Journal Cover Composites Part A : Applied Science and Manufacturing
  [SJR: 1.599]   [H-I: 113]   [204 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1359-835X
   Published by Elsevier Homepage  [3120 journals]
  • Fabrication and properties of novel porous CuAlMn shape memory alloys and
           polymer/CuAlMn composites
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Xiangwei Ji, Qingzhou Wang, Fuxing Yin, Chunxiang Cui, Puguang Ji, Gangling Hao
      Novel porous CuAlMn shape memory alloys (SMAs) with interconnected pores and polystyrene/CuAlMn composites with uniformly distributed polystyrene were successfully fabricated via sintering-dissolution and sol–gel methods. Properties tests indicated that the porous CuAlMn SMAs had excellent compression energy absorption and damping properties. Compared with porous CuAlMn SMAs, polystyrene/CuAlMn composites had higher compression strength and damping capacity, which had been ascribed to the hindering effect of polystyrene on the collapse of pores and the superposition of multiple damping sources, respectively. The addition of mica or graphite sheets in polystyrene could remarkably improve the elastic modulus, damping as well as storage modulus of the polystyrene/CuAlMn composites. The associated mechanisms were discussed.

      PubDate: 2018-02-04T18:20:04Z
       
  • Ductility and pseudo-ductility of thin ply angle-ply CFRP laminates under
           quasi-static cyclic loading
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): J.D. Fuller, M.R. Wisnom
      The quasi-static loading-unloading performance of thin ply carbon-epoxy [ ± 26 5 ] s , [ ± 27 5 ] s and [ ± 26 5 / 0 ] s laminates is presented. Consistent experimental results allow the reduction in laminate modulus to be evaluated using three different methods: secant modulus of each loading cycle; a secant modulus up to a constant stress, and the initial tangent modulus of reloading. It is shown, via all three methods, that these layups can undergo multiple cyclic loadings and display excellent retention of stiffness. The [ ± 26 5 / 0 ] s layup displays a limited modulus reduction, despite the gradual failure of the 0 ° layers. The [ ± θ 5 ] s specimens do not display any decrease in initial modulus and effectively suppress damage accumulation (shown via X-ray CT imaging), which both suggest that the stress–strain behaviour of these layups is ductile, rather than pseudo-ductile.

      PubDate: 2018-02-04T18:20:04Z
       
  • Comparative investigation on combustion property and smoke toxicity of
           epoxy resin filled with α- and δ-MnO2 nanosheets
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Wei Wang, Yongchun Kan, Kim Meow Liew, Lei Song, Yuan Hu
      Manganese dioxide (MnO2) as a promising green material has attracted widely attention in virtue of its outstanding chemical and physical properties. Herein, MnO2 nanosheets with α- and δ- crystal structures were used to comparatively study the influence of crystal structures on the fire resistance of EP resin. Cone calorimeter results confirmed that δ-MnO2 nanosheets achieved better improvements than α-MnO2 nanosheets in reducing the PHRR and THR values as well as suppressing smoke release during combustion process. Moreover, Raman data and SEM tests showed that δ-MnO2 nanosheets could effectively promote the char dense of char residues of EP composites. TG-IR results also indicated that the pyrolysis toxic products were significantly decreased after the incorporation of δ-MnO2 nanosheets. By the way, the mechanical property of EP/δ-MnO2 2% composites had no obvious reduction compared with pristine EP resin, which would not restrict the application of EP resin in fields requiring high mechanical properties.

      PubDate: 2018-02-04T18:20:04Z
       
  • Functionalized graphene as an effective antioxidant in natural rubber
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Lin Zhang, Hongqiang Li, Xuejun Lai, Xiaofeng Liao, Jing Wang, Xiaojing Su, Heng Liu, Wenjian Wu, Xingrong Zeng
      To improve the thermo-oxidative aging resistance of natural rubber, a kind of functionalized graphene (FGE) was prepared by grafting 2-tert-butyl-6-(3-tertbutyl-2-hydroxy-5-methylphenyl) methyl-4-methylp-henyl acrylate (GM) onto graphene oxide (GO) using (3-mercaptopropyl) trimethoxysilane as bridging agent. In comparison to GO, FGE appeared more curled surface and reached the higher water contact angle of 134°. By latex-mixing method, the uniformly dispersed FGE endowed NR vulcanizates with obviously improved thermal stability. Importantly, the NR/FGE nanocomposites exhibitd excellent thermo-oxidative aging resistance, which was attributed to not only the synergistic antioxidative effect of hindered phenol groups and thioether bonds, but also the barrier role of graphene sheets to oxygen. Our findings provide a new strategy to prepare functionalized graphene as effective antioxidant for rubber and other polymer materials.

      PubDate: 2018-02-04T18:20:04Z
       
  • Surface engineered poly(dimethylsiloxane)/carbon nanotube nanocomposite
           pad as a flexible platform for chemical sensors
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Yunjung Hwang, Jeong Yong Park, Chang-Soo Lee, Oh Seok Kwon, Sung-Hoon Park, Joonwon Bae
      This study demonstrated the sensing performance of surface-patterned poly(dimethylsiloxane) (PDMS)/carbon nanotube (CNT: 3–5 wt%) nanocomposite pads. PDMS/CNT nanocomposite pads as a flexible sensing platform were prepared by employing a series of techniques: 3-roll milling for mixing, 2-roll for pad formation, and imprinting for pattern development. Then, tailored surface engineering strategy was introduced. First, the silane coupling agent was incorporated to improve the surface compatibility of the nanocomposite pads. The change in surface property was monitored by shift in contact angle from 132 to 141°. Subsequently, the beta-cyclodextrin (CD) molecules were introduced as a sensing medium through a simple bio-conjugation reaction. The nanocomposite pads showed a sensitive response to methylparaben (MePRB), a representative preservative for cosmetics through host-guest interactions between CD and MePRB in the range of 1–100 nmol. Owing to the surface hydrophobicity of the nanocomposite pads, the sensor was found most effective under nonpolar solvents. The feasibility of surface engineered PDMS/CNT pad as a flexible sensor was demonstrated by measurement after 50 times manual bending. This study can be a useful example for the application of nanocomposites that show unique surface structure and properties.

      PubDate: 2018-02-04T18:20:04Z
       
  • Role of lignin nanoparticles in UV resistance, thermal and mechanical
           performance of PMMA nanocomposites prepared by a combined free-radical
           graft polymerization/masterbatch procedure
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Weijun Yang, Marco Rallini, De-Yi Wang, Daqian Gao, Franco Dominici, Luigi Torre, José M. Kenny, Debora Puglia
      In the present work, the preparation of lignin nanoparticles (LNP) reinforced Poly(methyl methacrylate) (PMMA) nanocomposites, obtained by combining solvent-free radical polymerization, micro extrusion and hot press methods through a masterbatch approach, was reported. Results from Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and Gel Permeation Chromatography (GPC) evidenced the successful grafting of LNP on MMA, confirmed by the higher glass transition temperatures observed by DSC in LNP grafted PMMA (PMMA-g-LNP) systems. Microstructural characterization proved good LNP dispersion in PMMA, achieved by means of the adopted masterbatch procedures. Furthermore, results from optical, thermal and mechanical characterization of the resulted PMMA nanocomposites confirmed improved hardness values, enhanced UV resistance, better thermal and scratch resistance for PMMA/LNP nanocomposites, opening the possibility of using these systems in many different sectors, such as automotive, flooring, acrylic glasses and lenses.

