, biaxial and triaxial) and the number of layers is also introduced. The test results show that the chemical treatment increased the ultimate flexural loading capacity of the tested slab by about 8.5% for one geogrid layer and 13% for two geogrid layers compared to untreated specimens. This work was extended to add two geogrid layers in addition to the slab’s steel reinforcement. The results show that adding geogrid decreased the ultimate flexural loading capacity but significantly increased the slab ductility.
      Citation: Fibers
      PubDate: 2020-04-13
      DOI: 10.3390/fib8040023
      Issue No: Vol. 8, No. 4 (2020)
  • Fibers, Vol. 8, Pages 24: Conductive Electrospun
           Polyaniline/Polyvinylpyrrolidone Nanofibers: Electrical and Morphological
           Characterization of New Yarns for Electronic Textiles

    • Authors: Perdigão, Faustino, Faria, Canejo, Borges, Ferreira, Baptista
      First page: 24
      Abstract: Advanced functionalities textiles embedding electronic fibers, yarns and fabrics are a demand for innovative smart cloths. Conductive electrospun membranes and yarns based on polyaniline/polyvinylpyrrolidone (PANI/PVP) were investigated using the chemical modification of PANI instead of using conventional coating processes as in-situ polymerization. PANI was synthesized from the aniline monomer and the influence of the oxidant-to-monomer ratio on electrical conductivity was studied. The optimized conductivity of pellets made with pressed PANI powders was 21 S·cm−1. Yarns were then prepared from the t-Boc-PANI/PVP electrospun membranes followed by PANI protonation to enhance their electrical properties. Using this methodology, electrospun membranes and yarns were produced with electrical conductivities of 1.7 × 10−2 and 4.1 × 10−4 S·cm−1.
      Citation: Fibers
      PubDate: 2020-04-20
      DOI: 10.3390/fib8040024
      Issue No: Vol. 8, No. 4 (2020)
  • Fibers, Vol. 8, Pages 25: Performance of Reinforced Concrete Slab with
           Opening Strengthened Using CFRP

    • Authors: Syafiqah Shahrul Aman, Bashar S. Mohammed, Mubarak Abdul Wahab, Abdullah Anwar
      First page: 25
      Abstract: Openings in reinforced concrete (RC) slabs are not commonly prescribed in design codes. Even when they are, they raise concerns regards to the size of the openings and the location of the applied loads. Lack of sufficient information about the load-carrying capacity of the slabs with openings and performance is another concern. Hence, this research addresses the structural behavior of slabs with openings coated with Carbon Fiber Reinforced Polymer (CFRP) sheet. In the experimental part, ten slabs were cast with a dimension of 1000 mm × 530 mm × 25 mm, among which nine slabs had openings and one slab was without opening (control slab). The configuration of the CFRP sheet includes coating in the form of single, double, and triple layers. Experimental results show that the slab with a triple coating of the CFRP layer offers the maximum resistance towards the loading rate. Moreover, with the increase in CFRP layers, the value of deflection is minimized.
      Citation: Fibers
      PubDate: 2020-04-21
      DOI: 10.3390/fib8040025
      Issue No: Vol. 8, No. 4 (2020)
  • Fibers, Vol. 8, Pages 18: New Silica Laser-Optimized Multimode Optical
           Fibers with Extremely Enlarged 100-μm Core Diameter for Gigabit Onboard
           and Industrial Networks

    • Authors: Vladimir A. Burdin, Michael V. Dashkov, Vladimir V. Demidov, Konstantin V. Dukelskii, Alexander S. Evtushenko, Artem A. Kuznetsov, Alexandra S. Matrosova, Oleg G. Morozov, Egishe V. Ter-Nersesyants, Alexander A. Vasilets, Elena S. Zaitseva, Alexander E. Zhukov, Anton V. Bourdine
      First page: 18
      Abstract: We present new type of silica graded index laser-optimized multimode optical fibers (LOMF) with extremely enlarged core diameter up to 100 μm and “typical” “telecommunication” cladding diameter 125 μm. This optical fiber was designed for harsh environment Gigabit onboard cable systems and industrial networks. It differs by special optimized graded refractive index profile, providing low differential mode delay (DMD) for selected guided modes. We present some results of tests, performed for manufactured pilot 520 m length of described LOMF 100/125, concerned with its geometry properties as well as key transmission parameters—attenuation and DMD map.
      Citation: Fibers
      PubDate: 2020-03-17
      DOI: 10.3390/fib8030018
      Issue No: Vol. 8, No. 3 (2020)
  • Fibers, Vol. 8, Pages 19: Influence of Cooling Methods on the Behavior of
           Reactive Powder Concrete Exposed to Fire Flame Effect

    • Authors: Hadeel K. Awad
      First page: 19
      Abstract: The construction of highly safe and durable buildings that can bear accident damage risks including fire, earthquake, impact, and more, can be considered to be the most important goal in civil engineering technology. An experimental investigation was prepared to study the influence of adding various percentages 0%, 1.0%, and 1.5% of micro steel fiber volume fraction (Vf) to reactive powder concrete (RPC)—whose properties are compressive strength, splitting tensile strength, flexural strength, and absorbed energy—after the exposure to fire flame of various burning temperatures 300, 400, and 500 °C using gradual-, foam-, and sudden-cooling methods. The outcomes of this research proved that the maximum reduction in mechanical properties is detected in case of 0% addition at burning temperature of 500 °C using sudden cooling to be 63.90%, 55.77% and 53.8% for compressive, splitting tensile, and flexural strength, respectively, while using 1.5% produced a modification in compressive strength, splitting tensile strength, and flexural strength to 6.67%, 4.15%, and 7.00% respectively, and 7.10 kN·mm for the absorbed energy for gradual cooling at 300 °C. From the results, the adopted cooling methods can be ordered according to their negative influence by sudden, foam, and gradual, while the optimum percentage of (Vf) is 1.5% when burning at 300 °C for all methods of cooling. 1.0% is considered the optimum percentage for all burning temperatures that exceed 400 °C using sudden-cooling method.
      Citation: Fibers
      PubDate: 2020-03-20
      DOI: 10.3390/fib8030019
      Issue No: Vol. 8, No. 3 (2020)
  • Fibers, Vol. 8, Pages 8: Experimental Investigation and Numerical Analysis
           of Bond Behavior in SRG-Strengthened Masonry Prisms Using UHTSS and
           Stainless-Steel Fibers

