Journal Cover
Composites Science and Technology
Journal Prestige (SJR): 1.702
Citation Impact (citeScore): 6
Number of Followers: 201  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0266-3538
Published by Elsevier Homepage  [3162 journals]
  • Time-concentration superpositioning principle accounting for the size
           effects of reinforcement and dissipation of polymer nanocomposites
    • Abstract: Publication date: 10 November 2018Source: Composites Science and Technology, Volume 168Author(s): Yihu Song, Qiang Zheng Understanding the linear rheology of polymer nanocomposites has great importance in designing and processing of soft materials. Herein linear rheological responses of silica/poly(2-vinylpyridine) and carbon black/polystyrene nanocomposites in wide ranges of filler volume fraction and polymer molecular weight are shown to be generalized and captured in a simple, unique time-concentration superpositioning principle, providing a potentially universal mean for rationalizing the apparent liquid-to-solid transition and an important guidance for understanding the role of dynamics of the non-Newtonian dispersing medium.
       
  • Synergetic enhancement on flame retardancy by melamine phosphate modified
           lignin in rice husk ash filled P34HB biocomposites
    • Abstract: Publication date: 10 November 2018Source: Composites Science and Technology, Volume 168Author(s): Wei Wu, Haibing He, Tao Liu, Ruichao Wei, Xianwu Cao, Qijun Sun, Shishir Venkatesh, Richard K.K. Yuen, Vellaisamy A.L. Roy, Robert K.Y. Li Lignin can be employed as a sustainable functional additive and reinforcement filler for polymers. In this work, melamine phosphate modified lignin (MAP-lignin) was synthesized as a bio-based halogen-free flame-retardant agent. The synergetic effects between MAP-lignin and rice husk ash (RHA) on the thermal stability, dynamic mechanical performance and flame-retardant properties of the poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) biocomposites were investigated. The results revealed that MAP-lignin and RHA could significantly increase the char residue and MAP-lignin had a good miscibility with P34HB. The incorporation of MAP-lignin and RHA as stiff fillers could enhance the storage modulus of the P34HB matrix. Moreover, the tensile strength and elongation at break of the P34HB/RHA composite could be improved due to the MAP-lignin could serve as a compatibilizer to improve the interaction between RHA and P34HB. Cone calorimetry data demonstrated that the addition of 30 wt% MAP-lignin and 5 wt% RHA reduced the peak heat release rate (PHRR) and total heat release (THR) of P34HB noticeably by 42.8 and 24.3%, respectively. In addition, the CO2 production rate and CO concentration could be significantly suppressed by the addition of MAP-lignin. The enhanced flame retardancy of P34HB composite should be ascribed to the barrier effect of the increased char residue with compact and intact structure, as well as the released gases from the decomposition of melamine.Graphical abstractImage 1
       
  • Self-healing thermoplastic polyurethane (TPU)/polycaprolactone (PCL)
           /multi-wall carbon nanotubes (MWCNTs) blend as shape-memory composites
    • Abstract: Publication date: Available online 10 October 2018Source: Composites Science and TechnologyAuthor(s): Xiaohui Xu, Peidong Fan, Jia Ren, Yu Cheng, Junkai Ren, Jun Zhao, Rui Song Polymer blends with self-healing capability when damaged have received increasing interests and have been developing rapidly because of their many potential applications. Here, the polymer blend comprising of thermoplastic polyurethane (TPU) and polycaprolactone (PCL) as shape memory matrix was initially prepared by melting blending, and then the multiwalled carbon nanotubes (MWCNTs) were incorporated to endow the blend with excellent self-healing property in the presence of near infrared (NIR) irradiation (808 nm, 0.14 W). Compared with the traditional heat-induced self-healing shape memory composites, NIR irradiation could not only reduce the healing time, but also can selectively repair the exposed damaged regions without distinct interference to the performance of surrounding parts. As revealed, these composites presented superior shape memory and self-healing behavior in the presence of NIR irradiation. Specifically, the blend containing 50% TPU, 50% PCL and 3 MWCNTs (U1C1-3) possesses shape memory properties as manifested by a ca. 96.8% shape fixing ratio (Rf) and ca. 63.9% shape recovery ratio (Rr). The surface crack and scratches can be completely recovered in 3 min NIR irradiation. And moreover, this NIR stimulated self-healing could performed repeatedly for at least 4 times, with healing efficiency of ca. 96%. All these observations could be attributed to the hybrid crystalline and amorphous regions of PCL and TPU, as well as the well distribution of MWCNTs in the polymeric matrix. The superior shape memory and self-healing properties, along with the easy and scalable process of fabrication, make these blends ideal candidates for an ensemble of applications, including biomedical, packing and microelectronics.
       