      PubDate: 2018-02-04T18:20:04Z
       
  • Experimental investigation of intra-tow fluid storage mechanisms in
           dual-scale fiber reinforcements
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Mathieu Imbert, Sebastien Comas-Cardona, Emmanuelle Abisset-Chavanne, David Prono
      Fiber reinforcements used for structural RTM applications feature dual-scale porous microstructures. During injections, these microstructures induce intra-tow resin storage that affects, significantly in fast curing cases, the distribution of temperature, viscosity and degree of cure. Storage is considered permanent in the literature; however, to optimize the process, a finer understanding of the storage and release mechanisms is required. To reach this goal, an experimental program has been implemented. Based on the injection of colored model and UV-curing fluids, the distribution of the colorant during the injection has been studied in a quantitative manner at the macroscopic and microscopic scales. It has been observed that storage is transient and that the release rate depends on the average FVF, the fiber orientation and the architecture of the reinforcement. Furthermore, the local intra-tow flow mechanisms have been identified. Finally the overall/tow permeability ratio has been identified as a good indicator to classify storage trends.

      PubDate: 2018-02-04T18:20:04Z
       
  • An energy-efficient composite by using expanded graphite stabilized
           paraffin as phase change material
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Xi Guo, Shaodi Zhang, Jinzhen Cao
      Thermal energy storage (TES) composites were prepared by employing expanded graphite (EG) stabilized paraffin as phase change material (PCM) and wood flour/high density polyethylene (WF/HDPE) as matrix. The morphology and structure of EG and form-stable phase change material (FSPCM) were investigated by scanning electron microscopy (SEM), X-ray diffractometer (XRD) and mercury intrusion porosimetry. The fabricated TES composites with different FSPCM types and contents were characterized by differential scanning calorimetry (DSC), thermogravimetric (TG), infrared thermography and laserflash thermal analysis. Physical and mechanical strength were also evaluated. The results showed that: (1) the EG had abundant pores and most of the pores were below 26 μm, the EG stabilized paraffin material showed perfect stability without any chemical reactions; (2) thermal performance indicated that the TES composites had efficient temperature-regulated ability, but thermal durability need to be further enhanced; (3) addition of paraffin and EG destroyed the interface bonding of the TES composites and mechanical properties appeared slight decrease; (4) the satisfying thermal performance and acceptable mechanical property indicating the TES composites can be used as building material for temperature conditioning.

      PubDate: 2018-02-04T18:20:04Z
       
  • An experimental study of water diffusion in carbon/epoxy composites under
           static tensile stress
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Corentin Humeau, Peter Davies, Frédéric Jacquemin
      The coupling between tensile stress and water diffusion in composites represents a major issue in many marine applications. Even if these two behaviours are well documented as separate subjects, there are still very few data on fully coupled mechanisms. The aim of this study is to understand what governs the coupled behaviour, by investigating the water diffusion in carbon/epoxy. The coupling is first evaluated on neat resin samples to characterise the matrix behaviour. Then the study focuses on composites with two types of woven fibre orientation: one at ±45°, in order to understand the coupling effects on materials loaded away from the reinforcement direction and another quasi-isotropic to obtain properties along the fibres. For each material the same approach was applied: first, the tensile behaviour, damage development and water diffusion were studied uncoupled. Then, semi-coupled effects were investigated. The final part of the paper combines both behaviours as fully coupled phenomena.

      PubDate: 2018-02-04T18:20:04Z
       
  • In-suit Mg(OH)2 template synthesis of nitrogen-doped porous carbon
           materials from glutinous rice for supercapacitors with excellent
           electrochemical performance
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Hong-yang Tang, Rui Zhao, Huan Yin, Dong-xu He, Wei-dong Xue
      In the present study, a new biomass-derived multilayer graphene-like low dimensional carbon material was prepared through the facile one-step carbonization of glutinous rice without conventional KOH chemical activation at 900 °C in an argon atmosphere. The formation of disordered microporous and mesoporous on carbon, the high specific surface area of 1,371.50 m2 g−1, and the pore volume of 2.351 cm3 g−1 were confirmed by N2 adsorption and desorption. As a merit of its favorable structural features, the graphene-like carbon electrode exhibits an enhanced electric double layer capacitance (high specific capacitance of 289.9 F g−1 and 174 F g−1 at 0.5 A g−1 and 10 A g−1) and excellent cycling stability of 88% after 20,000 cycles at a current density of 8 A g−1. This observed electrochemical performance clearly indicates that activated carbon derived from glutinous rice could be used as a promising electrode material in a supercapacitor for electrochemical energy storage.

      PubDate: 2018-02-04T18:20:04Z
       
  • Mechanical properties and strain monitoring of glass-epoxy composites with
           graphene-coated fibers
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Haroon Mahmood, Lia Vanzetti, Massimo Bersani, Alessandro Pegoretti
      An engineered interphase can improve the mechanical properties of epoxy/glass composites simultaneously inducing a piezoresistive response. To prove this concept, E-glass fibers were coated with graphene oxide (GO) by electrophoretic deposition, while reduced graphene oxide (rGO) coated fibers were obtained by subsequent chemical reduction. The fiber-matrix interfacial shear strength (measured by the single-fiber fragmentation test) increased for both GO and rGO coated fibers. Unidirectional composites with a high content of both uncoated and coated fibers were produced and mechanically tested under various configurations (three-point bending, short beam shear and mode-I fracture toughness, creep). Composites with coated fibers performed similarly or better than composites prepared with uncoated fibers. Finally, composites with rGO coated fibers were tested for their piezoresistive response under both static and dynamic conditions. The electrical resistance changed proportionally to applied strain thus confirming the possibility of using composites with rGO coated fibers as strain sensors in load-bearing components.

      PubDate: 2018-02-04T18:20:04Z
       
  • Insights from in-situ X-ray computed tomography during axial impregnation
           of unidirectional fiber beds
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Natalie M. Larson, Frank W. Zok
      In-situ X-ray computed tomography during axial impregnation of unidirectional fiber beds is used to study coupled effects of fluid velocity, fiber movement and preferred flow channeling on permeability. In order to interpret the experimental measurements, a new computational tool for predicting axial permeability of very large 2D arrays of non-uniformly packed fibers is developed. The results show that, when the impregnation velocity is high, full saturation is attained behind the flow front and the fibers rearrange into a less uniform configuration with higher permeability. In contrast, when the velocity is low, fluid flows preferentially in the narrowest channels between fibers, yielding unsaturated permeabilities that are lower than those in the saturated state. These insights combined with a new computational tool will enable improved prediction of permeability, ultimately for use in optimization of composite manufacturing via liquid impregnation.

      PubDate: 2018-02-04T18:20:04Z
       
  • Enhanced thermal conductivity of polyethylene/boron nitride multilayer
           sheets through annealing
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Shu-Ya Yang, Yan-Fei Huang, Jun Lei, Lei Zhu, Zhong-Ming Li
      Polyethylene/hexagonal boron nitride (PE/h-BN) composite sheets with enhanced thermal conductivity were fabricated through annealing a multilayered structure of alternating high density PE (HDPE)/h-BN composite and low density PE (LDPE) layers. Multilayer sheets possess a relatively low initial content filler, and after thermal annealing at 200 °C, the PE molecules in the composite layers diffused into neighboring layers. As a result, the h-BN concentration in the composite layers increased with the annealing time, resulting in the formation of thermal conduction pathways and enhancement of the final thermal conductivity. When the volume content of h-BN was 5.97 vol.%, the through-plane thermal conductivity of the annealed specimen was 1.37 W m−1 K−1, which showed an enhancement of ∼180% compared to the value of the neat composite with the same content of randomly dispersed h-BN. Our work suggests that this facile method is promising for the development of high-performance thermally conductive products.