    • Authors: Bencardino, Nisticò, Verre
      First page: 8
      Abstract: This paper deals with the experimental and numerical study of the bond behavior of two steel reinforced grout (SRG)-strengthened masonry systems. Ten shear bond tests were carried out on prismatic masonry specimens. The data of experimental tests are recorded and results are given in terms of load/stress-global slip curves, failure modes, tables, graphs and photographic reports, comparing the results of the two strengthening systems. Two kinds of steel fibers available in marketplace were used: ultra-high tensile strength steel galvanized micro-cords and stainless-steel strands. The main target is to obtain information on the behavior of the bond between masonry surface and the two types of SRG composites, which are characterized by two substantial differences: tensile strength with a ratio of 2.4 and the corresponding surface mass density with a ratio of 0.30. Finally, the influence of the matrices coupled with the two systems is critically analyzed. The characterization of the bond behavior is necessary in order to confirm the performance of the SRG systems that have become increasingly used and attractive. It also aims to make a contribution to the existing knowledge especially in relation to the use of low resistance steel fibers (stainless steel) which are still few studied today. Furthermore, using a suitable interface law proposed in the literature, a numerical model is defined and employed to simulate the behavior of the specimens tested in the laboratory. The comparisons show a good agreement between numerical and experimental results in terms of the maximum load, load versus global-slip curves, and crack patterns.
      Citation: Fibers
      PubDate: 2020-01-27
      DOI: 10.3390/fib8020008
      Issue No: Vol. 8, No. 2 (2020)
  • Fibers, Vol. 8, Pages 9: Mineralogical and Geochemical Characterization of
           Asbestiform Todorokite, Birnessite, and Ranciéite, and Their host Mn-Rich
           Deposits from Serra D’Aiello (Southern Italy)

    • Authors: Bloise, Miriello, De Rosa, Vespasiano, Fuoco, De Luca, Barrese, Apollaro
      First page: 9
      Abstract: Manganese ores, especially the oxyhydroxides in their different forms, are the dominant Mn-bearing minerals that occur in marine and terrestrial environments, where they are typically found as poorly crystalline and intermixed phases. Mn oxyhydroxides have a huge range of industrial applications and are able to exert a strong control on the mobility of trace metals. This paper reports the results of a detailed study on the Mn oxyhydroxides occurring in the manganiferous deposit outcropping in the Messinian sediments from Serra D'Aiello (Southern Italy). Nine Mn samples were characterized in detail using X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), thermogravimetry (TG), transmission electron microscopy combined with energy dispersive spectrometry (TEM/EDS), and X-ray fluorescence (XRF). The results indicated that the Mn deposit included the oxyhydroxide mineral species birnessite, todorokite, and rancièite. The size, morphology, and chemical composition of Mn oxyhydroxide samples were investigated in order to define their impact on the environment and human health. Todorokite displayed asbestiform shapes and could disperse fibers of breathable size in the air. Furthermore, since in-depth characterization of minerals within Mn deposits may be the first step toward understanding the genetic processes of manganese deposits, hypotheses about the genesis of the Mn oxyhydroxide deposits were discussed.
      Citation: Fibers
      PubDate: 2020-01-28
      DOI: 10.3390/fib8020009
      Issue No: Vol. 8, No. 2 (2020)
  • Fibers, Vol. 8, Pages 10: Modeling the Behavior of CFRP Strengthened
           Concrete Beams and Columns at Different Temperatures

    • Authors: Gawil, Wu, Elarbi
      First page: 10
      Abstract: The bonding of thin fiber-reinforced plastics (FRP) composites on the surface of concrete members has emerged as an effective method to increase both the strength and stiffness of concrete members. Although a large volume of experimental and numerical research has performed on existing concrete structures to increase their load carrying capacity, there appears to be less work reported on simulating the influence of temperature on the behavior of concrete structures. This study intends to examine the effects of changing temperature on the mechanical properties of FRP composites as well as deteriorated composites on the structural performance of FRP bonded concrete structures. The overall approach consists of computations using finite element models to simulate the structural behavior of FRP bonded beams and columns. Three-dimensional-extended finite element modeling X-FEM using ABAQUS-CAE v.6.13 program was performed to explore the influence of temperature of (25 °C, 100 °C and 180 °C) on failure loads of FRP strengthened beams and columns with adhesive material. Additionally, the cohesive traction–separation damage model was use to model the delamination of FRP from the concrete. The flexural strength, mid-span deflection, crack patterns, failure loads, and mode of failure for the tested models were compared with the previous experimental study. The results show that a FEM results were in good agreement with experimental results. The flexural strength decreases with temperature rise for FRP strengthened concrete beams. The high temperature 180 °C has an adverse influence on the compressive strength of the specimens. The way of FRP rupture in the simulation was similar to the mode that was observed during the experimental tests.
      Citation: Fibers
      PubDate: 2020-02-10
      DOI: 10.3390/fib8020010
      Issue No: Vol. 8, No. 2 (2020)
  • Fibers, Vol. 8, Pages 11: Analysis of the Behavior of FRCM Confined Clay
           Brick Masonry Columns

    • Authors: Ombres, Verre
      First page: 11
      Abstract: The behavior of FRCM (Fabric Reinforced Cementitious Mortar) confined clay brickmasonry columns is analyzed in this paper. The results of an experimental investigation conductedon small‐scale columns made by clay brick masonry confined with steel‐FRCM (or Steel ReinforcedGrout, SRG), PBO (poly‐paraphenylene‐benzo‐bisoxazole) FRCM and basalt‐FRCM, tested undermonotonic compressive load, are described and discussed. Tests were conducted on thirteenprismatic columns; eleven columns (two unconfined and nine confined) were tested underconcentric load while an eccentric load was applied on two confined columns. For each confinementsystem, the parameters investigated were the ‘confinement ratio’, the ‘load eccentricity’ and the‘overlap configuration of the fiber fabrics’. FRCM confinement improved the structural response ofmasonry columns in terms of ultimate strength, ultimate strain and ductility. Some models from theliterature were also examined to evaluate their applicability in predicting the axial capacity ofconfined columns.
      Citation: Fibers
      PubDate: 2020-02-10
      DOI: 10.3390/fib8020011
      Issue No: Vol. 8, No. 2 (2020)
  • Fibers, Vol. 8, Pages 12: Development of a Thulium Fiber Laser for an
           Atomic Spectroscopy Experiment