  • Characterization of injection-molded high-strength/high-stiffness
           thermoplastic hybrid materials containing thermotropic liquid crystal
           polymer (LCP), polyphenylene sulfide (PPS) with carbon fibers
    • Abstract: Publication date: Available online 9 October 2018Source: Composites Science and TechnologyAuthor(s): Myung Hyun Kim, Sung Han Kim, Byung Sun Kim, Jung-Wook Wee, Byoung-Ho Choi In this study, thermotropic liquid crystal polymer (LCP)-based hybrid materials with various carbon fiber (CF) and polyphenylene sulfide (PPS) contents were developed to replace the heavy metal brackets used for liquid crystal displays (LCDs) in thin, light mobile devices. To determine the physical properties of the composite, several characterization methods, including mechanical, thermal, and morphological tests, were used. As the CF content increases, the tensile and flexural moduli also increase because of the high modulus values of CF. However, some strength-related properties, such as the tensile, flexural, and impact strength, decrease because of the lack of interfacial compatibility between the CF and matrix polymers. Additionally, as the thickness of the LCP-based hybrid material decreases, the flexural strength and flexural modulus increase because of the highly oriented characteristics of LCPs at the surface. To improve the interfacial strength between the CF and LCP, epoxy is a good compatibilizer. In addition, PPS can be used to reduce the weld line formation of LCP and improve the processability of LCP-based hybrid materials with high CF contents.
       
  • Programming dynamic imine bond into elastomer/graphene composite toward
           mechanically strong, malleable, and multi-stimuli responsive vitrimer
    • Abstract: Publication date: Available online 6 October 2018Source: Composites Science and TechnologyAuthor(s): Yingjun Liu, Zhenghai Tang, Yi Chen, Siwu Wu, Baochun Guo A combination of malleability, supramechanical properties and multi-stimuli response into catalyst-free and commercially available polymer-based networks is particularly attractive to extend the realm of thermally malleable polymers. Toward this goal, herein we demonstrated a paradigm by introducing dynamic imine bonds into styrene-butadiene rubber (SBR)/graphene composites. SBR was firstly grafted with aldehyde groups and then cross-linked with p-phenylene diamine and it-modified graphene through imine condensation between aldehyde and amino groups. The crosslinked networks were able to alter their topologies via imine exchange reactions in both the bulk network and SBR-graphene interphase in the absence of catalyst, enabling them to be recycled and reshaped under heating or IR irradiation. The incorporation of graphene led to spectacular improvements on the mechanical properties of vitrimer composites, and the mechanical properties could be tuned through solid-state drawing. The relationships between morphological structure and dynamic properties as well as mechanical properties of the vitrimer composites were addressed.
       
  • Cork–PLA composite filaments for fused deposition modelling
    • Abstract: Publication date: Available online 5 October 2018Source: Composites Science and TechnologyAuthor(s): Fugen Daver, Kok Peng Marcian Lee, Milan Brandt, Robert Shanks We report design and development of cork–poly(lactic acid) (PLA) biodegradable filaments for fused deposition modelling (FDM), which is an additive manufacturing technique. Composites of varying cork composition were melt compounded in an internal mixer and compression moulded for characterisation of mechanical, thermal and morphological properties. Inclusion of cork granules decreased the tensile strength, but improved impact strength. As the cork percentage increased, density of the composites decreased. Hence, the specific modulus and specific tensile strength properties improved as the cork content increased in the composites. Tributyl citrate (TBC), a biodegradable plasticiser, was used to overcome the inherent brittleness of PLA. TBC decreased the modulus, tensile yield strength; however it increased ductility of the composites. A selected cork composite was used for filament production and it proved to be suitable for fused deposition modelling. 3D printed composites were compared with compression moulded composites. 3D printing resulted in slightly lower elastic modulus and tensile yield strength, but higher elongation at break compared with compression moulded composites.
       
  • Injection molded mechanoluminescent polymer composites
    • Abstract: Publication date: Available online 5 October 2018Source: Composites Science and TechnologyAuthor(s): Hyeon Kyeong Kim, Young Seok Song The aim of this study is to demonstrate the fabrication process of mechanoluminescent (ML) composites. As an ML component, ZnS:Cu was employed in the composite. ML powders embedded thermoplastic polyurethane (TPU) composites were prepared using injection molding. A wheel was considered as a final target application of the composite material. The manufacturing process and resulting mechanical behavior of the wheel were modeled numerically. The morphological, rheological, thermal, and mechanical properties of the composites were analyzed experimentally. As the particle content and mechanical stimulus imposed on the specimen increased, the induced ML was enhanced significantly. We showed the possibility of applying ML particles embedded composites to real engineering products.
       