      PubDate: 2018-02-04T18:20:04Z
       
  • Constructing hierarchical polymer@MoS2 core-shell structures for
           regulating thermal and fire safety properties of polystyrene
           nanocomposites
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Keqing Zhou, Gang Tang, Rui Gao, Hailin Guo
      Two dimensional MoS2 acting as reinforcing fillers had attracted intense interests in recent years. However, the homogeneous dispersion of MoS2 nanosheets in polymer matrix and exact interface control were still difficult to achieve due to potent van der Waals forces and surface inactiveness. In this work, hierarchical polystyrene@MoS2 core-shell structures were constructed by combining latex technology and self-assembly of oppositely charged MoS2 nanosheets onto the surface of polystyrene spheres. The formed core-shell structures were characterized by X-ray diffraction, Fourier transform infrared, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy and further employed as reinforcing fillers in a host polystyrene matrix by solvent blending method. It was clearly observed that the construction of polystyrene@MoS2 core-shell structures not only improved the dispersion of MoS2 in the matrix and the interfacial adhesion between MoS2 and polystyrene, but also obviously improved the thermal stability and fire safety of polystyrene. The method proposed here had proved to be an efficient and facile approach to fabricate polymer/MoS2 nanocomposites with good dispersion and markedly improved properties.

      PubDate: 2018-02-04T18:20:04Z
       
  • Mechanical response of multi-layer bacterial cellulose nanopaper
           reinforced polylactide laminated composites
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Martin Hervy, Jonny J. Blaker, Ana Letícia Braz, Koon-Yang Lee
      In this study, we investigated the mechanical response of polylactide (PLLA) reinforced with multiple layers of BC nanopaper. Laminated composites consisting of 1, 3, 6 and 12 sheet(s) of BC nanopaper were produced. It was observed that increasing the number of BC nanopaper led to an increase in the porosity of the resulting BC nanopaper-reinforced PLLA laminated composites. The tensile moduli of the laminated composites were found to be ∼12.5 – 13.5 GPa, insensitive to the number of sheets of BC nanopaper in the composites. However, the tensile strength of the laminated composites decreased by 21% (from 121 MPa to 95 MPa) when the number of reinforcing BC nanopaper sheets increased from 1 to 12 sheets. This was attributed to the presence and severity of the scale-induced defects increased with increasing BC nanopaper sheets in the PLLA laminated composites.

      PubDate: 2018-02-04T18:20:04Z
       
  • The formation of atomic-level interfacial layer and its effect on thermal
           conductivity of W-coated diamond particles reinforced Al matrix composites
           
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Zifan Che, Jianwei Li, Qingxiao Wang, Luhua Wang, Hailong Zhang, Yang Zhang, Xitao Wang, Jinguo Wang, Moon J. Kim
      Diamond particles coated with a 45 nm-thick W layer were used to produce diamond particles reinforced Al matrix composites (Al/diamond(W)) by a gas pressure infiltration method. The results show that W atoms have diffused into Al matrix and replaced Al atoms during infiltration. As a result, a uniform 0.5 nm-thick Al5W interfacial layer is formed in the composite produced with 20 min infiltration time. The generation of the Al5W layer strengthens not only the interfacial bonding but also impedes the formation of hydrolysable Al4C3 phase. With increasing infiltration time from 10 to 60 min, the thermal conductivity increases from 520 to 620 W/m K, which manifests the influence of interfacial layer thickness on thermal properties of the Al/diamond(W) composite. The study provides a new strategy to modifying the interfacial structure of Al/diamond composites on the aspects of both enhancing the thermal conductivity and preventing the formation of hydrolysable Al4C3 phase.
      Graphical abstract image

      PubDate: 2018-02-04T18:20:04Z
       
  • Effect of post curing temperature on mechanical properties of a flax fiber
           reinforced epoxy composite
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Charlotte Campana, Romain Leger, Rodolphe Sonnier, Laurent Ferry, Patrick Ienny
      Achieving a complete curing of biocomposites without damaging fibers is very challenging. This study assesses the impact of processing upon the mechanical properties of a unidirectional flax reinforced epoxy composite and identifies which component (resin, reinforcement or interphase) is the most sensitive to post-curing at high temperature (100, 120 or 150 °C). Post-curing temperature had a limited impact on the composite mechanical behavior excepted at 150 °C where ultimate stress and strain decreased drastically while the stabilized modulus slightly increases. Post curing is responsible of a slight decrease of the matrix tensile properties attributed to the polymer oxidation but cannot explain on its own the evolution of the composite behavior. Interfacial adhesion played a minor role in the composite behavior probably due to its intrinsic weakness. Finally, the flax fabric was highlighted to be the component most sensitive to thermal treatment thus governing the drop in the composite mechanical properties.

      PubDate: 2018-02-04T18:20:04Z
       
  • Synthesis and characterization of beeswax-tetradecanol-carbon
           fiber/expanded perlite form-stable composite phase change material for
           solar energy storage
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Fei Cheng, Ruilong Wen, Xiaoguang Zhang, Zhaohui Huang, Yaoting Huang, Minghao Fang, Yan'gai Liu, Xiaowen Wu, Xin Min
      In this study, beeswax-tetradecanol/expanded perlite composited with carbon fiber (BW-TD-CF/EP) composite phase change materials (CPCMs) have been prepared via vacuum impregnation method for solar energy utilization. The chemical compatibility, microstructure and thermal properties of CPCMs are characterized and measured, which proves that it is no chemical interaction among the raw materials but physical combination and BW-TD-CF is sufficiently absorbed into the EP porous structure with no leakage even in the molten state. According to differential scanning calorimeter (DSC) results, BW-TD-CF/EP composite melts at 34 °C with high enthalpy value of 178.7 kJ/kg, while thermal cycling measurements show that the form-stable composite PCM has adequate stability after being subjected to 200 melting/freezing cycles. Morever, thermal conductivity of BW-TD/EP composite is enhanced from 0.443 Wm−1 K−1 to 1.245 Wm−1 K−1 by adding CF. In result, the form-stable composite PCMs have more appropriate thermal properties and better thermal stability in building for solar energy utilization.

      PubDate: 2018-02-04T18:20:04Z
       
  • Cellulose/graphene bioplastic for thermal management: Enhanced isotropic
           thermally conductive property by three-dimensional interconnected graphene
           aerogel
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Li Chen, Xingshuang Hou, Na Song, Liyi Shi, Peng Ding
      Environment-friendly cellulose bioplastic is a promising material to replace fossil-fuel plastic for the more sustainable future. In present study, we reported a functional cellulose bioplastic that can be used for thermal management. The cellulose bioplastic was easily fabricated by impregnating three-dimensional graphene aerogel (GA) into the cellulose solution and then hot-pressed. The cellulose/GA composites exhibited enhanced isotropic thermal conductivity and good mechanical performance. The thermal conductivity of the cellulose/GA composite was 0.67 W m−1 K−1 in vertical direction increasing by 219% and 0.72 W m−1 K−1 in parallel direction, increasing by 44% respectively. Meanwhile, the hardness of the composites reached to 148 MPa and the Young's modulus is 2.3 GPa, superior to those of most common plastics, such as Nylon and Polymethyl methacrylate (PMMA). The integrated performance of the composites could be attributed to the formation of efficient thermally conductive network and the good adhesion between the graphene cell wall and the cellulose.