    • Authors: Ronnie Currey, Ali Khademian, David Shiner
      First page: 12
      Abstract: A convenient thulium fiber laser source is described with 3 W of output power operating at a wavelength of 2059 nm with a slope efficiency of 49% with respect to input pump power and 60% with respect to absorbed pump power. The laser was applied in an atomic helium spectroscopy experiment to quench 3He (2058.63 nm) and 4He (2058.69 nm) meta-stable singlets (21S0), allowing for further investigation of the helium fine structure. The customized laser effectively eliminates the singlet counts to well below a background level (1%). A simplified analysis describes the basic laser performance with fitted constants in reasonable agreement with previous work.
      Citation: Fibers
      PubDate: 2020-02-15
      DOI: 10.3390/fib8020012
      Issue No: Vol. 8, No. 2 (2020)
  • Fibers, Vol. 8, Pages 13: U-Jacketing Applications of Fiber-Reinforced
           Polymers in Reinforced Concrete T-Beams against Shear—Tests and Design

    • Authors: Chalioris, Zapris, Karayannis
      First page: 13
      Abstract: The application of externally bonded fiber-reinforced polymer (EB-FRP) as shear transverse reinforcement applied in vulnerable reinforced concrete (RC) beams has been proved to be a promising strengthening technique. However, past studies revealed that the effectiveness of this method depends on how well the reinforcement is bonded to the concrete surface. Thus, although the application of EB-FRP wrapping around the perimeter of rectangular cross-sections leads to outstanding results, U-jacketing in shear-critical T-beams seems to undergo premature debonding failures resulting in significant reductions of the predictable strength. In this work, five shear-critical RC beams with T-shaped cross-section were constructed, strengthened and tested in four-point bending. Epoxy bonded carbon FRP (C-FRP) sheets were applied on the three sides and along the entire length of the shear-strengthened T-beams as external transverse reinforcement. Furthermore, the potential enhancement of the C-FRP sheets anchorage using bolted steel laminates has been examined. Test results indicated that although the C-FRP strengthened beams exhibited increased shear capacity, the brittle failure mode was not prevented due to the debonding of the FRP from the concrete surface. Nevertheless, the applied mechanical anchor of the C-FRP sheets delayed the debonding. Moreover, the design provisions of three different code standards (Greek Code of Interventions, Eurocode 8 and ACI Committee 440) concerning the shear capacity of T-shaped RC beams retrofitted with EB-FRP jackets or strips in U-jacketing configuration are investigated. The ability of these code standards to predict safe design estimations is checked against 165 test data from the current experimental project and data available in the literature.
      Citation: Fibers
      PubDate: 2020-02-17
      DOI: 10.3390/fib8020013
      Issue No: Vol. 8, No. 2 (2020)
  • Fibers, Vol. 8, Pages 14: Terahertz Hollow Core Antiresonant Fiber with
           Metamaterial Cladding

    • Authors: Jakeya Sultana, Md. Saiful Islam, Cristiano M. B. Cordeiro, Alex Dinovitser, Mayank Kaushik, Brian W.-H. Ng, Derek Abbott
      First page: 14
      Abstract: A hollow core antiresonant photonic crystal fiber (HC-ARPCF) with metal inclusions is numerically analyzed for transmission of terahertz (THz) waves. The propagation of fundamental and higher order modes are investigated and the results are compared with conventional dielectric antiresonant (AR) fiber designs. Simulation results show that broadband terahertz radiation can be guided with six times lower loss in such hollow core fibers with metallic inclusions, compared to tube lattice fiber, covering a single mode bandwidth (BW) of 700 GHz.
      Citation: Fibers
      PubDate: 2020-02-17
      DOI: 10.3390/fib8020014
      Issue No: Vol. 8, No. 2 (2020)
  • Fibers, Vol. 8, Pages 15: Development and Multiscale Characterization of
           3D Warp Interlock Flax Fabrics with Different Woven Architectures for
           Composite Applications

    • Authors: Lansiaux, Soulat, Boussu, Labanieh
      First page: 15
      Abstract: Multiscale characterization of the textile preform made of natural fibers is an indispensable way to understand and assess the mechanical properties and behavior of composite. In this study, a multiscale experimental characterization is performed on three-dimensional (3D) warp interlock woven fabrics made of flax fiber on the fiber (micro), roving (meso), and fabric (macro) scales. The mechanical tensile properties of the flax fiber were determined by using the impregnated fiber bundle test. The effect of the twist was considered in the back-calculation of the fiber stiffness to reveal the calculation limits of the rule of mixture. Tensile tests on dry rovings were carried out while considering different twist levels to determine the optimal amount of twist required to weave the flax roving into a 3D warp interlock. Finally, at fabric-scale, six different 3D warp interlock architectures were woven to understand the role of the architecture of binding rovings on the mechanical properties of the dry 3D fabric. The results reveal the importance of considering the properties of the fiber and roving at these scales to determine the more adequate raw material for weaving. Further, the characterization of the 3D woven structures shows the preponderant role of the binding roving on their structural and mechanical properties.
      Citation: Fibers
      PubDate: 2020-02-18
      DOI: 10.3390/fib8020015
      Issue No: Vol. 8, No. 2 (2020)
  • Fibers, Vol. 8, Pages 16: Fibrous Material Science: Extensive and

    • Authors: Martin J. D. Clift
      First page: 16
      Abstract: It is my absolute pleasure to take up the position of Editor-in-Chief (EiC) of <ext-link ext-link-type="uri" xlink:href="https://www [...]
      Citation: Fibers
      PubDate: 2020-02-18
      DOI: 10.3390/fib8020016
      Issue No: Vol. 8, No. 2 (2020)
  • Fibers, Vol. 8, Pages 17: The Effect of Air, Ar and O2 Plasmas on the
           Electrical Resistivity and Hand-Feel Properties of Polyester/Cotton Blend