  • A methodology for modeling the relationship between process and
           topological yarn structure of 3D rotary braided rectangular preforms
    • Abstract: Publication date: 10 November 2018Source: Composites Science and Technology, Volume 168Author(s): Haiyang Mei, Zhenyu Han, Guangyu Lu, Hongyu Jin 3D braided composites have been widely used in high-performance fields due to their excellent properties closely related to the special yarn structures. However, the capability to fabricate various yarn structures with flexible 3D rotary braiding method has not been systematically investigated. This paper proposes a methodology to model the process/topological yarn structure relationship of 3D rotary braided rectangular preforms. A novel algorithm is developed to trace the carrier path with machine control code, in which the carrier motion is expressed as mathematical functions of switch rotation status. Without considering yarns’ volume, the lattice-like ideal yarn topology is established using the yarn trajectories. To construct the real yarn topology, yarn topologies at the nodes which depend on corresponding switch rotation direction are studied. The yarn structure is explored within a representative unit owing to its repetitiveness, and specific switch rotation direction combinations which allow yarns to maintain straight in the preforms are derived.
       
  • Manifold embedding of heterogeneity in permeability of a woven fabric for
           optimization of the VARTM process
    • Abstract: Publication date: Available online 4 October 2018Source: Composites Science and TechnologyAuthor(s): Min-young Yun, Elena Lopez, Francisco Chinesta, Suresh Advani In Vacuum Assisted Resin Transfer Molding (VARTM), fabrics are placed on a tool surface and a Distribution Media (DM) is placed on top to enhance the flow in the in-plane direction. Resin is introduced from one end and a vacuum is applied at the other end to create the pressure gradient needed to impregnate the fabric with resin before curing the resin to fabricate the composite part. Heterogeneity in through the thickness permeability of a woven fabric is one of the causes for the variability in the quality of the final composite part fabricated using the VARTM process. The heterogeneity is caused by the varying sizes of pinholes which are meso-scale empty spaces between woven tows as a result of the weaving process. The pinhole locations and sizes in the fabric govern the void formation behavior during impregnation of the resin into the fabric. The pinholes can be characterized with two parameters, a gamma distribution function parameter α and Moran's I (MI). In this work, manifold embedding methods such as t – Distributed Stochastic Neighborhood Embedding (t_SNE) and Principal Component Analysis (PCA) are used to visually characterize fabrics of interest with the two variables, α and MI, through the reduction of dimensionality. To demonstrate the manifold embedding method, a total of 450 training sample data with ranges of α from 1 to 3 and MI from 0 to 0.5 were used to create a map in three-dimensional space for ease of visualization and characterization. The method is validated with a plain-woven fabric sample in a testing step to show that the two parameters of the fabric are identified with its corresponding α and MI using these machine learning algorithms. Numerical flow simulations were carried out for varying α, MI, and DM permeability, and the results were used to predict final void percentage. The quick online identification of the fabric parameters with machine learning algorithms can instantly provide expected variability in void formation behavior that will be encountered in a VARTM process.
       
  • Effects of grafting strength and density on interfacial shear strength of
           carbon nanotube grafted carbon fibre reinforced composites
    • Abstract: Publication date: Available online 2 October 2018Source: Composites Science and TechnologyAuthor(s): Yan Deng, Mohammad S. Islam, Liyong Tong This paper presents a test method of twin-fibre single-lap joint bonded with a micro-droplet of epoxy and subjected to tensile loading for determining fibre-matrix interfacial shear strength (IFSS). Twenty-five carbon fibre (CF)/epoxy specimens and fifty-six carbon nanotube (CNT)-grafted CF/epoxy specimens were prepared and tested. The average IFSS measured for specimens with a mean grafting density of 10.9, 25.8, 35.1 or 58.8 CNTs per μm2 can be improved by 51%, 101%, 155% and 273% (223%) respectively comparing to that without grafted CNTs. A multi-scale analytical model that relates micro-scale IFSS to nanoscale CNT grafting strength and density is developed and then used for predicting the IFSS of CNT-CF reinforced composites. There exists a good correlation between the measured and predicted IFSS of specimens with different grafting densities.
       