      PubDate: 2018-02-04T18:20:04Z
       
  • Numerical analysis of viscoelastic process-induced residual distortions
           during manufacturing and post-curing
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Maria Benavente, Lionel Marcin, Alice Courtois, Martin Lévesque, Edu Ruiz
      Degree of cure- and temperature-dependent elastic and viscoelastic models were implemented into ABAQUS to compute the geometrical distortion developed during the RTM manufacturing and post-curing of asymmetric plates and corner shaped parts. Comparisons between the predicted and experimental geometrical distortion for an asymmetric plate reinforced with 3D interlock woven fabric are presented. The results showed that the parts can experience creep behavior when submitted to free-standing post-curing, increasing the total geometrical distortion up to 30%, depending on post-curing cycle and part geometry. The numerical results of this work demonstrate that a temperature-dependent viscoelastic model is needed to accurately predict the geometrical distortion evolution developed during cure cycles where post-curing processes are involved.

      PubDate: 2018-02-04T18:20:04Z
       
  • Out-of-autoclave scarf repair of interlayer toughened carbon fibre
           composites using double vacuum debulking of patch
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): H.M. Chong, S.L. Liu, A.S. Subramanian, S.P. Ng, S.W. Tay, S.Q. Wang, S. Feih
      Interlayer particle toughened carbon fibre composites play an integral role in the lightweight design of primary aerospace structures. We investigate an out-of-autoclave method using double vacuum debulking (DVD) to perform in-situ soft patch repairs. Utilizing the DVD process decreases the porosity of the co-cured film adhesive and patch from 4.7% to 0.4%, thereby increasing the flexural and interlaminar shear strength of 1D repair laminates by 30% to levels equal to autoclave cured laminates. In contrast, the higher void content did not significantly affect straight (2D) and round (3D) scarf repair strengths. 3D repairs showed significantly improved strength recovery compared to 2D repairs due to the stress shedding in the hoop direction. Finally, DVD process parameters may be optimized to reduce repair time by increasing the temperature and ramp rates while reducing the soak times, with no detrimental effects on porosity or strength observed.

      PubDate: 2018-02-04T18:20:04Z
       
  • Effect of interface on composites made from DREF spun hybrid yarn with low
           twisted core flax yarn
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Mahadev Bar, Apurba Das, R. Alagirusamy
      In the present work, the influence of interface and hybrid yarn structure on flax-PP based unidirectional composite properties have been studied thoroughly. Flax-PP based core-sheath structured DREF spun hybrid yarns are manufactured after varying the core yarn twist and sheath percentage at three different levels and using MAgPP treated and untreated flax yarn as core. These hybrid yarns are consolidated to manufacture unidirectional composite samples and the resultant composites are tested accordingly. It is observed that MAgPP treatment of the core flax yarn improves the tensile and flexural properties of the hybrid yarn reinforced unidirectional composites while impact strength decreases after the treatment. A negative impact on the tensile and flexural properties of the unidirectional composite samples is observed with increasing core twist and sheath content of the reinforcing hybrid yarn. The impact strength of the composite samples increases for similar changes in hybrid yarn parameters.

      PubDate: 2018-02-04T18:20:04Z
       
  • Design and synthesis of wool-like Co-Mg compound@NiMoO4 nanosheet material
           for high performance supercapacitors
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Yu Zhang, Wei-dong Xue, Huan Yin, Dong-xu He, Rui Zhao
      We have elaborated nanocomposite electrodes, which were designed and synthesized via facile hydrothermal with further annealing processes of NiMoO4 nanosheets on cobalt and magnesium double hydroxide (DH) growing directly on Ni foam. The integrated electrode (the optimum hydrothermal time 6 h) designed according to this structural pattern, had an excellent electrochemical performance along with a high areal-specific capacitance of 6.50 F cm−2 at 5 mA cm−2 and retained 56% at 60 mA cm−2, the capacitance of the electrode material remained 74% after 5000 cycles at 40 mA cm−2. The Co-Mg compound@NiMoO4 and activated carbon were assembled into an asymmetric supercapacitor (Co-Mg compound@NiMoO4//AC), which allowed the feasible voltage could reach 1.6 V and a high energy density of 57 W h kg−1 at the power density of 0.4 kW kg−1. The Co-Mg compound@NiMoO4//AC also showed significant cyclic stability with the capacitance retention of 87% after 5000 cycles.

      PubDate: 2018-02-04T18:20:04Z
       
  • Identification of the anisotropic elastic and damping properties of
           complex shape composite parts using an inverse method based on finite
           element model updating and 3D velocity fields measurements (FEMU-3DVF):
           Application to bio-based composite violin soundboards
    • Abstract: Publication date: March 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 106
      Author(s): Romain Viala, Vincent Placet, Scott Cogan
      Inverse methods have been used for decades to identify material properties, in parallel, or as a substitution for direct methods. Although it has proven a useful method for many types of materials and simple geometrical shapes, it has barely been used on complex shape parts. This is the main objective of the non-destructive method proposed in this study. The proposed inverse approach, based on both vibrational experiment data and Finite Element Model Updating (FEMU), is successfully applied to a violin soundboard made of flax-epoxy composite. Results show that, by minimizing the discrepancy between the experimental and numerical data, three rigidities and three loss factors can be determined simultaneously. The identified values of the constitutive elastic moduli and longitudinal loss factor are in agreement with those determined using quasi-static tests and dynamic mechanical analysis.

      PubDate: 2018-02-04T18:20:04Z
       
  • Polydopamine as sizing on carbon fiber surfaces for enhancement of epoxy
           laminated composites
    • Abstract: Publication date: Available online 3 February 2018
      Source:Composites Part A: Applied Science and Manufacturing
      Author(s): Wei Han, Hong-Ping Zhang, Javad Tavakoli, Jonathan Campbell, Youhong Tang
      Carbon fiber reinforced polymer (CFRP) laminate normally has plastic dominant crack propagation behavior, inducing potential insecurity in the safety and reliability of structures in practical applications. In this study, we report a simple process to increase the stability of crack growth by using polydopamine (PDA) as sizing on the surface of carbon fiber (CF) fabric. The crack propagation behavior changes from a saw-tooth-shaped curve in neat CFRP laminate to a relatively smooth trending curve in PDA coated CFRP laminate with increased Mode I interlaminar fracture toughness. Enhanced impact strength and interlaminar shear strength of PDA coated CFRP laminates is also observed. A single fiber pull-out experiment and morphological study reveal that, with PDA coating on CF fabrics, cracks tend to fracture through the epoxy matrix rather than between fiber and matrix interfaces. The use of PDA as sizing on the CF contributes to improving the load transfer between the CF and the polymer matrix by enhancing the interfaces between the epoxy and the CF, increasing the friction of the fractured interface, reducing unstable crack growth, and thereby enhancing interfacial fracture toughness and impact performance.