    • Authors: Baye Berhanu Yilma, Joern Felix Luebben, Govindan Nalankilli
      First page: 17
      Abstract: The conventional chemical-based antistatic agents possess ecological and technological drawbacks, such as altering the bulk characteristics, flammability, and toxicity, but not the cost effective process. Recently, using conductive metal fibers in the woven structure also affects the mechanical properties of the fabric. To overcome these challenges, plasma treatment needs to be quite an effective method. In this study, polyester/cotton (P/C), 65/35%, blend fabric was treated in a vacuum-plasma-chamber using air, argon and oxygen. The electro-physical property of the samples were evaluated by measuring the surface and volume resistivities (ρs, ρv) using textile electrode Tera Ohmmeter (TO-3). Textile Softness Analyzer (TSA) has also been used to investigate hand-feel properties of the fabric. After treatment, the results revealed that the surface resistivity was reduced by 35.5% in the case of O2, 27.3% for air and 18.4% for Ar, and also volume resistivity was decreased by 40.9%, 20.3% and 20% after O2, air and Ar-plasma, respectively, whereas hand-feel properties are slightly affected at a higher power level and treatment time. Out of the three gases, oxygen had less effect on hand-feel properties and highly reduced the fabric resistivity. In addition, the SEM images showed that the surface morphology of the fibers changed to being rough due to the plasma.
      Citation: Fibers
      PubDate: 2020-02-24
      DOI: 10.3390/fib8020017
      Issue No: Vol. 8, No. 2 (2020)
  • Fibers, Vol. 8, Pages 72: An Experimental Investigation on Optimizing
           Liquid Repellency of Fluorochemical Urethane Finish and Its Effect on the
           Physical Properties of Polyester/Cotton Blended Fabric

    • Authors: Sunidhi Mehta
      First page: 72
      Abstract: This paper aims to optimize the liquid repellency performance of fluorochemical urethane (FU)—a patented technology with a shorter fluorocarbon chain (C4). FU is free from persistent bioaccumulative toxins such as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS), unlike the long-chain fluorinated chemicals (>C6). Different sets of varied finish concentrations with an extender and a wetting agent were prepared to treat the 65/35% polyester/cotton blended fabric. The finish concentration was optimized based on the liquid repellency (water and oil-repellency) of the treated fabric and its laundering durability. In addition, the effect of the finish concentration on selected physical properties of the treated fabric was studied as well. The liquid repellency, laundering durability, and selected physical properties of the treated and untreated fabrics were analyzed using ASTM and AATCC standard test methods. The results of textile substrates treated with 60 g/L of FU show an optimum balance of desired liquid repellency without affecting the physical properties of the fabric significantly.
      Citation: Fibers
      PubDate: 2020-12-01
      DOI: 10.3390/fib8120072
      Issue No: Vol. 8, No. 12 (2020)
  • Fibers, Vol. 8, Pages 73: Acetylation Treatment for the Batch Processing
           of Natural Fibers: Effects on Constituents, Tensile Properties and Surface
           Morphology of Selected Plant Stem Fibers

    • Authors: Isiaka Oluwole Oladele, Omokafe Seun Michael, Adeolu Adesoji Adediran, Oluwayomi Peter Balogun, Folorunso Ojo Ajagbe
      First page: 73
      Abstract: This work was on the comparative evaluation of the property effects obtainable when acetylation is applied to parts of selected agro fibers that are obtainable within common localities. The fibers were subjected to different concentrations of acetylation treatment at ambient temperature for 3 h. The physico-chemical, morphological, and tensile properties of the fibers were examined after the treatment. It was discovered from the results that the procedures variedly influenced the constituents of the fibers, their resulting tensile properties as well as their post-acetylation treatment surface morphology. The proportion of crystalline cellulose in the starting fibers greatly influenced their post treatment composition, behaviour and properties. The results show that plantain fibers had the highest aspect ratios, followed by banana fibers with values of about 1000 and 417, respectively. These fibers exhibited the least density and are thus potential plant fibers for composite development. Banana fiber had the least density of about 1.38 g/cm3 while that of DombeyaBuettneri fiber possessed the highest value of 1.5 g/cm3. There was significant enhancement in the hemicellulose content of Combretum Racemosum, while the lignin content of the plantain fibers was highly reduced. The treatment favoured the enhancement of the tensile properties in Combretum Racemosum fibers, which had enhanced tensile strength and strain at all compositions of the treatment. Optimum tensile strength and strain values of 155 MPa and 0.046, respectively, are achieved at 4% composition. Dombeya Buettneri fibers showed the highest ultimate tensile strength among the plant fibers in the untreated condition, which was gradually decreased as the concentration of the reagents was increased. Overall, 4% acetylation treatment is optimum for tensile properties’ enhancement for most of the natural fibers evaluated.
      Citation: Fibers
      PubDate: 2020-12-01
      DOI: 10.3390/fib8120073
      Issue No: Vol. 8, No. 12 (2020)
  • Fibers, Vol. 8, Pages 74: Experimental Tests and Reliability Analysis of
           the Cracking Impact Resistance of UHPFRC

    • Authors: Hussain A. Jabir, Sallal R. Abid, Gunasekaran Murali, Sajjad H. Ali, Sergey Klyuev, Roman Fediuk, Nikolai Vatin, Vladimir Promakhov, Yuriy Vasilev
      First page: 74
      Abstract: Ultra-high performance (UHP) concrete is a special type of fibrous cementitious composite that is characterized by high strength and superior ductility, toughness, and durability. This research aimed to investigate the resistance of ultra-high performance fiber-reinforced concrete (UHPFRC) against repeated impacts. An adjusted repeated drop mass impact test was adopted to evaluate the impact performance of 72 UHPFRC disc specimens. The specimens were divided into six mixtures each of 12 discs. The only difference between the mixtures was the types of fibers used, while all other mixture components were the same. Three types of fibers were used: 6 mm micro-steel, 15 mm micro-steel, and polypropylene. All mixtures included 2.5% volumetric content of fibers, however with different combinations of the three fiber types. The test results showed that the mixtures with the 15 mm micro-steel fiber absorbed a higher number of impact blows until cracking compared to other mixtures. The mixture with pure 2.5% of 15 mm micro-steel fiber exhibited the highest impact resistance, with percentage increases over the other mixtures ranging from 25 to 140%. In addition, the Weibull distribution was used to investigate the cracking impact resistance of UHP at different levels of reliability.
      Citation: Fibers
      PubDate: 2020-12-04
      DOI: 10.3390/fib8120074
      Issue No: Vol. 8, No. 12 (2020)
  • Fibers, Vol. 8, Pages 75: Investigation of Flow Behavior and Porous Medium
           Resistance Coefficients for Metallic-Cloth Fibers

