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Journal Cover Composites Part A : Applied Science and Manufacturing
  [SJR: 1.599]   [H-I: 113]   [183 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1359-835X
   Published by Elsevier Homepage  [3043 journals]
  • Effects of surface modification on dispersion, mechanical, thermal and
           dynamic mechanical properties of injection molded PLA-hydroxyapatite
           composites
    • Abstract: Publication date: December 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 103
      Author(s): John O. Akindoyo, Mohammad D.H. Beg, Suriati Ghazali, Hans P. Heim, Maik Feldmann
      In this study, poly(lactic acid) (PLA)/hydroxyapatite (HA) composites were produced through extrusion and injection moulding. In order to foster good interaction between PLA and HA, a phosphate based modifier (Fabulase(R) 361) was used to modify the HA surface. Spectroscopic analysis reveals that surface of the HA was effectively modified without changing the HA into another material. Morphological study shows effective dispersion of HA in the PLA matrix after modification, with significant influence on the composite properties. Thermal properties of the modified HA composite was improved, alongside an enhancement of about 25%, 20% and 42% in tensile, modulus and impact properties of the modified PLA-HA composite respectively. Furthermore, dynamic properties of the modified HA composite was notably improved with obvious reduction of the damping factor. Thus, surface modification was effective to enhance dispersion and compatibility of HA and PLA to produce polymeric biomaterials suitable for good load bearing applications.

      PubDate: 2017-10-11T11:24:47Z
       
  • Property improvements of CNT films induced by wet-stretching and
           tension-heating post treatments
    • Abstract: Publication date: December 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 103
      Author(s): Shaokai Wang, Qianli Liu, Min Li, Tianshu Li, Yizhuo Gu, Qingwen Li, Zuoguang Zhang
      Various stretching and heating treatments were conducted on a carbon nanotube (CNT) film, so as to transfer the excellent properties of individual CNTs into a useful material. It shows that the wet-stretching improves the tensile strength and modulus to 2.3 and 5.9 times of the CNT film treated by traditionally dry stretching. Inspired by carbonization process of carbon fiber, tension force was further applied on the CNT film during subsequent heat treatment. Therefore, tensile strength and modulus of the CNT film are dramatically improved to 6.3 and 39.7 times respectively comparing with the as-prepared film. The tensile modulus reaches up to 127.1 GPa, far beyond most reported moduli of nanocarbon-based films and papers. Herein, the higher tensile moduli of the post-treated CNT films the smaller fracture elongation. Moreover, the post-treated CNT film manifests stable piezoresistive behavior with the gauge factor of 13.2, indicating of good sensitivity of the network.

      PubDate: 2017-10-11T11:24:47Z
       
  • Non-covalent functionalization of GO for improved mechanical performances
           of pectin composite films
    • Abstract: Publication date: Available online 7 October 2017
      Source:Composites Part A: Applied Science and Manufacturing
      Author(s): Andreea Madalina Pandele, Corina Andronescu, Eugeniu Vasile, Ionut Cristian Radu, Paul Stanescu, Horia Iovu
      The present work is aimed to develop new composite filmsbased on pectin and functionalized graphene oxide (GOf) by using a simple casting method. The non-covalent functionalization of graphene oxide (GO) was performed by using a non-ionic surfactant (Tergitol NP9) and therefore the interaction between GO and the polymer matrix was significantly enhanced. X-ray diffraction (XRD), X-ray photoelectron spectrometry (XPS) and Fourier-transform infrared (FT-IR) were used to prove the GO functionalization. The functionalization was evidenced also by Raman spectrometry and thermogravimetric analysis (TGA). According to the mechanical tests, an improvement of the Young’s modulus was recorded even at low loading of GOf within the pectin matrix which indicates a strong interaction between the polymer and GOf. By incorporation of GOfwithin pectin a modification of the morphology of the composite materials was observed by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy(SEM) analysis.

      PubDate: 2017-10-11T11:24:47Z
       
  • Electrical, morphological and thermal properties of microinjection molded
           polyamide 6/multi-walled carbon nanotubes nanocomposites
    • Abstract: Publication date: December 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 103
      Author(s): Shengtai Zhou, Andrew N. Hrymak, Musa R. Kamal
      A series of polyamide 6/multi-walled carbon nanotubes (PA6/CNT) nanocomposites were prepared using a masterbatch dilution process, followed by microinjection molding of a part with a three-step decrease in thickness along the flow direction. Morphology observations revealed that there was a preferential orientation of CNT in the flow direction, which is attributed to the prevailing high shear rates in µIM. The distribution of CNT after melt processing was evaluated by dissolving experiments. Additionally, the correlation between electrical resistivity and development of microstructure for each section of the microparts was considered. The thermal behavior of PA6/CNT nanocomposites and corresponding microparts was evaluated using differential scanning calorimetry. Results indicated that the addition of CNT had little effect on the melting behavior of PA6/CNT nanocomposites and corresponding microparts. However, the crystallization behavior was changed significantly and a double crystallization peak was observed for samples incorporating CNT.

      PubDate: 2017-10-03T18:09:13Z
       
  • An effective route for the fabrication of multi-walled carbon
           nanotubes-reinforced ROMP-based nanocomposites by solution casting
           technique
    • Abstract: Publication date: December 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 103
      Author(s): Guang Yang, Jing Yan, Young Gyu Jeong, Jong Keun Lee
      This work reports the solvent-soluble multi-walled carbon nanotubes (MWCNTs), which can be used for the fabrication of ring-opening metathesis polymerization (ROMP)-based nanocomposites by solution casting technique. As the first and most important step of the solution casting technique, the excellent dispersibility of the MWCNTs in different solvents is achieved by the functionalization of the nanotube surface with norbornene oligomers. The norbornene-functionalized MWCNTs (nMWCNTs) have outstanding dispersion stability in water, tetrahydrofuran (THF), acetone, and ethanol, especially the maximum nanotube concentration of 3.9mg/mL in THF. The incorporation of nMWCNTs into poly(5-ethylidene-2-norbornene) (poly(ENB)) by solution casting technique results in significant improvements in the mechanical properties over the neat poly(ENB) and the pristine MWCNT-reinforced poly(ENB) nanocomposites. The route developed here not only avoids the dramatic increase of the viscosity occurring in the bulk polymerization but also provides the feasibility of high loadings of MWCNT reinforcements, consequently broadening the potential applications of ROMP-based nanocomposites.

      PubDate: 2017-09-26T13:09:01Z
       
  • Improving thermal and flame retardant properties of epoxy resin by
           functionalized graphene containing phosphorous, nitrogen and silicon
           elements
    • Abstract: Publication date: December 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 103
      Author(s): Yuezhan Feng, Chengen He, Yingfeng Wen, Yunsheng Ye, Xingping Zhou, Xiaolin Xie, Yiu-Wing Mai
      As alternative flame-retardant additive for polymers, reduced graphene oxide (RGO) is often limited by its poor interfacial compatibility with matrix. In this work, a new flame retardant, containing phosphorous, nitrogen and silicon elements was used to functionalize RGO. The wrapped flame retardant chains induced the improvement in the dispersion and compatibility of RGO in epoxy (EP) matrix. Asa result, the mechanical, thermal and flame retardant properties of EP-based composites were significantly improved by adding flame retardant-functionalized RGO. The peak heat release rate, total heat release and total smoke production reduced by 34%, 14% and 30%, respectively, compared to neat resin. Based the char analyses, the enhancement in flame retardancy is attributed to the outstanding char layers with high strength and thermal stability resulting from the template effect of graphene, the charring effect of phosphorus and nitrogen elements and the enhancing effect of silicon element in grafted flame retardant chains.