      PubDate: 2018-02-04T18:20:04Z
       
  • Bioinspired mechanical and thermal conductivity reinforcement of highly
           explosive-filled polymer composites
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Guansong He, Jiahui Liu, Feiyan Gong, Congmei Lin, Zhijian Yang
      The low mechanical and thermal conductivity property of polymer bonded explosives (PBX) could greatly restrict its further practical application. In this study, inspired by mussels, a facile and noncovalent modification for three carbon nanofillers including multiwalled carbon nanotubes (CNTs), graphene and graphene nanoplates (GNPs), was adopted by the self-polymerization of dopamine. Next, in-depth characterizations, including SEM, TEM, FTIR, FT-Raman and TGA, confirmed that the carbon nanofillers were successfully coated by a dense graphite-like structure polydopamine (PDA) without destroying the original structures, through the oxidation of dopamine at room temperature. The polydopamine-coated nanofillers (pFillers) were further incorporated into PBX matrix. Compared to neat PBX and PBX/carbon nanocomposites, the PBX/pFillers nanocomposites exhibited improved tensile and compression strength, creep resistance, and thermal conductivity. The work presented herein greatly broadens the application scope of the bioinspired dopamine, and will be potential of interest to the communities in highly particle-filled polymer composites.

      PubDate: 2017-12-27T03:25:03Z
       
  • A multi-pattern compensation method to ensure even temperature in
           composite materials during microwave curing process
    • Abstract: Publication date: April 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 107
      Author(s): Jing Zhou, Yingguang Li, Nanya Li, Shuting Liu, Libing Cheng, Shaochun Sui, James Gao
      Microwave curing technologies have many advantages in manufacturing fiber reinforced polymer composite materials used in aerospace products, compared with traditional autoclave curing technologies. However, the uneven electromagnetic field of microwave in the cavity of the curing chamber results in uneven temperature on the surface of composite laminates during curing, which has been a major obstacle in industrial applications worldwide. Existing methods attempted to solve the problem by the random superposition of uneven electromagnetic fields, but the results were still not satisfactory to meet the high quality requirements of aerospace parts. This paper reveals the one-to-one correspondence between heating patterns of composite parts and microwave curing system settings, and reports a new concept to solve this problem by continuously monitoring and compensating the uneven temperature distribution in real-time. Experimental results from both fiber optical fluorescencesensors and infrared thermal imagers showed significant improvement in temperature uniformity compared with existing methods.

      PubDate: 2017-12-27T03:25:03Z
       
  • Dynamic bridging mechanisms of through-thickness reinforced composite
           laminates in mixed mode delamination
    • Abstract: Publication date: March 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 106
      Author(s): Hao Cui, Mehdi Yasaee, Stephen R. Hallett, Ivana K. Partridge, Giuliano Allegri, Nik Petrinic
      Delamination resistance of composite laminates can be improved with through-thickness reinforcement such as Z-pinning. This paper characterises the bridging response of individual carbon fibre/BMI Z-pins in mixed mode delamination at high loading rate using a split Hopkinson bar system. The unstable failure process in quasi-static tests, was also captured with high sampling rate instruments to obtain the complete bridging response. The energy dissipation of the Z-pins were analysed, and it was found that the efficacy of Z-pinning in resisting delamination growth decreased with an increase in mixed mode ratio, with a transition from pull-out to pin rupture occurring. The Z-pin efficacy decreased with loading rate for all mode mix ratios, due to the changing in failure surface with loading rate and rate-dependent frictional sliding.

      PubDate: 2017-12-27T03:25:03Z
       
  • Thermal conductivity and mechanical properties of flake graphite/copper
           composite with a boron carbide-boron nano-layer on graphite surface
    • Abstract: Publication date: March 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 106
      Author(s): H Bai, C Xue, JL Lyu, J Li, GX Chen, JH Yu, CT Lin, DJ Lv, LM Xiong
      Graphite/copper composites had attracted significant recent attention for thermal management applications due to their superior thermal properties, low cost and ease of machining. However, achieving the enhancement of mechanical properties of composites with high thermal conductivity remained challenging. In this study, graphite/copper composites had been produced by vacuum hot pressing process, in which the boron carbide-boron coating was synthesized on graphite to improve the mechanical properties of copper matrix composites with high volume fraction of graphite. The resulting composites had superior thermal conductivity (676 W/mK, 180% of copper) and apposite coefficient of thermal expansion (7.1 ppm/K), which was attributed to the homogeneous dispersion and well-controlled alignment of graphite in the composite. And the results showed that the coating on graphite slightly decreased the thermal conductivity and coefficient of thermal expansion of the composites, but evidently improved the bending strength. The flexural strength raised to 74 MPa, 42% increased with that of uncoated composite.

      PubDate: 2017-12-27T03:25:03Z
       
  • Cavitation in epoxies under composite-like stress states
    • Abstract: Publication date: March 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 106
      Author(s): Anupam Neogi, Nilanjan Mitra, Ramesh Talreja
      In a previous study (Asp et al., 1995) the experimentally observed low strains to transverse tensile failure of unidirectional (UD) polymer matrix composites were explained as an effect of triaxial (composite- like) stress state in the epoxy matrix. Assuming cavitation as an underlying mechanism for brittle cracking under triaxial stress states, a dilatation energy density based criterion was put forth (Asp et al., 1996) and was shown to predict well the transverse failure of epoxy based UD composites (Asp et al., 1996). The assumption of cavitation in the epoxy matrix has hitherto not been supported by a mechanism study. The current study attempts to provide a systematic clarification of the cavitation mechanism by molecular dynamic simulation. By imposing uniaxial, equi-biaxial and equi-triaxial tension on a simulation cell of a crosslinked epoxy, the degrees of cavitation at various stages of the stress- strain response are revealed. The results show that triaxiality of the stress states is a governing factor in cavitation of epoxies.

      PubDate: 2017-12-27T03:25:03Z
       
  • Development of biocomposites from denim waste and thermoset bio-resins for
           structural applications
    • Abstract: Publication date: March 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 106
      Author(s): Robin Temmink, Behnaz Baghaei, Mikael Skrifvars
      This paper examines the use of post-consumer denim fabric in combination with thermoset bio-resins in composite manufacturing for structural applications. Bio-epoxy and acrylated epoxidized soybean oil resin (AESO) were used as bio-resins with four different manufacturing techniques in order to create a wide scope of possibilities for research. The four techniques are: compression moulding (COM), vacuum infusion (VAC), resin transfer moulding (RTM) and hand lay-up (HND). The bio-resins were compared to a conventional polyester resin, as this is highly used for structural applications. To determine suitability for structural applications, the biocomposites were tested for their mechanical and thermal properties. Fabricated composites were characterised regarding porosity, water absorption and analysed through microscopic images of the composite. Results show both bio-epoxy and AESO are suitable for use in structural applications over a range of manufacturing techniques. Furthermore, biocomposites from bio-epoxy are superior to those from AESO resin. The conventional polyester has shown to be unsuitable for structural applications.

      PubDate: 2017-12-27T03:25:03Z
       
  • Interaction of textile variability and flow channel distribution systems
           on flow front progression in the RTM process
    • Abstract: Publication date: March 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 106
      Author(s): C. Kracke, A. Nonn, C. Koch, M. Nebe, E. Schmidt, S. Bickerton, T. Gries, P. Mitschang
      The high volume production of carbon fibre reinforced plastics needs cost efficient and robust processes. This paper investigates the influence of local textile variation on flow front progression in resin transfer moulding (RTM). To quantify the textile variation, the textile has been tested with laser triangulation, to achieve the thickness profile map of the flat textile preform. This preform is placed in a transparent flow visualisation tool and an oil is injected into the mould via two different flow channel distribution systems. The flow front progression of the fluid is continuously measured from both sides with two cameras. Furthermore, to demonstrate the influence of defects like folds from the draping process on the local filling behaviour, the textile is prepared with an artificial fold, made of additional non-crimp fabric (NCF) strips. The results show how different defects in the textile influence the local filling behaviour and how the additional flow channel distribution system can decrease the effect of these defects.