  • Rheology, crystal structure, and nanomechanical properties in large-scale
           additive manufacturing of polyphenylene sulfide/carbon fiber composites
    • Abstract: Publication date: Available online 1 October 2018Source: Composites Science and TechnologyAuthor(s): Peng Liu, Ralph Dinwiddie, Jong K. Keum, Rama K. Vasudevan, Stephen Jesse, Ngoc A. Nguyen, John M. Lindahl, Vlastimil Kunc Extrusion based high-throughput Additive Manufacturing (AM) provides a rapid and versatile approach for producing complex structures by using a variety of polymer materials. An underexplored aspect of this technique is concerned with the formation of interfaces between successively deposited layers. This is particularly important for large-scale additive manufacturing of semi-crystalline polymers because of the highly non-isothermal conditions involved, which influence both nucleation and crystal growth. The objective of this work is to investigate the microstructure and the corresponding viscoelastic properties of carbon fiber (CF) reinforced polyphenylene sulfide (PPS) resulting from extrusion-based high-throughput AM process. Questions on development of morphology focus on polymer crystal structure and carbon fiber orientation in the vicinity of the interface between successive layers. This study attempts to establish a fundamental understanding of the role of the AM has in transferring a set of intrinsic material properties to the macroscopic properties of the final AM structure.
       
  • High temperature response capability in carbon nanotube/polymer
           nanocomposites
    • Abstract: Publication date: Available online 29 September 2018Source: Composites Science and TechnologyAuthor(s): Tao Xiao, Shen Gong, Xing Lei, Zhaohan Jiang, Yang Wang, Di Wu, Zhu Xiao, Zhenghong Zhu, Zhou Li High temperature response capability is critical for multifunctional carbon nanotube polymer nanocomposites. In this work, a CNT/polymer nanocomposite with high temperature coefficients of resistance (Average value = −3%/K, Peak value = −7%/K, Response range = 323 K–473 K) was fabricated successfully. By developing a percolation network model, this work reveals theoretically that the observed high temperature response is mainly resulted from glass transition of polymer matrix. During this process, the electron transport at CNT junctions switched from quantum tunneling to thermally activated hopping. The simulation results also reveal that the temperature response capability can be further improved (Average value = −4.7%/K, Peak value = −10%/K, Response range = 380 K–500 K) by using Polytetrafluoroethylene as polymer matrix with 0.5 wt% CNT loadings. These highly sensitive, low cost composites have a great potential for wide range applications, such as temperature sensors and temperature threshold switches.
       
  • Graphene-functionalized polymer composites for self-sensing of ultrasonic
           waves: An initiative towards “sensor-free” structural health
           monitoring
    • Abstract: Publication date: Available online 28 September 2018Source: Composites Science and TechnologyAuthor(s): Yehai Li, Yaozhong Liao, Zhongqing Su With recognized bottlenecks of guided ultrasonic wave (GUW)-based structural health monitoring (SHM) for composites, conventional polymers are nano-engineered and endowed with capability of self-perceiving GUWs. A built-in sensing network is formed with graphene nanoparticles, optimized and diffused in fibre-reinforced polymers, in which the quantum tunneling effect can be locally triggered when GUWs traverse the composites. The diffuse sensing network makes it possible to acquire GUWs at any site of the functionalized composites, avoiding use of conventional ultrasonic transducers that must be externally attached to or internally embedded in the composites. With an optimized nano-structure, the functionalized composites have been demonstrated self-responsive to GUWs up to 500 kHz. In experimental validation, GUWs propagating in a glass fibre/epoxy laminate are self-sensed by the laminate at the sites arbitrarily selected, to observe no discrepancy against counterpart signals obtained with piezoelectric sensors. To take a step further, barely visible impact damage (BVID) in the laminate is located accurately using the self-sensed GUW signals. This study has spotlighted a new breed of functional polymers with capability of self-health monitoring, without using external sensors. The use of associated cables and wires is also minimized. Not only does it facilitate a reduced weight/volume penalty to the original composites, but also minimizes mechanical degradation of the composites due to the intrusion of sensors, blazing a potential trail in developing “sensor-free” SHM for composites.
       
  • An analytical model of square CFRP tubes subjected to axial compression
    • Abstract: Publication date: Available online 24 September 2018Source: Composites Science and TechnologyAuthor(s): Rafea Dakhil Hussein, Dong Ruan, Guoxing Lu A novel analytical model has been developed to predict the mean crushing force of square carbon fibre reinforced plastic (CFRP) tubes subjected to axial crushing. The model has captured the experimentally observed major energy dissipating mechanisms of CFRP tubes under axial compression, i.e. crack propagation, transverse shearing and friction. Transverse shearing has been taken into account for the first time in this model. Quasi-static compressive tests have been conducted on 16 square CFRP tubes with various side lengths and wall thicknesses to determine their mean crushing forces. The discrepancy between analytically predicted and experimentally measured mean crushing forces of these square CFRP tubes is no more than 7%. Moreover, the proposed analytical model is very simple with only several parameters, which can be determined via relatively simple experimental tests.
       