      PubDate: 2017-09-26T13:09:01Z
       
  • Automated braiding of a complex aircraft fuselage frame using a
           non-circular braiding model
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Philippe Monnot, Jonathan Lévesque, Louis Laberge Lebel
      Braided structural composites have the potential to replace aerospace primary structure traditionally manufactured with preimpregnated fabrics and cured in autoclave. An improved braiding model was developed and applied to a complex fuselage frame technological demonstrator. Numerical case studies were performed in order to assess their effectiveness and to determine the best braiding parameters. A radial braiding machine was coupled to an industrial robot. The fuselage frame demonstrator mandrel was overbraided with carbon fiber yarns. Measured braid angles showed a greater difference than what was expected between the web and the flange faces. Yarn friction and interlacing forces caused the yarns to curve near the edges of the face, therefore causing the measured braid angles to vary along the face width. Moreover, discrepancies in the model’s outputs prevented the braid fell front to conform around the severe cross-section variations as well as causing yarn slip over the corners.

      PubDate: 2017-09-26T13:09:01Z
       
  • Enhanced tensile properties of Al matrix composites reinforced with
           β-Si3N4 whiskers
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Chenxu Zhang, Jinwei Yin, Dongxu Yao, Kaihui Zuo, Yongfeng Xia, Hanqin Liang, Yuping Zeng
      Al matrix composites reinforced with β-Si3N4 whiskers (β-Si3N4w) were fabricated by hot pressing method. The microstructures showed that the whiskers were uniformly dispersed in the matrix and the Al/β-Si3N4 interface was well bonded without interface reaction. Effects of β-Si3N4w content and sintering parameters on the densification and tensile behavior of composites were investigated. The results indicated that β-Si3N4w could both enhance the ultimate tensile strength (UTS) and maintain the ductility of Al matrix when the whisker content was 5vol%, corresponding to an elongation at break and an UTS of 21.2% and 239MPa, respectively. However, higher whisker content could improve UTS of composites to the maximum value of 312MPa, which was 158MPa higher than pure Al, while reducing elongation of composites. The fracture mechanism changed from ductile fracture to a combination of both ductile and brittle fracture mechanism with the increase of whisker content.

      PubDate: 2017-09-26T13:09:01Z
       
  • Elastomer reinforcement by graphene nanoplatelets and synergistic
           improvements of electrical and mechanical properties of composites by
           hybrid nano fillers of graphene-carbon black & graphene-MWCNT
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Soumya Mondal, Dipak Khastgir
      Present work deals with the reinforcement behaviour of graphene nanoplatelets (GNP) in elastomer matrix of acrylonitrile butadiene (NBR) co-polymer. The addition of 20phr GNP in NBR matrix a significant improvement in tensile strength (∼528%), and elongation at break (∼60%) compared to neat NBR is observed. Hybrid composites of NBR filled with GNP-CB and GNP-MWCNT at judicious proportion exhibit further improvement in the mentioned properties compared to those exhibited by composites containing individual fillers at same loading. This reflects strong synergistic effect on properties by hybrid fillers. Morphological studies reveal the state of dispersion of filler in matrix polymer, and this can be correlated with property improvements. The better synergistic effect of GNP-CB hybrid filler in comparison to GNP-MWCNT for improvement in mechanical and electrical properties as well as thermal stability may be attributed to the better filler dispersion and higher polymer-filler interaction for NBR-GNP-CB hybrid system compared to NBR-GNP-MWCNT system.

      PubDate: 2017-09-26T13:09:01Z
       
  • Creep behaviour of graphite oxide nanoplates embedded glass fiber/epoxy
           composites: Emphasizing the role of temperature and stress
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Sohan Kumar Ghosh, Rajesh Kumar Prusty, Dinesh Kumar Rathore, Bankim Chandra Ray
      Graphene based nano-reinforcements have emerged as promising fillers in polymeric materials. The objective of the present article is to elucidate the reinforcement effect of graphite oxide nanoplates (GONP) on the thermal, flexural and creep performance of glass fiber/epoxy (GE) composites. Thermal analyses by DSC, DMA and TGA showed reduced glass transition temperature of GE composite due to GONP incorporation, whereas no significant impact has been observed on the decomposition temperature. GONP addition has been found to be beneficial on the flexural properties of GE composite. To understand the effect of temperature on long-term mechanical durability, creep tests have been performed at various temperatures (50, 80 and 110°C). Further, elevated temperature creep behaviour has been assessed at various stresses (10, 20 and 40MPa) to comprehend the combined effect of temperature and stress. Improved creep resistance has been observed in GONP modified GE composites at relatively lower temperature and stress.

      PubDate: 2017-09-26T13:09:01Z
       
  • Enhanced thermal conductivity of commercial polystyrene filled with
           core-shell structured BN@PS
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Weifang Han, Yufeng Bai, Shicai Liu, Chunhua Ge, Lixia Wang, Zhiyan Ma, Yuxuan Yang, Xiangdong Zhang
      Polystyrene-wrapped boron nitride/commercial polystyrene (BN@PS/CPS) composites with high thermal conductivity were fabricated by a novel approach. The route included two steps, BN@PS core-shell structured fillers were prepared by using modified BN and styrene (St) as the raw materials via suspension polymerization, and then the BN@PS were kneaded with the CPS by mechanically mixed method. The composite achieves a high thermal conductivity of 0.692W/mK containing 30wt% BN@PS (∼15.9wt% BN), which is 3.72 times higher than that of pure CPS of ∼0.186W/mK and 1.78 times higher than that BN/CPS blend composite with at the same BN loading of 0.332W/mK. Compared with traditional routes, the novel preparation process requires less BN fillers when improving the same thermal conductivity. Importantly, other polymers can also encapsulate BN through this strategy, which paves a new way for preparing thermally conductive polymer-matrix composites.

      PubDate: 2017-09-26T13:09:01Z
       
  • Fabrication of high quality composite laminates by pressurized and
           heated-VARTM
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): M. Akif Yalcinkaya, E. Murat Sozer, M. Cengiz Altan
      Although vacuum-assisted transfer molding (VARTM) is preferred for manufacturing medium to large composite parts due to its simple tooling and low cost, part quality dictated by dimensional tolerances, void content and mechanical properties is usually low due to inherent limitations of the process. In this study, the conventional VARTM process was modified by external pressurization of a heated mold to increase fiber volume fraction and improve mechanical properties of laminates. During post-filling, various levels of external pressure were applied in a pressure chamber mounted on top of the mold. It was observed that pressurized VARTM led to laminates with less than 1% void content. In addition, fiber volume fraction and flexural strength were increased 25% and 13% with respect to non-pressurized VARTM, respectively which demonstrates the potential for manufacturing considerably higher quality composites by pressurized VARTM.