    • Authors: Erdem Gorgun, Yahya Dogu, Mahmut Faruk Aksit
      First page: 75
      Abstract: The flow through porous metallic-cloth fibers influences the cloth seal leakage performance. Measuring the actual seal leakage proves difficult with challenging turbine operating conditions. A non-Darcian porous medium Computational Fluid Dynamics (CFD) model was employed for the flow within porous metallic-cloth fibers. CFD analyses need leakage data depending on the pressure load to calibrate flow resistance coefficients. A test rig was built to measure leakage with respect to the pressure load and weave orientation in four directions. The Sutherland-ideal gas approach was utilized to determine the flow resistance coefficients for Dutch twill metallic-cloth fibers as a function of pressure load. The results show that metallic-cloth fiber leakage is a linear function of pressure load. The best–worst order for leakage performance was the warp, diagonal, shute, and cross directions. For the best sealing performance, the flow direction in metallic-cloth fibers would be the warp direction. The flow resistance coefficients depend on the evaluation of the pressure level, which changes over the weave flow thickness. This is represented with the pressure constant (Cdown). The best match between the test and CFD leakages was obtained for the weave directions of warp (0.9), shute (0.9), diagonal (0.7), and cross (0.0). Calibrating the resistance coefficients with respect to the pressure and temperature enables performing CFD analyses in turbine conditions.
      Citation: Fibers
      PubDate: 2020-12-07
      DOI: 10.3390/fib8120075
      Issue No: Vol. 8, No. 12 (2020)
  • Fibers, Vol. 8, Pages 76: Optical Characterisations of Bi-Phosphosilicate
           Fiber for O Band Amplification

    • Authors: Amilia Mansoor, Nasr Y. M. Omar, Katrina D. Dambul, Hairul Azhar Abdul-Rashid, Zulfadzli Yusoff
      First page: 76
      Abstract: We report on the optical properties of Bi-doped phosphosilicate fiber. The fiber with a core and a clad diameter of 7.75 µm and 125 µm, respectively, is fabricated in-house using the modified chemical vapor deposition (MCVD) with in-situ solution doping technique. The spectroscopic properties of the fabricated fiber are characterized in terms of absorption, emission and lifetime. The lifetime decay is measured to be 800 µs; indicating a good potential optical amplification in the range of 1300 to 1500 nm. A Bismuth-doped fiber amplifier (BDFA) operating within the O-band region was successfully demonstrated. At 1340 nm, a 14.8 dB gain is achieved with 300 mW pumping power.
      Citation: Fibers
      PubDate: 2020-12-09
      DOI: 10.3390/fib8120076
      Issue No: Vol. 8, No. 12 (2020)
  • Fibers, Vol. 8, Pages 77: Numerical Simulation for the Sound Absorption
           Properties of Ceramic Resonators

    • Authors: Giuseppe Ciaburro, Gino Iannace
      First page: 77
      Abstract: This work reports the results of experimental measurements of the sound absorption coefficient of ceramic materials using the principle of acoustic resonators. Subsequently, the values obtained from the measurements were used to train a simulation model of the acoustic behavior of the analyzed material based on artificial neural networks. The possible applications of sound-absorbing materials made with ceramic can derive from aesthetic or architectural needs or from functional needs, as ceramic is a fireproof material resistant to high temperatures. The results returned by the simulation model based on the artificial neural networks algorithm are particularly significant. This result suggests the adoption of this technology to find the finest possible configuration that allows the best sound absorption performance of the material.
      Citation: Fibers
      PubDate: 2020-12-18
      DOI: 10.3390/fib8120077
      Issue No: Vol. 8, No. 12 (2020)
  • Fibers, Vol. 8, Pages 67: Heat Treatment of Basalt Fiber Reinforced
           Expanded Clay Concrete with Increased Strength for Cast-In-Situ

    • Authors: Makhmud Kharun, Sergey Klyuev, Dmitry Koroteev, Paschal C. Chiadighikaobi, Roman Fediuk, Andrej Olisov, Nikolai Vatin, Nataliya Alfimova
      First page: 67
      Abstract: Expanded clay concrete (ECC) is a promising structural material for buildings due to its light weight and heat- and sound-insulating properties. Adding basalt fibers (BFs) in ECC reduces its brittleness and enhances its mechanical properties. The heat treatment (HT) of BF-reinforced ECC can significantly accelerate the strength growth during cast-in-situ construction, which allows the reduction of the turnover of the formwork and the construction period, as well as leading to lower construction costs. This paper presents an HT technology for load-bearing structures, containing a BF-reinforced ECC mix and using infrared rays for cast-in-situ construction. The issue of the strength growth of BF-reinforced ECC during HT has been studied. Microsilica and fly ash were added to the ECC mix to obtain a compressive strength of more than 20 MPa. Four different mixes of ECC with chopped BFs in the ratios of 1:0, 1:0.0045, 1:0.009 and 1:0.012 by weight of cement were studied. Test specimens were heated by infrared rays for 7, 9, 11, 13, 16 and 24 h. Then, the heat-treated specimens were tested for compressive strength after 0.5, 4, 12 and 24 h cooling periods. The analysis and evaluation of the experimental data were carried out based on probability theory and mathematical statistics. Mathematical models are proposed for forecasting the strength growth of BF-reinforced ECC during cast-in-situ construction.
      Citation: Fibers
      PubDate: 2020-11-02
      DOI: 10.3390/fib8110067
      Issue No: Vol. 8, No. 11 (2020)
  • Fibers, Vol. 8, Pages 68: Effects of Different Test Setups on the
           Experimental Tensile Behaviour of Basalt Fibre Bidirectional Grids for
           FRCM Composites