  • Influence of hole eccentricity on failure progression in a double shear
           bolted joint (DSBJ)
    • Abstract: Publication date: Available online 22 September 2018Source: Composites Science and TechnologyAuthor(s): Alastair M. Croxford, Paul Davidson, Anthony M. Waas Experimental results on the influence of bolt hole to edge eccentricity for Double Shear Bolted Joints (DSBJ) used to attach fiber reinforced composite laminates are presented. Four different eccentricities of DSBJs were examined and microCT imaging conducted at different stages of the loading history are presented. The macroscopic load-hole elongation results along with the microCT images exhibit a distinct progression of failure which dictate not only the bearing load but also the ultimate load of the joint. The experimental procedure, microCT images and failure progression mechanisms are reported in this paper. The results can serve to develop a mechanism based model of DSBJ failure progression.
       
  • Low-velocity impact of sandwich beams with fibre-metal laminate
           face-sheets
    • Abstract: Publication date: Available online 21 September 2018Source: Composites Science and TechnologyAuthor(s): Jianxun Zhang, Yang Ye, Qinghua Qin, Tiejun Wang Low-velocity impact of fully clamped sandwich beams with fibre-metal laminate face-sheets and metal foam core struck by a heavy mass is investigated. Analytical solutions are developed for the dynamic response of sandwich beams with fibre-metal laminate face-sheets considering the interaction of bending and stretching induced by large deflections. According to the rigid-plastic material approximation with modifications, simple formulae are obtained for the large deflection of sandwich beams with fibre-metal laminate face-sheets. Numerical calculations are carried out, and analytical solutions capture numerical results reasonably. The effects of the composite volume fraction, the ratio of metal layer strength to composite layer strength, and core strength on the structural response are discussed. Using the analytical formulae, optimal design charts are constructed to minimize the mass of sandwich beams. It is demonstrated that the present analytical model can predict the post-yield behavior of sandwich beams with fibre-metal laminate face-sheets reasonably.
       
  • Multiscale approach for identification of transverse isotropic carbon
           fibre properties and prediction of woven elastic properties using
           ultrasonic identification
    • Abstract: Publication date: Available online 21 September 2018Source: Composites Science and TechnologyAuthor(s): R.D.B. Sevenois, D. Garoz, E. Verboven, S.W.F. Spronk, F.A. Gilabert, M. Kersemans, L. Pyl, W. Van Paepegem In this work the possibility to reverse engineer the transverse isotropic carbon fibre properties from the 3D homogenized elastic tensor of the UD ply for the prediction of woven ply properties is explored. Ultrasonic insonification is used to measure the propagation velocity of both the longitudinally and transversally polarized bulk waves at various symmetry planes of a unidirectional (UD) Carbon/Epoxy laminate. These velocities and the samples' dimensions and density are combined to obtain the full 3D orthotropic stiffness tensor of the ply. The properties are subsequently used to reverse engineer the stiffness tensor, assumed to be transversely isotropic, of the carbon fibres. To this end, four micro-scale homogenization methods are explored: 2 analytical models (Mori-Tanaka and Mori-Tanaka-Lielens), 1 semi-empirical (Chamis) and 1 finite-element (FE) homogenization (randomly distributed fibres in a Representative Volume Element). Next, the identified fibre properties are used to predict the elastic parameters of UD plies with multiple fibre volume fractions. These are then used to model the fibre bundles (yarns) in a meso-scale FE model of a plain woven carbon/epoxy material. Finally, the predicted elastic response of the woven carbon/epoxy is compared to the experimentally obtained elastic stiffness tensor. The predicted and measured properties are in good agreement. Some discrepancy exists between the ultrasonically measured value of the Poisson's ratio and the predicted value. Nonetheless, it is shown that virtual identification and prediction of mechanical properties for woven plies is feasible.
       