      PubDate: 2017-12-27T03:25:03Z
       
  • Impact resistance of shear thickening fluid/Kevlar composite treated with
           shear-stiffening gel
    • Abstract: Publication date: March 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 106
      Author(s): Qianyun He, Saisai Cao, Yunpeng Wang, Shouhu Xuan, Pengfei Wang, Xinglong Gong
      In this work, shear-stiffening gel (STG) was introduced into shear thickening fluid (STF)-impregnated-Kevlar® woven fabric (Kevlar/STF) to improve the impact resistance. The STF filled within the yarns of Kevlar and the STG covered the Kevlar/STF to form Kevlar/STF/STG composite. The STG in the Kevlar/STF/STG not only protected STF but also improved the impact resistance of the fabric because of its excellent shear-stiffening characteristics. A series of experiments including the yarn pull-out test, the split Hopkinson pressure bar impact test, rod penetration test, and knife cutting test were carried out to verify the enhancement effect. The improvement mechanism of the impact resistance for the Kevlar/STF/STG was studied. Under the similar anti-impact performance, the Kevlar/STF/STG possessed lower weight than the Kevlar and its strong impact resistance originated from the synergetic effect among the STF, STG and Kevlar. Therefore, the Kevlar/STF/STG exhibited broad potential in the soft body armor.

      PubDate: 2017-12-27T03:25:03Z
       
  • Carbon foam based on epoxy/novolac precursor as porous micro-filler of
           epoxy composites
    • Abstract: Publication date: February 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 105
      Author(s): Urszula Szeluga, Sławomira Pusz, Bogumiła Kumanek, Jerzy Myalski, Bartosz Hekner, Boyko Tsyntsarski, Rafał Oliwa, Barbara Trzebicka
      The concept of application of crumbled carbon foam obtained from polymer precursor as a filler in polymer/carbon composite was described. The carbon foam used as powdered reinforcement of composites was prepared from epoxy resin cross-linked with phenol–formaldehyde resin (novolac) in a self-foaming process followed by carbonization at not very high temperature and ambient pressure. The structure of the carbon foam filler and resultant composites was studied by microscopic and spectroscopic methods. In the final composites, there were observed good quality dispersion of micronized grains of carbon foam, with the sizes that preserve their specific porous structure, in epoxy matrix and excellent adhesion at interfacial areas. The influence of the CF filler on the properties of resultant composites were investigated. Due to valuable properties of carbon foam, resultant composites occurred to have interesting characteristics: densities similar to those of pure polymer matrix, advantageous thermal and viscoelastic properties and enhanced tribological features.

      PubDate: 2017-12-13T08:00:47Z
       
  • Hierarchical pseudo-ductile hybrid composites combining continuous and
           highly aligned discontinuous fibres
    • Abstract: Publication date: February 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 105
      Author(s): HaNa Yu, Marco L. Longana, Meisam Jalalvand, Michael R. Wisnom, Kevin D. Potter
      Hybrid composites allow avoiding catastrophic failure, a key limitation of composite materials, and can provide a balanced suite of modulus, strength and ductility. The aim of this research is to manufacture hierarchical hybrid composites using a combination of continuous high elongation fibres and intermingled hybrids made out of highly aligned discontinuous fibres with lower elongation to achieve pseudo-ductility through control of failure development. The HiPerDiF (High Performance Discontinuous Fibres) method that allows a high level of fibre alignment, leading to excellent mechanical properties close to continuous fibre composites, was used to produce the intermingled hybrid discontinuous fibre preforms. The hierarchical hybrid composite configuration is composed of an intermingled hybrid discontinuous fibre layer sandwiched between continuous S-glass layers. The overall stress-strain response of the intermingled hybrid composites and the hierarchical hybrid composites was investigated for different fibre types and ratios. The analytical modelling approach previously developed by the authors for interlaminated hybrid composites was modified for this new type of hierarchical composite. The experimental results were analysed and the analytical model was used to evaluate the optimised balance of constituents to maximise pseudo-ductile strain in tension.

      PubDate: 2017-12-13T08:00:47Z
       
  • Influence of temperature on the strength of resistance welded glass fibre
           reinforced PPS joints
    • Abstract: Publication date: February 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 105
      Author(s): N. Koutras, I. Fernandez Villegas, R. Benedictus
      In this work, the effect of temperature exposure on the strength of resistance welded joints is analysed. Glass fibre reinforced polyphenylene sulphide (GF/PPS) adherends were joined using the resistance welding technique, using a stainless steel mesh as the heating element. Single lap shear tests were performed at temperatures ranging between −50 °C and 150 °C to evaluate the strength of the welded joints. The results showed that the lap shear strength decreased with increasing temperature, except for the region between 50 °C and 90 °C where it remained constant. Fractography analysis revealed that the main failure mechanism was glass fibre/matrix debonding and the connection between the mesh and the matrix was not the weakest link at the interface of the joint at any temperatures under study. The fibre/matrix interfacial strength and the stress distribution at the joint overlap were identified as the main factors influencing the behaviour of lap shear strength with temperature.

      PubDate: 2017-12-13T08:00:47Z
       
  • Segregated conductive polymer composite with synergistically electrical
           and mechanical properties
    • Abstract: Publication date: February 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 105
      Author(s): Wei Zhai, Shuaiguo Zhao, Yan Wang, Guoqiang Zheng, Kun Dai, Chuntai Liu, Changyu Shen
      The potential of segregated conductive polymer composites is greatly hampered due to its poor mechanical strength and brittle nature. In this work, plunger type injection molding (PTIM) is developed to achieve synergistically electrical and mechanical properties on carbon nanotubes (CNTs)/polypropylene (PP)/ultra-high molecular weight polyethylene (UHMWPE) segregated conductive polymer composite. Morphology observation indicates that the segregated CNTs conductive network was formed along the interfaces between PP and UHMWPE grains. An ultralow percolation threshold of 0.13 vol% is achieved, which is much lower than that of conventional injection molding. The strength of PTIM sample is improved; importantly, more than 10 times of improvement in elongation at break has been achieved compared to the sample obtained from frequently-used compression molding. Stability of the segregated conductive network was evaluated through dynamic strain-sensing behaviors. This paper presents a meaningful strategy towards the improvement of comprehensive performance of segregated conductive polymer composite.

      PubDate: 2017-12-13T08:00:47Z
       
  • A new approach to enhancing interlaminar strength and galvanic corrosion
           resistance of CFRP/Mg laminates
    • Abstract: Publication date: February 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 105
      Author(s): Yingcai Pan, Xuan Wu, Zheng Huang, Guoqing Wu, Siqiang Sun, Hengjian Ye, Zongke Zhang
      In the present research, AZ31 magnesium alloy was treated by electrochemical methods in Na2SiO3-KOH-KF and KOH-KF electrolytes, and the morphological features of films formed on magnesium alloy were assessed. Besides, the effect of Mg surface features on interlaminar failure load, failure mode and galvanic corrosion resistance of CFRP/Mg laminates were investigated. The results show that removal of silicate in the Na2SiO3-KOH-KF electrolyte can cause the transition of conversion film from ceramic-like oxide film to pitted oxide film. The pitted oxide film can effectively enhance the peel strength of CFRP/Mg laminates compared with the ceramic-like oxide film, and an average enhancement of 6.5 times was observed. The pitted oxide film on magnesium can provide an excellent protection against the galvanic corrosion in CFRP/Mg laminates as the ceramic-like oxide film.