    • Authors: Jennifer D’Anna, Giuseppina Amato, Jianfei Chen, Giovanni Minafò, Lidia La Mendola
      First page: 68
      Abstract: Fibre-reinforced cementitious matrix (FRCM) composites have been effectively used during the last ten years for the strengthening of existing concrete and masonry structures. These composite materials are made of medium- and high-strength fibre meshes embedded in inorganic matrices. Synthetic fibres are the ones that are currently the most used; however, natural fibres, such as basalt fibres, have recently been receiving growing attention. This work presents an extensive experimental study on the mechanical characterisation of a primed basalt fibre bidirectional grid. Fifty monotonic tensile tests on basalt grid strips were performed by varying different parameters, such as the dimension of the specimens, the clamping system, the measurement system and the test rate. Some of the tests were carried out using a video-extensometer to measure each specimen’s strain. The aim of the study was to find the most suitable setup for the tensile characterisation of basalt textiles, in particular, to prevent slippage of the samples at the gripping area and fully exploit the tensile capacity of the grid.
      Citation: Fibers
      PubDate: 2020-11-08
      DOI: 10.3390/fib8110068
      Issue No: Vol. 8, No. 11 (2020)
  • Fibers, Vol. 8, Pages 69: Investigation of the Potential Use of Curauá
           Fiber for Reinforcing Mortars

    • Authors: Afonso R. G. de Azevedo, Sergey Klyuev, Markssuel T. Marvila, Nikolai Vatin, Nataliya Alfimova, Thuany E.S. de Lima, Roman Fediuk, Andrej Olisov
      First page: 69
      Abstract: Curauá is a bromeliad of Amazonian origin, present in some states in the northern region of Brazil and in other countries in South America. Its natural fibers have several technological advantages for application in composite materials. The objective of this research was to investigate the potential of using the fiber of Curauá as a reinforcement element in mortars for wall covering. Mortars were made with a 1:1:6 ratio (cement:lime:sand) in relation to their mass, evaluating the effect of adding 1%, 2% and 3% of Curauá fiber natural and fiber treated in NaOH solution in relation to the mass of cement, compared to the reference mixture (0%). Technological properties such as consistency, water retention and incorporated air content, compressive strength, water absorption and durability in wetting and drying cycles were evaluated. The results showed that the addition of the Curauá fiber causes an improvement in the mechanical properties of mortars, and at levels of addition 3% or more, it causes problems of workability and incorporation of air into the dough, thus, the fiber addition in 2% presented better results for application in coating mortars, in relation a Brazilian norm, even improving the durability of external coatings.
      Citation: Fibers
      PubDate: 2020-11-11
      DOI: 10.3390/fib8110069
      Issue No: Vol. 8, No. 11 (2020)
  • Fibers, Vol. 8, Pages 70: Influence of the Solidification Process on the
           Mechanical Properties of Solid-State Drawn PCL/Sepiolite Nanocomposite

    • Authors: Maria Eriksson, Han Goossens, Ton Peijs
      First page: 70
      Abstract: In this research, poly(ε-caprolactone) (PCL) was melt-mixed with sepiolite nanoclays in a twin-screw extruder. In a subsequent step, the extruded films were drawn in the solid state to highly oriented nanocomposite films or tapes. A twin-screw extruder equipped with a Sultzer mixer for improved mixing in combination with a bench top drawing unit was used to prepare oriented nanocomposite tapes of different sepiolite loading and draw ratios. In order to study the influence of the solidification step on the drawability of the materials, different cooling procedures were applied prior to drawing. Optical microscopy images showed that slow or fast solidification using different chill rolls settings (open or closed) for the cast films resulted in different morphological conditions for subsequent drawing. The addition of sepiolite nanofillers led to nucleation and faster crystallization kinetics and oriented tapes which deformed by homogenous deformation rather than necking. The addition of sepiolite significantly improved the mechanical properties of both undrawn and drawn PCL tapes and Young’s modulus (1.5 GPa) and tensile strength (360 MPa) for composites based on 4 wt% sepiolite were among the highest ever reported for PCL nanocomposites. Interestingly, samples cooled with open chill rolls (slow crystallization) showed the highest modulus while solidification with closed rolls (fast crystallization) showed the highest tensile strength after drawing.
      Citation: Fibers
      PubDate: 2020-11-17
      DOI: 10.3390/fib8110070
      Issue No: Vol. 8, No. 11 (2020)
  • Fibers, Vol. 8, Pages 71: Synthesis and Characterization of a Core-Shell
           Copolymer with Different Glass Transition Temperatures

    • Authors: Panagiotis Goulis, Ioannis A. Kartsonakis, Costas A. Charitidis
      First page: 71
      Abstract: The aim of this study is to synthesize an organic core-shell co-polymer with a different glass transition temperature (Tg) between the core and the shell that can be used for several applications such as the selective debonding of coatings or the release of encapsulated materials. The co-polymer was synthesized using free radical polymerization and was characterized with respect to its morphology, composition and thermal behavior. The obtained results confirmed the successful synthesis of the co-polymer copolymer poly(methyl methacrylate)@poly(methacrylic acid-co-ethylene glycol dimethacrylate), PMMA@P(MAA-co-EGDMA), which can be used along with water-based solvents. Furthermore, the Tg of the polymer’s core PMMA was 104 °C, while the Tg of the shell P(MAA-co-EGDMA) was 228 °C, making it appropriate for a wide variety of applications. It is worth mentioning that by following this specific experimental procedure, methacrylic acid was copolymerized in water, as the shell of the copolymer, without forming a gel-like structure (hydrogel), as happens when a monomer is polymerized in aqueous media, such as in the case of super-absorbent polymers. Moreover, the addition and subsequent polymerization of the monomer methyl methacrylate (MAA) into the mixture of the already polymerized PMMA resulted in a material that was uniform in size, without any agglomerations or sediments.
      Citation: Fibers
      PubDate: 2020-11-23
      DOI: 10.3390/fib8110071
      Issue No: Vol. 8, No. 11 (2020)
  • Fibers, Vol. 8, Pages 61: Development of Interlocking Concrete Blocks with
           Added Sugarcane Residues