      PubDate: 2017-09-26T13:09:01Z
       
  • Amending the thermo-mechanical response and mechanical properties of epoxy
           composites with silanized chopped carbon fibers
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Subhankar Das, Sudipta Halder, Jialai Wang, M.S. Goyat, A Anil Kumar, Yi Fang
      This study demonstrates the ability of functionalized chopped carbon fibers (CCFs) chosen from industrial waste to improve the thermo-mechanical properties of CCFs/epoxy composites. The defect sites onto the CCFs were created by their oxidation and the oxidized CCFs were covalently linked with siloxane functional groups to conceal their defects. The surface functionalization of CCFs was characterized by a simple chemical route, FTIR and TGA analysis, respectively. The surface morphology of functionalized CCFs showed the generation of highly dense networked globules. Epoxy composites filled with 0.5wt% of siloxane attached CCFs (S-CCFs) showed a tremendous enhancement in storage modulus (∼376%) without sacrificing their thermal stability. Furthermore, the S-CCFs reinforced epoxy composites demonstrate a significant improvement in the tensile and fracture properties. Such enhancement in the mechanical properties can open up the scope for the utilization of CCFs as a potential cost-effective candidate for high-performance next generation structural composites.

      PubDate: 2017-09-26T13:09:01Z
       
  • Enhance interfacial properties of glass fiber/epoxy composites with
           environment-friendly water-based hybrid sizing agent
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Yubing Dong, Yaofeng Zhu, Yongzhen Zhao, Fuyao Liu, Enliang Wang, Yaqin Fu
      The interface improvement of fiber-reinforced composites has remained a vexing problem that limits the use of the excellent properties of fiber in composite applications. In this study, a novel water-based hybrid sizing agent was synthesized by in-situ generated silica within waterborne epoxy/waterborne epoxy curing agent system, which was used asa glass fiber (GF) surface modifier to enhance the interfacial properties of GF/epoxy (EP) composites. The morphology and wetting ability of GF after treated with the hybrid sizing agent, the single-GF tensile strength and the interfacial shear strength (IFSS) of the single-GF/EP composites were investigated. Experimental results showed that the wetting ability of GF and the IFSS of the single-GF/EP composites were significantly improved after being treated by the hybrid sizing agent. This work is aimed at developing an environment-friendly, safe, and effective water-based sizing for substituting the traditional solvent-based sizing.

      PubDate: 2017-09-26T13:09:01Z
       
  • Complete simulation process chain for the manufacturing of braided
           composite parts
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): E.E. Swery, T. Hans, M. Bultez, W. Wijaya, P. Kelly, R. Hinterhölzl, S. Bickerton
      A complete simulation process chain has been used to predict the production and subsequent injection of over-braided textile preforms. A range of mandrel geometries and braiding configurations were used to illustrate how these factors affect the resin injection of the part. Braiding simulations were first completed, predicting the geometry of the braided textile throughout the mandrel. Following this, a range of multi-layered unit-cells were modelled, capturing the variations in geometry. These virtual stacks were produced with both no and maximum in-plane ply shift so as to capture the range of stacking configurations possible. Following a compaction simulation of these stacks, their in-plane permeability tensor was predicted and used to identify the permeability of the braided preform at different regions. This was used to predict the propagation of the resin flow front, highlighting the effects that the mandrel geometry, braiding process parameters and stacking method have on the resulting resin injection.

      PubDate: 2017-09-26T13:09:01Z
       
  • Graphene foam/carbon nanotube/poly(dimethyl siloxane) composites as
           excellent sound absorber
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Ying Wu, Xinying Sun, Wei Wu, Xu Liu, Xiuyi Lin, Xi Shen, Zhenyu Wang, Robert K.Y. Li, Zhiyu Yang, Kin-Tak Lau, Jang-Kyo Kim
      The sound damping capabilities of graphene foam (GF)/carbon nanotube (CNT)/poly(dimethyl siloxane) (PDMS) composites to low-frequency sound waves are studied. To our best knowledge, this work reports for the first time the development of three dimensional graphene-based composites for sound absorption achieving a commercially viable absorption coefficient higher than 0.3 over a wide frequency range of 100–1000Hz. Cellular GF is fabricated by template-directed chemical vapor deposition and the composites are prepared by infiltrating solvent-diluted PDMS with and without multi-walled CNTs (MWCNTs) into the porous structure of GF. The GF/PDMS composites with a porosity of 51.5% and a thickness of 1.6mm are capable of shielding a maximum 70% of the incident sound waves at a low frequency between 100 and 200Hz. This value is much better than the damping performance of commercial sound absorbing materials with much larger thicknesses. The incorporation of MWCNTs into the PDMS matrix allows the frequency band to be expanded to a wider range from 100 to 1000Hz while achieving a uniform absorption of more than 30% of the incident sound waves. The outstanding sound damping capabilities of GF/PDMS and GF/CNT/PDMS composites make them excellent candidates for low-frequency noise shielding in many premises.

      PubDate: 2017-09-26T13:09:01Z
       
  • Significance of combined functional nanoparticles for enhancing
           tribological performance of PEEK reinforced with carbon fibers
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Lihe Guo, Ga Zhang, Daoai Wang, Fuyan Zhao, Tingmei Wang, Qihua Wang
      Tailoring a robust and slippery tribo-film on polymer-metal interface is a potential approach for improving the tribological performance. In this work, hybrid soft-hard nanoparticles were compounded into polyetheretherketone (PEEK) reinforced with carbon fibers. Effects of nanoparticle combinations on tribological performance of the composites and tribo-film’s functionality were explored. It was demonstrated that hybrid oxide nanoparticles, i.e. Bi2O3-SiO2 and CuO-SiO2, accelerated formation speed of tribo-films. The soft nanoparticles, i.e. Bi2O3 and CuO, having low-melting points expedited tribo-sintering of wear products on the interface. Moreover, combination of WS2-SiC nanoparticles resulted in a “slippery” tribo-film withstanding harsh rubbing conditions. Hard species endowed the tribo-film a high load-carrying capability, while the soft ones imparted the tribo-film an easy-to-shear characteristic. Striking stretching and re-orientation of PEEK molecules in tribo-film were identified and corroborated the “slippery” characteristic. It is expected that this work can pave a route for developing new self-lubrication composites under extreme running conditions.
      Graphical abstract image

      PubDate: 2017-09-26T13:09:01Z
       
  • The importance of translaminar fracture toughness for the penetration
           impact behaviour of woven carbon/glass hybrid composites
    • Abstract: Publication date: December 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 103
      Author(s): Yentl Swolfs, Yoran Geboes, Larissa Gorbatikh, Silvestre T. Pinho
      The impact resistance of fibre-reinforced composites is vital in many applications, and can be improved by exploiting synergies in fibre-hybridisation. These effects are however not sufficiently well understood in the literature. Penetration impact tests were hence performed on carbon/glass hybrids, and the results were linked to the flexural behaviour and translaminar fracture toughness. The results revealed large synergetic effects of up to 40% compared to the linear rule-of-mixtures. The results are also the first to reveal that creating a translaminar fracture surface can strongly contribute to the energy absorbed during penetration impact: 56% for an all-carbon fibre composite and 13% for an all-glass fibre composite. These results prove that strategies for maximising the translaminar fracture toughness can also be exploited to maximise the penetration impact resistance of fibre-hybrids. In carbon fibre composites in particular, ply blocking, using larger yarns and introducing micro-cuts should therefore increase the penetration impact resistance.