  • Analysis of the influence of interphase characteristics on thermal
           conduction in surface-modified carbon nanotube-reinforced composites using
           an analytical model
    • Abstract: Publication date: Available online 18 September 2018Source: Composites Science and TechnologyAuthor(s): Hoi Kil Choi, Hana Jung, Yuna Oh, Hyunkee Hong, Jaesang Yu, Eui Sup Shin In this study, the influence of interphase characteristics on thermal conductivity of carbon nanotube (CNT)-reinforced polymer composites was investigated using a thermal resistance theory-based analytical model. Pristine, nitrogen doped, and carboxyl functionalized CNTs were used to verify the effect of surface modifications. Interfacial thermal conductivities of nanocomposites containing three different CNTs were calculated from non-equilibrium molecular dynamics (NEMD) simulations, to analyze the influence of functionalization on the interphase characteristics. Equilibrium molecular dynamics (EMD) simulations of three different CNTs and epoxy matrix were performed to estimate their effective thermal conductivities. The thermal conductivities of the nanocomposites were predicted by applying the results obtained from the MD simulations in the analytical model. The results predicted by the analytical model show that while thermal conduction in the longitudinal direction of the nanocomposites depends on thermal conductive performance of the CNTs, transverse thermal conductivity could be significantly influenced by the interphase characteristics.
       
  • Transition from buckling to progressive failure during quasi-static
           in-plane crushing of CF/EP composite sandwich panels
    • Abstract: Publication date: Available online 18 September 2018Source: Composites Science and TechnologyAuthor(s): Yuan Chen, Lin Ye, Kunkun Fu, Xu Han Global buckling failure should be avoided when designing a structure with the requirement of crashworthiness performance. This study characterises the quasi-static in-plane crushing of CF/EP composite sandwich panels by tailoring their bevel angles. A finite element model was developed describing the interlaminar and intralaminar damage of a composite sandwich panel; this model was validated by in-plane compression experiments. A numerical analysis and compression experiments were then performed to determine the responses and failure modes in the CF/EP composite sandwich panels with various bevel angles. The results showed that the global buckling-to-progressive failure transition under compression occurred in the composite sandwich panels when the bevel angle reached a critical value. A microscopic analysis showed that the composite sandwich panels with buckling failure behaviours exhibited an apparently classical post-buckling transverse shearing mode, while those with progressive failure presented individual lamina bending with inward and outward fronds. This study provides some useful data for the design of the crashworthiness of a sandwich composite panel by introducing a progressive failure mode.
       
  • A model for the electrical conductivity variation of molten polymer filled
           with carbon nanotubes under extensional deformation
    • Abstract: Publication date: Available online 17 September 2018Source: Composites Science and TechnologyAuthor(s): Marjorie Marcourt, Philippe Cassagnau, René Fulchiron, Dimitri Rousseaux, Olivier Lhost, Simon Karam This work is dedicated to analyzing the variation of conductivity of polymer composites (polystyrene filled with Carbon Nanotubes) under extensional deformation. In a previous work, a conductor-insulator transition has been observed and the predominant role of the polymer dynamics has been brought to light. The evolution of the filler network within a polymer matrix can be described by a kinetic equation that takes into account a structuring mechanism that is controlled by the mobility in the melt matrix and a destruction mechanism that is induced by the extensional deformation. The solution of this equation that describes the filler network at a microscale is used in the percolation law to obtain the macroscopic conductivity of the composite. It turned out that the structuring parameter does not depend on the extensional deformation but only relies on the polymer matrix dynamics. In addition, the breaking parameter only depends on the Hencky strain, whatever the extensional rate. This model has been successfully applied for a large range of filler concentrations and experimental conditions from low to large Weissenberg numbers.
       
  • Flexible printed humidity sensor based on
           poly(3,4-ethylenedioxythiophene)/reduced graphene oxide/Au nanoparticles
           with high performance
    • Abstract: Publication date: Available online 15 September 2018Source: Composites Science and TechnologyAuthor(s): Rongjin Zhang, Bo peng, Yan Yuan Wearable and flexible humidity-sensing devices are essential for the real-time monitoring of air humidity in health and environmental applications. We propose a flexible sensor based on a conductive polymer comprising poly(3,4-ethylenedioxythiophene) (PEDOT) and reduced graphene oxide(rGO) to monitor changes in humidity. GO was used as a hard template for the in situ polymerization of EDOT to obtain PEDOT:rGO. Then, PEDOT:rGO-PEI/Au nanoparticles (NPs) ink was prepared through the in situ reduction of Au NPs modified with polyethylenimine (PEI). The ink was printed on the surface of a hydrophilic modified polyethylene terephthalate (PET) substrate using an ink-jet printer to form a specific pattern. After assembly, a PET-based PEDOT:rGO-PEI/Au NPs (PrGANPs) sensor device with high electrical performance, transparency, and sensitivity was obtained for testing at a variety of RH levels. The prepared PET-based PrGANPs sensor printed with 50 layers had a transmittance up to 61% at 500 nm. And the response and recovery times were approximately 20 and 35 s at 98% RH, respectively. Stability was maintained even after bending 200 times, and the sensor could respond within the humidity range of 11%–98% RH, while in response to a wide resistance range of 7.41%–51.60%.
       