    • Authors: Bruno Ribeiro, Tadaaki Uchiyama, Jun Tomiyama, Takashi Yamamoto, Yosuke Yamashiki
      First page: 61
      Abstract: The use of sugarcane residues in mortar and concrete is believed to contribute to a reduction of costs and environmental problems, such as the reduction of mining of natural aggregates and incorrect disposal of the sugarcane residues. Bagasse fiber has a high water retention rate and thus may be considered as a countermeasure for urban heat islands. Because of these properties, bagasse fiber and bagasse sand were added into the preparation of the interlocking concrete blocks. An investigation of the flexural strength and the contribution of the sugarcane residues against an urban heat island was made. The results showed that, by adding 2.0% of bagasse fiber and 5.0% of bagasse sand in concrete, the flexural strength and the water retention content increased in comparison to the control composite. Moreover, the surface temperature and the water evaporation rate of the blocks were smaller in comparison to the control composite.
      Citation: Fibers
      PubDate: 2020-09-25
      DOI: 10.3390/fib8100061
      Issue No: Vol. 8, No. 10 (2020)
  • Fibers, Vol. 8, Pages 62: Direct Comparison of the Structural Compression
           Characteristics of Natural and Synthetic Fiber-Epoxy Composites: Flax,
           Jute, Hemp, Glass and Carbon Fibers

    • Authors: Mike R. Bambach
      First page: 62
      Abstract: Recent decades have seen substantial interest in the use of natural fibers in continuous fiber reinforced composites, such as flax, jute and hemp. Considering potential applications, it is of particular interest how natural fiber composites compare to synthetic fiber composites, such as glass and carbon, and if natural fibers can replace synthetic fibers in existing applications. Many studies have made direct comparisons between natural and synthetic fiber composites via material coupon testing; however, few studies have made such direct comparisons of full structural members. This study presents compression tests of geometrically identical structural channel sections fabricated from fiber-epoxy composites of flax, jute, hemp, glass and carbon. Glass fiber composites demonstrated superior tension material coupon properties to natural fiber composites. However, for the same fiber mass, structural compression properties of natural fiber composite channels were generally equivalent to, or in some cases superior to, glass fiber composite channels. This indicates there is substantial potential for natural fibers to replace glass fibers in structural compression members. Carbon fiber composites were far superior to all other composites, indicating little potential for replacement with natural fibers.
      Citation: Fibers
      PubDate: 2020-09-28
      DOI: 10.3390/fib8100062
      Issue No: Vol. 8, No. 10 (2020)
  • Fibers, Vol. 8, Pages 63: Numerical Modeling of a Rectangular Hollow-Core
           Waveguide for the Detection of Fuel Adulteration in Terahertz Region

    • Authors: Md. Ahasan Habib, Erick Reyes-Vera, Juan Villegas-Aristizabal, Md. Shamim Anower
      First page: 63
      Abstract: A petrol adulteration sensor based on a rectangular shaped hollow-core photonic crystal fiber is proposed and numerically analyzed in the terahertz regime. The performance of the proposed sensor was evaluated when it is employed to characterize different kerosene mixtures. In this research, the adulterated fuel sample is filled in the rectangular hollow channel and the electromagnetic signal of the terahertz band is also driven through the same channel. The received signal after the interaction of fuel with the terahertz signal will advise the refractive index of the fuel oil inside the core, which will also bear the information of how much extrinsic component is present in the fuel. The finite element method based simulation shows that the proposed sensor can reach a high relative sensitivity of 89% and presents low confinement losses at 2.8 THz. The reported sensing structure is easily realizable with the conventional manufacturing techniques. Consequently, this proposed fiber may be treated as an essential part of real-life applications of petrol adulteration measurements.
      Citation: Fibers
      PubDate: 2020-10-08
      DOI: 10.3390/fib8100063
      Issue No: Vol. 8, No. 10 (2020)
  • Fibers, Vol. 8, Pages 64: Damping Properties of Flax/Carbon Hybrid
           Epoxy/Fibre-Reinforced Composites for Automotive Semi-Structural

    • Authors: George Fairlie, James Njuguna
      First page: 64
      Abstract: The ever-increasing demand for environmentally friendly biocomposites for use in various engineering applications requires a strong understanding of these materials properties, especially in automotive applications. This study focused on investigating how the stacking sequence and fibre orientation impacts the damping properties of hybrid flax/carbon fibre-reinforced composites. Different hybrid carbon fibre/flax fibre-reinforced composites using epoxy resin as the matrix were manufactured using vacuum-assisted resin infusion moulding technique. Each composite material was then tested for tensile properties using a universal testing machine, and the damping experiment was conducted using an impulse hammer and a Laser Doppler Vibrometer. The tensile study found out that adding a flax layer to the external layers of carbon fibre laminate reduced Young’s modulus by 28% for one layer and 45% for two layers. It was noted that when the fibre orientation of the internal layer of [C/F2/C]s was replaced with two ±45° layers, this had a very little effect on Young’s modulus but reduced the ultimate tensile strength by 61%. This experimental study also showed that the most important layer when it comes to damping properties is the external layers. By adding an external flax layer into an epoxy/carbon fibre-reinforced composite considerably enhanced its damping ratio by 53.6% and by adding two layers increased it by 94%. The results indicated a high potential for the automotive semi-structural applications to improve damping properties of the vehicle.
      Citation: Fibers
      PubDate: 2020-10-08
      DOI: 10.3390/fib8100064
      Issue No: Vol. 8, No. 10 (2020)
  • Fibers, Vol. 8, Pages 65: Humidity Controlled Mechanical Properties of
           Electrospun Polyvinylidene Fluoride (PVDF) Fibers