      PubDate: 2017-09-19T14:32:44Z
       
  • A fast water-induced shape memory polymer based on hydroxyethyl
           cellulose/graphene oxide composites
    • Abstract: Publication date: December 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 103
      Author(s): Yongkang Bai, Xin Chen
      Herein, a fast water responsive shape memory polymer composites based on hydroxyethyl cellulose (HEC) has been fabricated by crosslinking with graphene oxide (GO) and citric acid (CA). The swelling behavior, mechanical properties, micro-topography, thermal stability, as well as water and moisture induced shape memory performance of this composite were all fully investigated to demonstrate its functions. After crosslinking with GO and CA, the composite exhibited excellent mechanical properties with tensile strength over 100MPa, which was nearly 4 times higher than pure HEC. Moreover, the pre-deformed composite was able to fully recover to its original shape in aqueous environment, which not only quickly happened in water (14s), but also occurred in wet air with relative humidity about 70 within only 5min. With such outstanding properties, we envisage that this composite could play a significant role in developing new generations of water responsive sensors, actuators and biomedical devices.
      Graphical abstract image

      PubDate: 2017-09-19T14:32:44Z
       
  • The influence of N-doping types for carbon nanotube reinforced epoxy
           composites: A combined experimental study and molecular dynamics
           simulation
    • Abstract: Publication date: December 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 103
      Author(s): Hana Jung, Hoi Kil Choi, Soyoung Kim, Hun-Su Lee, Yonjig Kim, Jaesang Yu
      In this study, nitrogen doped carbon nanotube reinforced epoxy nanocomposites were characterized through experiments and molecular dynamics (MD) simulation. Carbon nanotubes were functionalized by nitrogen inductively coupled plasma. They were made into a nanocomposite by a solvent-free mixing method. The various characteristics of nanocomposites, including nitrogen doped carbon nanotubes were analyzed by the following experiments: a Raman spectra, an X-ray photoelectron spectroscopy (XPS), quasi-static tensile tests, a scanning electron microscopy (SEM), and a transmission electron microscopy (TEM). In addition, an MD simulation was performed to predict the mechanical properties of nanocomposites and the results were compared to the test measurements. It showed that the effective dispersion of nitrogen doped carbon nanotubes was important to improve the mechanical characteristics of the nanocomposites.

      PubDate: 2017-09-19T14:32:44Z
       
  • New BN-epoxy composites obtained by thermal latent cationic curing with
           enhanced thermal conductivity
    • Abstract: Publication date: December 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 103
      Author(s): Isaac Isarn, Lluís Massagués, Xavier Ramis, Àngels Serra, Francesc Ferrando
      A series of boron nitride (BN) composites, with different BN content, were prepared and characterized by cationic curing of DGEBA/BN formulations. As cationic initiator a commercial benzylanilinium salt was used. This cationic system shows good latent characteristics that were not lost on adding the filler. The performance of the catalytic system was optimized by varying the amount of initiator and adding little proportions of glycerol. The kinetics of the curing process was evaluated by calorimetric measurements. The addition of BN allowed increasing thermal conductivity without loss of mechanical properties like Young modulus, impact resistance, adhesion and other thermal characteristics like Tg or thermal stability. In addition, dielectric properties were improved with the increment of filler.

      PubDate: 2017-09-19T14:32:44Z
       
  • Environmentally assisted crack growth in adhesively bonded composite
           joints
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Jared Tracy, Yikai Yin, Jeffrey Yang, John C. Osborne, Kay Y. Blohowiak, Reinhold Dauskardt
      Adhesively bonding composite components is a reliable alternative to conventional joining processes that minimizes part weight and reduces fabrication costs. Regarding performance and reliability, of particular interest is developing adherend surface treatments that enhance adhesion of the joint interfaces in aggressive chemical environments. Using fracture mechanics-based adhesion metrologies, critical and subcritical crack growth were evaluated for several peel-ply-treated, adhesively bonded composite joints. Fracture toughness, Gc, and corresponding failure modes were evaluated for specimens constructed using two different bonding processes (co-bonding and secondary bonding) and four different peel ply treatments. Environmentally assisted crack growth was evaluated as a function of time in several environments: humid, high temperature humid, and hydraulic fluid immersion. It is shown that humid environments accelerate crack growth rates, da/dt, relative to the strain energy release rate, G. This effect was amplified at elevated temperatures and further amplified in the presence of hydraulic fluid.

      PubDate: 2017-09-19T14:32:44Z
       
  • Simulation-driven mold compensation strategy for composites: Experimental
           validation on a doubly-curved part
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): B. Wucher, Ph. Martiny, F. Lani, T. Pardoen, C. Bailly, D. Dumas
      Thermoset-based composites exhibit irreversible distortions during manufacturing, which are detrimental to the assembly and then to the mechanical integrity. The optimal mold geometry can be determined by numerical simulation such that the produced composite component matches the target design. A simple mold compensation methodology as well as an all-around experimental validation are proposed for a doubly-curved part made of a carbon fiber reinforced composite. Non-compensated and compensated parts are processed in order to quantify the gain obtained by the compensation procedure and to validate the method. The spring-in is reduced by more than 90% and the overall distortions are reduced by about 70%.

      PubDate: 2017-09-02T12:56:54Z
       
  • CFRP manufacturing method using electrodeposition resin molding for
           curvilinear fiber arrangements
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Kazuaki Katagiri, Katsuhiko Sasaki, Shinya Honda, Hikaru Nakashima, Shimpei Yamaguchi, Tomoatsu Ozaki, Hirosuke Sonomura, Atsushi Kakitsuji
      Recently, theoretical and experimental methods were proposed for organizing carbon fibers in straight and curvilinear arrangements to obtain a uniform stress distribution in the design of three-dimensional (3D) carbon fiber reinforced thermosetting plastic (CFRP). In this study, to establish an efficient CFRP manufacturing method and realize the curvilinear arrangement of carbon fibers, we develop an electrodeposition resin molding technique. That is, immersing a noncrimp fabric in the electrodeposition solution and energizing electricity, the fabric is impregnated by the resin; thus, a CFRP with curvilinear carbon fibers can be efficiently produced without autoclaving and vacuum packing. We then confirm the optimal electrodeposition conditions for maximizing the tensile strength of the CFRP, and obtain the 3D shape of the CFRP by keeping the noncrimp fabric in solution along the mold.