  • Preparation of β-cyclodextrin reinforced waterborne polyurethane
           nanocomposites with excellent mechanical and self-healing property
    • Abstract: Publication date: Available online 14 September 2018Source: Composites Science and TechnologyAuthor(s): Ting Wan, Dajun Chen Cyclodextrin is an eco-friendly material with extensive application range. In this work, polyethylene glycol (PEG) modified β-cyclodextrin (CD) was added to a self-healing waterborne polyurethane (SHWPU) through a simple solution blending method. The morphologies, chemical structures, emulsion stability, thermal behavior, mechanical and self-healing properties of the SHWPU/CD nanocomposites were investigated. The results indicated that CDs were well dispersed in the SHWPU matrix and the blended emulsions were stable. The thermal stability of the SHWPU was improved by the addition of CD. When the mass fraction of CD was lower than 5%, the mechanical and self-healing property of the nanocomposites were obviously improved, which indicates the CD modified SHWPU can find potential applications in durable coatings and adhesives in areas, such as textile, wood, aerospace and infrastructure.
       
  • Preparation of poly (propylene carbonate)/graphite nanoplates-spherical
           nanocrystal cellulose composite with improved glass transition temperature
           and electrical conductivity
    • Abstract: Publication date: Available online 14 September 2018Source: Composites Science and TechnologyAuthor(s): Shaoying Cui, Pingfu Wei, Li Li Poly(propylene carbonate) (PPC) is a new attractive biodegradable polymers synthesized from inexhaustible carbon dioxide and propylene epoxide, but shows low glass transition temperature (Tg) and poor mechanical properties, which greatly limits its practical applications and industrialization development. To improve Tg and the practicability of PPC, in this work, graphite nanoplates-spherical nanocrystalline cellulose (GNP-SNCC) hybrids, which were bonded by both physical and chemical forces, were prepared by ball milling from graphite and microfibrillated cellulose, and the structure formation as well as properties of PPC/GNP-SNCC composites were studied. The results showed that the improved interfacial interactions between GNP-SNCC and PPC, and the rigid two-dimensional structure of GNP-SNCC were beneficial for the constraint of PPC molecular chains, thus significantly improving Tg and the mechanical properties of PPC matrix, e.g. Tg increased from 34.0 °C of neat PPC to 51.3 °C, and the yield strength increased from 27 MPa to 52.8 MPa. Moreover, facilitated by SNCC, a conductive pathway of GNP was effectively constructed, leading to the great increase in the electrical conductivity of PPC/GNP-SNCC composite. The composite with 10 wt% (5.71 vol%) graphite showed 9 orders of magnitude higher than that of PPC/graphite composite with the same graphite content, and the percolation threshold was drastically decreased from 15 to 5 wt% (8.56–2.85 vol%).
       
  • A highly stretchable carbon nanotubes/thermoplastic polyurethane
           fiber-shaped strain sensor with porous structure for human motion
           monitoring
    • Abstract: Publication date: Available online 13 September 2018Source: Composites Science and TechnologyAuthor(s): Xiaozheng Wang, Hongling Sun, Xiaoyan Yue, Yunfei Yu, Guoqiang Zheng, Kun Dai, Chuntai Liu, Changyu Shen Highly flexible and stretchable strain sensors play an important role in the wearable electronic systems. Up to now, it is still an enormous challenge to achieve a good balance between the wide response range and high sensitivity for a resistive-type flexible strain sensor. In this work, we prepared a fiber-shaped strain sensor based on thermoplastic polyurethane (TPU) and multi-walled carbon nanotubes (MWCNTs) via a simple and cost-efficient wet-spun method. The production process can satisfy continuous and large-scale preparation. The generation of the interesting porous structure is related to the solvent exchange in solidification process and beneficial to the improvement of the sensing range. In the uniaxial stretching test, the MWCNTs/TPU fiber-shaped sensor showed an ultra-wide workable strain range (320%), a high sensitivity (gage factor of 22.2 within 160% strain and 97.1 for strain of 160–320%) and a fast response time (
       