    • Authors: Piotr K. Szewczyk, Daniel P. Ura, Urszula Stachewicz
      First page: 65
      Abstract: Processing parameters in electrospinning allow us to control the properties of fibers on a molecular level and are able to tailor them for specific applications. In this study, we investigate how relative humidity (RH) affects the mechanical properties of electrospun polyvinylidene fluoride (PVDF). The mechanical properties of single fibers were carried out using a specialized tensile stage. The results from tensile tests were additionally correlated with high-resolution imaging showing the behavior of individual fibers under tensile stress. The mechanical characteristic is strongly dependent on the crystallinity, chain orientation, and fiber diameter of electrospun PVDF fibers. Our results show the importance of controlling RH during electrospinning as the mechanical properties are significantly affected. At low RH = 30% PVDF fibers are 400% stiffer than their counterparts prepared at high RH = 60%. Moreover, the vast differences in the strain at failure were observed, namely 310% compared to 75% for 60% and 30% RH, respectively. Our results prove that humidity is a crucial parameter in electrospinning able to control the mechanical properties of polymer fibers.
      Citation: Fibers
      PubDate: 2020-10-16
      DOI: 10.3390/fib8100065
      Issue No: Vol. 8, No. 10 (2020)
  • Fibers, Vol. 8, Pages 66: Experimental Investigation of Transverse Loading
           Behavior of Ultra-High Molecular Weight Polyethylene Yarns

    • Authors: Karan Shah, Subramani Sockalingam
      First page: 66
      Abstract: Ultra-high molecular weight polyethylene (UHMWPE) Dyneema® SK-76 fibers are widely used in personnel protection systems. Transverse ballistic impact onto these fibers results in complex multiaxial deformation modes such as axial tension, axial compression, transverse compression, and transverse shear. Previous experimental studies on single fibers have shown a degradation of tensile failure strain due to the presence of such multi-axial deformation modes. In this work, we study the presence and effects of such multi-axial stress-states on Dyneema® SK-76 yarns via transverse loading experiments. Quasi-static transverse loading experiments are conducted on Dyneema® SK-76 single yarn at different starting angles (5°, 10°, 15°, and 25°) and via four different indenter geometries: round (radius of curvature (ROC) = 3.8 mm), 200-micron, 20-micron, and razor blade (ROC ~2 micron). Additionally, transverse loading experiments were also conducted for a 0.30 cal. fragment simulating projectile (FSP) and compared to other indenters. Experimental results show that for the round, 200-micron indenter, and FSP geometry the yarn fails in tension with no degradation in axial failure strain compared to the uniaxial tensile failure strain of SK-76 yarn (2.58%). Whereas for the 20-micron indenter and razor blade, fibers fail progressively in transverse shear followed by progressive strength degradation of the yarn. Strength degradation of yarn occurs at relatively low strains of 0.6–0.7% with eventual failure of the yarn at approximately ~1.8% and ~1.5% strain for the 20-micron indenter and razor blade, respectively. Breaking angles (range of 10°–30°) are observed to have little effect on the failure strain for all indenter geometries.
      Citation: Fibers
      PubDate: 2020-10-19
      DOI: 10.3390/fib8100066
      Issue No: Vol. 8, No. 10 (2020)
  • Fibers, Vol. 8, Pages 5: Compressive Behaviour of Coconut Fibre (Cocos
           nucifera) Reinforced Concrete at Elevated Temperatures

    • Authors: Gideon Bamigboye, Ben Ngene, Omotolani Aladesuru, Oluwaseun Mark, Dunmininu Adegoke, Kayode Jolayemi
      First page: 5
      Abstract: Fire outbreaks in buildings have been a major concern in the world today. The integrity of concrete is usually questioned due to the fact that after these fire outbreaks the strength of the concrete is reduced considerably. Various methods have been adopted to improve the fire resistance property of concrete. This study focused on the use of coconut fibre to achieve this feat. In this study, varying percentages of treated and untreated coconut fibres were incorporated into concrete and the compressive strength was tested for both before heating and after heating. The percentages of replacement were 0.25, 0.5, 0.75 and 1% fibre content by weight of cement. Concrete cubes that had 0% fibre served as control specimens. After subjecting these concrete cubes to 250 °C and 150 °C for a period of 2 h, the compressive strength increased when compared to the control. The compressive strength increased up to 0.5% replacement by 3.88%. Beyond 0.5% fibre, the compressive strength reduced. Concrete having coconut fibre that had been treated with water also exhibited the highest compressive strength of 28.71 N/mm². It is concluded that coconut fibres are a great material in improving the strength of concrete, even after it was exposed to a certain degree of elevated temperature.
      Citation: Fibers
      PubDate: 2020-01-01
      DOI: 10.3390/fib8010005
      Issue No: Vol. 8, No. 1 (2020)
  • Fibers, Vol. 8, Pages 6: CFRP Laminates Reinforcing Performance of
           Short-Span Wedge-Blocks Segmental Beams

    • Authors: Ali A. Abdulhameed, AbdulMuttalib I. Said
      First page: 6
      Abstract: Two of the main advantages of segmental construction are economics, as well as the rapid construction technique. One of the forms of segmental construction, for structural elements, is the segmental beams that built-in short sections, which referred to segments. This research aims to exhibit a new technique for the fabrication of short-span segmental beams from wedge-shaped concrete segments and carbon fiber reinforced polymers (CFRP) in laminate form. The experimental campaign included eight short-span segmental beams. In this study, two selected parameters were considered. These parameters are; the number of layers of CFRP laminates and the adhesive material that used to bond segments to each other, forming short-span segmental beams. The test results showed that for segmental beams reinforced by 2-layer of CFRP laminates, undergoes less deflection and sustained considerable ultimate loading value of 38.4%–104% than beams reinforced by 1-layer. Moreover, the test of segmental beams fabricated by adhering to the concrete segments with epoxy resin exhibited an increase in ultimate loading by 16%–65% than beams constructed using cementitious adhesive for bonding the wedge-shaped segments. Theoretically, segmental beams were analyzed by the American Concrete Institute (ACI) 440.2R-17 procedure with slight modifications. The analysis gave an overestimation of flexural strength for segmental beams when compared with experimental outcomes.
      Citation: Fibers
      PubDate: 2020-01-10
      DOI: 10.3390/fib8010006
      Issue No: Vol. 8, No. 1 (2020)
  • Fibers, Vol. 8, Pages 7: Acknowledgement to Reviewers of Fibers in 2019
    • Fibers, Vol. 8, Pages 7: Acknowledgement to Reviewers of Fibers in 2019

      Fibers doi: 10.3390/fib8010007

      Authors: Fibers Editorial Office

      DOI: 10.3390/fib8010007
      Issue No: Vol. 8, No. 1 (2020)
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Heriot-Watt University
Edinburgh, EH14 4AS, UK
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