      PubDate: 2017-09-02T12:56:54Z
       
  • Influence of surface morphology on processing of C/SiC composites via
           femtosecond laser
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Zhaoyang Zhai, Wenjun Wang, Jie Zhao, Xuesong Mei, Kedian Wang, Fangcheng Wang, Huizhu Yang
      Carbon fiber reinforced silicon carbide (C/SiC) was processed with an 800nm femtosecond laser, and the results were analyzed through theoretical calculations and wave optics simulations. In the ablation experiment, C/SiC morphologies for different parameters such as laser power, defocus distance, and scanning speed were compared. It was found that the roughness prior to processing of the C/SiC surface noticeably affects the ablation effect. Beam waist radius, curvature radius, and electric field intensity of the femtosecond laser were calculated theoretically and the wave optics module was simulated in finite element software. Causes for the different morphologies can be explained directly through the simulation results from the perspective of the electromagnetic field. It was found that the microgroove quality of C/SiC processed subject to the femtosecond laser with high fluence is relatively higher and that the edge oxidation of the processing area can be effectively controlled through argon protection. The comparison between the simulation and the experiment results deepens the understanding of the ablation mechanism, which can provide references for the improvement in processing quality of ceramic matrix composites (CMC) by laser treatment.

      PubDate: 2017-09-02T12:56:54Z
       
  • Nanopolydopamine coupled fluorescent nanozinc oxide reinforced epoxy
           nanocomposites
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Chaobo Liang, Ping Song, Hongbo Gu, Chao Ma, Yongqiang Guo, Hongyuan Zhang, Xiaojiang Xu, Qiuyu Zhang, Junwei Gu
      Fluorescent epoxy nanocomposites reinforced with polydopamine (PDA) functionalized zinc oxide (ZnO) nanoparticles have been obtained. Results reveal that the PDA functionalized ZnO nanoparticles are dispersed uniformly in the epoxy nanocomposites. The enhanced tensile strength of the epoxy nanocomposites filled with PDA functionalized ZnO nanoparticles (up to 106.7MPa) is obtained compared with that of pure epoxy (83.8MPa) and epoxy nanocomposites filled with the same loading pristine ZnO nanoparticles (around 91.5MPa). The glass transition temperature (T g) of the epoxy nanocomposites filled with PDA functionalized ZnO nanoparticles has shifted to a higher temperature (127.0–132.0°C) compared with that of pure epoxy (118.3°C). The interaction between PDA and epoxy matrix is also explored by Fourier transform infrared (FTIR) and contact angle. The introduction of PDA can enhance the mechanical and thermal properties of epoxy nanocomposites without damaging the fluorescent property of ZnO nanoparticles.
      Graphical abstract image

      PubDate: 2017-09-02T12:56:54Z
       
  • Multistep modeling of Young’s modulus in polymer/clay nanocomposites
           assuming the intercalation/exfoliation of clay layers and the interphase
           between polymer matrix and nanoparticles
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Yasser Zare, Kyong Yop Rhee
      In the present paper, a multistep technique for prediction of Young’s modulus in polymer/clay nanocomposites (PCN) is developed considering the intercalation/exfoliation of clay layers and the interphase between polymer matrix and nanoparticles. This methodology is evaluated by the experimental data of various samples. In addition, the effects of several parameters attributed to intercalation/exfoliation of clay layers and interphases on the modulus are examined. The predictions demonstrate good agreement with the experimental data by proper levels of intercalation/exfoliation of clay layers and interphase properties, while the modulus is under-predicted by disregarding of these factors. The findings also indicate that more exfoliation of thinner clay layers and stronger interphase cause a higher modulus in PCN.

      PubDate: 2017-09-02T12:56:54Z
       
  • Measurement method of multi scale thermal deformation inhomogeneity in
           CFRP using in situ FE-SEM observations
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Y. Tanaka, K. Naito, H. Kakisawa
      The measurement of nano scale thermal deformation and strain inhomogeneity in the transverse direction in carbon fiber-reinformed polmer (CFRP) in the temperature range 170–370K has been carried out by in-situ Field Emission Scanning Electron Microscopy (FE-SEM) observation using a heating and cooling stage in the FE-SEM chamber. A grid pattern and also random patterns were drawn on the polished sample surface at different length scales. The electron moiré method was applied to measure the macroscopic deformation and the digital imaging correlation method was applied to measure the nano-scale deformation around the fiber/matrix interface. The strain inhomogeneity of the pitch-based carbon fiber in the transverse direction and the debonding at the interface between fiber and matrix has been evaluated quantitatively.

      PubDate: 2017-09-02T12:56:54Z
       
  • A clustering method for analysis of morphology of short natural fibers in
           composites based on X-ray microtomography
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Anna Madra, Jérôme Adrien, Piotr Breitkopf, Eric Maire, François Trochu
      The work presented here concerns the methodology for the analysis of X-ray micro-CT scans of composite materials with a discontinuous phase. An automatized method has been devised for the measurement of geometric features and identification of distinct morphological types. This approach offers new insights into the composition of a microstructure based on the analysis of phase morphology and its relative volume percentage. It stays in contrast to the frequency-based approach that attributes the same importance to all elements of the structure, and is thus biased towards numerous, but not necessarily essential components of the material. The method is general and can be applied to any type of discontinuous, dispersed phase in composites identified with X-ray micro-tomography. We have verified our approach for short natural fibers but it may be of interest for characterizing void distribution in RTM manufactured composites or cracks after failure.

      PubDate: 2017-09-02T12:56:54Z
       
  • Understanding and predicting defect formation in automated fibre placement
           pre-preg laminates
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Jonathan P.-H. Belnoue, Tassos Mesogitis, Oliver J. Nixon-Pearson, James Kratz, Dmitry S. Ivanov, Ivana K. Partridge, Kevin D. Potter, Stephen R. Hallett
      Fibre path defects are detrimental to the structural integrity of composite components and need to be minimised through process optimization. This requires understanding of the uncured pre-preg material, which is influenced by multiple process parameters, and sophisticated multi-scale modelling tools. Even though the capabilities of process modelling techniques have been improved over the past decades, the occurrence of localised wrinkles remains challenging to predict. One of the processes known to influence the formation of fibre path defects is the consolidation of laminates manufactured by automated fibre placement. The particular focus of this paper is to understand how out-of-plane wrinkles form during debulking and autoclave curing of laminates with embedded gaps and overlaps between the deposited tapes. Predictions are made using a novel modelling framework and validated against micro-scale geometry characterisation of artificially manufactured samples. The paper demonstrates the model’s ability to predict consolidation defects for the latest generation of toughened pre-pregs.

      PubDate: 2017-09-02T12:56:54Z
       
  • The Tsai-Wu failure criterion rationalised in the context of UD composites
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Shuguang Li, Elena Sitnikova, Yuning Liang, Abdul-Salam Kaddour
      This paper is to rationalise the empirical aspect of the Tsai-Wu failure criterion in the context of UD composites associated with the determination of the interactive strength property F 12 based on the analytic geometry. It reveals that the condition of closed failure envelope cannot be satisfied by all UD composites and hence the restriction should be abandoned. Depending on the way the failure envelope opens, UD composites can be classified into two categories. (a) F 12 can be determined uniquely using the conventional strength properties with an additional assumption that the material exhibits very high or infinite strength under triaxial compression at a specific stress ratio; or (b) The Tsai-Wu criterion leads to one of the two scenarios: either allowing infinite strength for an in-plane stress state or allowing infinite strength under triaxial stresses involving tension along fibres.