      PubDate: 2017-12-13T08:00:47Z
       
  • Microstructure and synergistic-strengthening efficiency of CNTs-SiCp
           dual-nano reinforcements in aluminum matrix composites
    • Abstract: Publication date: February 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 105
      Author(s): Xin Zhang, Shufeng Li, Deng Pan, Bo Pan, Katsuyoshi Kondoh
      In this study, reinforcements of carbon nanotubes (CNTs) and silicon carbide particle (SiCp) in CNTs-SiCp reinforced aluminum matrix nanocomposites (AMNCs) are studied. The tensile strength of 0.5CNTs-0.5SiCp/Al increase by 94% compared with pure Al reaching 247 MPa, it also has a lifting of 14% and 56% compared with 1.0CNTs/Al and 1.0SiCp/Al. CNT-SiCp reinforcements have the synergistic enhancement effect of 1 + 1 > 2 in tensile strength. It is found that SiCp as a dispersed particle around CNTs can inhibit and delay the pulling out and peeling of CNTs to further enhance the strengthening effect of CNTs by pinning effect. Between CNTs and Al matrix, there is a nano-scale reaction transition layer which improves the mechanical properties of AMNCs by strengthening the interfacial bonding. The existences of SiCp inhibit the excessive reaction of the interface, when the tensile strength of AMNCs increases compared with pure Al, the elongation and conductivity have similar maintaining.

      PubDate: 2017-12-13T08:00:47Z
       
  • Rheological percolation behaviour and fracture properties of
           nanocomposites of MWCNTs and a highly crosslinked aerospace-grade epoxy
           resin system
    • Abstract: Publication date: February 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 105
      Author(s): Yan Liu, Arthur Wilkinson
      The effects of incorporating MWCNT in a high-functionality epoxy resin system are reported. Oscillatory-shear rheology showed as-received MWCNT (AR-MWCNT) to have a low degree of interaction with the resin and consequently G′ values were low, whereas G′ values for functionalized MWCNTs (amino and oxidised) were higher due to increased resin-nanotube interactions. Three approaches used to obtain rheological percolation thresholds showed values to increase in an order reflecting the improved MWCNT dispersion imparted by functionalisation. Analysis using colloidal dispersion theory fitted better with the experimental data than statistical percolation theory, and more closely mirrors the clustering of MWCNT agglomerates to form a percolated network. In fracture studies, toughness decreased with AR-MWCNT addition whereas for functionalised MWCNT addition toughness increased. For AR-MWCNT nanocomposites large agglomerates were formed which reduced toughness. In contrast, functionalised MWCNTs exhibited pull-out and fracture and formed smaller agglomerates which toughened the matrix via crack-deflection and pinning.

      PubDate: 2017-12-13T08:00:47Z
       
  • Impedance spectroscopy as a tool for moisture uptake monitoring in
           construction composites during service
    • Abstract: Publication date: February 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 105
      Author(s): Sotirios A. Grammatikos, Richard J. Ball, Mark Evernden, Ryan G. Jones
      This is a first study comparing dielectric spectroscopy and gravimetric measurements of moisture uptake in pultruded glass fibre reinforced polymers (FRPs). Specimens were subjected to sub-Tg hygrothermal aging for 224 days. Impedance spectra in the frequency range 0.1 Hz to 10 MHz were captured during exposure and compared with gravimetric measurements. Moisture concentration was found to increase the FRP’s dielectric permittivity monotonically and decrease bulk resistance. High quality dielectric data was obtained as moisture uptake is independent of inherent changes suggested by mass loss which compromise gravimetry. Dielectric measurements remained sensitive to moisture despite significant mass loss, which typically distorts the weight gain process complicating the commonly adopted gravimetric methodology. Real-time dielectric measurements were obtained from FRP specimens continuously immersed in water and without making use of any additional sensing elements. The novel approach adopted is of high commercial impact as moisture uptake control is recognized as a significant problem by industry.

      PubDate: 2017-12-13T08:00:47Z
       
  • A particular interfacial strategy in PVDF/OBC/MWCNT nanocomposites for
           high dielectric performance and electromagnetic interference shielding
    • Abstract: Publication date: February 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 105
      Author(s): Xiang-Jun Zha, Jun-Hong Pu, Li-Feng Ma, Ting Li, Rui-Ying Bao, Lu Bai, Zheng-Ying Liu, Ming-Bo Yang, Wei Yang
      Multi-walled carbon nanotubes (MWCNTs) were easily dispersed at the interface of polyvinylidene difluoride (PVDF) and ethylene-α-octene block copolymer (OBC) blend by melt compounding and the nanocomposites exhibited enhanced dielectric performance, electromagnetic interference shielding effectiveness (EMI SE) and balanced mechanical performance. Through the simple, efficient and scalable interfacial strategy to disperse MWCNTs at the interface of PVDF and OBC phases, the accumulation of charge carriers at the interfaces and strong interfacial polarization effect can be achieved. At low frequency, PVDF/OBC/MWNCT nanocomposite exhibits high dielectric permittivity (753.8) and low dielectric loss tangent (0.8), offering great potential in energy storage applications. Simultaneously, in X-band range, PVDF/OBC/MWNCT nanocomposite shows high EMI SE of around 34 dB which is higher than the industrial requirement when the content of MWCNTs is as low as 2.7 vol.%. This study provides possibilities to realize high-performance polymer nanocomposites via the particular interfacial structure through one-step melt processing.
      Graphical abstract image

      PubDate: 2017-12-13T08:00:47Z
       
  • Microstructure, microhardness and thermal expansion of CNT/Al composites
           prepared by flake powder metallurgy
    • Abstract: Publication date: February 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 105
      Author(s): Pham Van Trinh, Nguyen Van Luan, Doan Dinh Phuong, Phan Ngoc Minh, Alicia Weibel, David Mesguich, Christophe Laurent
      Carbon nanotube/aluminum (CNT/Al) composites are prepared by a combination of flake powder metallurgy and hot-isostatic-pressing. The specimens are investigated by several techniques including Raman spectroscopy, optical microscopy, scanning- and transmission electron microscopy. The composites show a layered-microstructure with a stacking of CNT/Al flakes with a CNT-rich layer between two flakes. The individual Al grains forming the flakes are about 500 nm in size. The CNTs are well dispersed within a flake and they bridge the micro-cracks. The results reveal that the coefficient of thermal expansion (CTE) decreases markedly upon the increase in carbon content, reaching 15.4 × 10−6 K−1 for the specimen with a carbon content of 2.0 wt% (2.9 vol%), i.e. a 30% decrease compared to the CTE of pure Al. This could arise from the layered-microstructure resulting from the utilization of Al flakes as opposed to rounded particles.