      PubDate: 2017-09-02T12:56:54Z
       
  • Enhancing thermal conductivity and mechanical properties of poly(methyl
           methacrylate) via adding expanded graphite and injecting water
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Min Wu, Han-Xiong Huang, Jun Tong, Dong-Ying Ke
      Poly(methyl methacrylate)/expanded graphite (PMMA/EG) composites are prepared using water-assisted mixing extrusion (WAME) technique. Scanning and transmission electron microscopy micrographs show that the EG exhibits better exfoliation and dispersion in the composite samples prepared with water injection than that in those without water injection. More EG layer networks and stronger PMMA-EG interfacial interaction are formed in the composite samples prepared with water injection, which are confirmed by the results of the FTIR and rheological measurements and the linear fits of experimentally obtained tensile yield stresses. The composite samples with well exfoliated and dispersed EG layers exhibit higher thermal conductivity and mechanical properties, which are ascribed to lower interfacial thermal resistance and stronger interfacial interaction, respectively. Finally, a mechanism for promoted EG exfoliation and dispersion in the PMMA matrix during the WAME is interpreted by analyzing the combined effect of injected high-pressure water with the shear force provided by the extruder screw.

      PubDate: 2017-09-02T12:56:54Z
       
  • Enhanced mechanical and thermal properties of SBR composites by
           introducing graphene oxide nanosheets decorated with silica particles
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Zijin Liu, Yong Zhang
      Synergistic enhancement of fillers in the polymer matrix has emerged as a subject of scientific and industrial interest. A hybrid with the silica decorating on GO surface (SiO2@GO) was fabricated by an electrostatic self-assembly method, and its morphology, structure and composition were characterized. GO, silica, silica/GO mixture (SiO2-GO), and SiO2@GO were separately filled in styrene-butadiene rubber (SBR) to obtain composites. SBR/SiO2@GO (100/20) composite exhibited the best performance, and its tensile strength increased by 308% compared with that of SBR. This is due to SiO2@GO was uniformly embedded in the SBR matrix brought by the synergistic dispersion of silica and GO. SiO2@GO acted as the barrier in SBR composites, and increased the temperature at 50% weight loss for SBR/SiO2@GO (100/20) by 13.1°C compared to SBR. Anchoring silica on GO surface is an effective way to develop various high-performance rubber composite materials with good potential in industrial applications.

      PubDate: 2017-09-02T12:56:54Z
       
  • Carbon nanotubes coated hybrid-fabric composites with enhanced mechanical
           and thermal properties for tribological applications
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Junya Yuan, Zhaozhu Zhang, Mingming Yang, Fang Guo, Xuehu Men, Weimin Liu
      Poor interfacial adhesion and inferior thermal property of resin matrix severely obstruct the continued development of fabric-reinforced polymer composites for potential advanced tribological applications. Herein, carbon nanotubes (CNTs) encapsulated by copolymer of polydopamine (PDA) and polyethylenimine (PEI) directly deposited onto hybrid Nomex/PTFE fabric leading to a hierarchical reinforcing structure was successfully carried out via a facile one-pot synthesis. The achieved organic-inorganic hybrid functional coating significantly increased the wettability, reactive functional groups and surface roughness of hybrid-fabric. Tensile and peeling tests show that the hierarchical composites exhibited 38.4% and 63% enhancement in tensile strength and interfacial bonding strength compared to that of the pristine fabric composites. Furthermore, CNTs modification forming percolating networks on hybrid-fabric within the resin matrix effectively promotes the thermal stability of the fabric composites. Results of wear tests prove that the hierarchical composites exhibited outstanding tribological properties under varied applied loads.

      PubDate: 2017-09-02T12:56:54Z
       
  • Preparation and performance of bio-based carboxylic elastomer/halloysite
           nanotubes nanocomposites with strong interfacial interaction
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Xinxin Zhou, Qinan Zhang, Runguo Wang, Baochun Guo, Yuri Lvov, Guo-Hua Hu, Liqun Zhang
      Poly(dibutyl itaconate-co-isoprene-co-methacrylic acid) (PDIM)/halloysite nanotubes (HNTs) nanocomposites with strong interfacial interaction were prepared by co-coagulation of PDIM latex and HNTs aqueous suspension, followed by mechanical kneading with rubber additives. The interfacial interaction, thermal properties, morphology, and mechanical properties of the nanocomposites were investigated. The hydrogen bonds were confirmed in the nanocomposites. Morphology investigation showed uniform and individual dispersion of HNTs in the PDIM matrix. With the incorporation of HNTs into the PDIM matrix, the tensile strength and the fracture energy were significantly improved without sacrificing the extensibility. The improved mechanical properties were correlated to the co-coagulation and the strong hydrogen bonds. Especially, the morphology investigation of tensile fracture surfaces revealed a mechanism for the improved mechanical performance, in which the stress was efficiently transferred from PDIM to HNTs via hydrogen bonds and then the dissociation of the hydrogen bonds dissipated energy to increase the fracture energy of the nanocomposites.

      PubDate: 2017-09-02T12:56:54Z
       
  • Experimental study of the effects of graphene oxide on microstructure and
           properties of cement paste composite
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Haibin Yang, Manuel Monasterio, Hongzhi Cui, Ningxu Han
      Graphene oxide (GO) has been utilized to strengthen composite materials. In this study, the effects of GO on hydration degrees, macro-mechanical strength and calcium-silicate-hydrate (C-S-H) structure of cement based composites were investigated through comprehensive experimental tests. In addition, the aggregation mechanism of GO was verified by alkaline solution simulations, using Ca(OH)2 and NH3·H2O. Based on the experimental results, it was found that the 3-day and 7-day compressive strengths of cement based composites with 0.2wt% of GO were increased by 35.7% and 42.3%, respectively as compared to the control. Moreover, the C-S-H structure of cement paste with GO was not observed to have undergone any change via qualitative and quantitative analyses combined with FT-IR, XRD and 29Si-NMR. Besides, the test results of TGA, DTG and 29Si-NMR showed that the hydrated degree of cement paste increased to 10.4% at 28days when incorporating with 0.1% of GO.

      PubDate: 2017-09-02T12:56:54Z
       
  • A critical review on research progress of graphene/cement based composites
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Haibin Yang, Hongzhi Cui, Waiching Tang, Zongjin Li, Ningxu Han, Feng Xing
      Cement based composite materials (CBCM) with superior mechanical strength and excellent durability are always desirable in practical applications. Although considerable research has been reported in the past decades about the use of Nano materials (NMs) for strength and durability enhancement of cement matrix, there is little information available on the use of graphene nano-sheets and their derivatives (GND) in cement-based materials. Particularly the role of GND in hydration processes and their mechanisms of strengthening in cement matrix are unclear. In this paper, a critical review on recent research findings about GND modified cement-based materials was conducted. The review mainly discussed the influence of GND on properties of cement matrix including microstructure, hydration, mechanical properties, etc. The information revealed in this paper would not only provide a comprehensive understanding of the effect of GND on cement composites, but also provide valuable ideas and guidance for similar studies in the future.