      PubDate: 2017-12-13T08:00:47Z
       
  • Healing Mechanisms Induced by Synergy of Graphene-CNTs and Microwave
           Focusing Effect for the Thermoplastic Polyurethane Composites
    • Abstract: Publication date: Available online 11 December 2017
      Source:Composites Part A: Applied Science and Manufacturing
      Author(s): Yunbo Luan, Feilong Gao, Yongcun Li, Jinglei Yang, Yinchun Hu, Zhangxin Guo, Zhihua Wang, Aijuan Zhou
      Healing is a vital factor of polymer materials. Herein, an investigation on the healing performance of Graphene-CNTs reinforced thermoplastic polyurethane (TPU) composites induced by microwave was carried out. The results show that the graphene sheet and CNTs formed a combined structure of Graphene-CNTs. This Graphene-CNTs may have a synergy effect on the coupling between microwave and Graphene-CNTs on the interface, and promote the fully healing of damaged composites. The tensile strength of the healed composites even exceeds the value of the virgin specimens. Simultaneously, there is a microwave focusing effect within the region of crack, and on the surfaces of graphene or CNTs that exposed on the fracture surfaces. This effect will also promote the healing of damaged composites, and can realize the preferential healing of crack as compared with the non-damaged regions. These results may help us to get a deeper understanding of healing mechanisms of some thermoplastic composites.

      PubDate: 2017-12-13T08:00:47Z
       
  • Tailoring Viscoelastic Response, Self-heating and Deicing Properties of
           Carbon-Fibre Reinforced Epoxy Composites by Graphene Modification
    • Abstract: Publication date: Available online 8 December 2017
      Source:Composites Part A: Applied Science and Manufacturing
      Author(s): Jamal Seyyed Monfared Zanjani, Burcu Saner Okan, Panagiotis-Nektarios Pappas, Costas Galiotis, Yusuf Ziya Menceloglu, Mehmet Yildiz
      Vacuum infusion process was employed for the fabrication of carbon fiber reinforced polymeric composites modified by graphene. Three different methods were utilized for the incorporation of graphene into the CFRP composites. In the first and second approaches, graphene were respectively electrosprayed on the surface of carbon fibers as interface modifiers and dispersed into the epoxy resin to improve the matrix properties. The third method includes the concurrent usage of both treatments just mentioned above. The viscoelastic behavior of composites was examined by dynamical mechanical testing at different temperatures, frequencies and graphene integration configurations. In addition, the effect of graphene on the electrical conductivity, thermal diffusivity and electro-thermal performance of composites was also studied in detail. The results indicated that the FRP composites gain multi-functionality while preserving their mechanical integrity for all graphene integration configurations with significant improvements when graphene is used simultaneously as the interface modifier and the matrix reinforcement.

      PubDate: 2017-12-13T08:00:47Z
       
  • THE electric field alignment of short carbon fibres to enhance the
           toughness of epoxy composites
    • Abstract: Publication date: Available online 7 December 2017
      Source:Composites Part A: Applied Science and Manufacturing
      Author(s): Anil R. Ravindran, Raj B. Ladani, Shuying Wu, Anthony J. Kinloch, Chun H. Wang, Adrian P. Mouritz
      An investigation is presented on increasing the fracture toughness of epoxy/short carbon fibre (SCF) composites by alignment of SCFs using an externally applied alternating current (AC) electric field. Firstly, the effects of SCF length, SCF content and AC electric field strength on the rotation of the SCFs suspended in liquid (i.e. uncured) epoxy resin are investigated. Secondly, it is shown the mode I fracture toughness of the cured epoxy composites increases with the weight fraction of SCFs up to a limiting value (5 wt.%). Thirdly, the toughening effect is greater when the SCFs are aligned in the composite normal to the direction of crack growth. The SCFs increases the fracture toughness by inducing multiple intrinsic and extrinsic toughening mechanisms, which are identified. Based on the identified toughening mechanisms, an analytical model is proposed to predict the enhancement to the fracture toughness due to AC electric field alignment of the SCFs.

      PubDate: 2017-12-13T08:00:47Z
       
  • High thermal conductivity and stretchability of layer-by-layer assembled
           silicone rubber/graphene nanosheets multilayered films
    • Abstract: Publication date: February 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 105
      Author(s): Jianan Song, Caibao Chen, Yong Zhang
      Thermally conductive silicone rubber composites used for heat removal from electronic devices have attracted great attention. A facile spin-assisted layer-by-layer assembly approach was used to fabricate highly thermally conductive multilayered silicone rubber/graphene films. The films exhibit highly ordered lamellar structure with the high orientation of graphene which provides continuous thermally conductive pathways in horizontal direction. A multilayered film with 40 assembly cycles has the thermal conductivity of 2.03 W/(m·K) in in-plane direction. Moreover, the film can be highly twisted to any angle and has the elongation at break of 325%, which is rarely achieved in previously reported graphene-based multilayered films. Even up to 500 stretch-recovery cycles at 50% strain, the change of the thermal conductivity was negligible, indicating the high durability, excellent flexibility and stretchability of the film. The films with high thermal conductivity and stretchability have potential applications in flexible electronics, wearable devices and electronic skin.

      PubDate: 2017-11-16T10:31:49Z
       
  • Synergistic effects of spray-coated hybrid carbon nanoparticles for
           enhanced electrical and thermal surface conductivity of CFRP laminates
    • Abstract: Publication date: February 2018
      Source:Composites Part A: Applied Science and Manufacturing, Volume 105
      Author(s): Yan Li, Han Zhang, Yi Liu, Huasheng Wang, Zhaohui Huang, Ton Peijs, Emiliano Bilotti
      Carbon fibre reinforced plastics (CFRPs) are intensively used in modern aircraft structures because of their superb specific mechanical properties. Unfortunately their electrical and thermal conductivities are not sufficiently high for some applications like electromagnetic interference (EMI) shielding and lighting strike protection (LSP). The addition of external metallic structures, such as aluminium or copper mesh, is generally required with a compromise in terms of increased mass and manufacturing cost as well as reduced corrosion resistance. In the present work spray coating of carbon nanoparticles was utilized as a simple method to locally increase the electrical and thermal suface conductivity of CFRPs. The combined use of carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) synergistically reduced the CFRPs surface resistivity by four orders of magnitude (from 2–3 Ω/sq to 3 × 10−4 Ω/sq) and increased the thermal conductivity by more than 7 times (from 200 W m−1 K−1 to 1500 W m−1 K−1), opening up possibilities for the replacement of metallic mesh structures for EMI shielding and LSP. An analytical model was introduced based on a one-dimensional heat conduction approach to predict the effective thermal conductivity for the hybrid nanofiller coating layer and its findings showed good agreement with experimental data.

      PubDate: 2017-11-16T10:31:49Z
       
  • Single Fiber Pull-Out Test of Regenerated Cellulose Fibers in
           Polypropylene: An Energetic Evaluation
    • Abstract: Publication date: Available online 7 November 2017
      Source:Composites Part A: Applied Science and Manufacturing
      Author(s): J.-C. Zarges, C. Kaufhold, M. Feldmann, H.-P. Heim
      This paper focuses on the energetic evaluation of the single fiber pull-out test (SFPT) using regenerated cellulose fibers (RCF) in a PP matrix with a varying MAPP content. Glass fibers were used for reference purposes. By means of the SFPT the interfacial shear strength (IFFS), the critical fiber length (lc), the consumed energy of a fiber pull-out and the consumed energy of a fiber rupture were determined. Results were related to the fiber length distribution in injection molded specimens. It was shown that theoretically more fiber ruptures appear in composites with RCF than with GF. But RCF composites offer a larger number of long fibers, slightly underneath the critical fiber length, consuming a high amount of energy by being pulled out at a composite failure. The consumed energy of a fiber pull-out per length was increased by using MAPP but simultaneously the critical fiber length was significantly reduced.

      PubDate: 2017-11-09T08:38:53Z
       
 
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327
 
Home (Search)
Subjects A-Z
Publishers A-Z
Customise
APIs
Your IP address: 54.226.33.117
 
About JournalTOCs
API
Help
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-