      PubDate: 2017-09-02T12:56:54Z
       
  • Highly aligned graphene oxide/poly(vinyl alcohol) nanocomposite fibers
           with high-strength, antiultraviolet and antibacterial properties
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Xinjun Hu, Nan Ren, Yuanzhi Chao, Huilin Lan, Xiaojie Yan, Yan Sha, Xiaolin Sha, Yongxiao Bai
      Demands for the strong and multifunctional fiber has substantially increased in textile industry, biomedical, and biotechnological applications. This study explores to fabricate nanocomposite functional fibers by embedding highly oriented graphene oxide (GO) into the poly (vinyl alcohol) (PVA) matrix. The GO/PVA nanocomposite fibers were prepared via gel spinning and subsequent hot drawing process. The tensile strength of the produced GO/PVA nanocomposite fibers was significantly enhanced owing to the uniformly dispersed and oriented GO nanosheets. Additionally, the ultraviolet protection factor of the highly aligned GO/PVA nanocomposite fibers is about 16 times than that of the neat PVA fiber. The as-prepared GO/PVA nanocomposite fibers also exhibit significant activity against both Gram-negative and Gram-positive bacteria. This highly aligned and integrated approach suggests an effective method to prepare graphene-based nanocomposites fibers with high performances and novel functional characteristics.

      PubDate: 2017-09-02T12:56:54Z
       
  • The effect of multi-wall carbon nanotube morphology on electrical and
           mechanical properties of polyurethane nanocomposites
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Jatin Sethi, Essi Sarlin, Seyyed Shayan Meysami, Reija Suihkonen, Arunjunai Raja Shankar Santha Kumar, Mari Honkanen, Pasi Keinänen, Nicole Grobert, Jyrki Vuorinen
      In this study, we examine the effect of multi-wall carbon nanotubes (MWCNT) morphology on electrical and mechanical properties of MWCNT-filled polyurethane (PU) nanocomposites. The main objective of this study is to understand the role of aspect ratio and length of MWCNTs in determining the performance of nanocomposites. Highly aligned MWCNTs were prepared by aerosol-assisted chemical vapour deposition method and compared to commercially available MWCNTs in PU matrix for ease of dispersibility and performance. We observed opposing influence of the MWCNT on electrical and mechanical behaviour of the nanocomposites. The electrical properties were proportional to length of the MWCNTs whereas the mechanical properties were dependent on the aspect ratio of the MWCNTs. Moreover, thicker nanotubes (approximately 40nm) with a higher aspect ratio (approximately 225) are less prone to shortening and impart better tensile and storage modulus along with improved electrical and therefore are more suitable for the MWCNT nanocomposites.
      Graphical abstract image

      PubDate: 2017-09-02T12:56:54Z
       
  • Layer-by-layer assembly of layered double hydroxide/rubber multilayer
           films with excellent gas barrier property
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Lumei Wang, Yibo Dou, Jiajie Wang, Jingbin Han, Li Liu, Min Wei
      Rubber nanocomposites with high gas barrier property have extensive application prospects in sealing and packing industry, while developing a novel and cost-effective rubber-based material with low gas permeability and good mechanical property still remains a challenge. Herein, we designed and fabricated an excellent gas barrier film by using polyvinyl pyrrolidone modified ultrathin layered double hydroxide nanoplatelets (U-mLDH) and nitrile butadiene rubber (NBR) as building blocks. The resultant (U-mLDH/NBR)30 film displays significantly decreased (reduced by 92.2% compared with NBR film) oxygen transmission rate with 0.626cm3 m–2 day–1 atm–1, and much lower relative permeability in comparison with reported rubber composites. The improved gas barrier performance is ascribed to the prolonged passage of oxygen molecules and the decreased free space arising from large aspect ratio of U-mLDH and good interfacial compatibility. In addition, the (U-mLDH/NBR)30 film also possesses high thermal stability and satisfactory mechanical property, which would guarantee its practical applications.

      PubDate: 2017-09-02T12:56:54Z
       
  • A macroscopic approach to simulate the forming behaviour of stitched
           unidirectional non-crimp fabrics (UD-NCF)
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): F.J. Schirmaier, D. Dörr, F. Henning, L. Kärger
      Thin composite shell structures manufactured from stitched unidirectional non-crimp fabrics (UD-NCF) in a liquid composite moulding process provide high lightweight design capabilities. For complex geometries, the forming process of the textile pre-products is challenging and requires intensive investigations to avoid defects like macroscopic wrinkling or fibre gapping. In contrast to biaxial engineering fabrics, UD-NCF has been investigated only sparsely in terms of its forming behaviour, both experimentally and numerically. To close this gap, a macroscopic forming simulation model for UD-NCF is proposed in this work, including a new non-orthogonal and linear strain measure for large strains and the corresponding nominal stress measure. To parameterize the constitutive laws and to investigate the multiaxial deformation behaviour of UD-NCF, supplementary off-axis-tension tests with optical strain measurement are performed in this work. The new forming simulation model is validated via forming simulation of a hemisphere test and of a preforming process of an automotive component.

      PubDate: 2017-09-02T12:56:54Z
       
  • Enhanced thermal conductivity of free-standing 3D hierarchical carbon
           nanotube-graphene hybrid paper
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Huifen Lu, Jun Zhang, Jie Luo, Wenbin Gong, Chaowei Li, Qiulong Li, Kai Zhang, Ming Hu, Yagang Yao
      Light-weight materials with superior thermal and electrical transport properties have received much attention for effective thermal management. In this study, we develop a three-dimensional (3D) hybrid hierarchical structure with carbon nanotube (CNT) intercalated graphene sheets by thermal annealing of carbon nanotube/graphene oxide (CNT/GO) films. In this full-carbon architecture, CNTs are employed to bridge adjacent graphene sheets to facilitate the phonon propagation and prevent the corrugation of graphene layers during thermal treatment. The as-obtained carbon nanotube/graphene (CNT/G) film with 15wt% CNTs content exhibits ultrahigh in-plane thermal conductivity of 1388.7W/mK and favorable electric conductivity of 1.7×105 S/m. The mechanisms of the enhanced thermal conductivities of the hybrid films are then analyzed by theoretical simulation. These films could be useful in thermal management for next generation commercial portable electronics.

      PubDate: 2017-08-03T05:01:42Z
       
  • Polyimide-based lubricating coatings synergistically enhanced by MoS2@HCNF
           hybrid
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Hong Yuan, Shengrong Yang, Xiaohong Liu, Zhaofeng Wang, Limin Ma, Kaiming Hou, Zhigang Yang, Jinqing Wang
      In this work, we report a facile and efficient approach to overcome the poor dispersion of MoS2 nanoflowers in polyimide (PI) by carefully grafting them onto the surface of hollow carbon nanofibers (HCNF). The obtained MoS2@HCNF hybrid was then utilized as homogeneous filler to enhance the tensile strength and lubricity of the PI-based protective coating. The results revealed that the tensile strength can be effectively improved by 46% accompanying with a slight decrease in elongation (19%) after the incorporation of 2.0wt% MoS2@HCNF. Furthermore, the MoS2@HCNF/PI composite coatings also manifested outstanding anti-wear and friction reduction characteristics under the lubrication conditions of water (0.5wt%, 72.5% reduction in wear rate) and liquid paraffin oil (1.5wt%, 56% reduction in wear rate), demonstrating that the formed stable MoS2@HCNF hybrid could collaboratively alleviate the wear caused by the friction shear force in PI matrix through water or oil medium. The outstandingly enhanced behaviors of MoS2@HCNF hybrid suggest its potential application as the novel filler in anti-wear composite coatings.

      PubDate: 2017-08-03T05:01:42Z
       
  • Quantitative analysis by micro-CT of damage during tensile test in a woven
           hemp/epoxy composite after water ageing
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Amélie Perrier, Fabienne Touchard, Laurence Chocinski-Arnault, David Mellier
      The influence of water ageing on the evolution of damage during tensile loading in woven hemp/epoxy composites is studied. First, the water uptakes of several types of samples are compared. Micro-CT observations show that, from the beginning of desorption but not during the water ageing, damage appears in the composites. At macroscopic scale, tensile tests reveal a significant modification of mechanical properties of the composite after water ageing. Then, an original test, combining tensile loading and X-ray microtomography, is performed on a ±45 hemp/epoxy composite material. The volume of damage inside two specimens (with and without water ageing) at several steps during a tensile test can be quantified. Results highlight significant differences in the evolution of the volume of damage between the two samples. This work shows how the mechanisms of deformation and damage of plant fibre composites are governed by their moisture exposure history.

      PubDate: 2017-08-03T05:01:42Z
       
  • A novel fabrication method and mechanical behavior of all-composite
           tetrahedral truss core sandwich panel
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Jie Mei, Jiayi Liu, Jialin Liu
      A novel hot-press molding method was developed to manufacture all-composite sandwich panel with tetrahedral truss cores in this paper. The out-of-plane compressive and in-plane shear behaviors of this structure were investigated by experiments. The results have shown that the tetrahedral truss core sandwich panel had a high compressive specific strength compared to metallic truss core sandwich panels. The node failure was observed in the experimental process. Finite element analysis (FEA) with a progressive failure model was involved to simulate the damage evolution process and predict the mechanical properties. The analytical formulae were also presented to predict the stiffness and strength of sandwich panel. Good agreement was found between FEA calculated results and the experimental results. It is expected that this study can provide useful information for the fabrication and application of all-composite tetrahedral truss core sandwich panel.

      PubDate: 2017-08-03T05:01:42Z
       
  • Thermo-gravimetric analysis method to determine the fiber volume fraction
           for PAN-based CFRP considering oxidation of carbon fiber and matrix
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): YunHo Kim, Chunghyeon Choi, Sarath Kumar Sathish Kumar, Chun-Gon Kim, Sun-Won Kim, Jae Hyuk Lim
      The properties of fiber reinforced composites are mainly determined by the fraction of reinforcement and matrix. Thus, to design a system based on composite materials, it is vital to carefully measure the volume fractions of the composites with a proper method. Digestion by strong acid or ignition at high temperature in an oxidizing environment are conventional for measuring content fractions. In essence, these methods assume that the reinforcement does not lose weight by digestion or ignition. However, by neglecting reported vulnerable oxidization characteristics of carbon fiber, these conventional methods result in inaccurate fiber volume fractions of carbon fiber/epoxy composites. In this study, an effective and accurate method, having only 2 steps in measuring process and 1.5%p maximum error, for determining the fiber volume fractions of two different PAN (Polyacylonitrile)-based carbon fiber reinforced composites via thermo-gravimetric analysis was developed and subsequently verified using the results from 80 microscopic images.

      PubDate: 2017-08-03T05:01:42Z
       
  • Experimental investigation of randomly-oriented tow-based discontinuous
           composites and their equivalent laminates
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Yizhuo Li, Soraia Pimenta, Jordan Singgih, Stefan Nothdurfter, Karsten Schuffenhauer
      The equivalent laminate assumption is a commonly-used method to model the random architecture of discontinuous composites, but which has never been validated experimentally. This study aims to verify the equivalent laminate assumption, focusing on tow-based discontinuous composites (TBDCs), which have higher fibre-content and thus improved modulus and strength, compared to conventional discontinuous-fibre composites. This verification was achieved by manufacturing and testing (i) actual TBDCs with randomly oriented tows and (ii) their equivalent laminates (ELs), at two different tow thicknesses. The results show that ELs exhibit the same failure mechanisms as TBDCs, and are similarly weakened by an increase in tow thickness. However, ELs lack the spatial variability in local fibre-content and local tow orientations, which makes ELs stronger than TBDCs. Therefore, the equivalent laminate assumption is suitable for predicting the modulus of discontinuous composites, but cannot predict their strength without considering the local variability in their microstructure.

      PubDate: 2017-08-03T05:01:42Z
       
  • A simple chemical approach to regenerating the strength of thermally
           damaged glass fibre
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): S.T. Bashir, L. Yang, R. Anderson, P.L. Tang, J.J. Liggat, J.L. Thomason
      Process-induced strength loss is a major technical barrier to the effective reuse of thermally recycled glass fibres in composite applications. We have developed a novel approach to effectively restore strength in glass fibres through treatment in alkaline solutions. Glass fibres were treated at elevated temperature and experienced significant strength loss found typically after thermal recycling processes. Different alkaline treatments were then applied to the thermally damaged fibres in an attempt to restore strength which had been lost as a result of the heat conditioning procedure. Results indicated that these treatments were able to generate considerable fibre strength recovery. The degree of strength regeneration was found to be highly dependent on reaction conditions, which were investigated and optimised. The positive effect of these simple chemical treatments demonstrated great potential for facilitating the reuse of thermally recycled glass fibres in composite applications.

      PubDate: 2017-08-03T05:01:42Z
       
  • Spatial Confining Forced Network Assembly for preparation of
           high-performance conductive polymeric composites
    • Abstract: Publication date: November 2017
      Source:Composites Part A: Applied Science and Manufacturing, Volume 102
      Author(s): Daming Wu, Xiaolong Gao, Jingyao Sun, Dan Wu, Ying Liu, S. Kormakov, Xiuting Zheng, Lili Wu, Yao Huang, Zhanhu Guo
      Constructing a network of conductive fillers in polymeric matrix is essential for the preparation of conductive polymer composites. Although the conductivity of the composites could increase remarkably after the percolation threshold, it is still much lower than expected due to a limited self-assembly interaction between filler particles. In this paper, high-performance conductive polymer composites were prepared by the method of Spatial Confining Forced Network Assembly (SCFNA). The compound of homogenous polymer and conductive fillers, prepared by conical twin-screw mixer, was placed in a compression mold with confining space to carry out two-stage compression, free compression and spatial confining compression. The electrical conductivity of the SCFNA prepared polypropylene/short carbon fibers was increased up to 4 orders of magnitude higher than that of by ordinary compounding technology.

      PubDate: 2017-08-03T05:01:42Z
       
 
 
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