  • Cavitation-crazing transition in rubber toughening of poly(lactic
           acid)-cellulose nanocrystal composites
    • Abstract: Publication date: 10 November 2018Source: Composites Science and Technology, Volume 168Author(s): Joseph K. Muiruri, Songlin Liu, Wern Sze Teo, Jayven Chee Chuan Yeo, Warintorn Thitsartarn, Chaobin He In this work, the mechanism behind rubber toughening of poly(lactic acid)/cellulose nanocrystal-g-rubber-g-poly(d-lactide) (CNC-rDx-PDLA) composites was elucidated through systematic study of the effects of rubber segment content (length) in CNC-rDx-PDLA nanofillers and the nanofiller concentrations on the deformation behavior of the nanocomposites. It was shown that with an increase of rubber segment length and rubber filler concentration, the elongation at break of the resulting composites increased. Moreover, a dramatic increase in elongation at break (from 20% to 200%) was observed when the rubber segment content (length) in the CNC-rDx-PDLA nanofillers was increased from 52 to 68%. Cavitation mechanism was found dominant when the rubber segment content in the nanofillers was 52% and below, whereas, stable crazes were formed and followed by fibrillation when the rubber segment content in the nanofillers was increased to 68%, which was evident by small angle X-ray scattering (SAXS) study and scanning electron microscopy (SEM) analysis. The existence of a transition from cavitation to crazing in the composite systems could be attributed to a more mobile rubber phase because of longer rubber chain length. Our study suggests that the effective toughening mechanism for thermoplastics such as PLA is crazing induced plastic deformation.
       
  • Geometrical deviation analysis of CFRP thin laminate assemblies: Numerical
           and experimental results
    • Abstract: Publication date: 10 November 2018Source: Composites Science and Technology, Volume 168Author(s): Andrea Corrado, Wilma Polini, Luca Sorrentino, Costanzo Bellini During the cure process, the anisotropic characteristics of composite material, combined with high temperature and high pressure to which the material is subjected, cause the development of residual stresses. Consequently, laminate deformations arise and dimensional and geometrical requirements are not reached. Laminate deformations transfer into product distortions through assembly process. Distortions result in uncertainty in the performance of manufactured goods and they require effective management to ensure correct performance.The present work shows a numerical approach suitable to determine the geometrical deviations of an assembly constituted by thin laminates in composite material. The proposed model considers the geometrical deviations of the assembly parts, due to the manufacturing process, the assembly sequence and the presence of adhesive to put together the parts.The proposed model was experimentally verified by considering a T-shaped assembly constituted by flat and L-shaped components. The obtained results show a good agreement with the experimental ones.
       
  • Development of electrically conductive structural BMI based CFRPs for
           lightning strike protection
    • Abstract: Publication date: 20 October 2018Source: Composites Science and Technology, Volume 167Author(s): Z.J. Zhao, G.J. Xian, J.G. Yu, J. Wang, J.F. Tong, J.H. Wei, C.C. Wang, P. Moreira, X.S. Yi In the present paper, bismaleimide resin (BMI) based carbon fiber reinforced composite (CFRP) with remarkable lightning strike protection (LSP) capability was developed. A light weight conductive veil was prepared and interleaved to CFRP with the through thickness conductivity of 27.9 S/m, while its static mechanical strength was unaffected. We prove that the through thickness conductive pathways made CFRP to disperse the lightning current more effectively; reducing the lightning damage toward the inner part of the CFRP. The deepening Joule heat was proved to be the major reason of the penetrating structure failure. Comparing to the state-of-art metal sacrifice layer for LSP, the through thickness conductive CFRP has lighter weight and similar LSP capability, without compromising the mechanical strength.
       
  • Lightweight and strong microcellular injection molded PP/talc
           nanocomposite
    • Abstract: Publication date: Available online 13 September 2018Source: Composites Science and TechnologyAuthor(s): Guilong Wang, Guoqun Zhao, Guiwei Dong, Yue Mu, Chul B. Park Lightweight is of great significance for reducing material and energy consumptions. Microcellular injection molding is an advanced technology for fabricating lightweight plastic structural components, but the deteriorated mechanical performance is a big challenge. In this study, we reported a facile and scalable way to fabricate the lightweight and strong microcellular polypropylene/talcum (PP/talc) component. Both PP/talc microcomposite and PP/talc nanocomposite were prepared by the twin-screw compounding, and the SEM images show a uniform dispersion of talc. The DSC analysis results demonstrate that either the micro or nano talc is very effective in promoting the crystallization of PP. The rheological tests show that both the micro talc and the nano talc lead to obviously enhanced viscoelastic properties of the PP melt, while the effect of the nano talc is much more pronounced than that of the micro talc. Thanks to the enhanced crystallization and improved viscoelastic behavior, both the microcomposite foam and the nanocomposite foam shows much refined cellular structure than the pure PP foam. The PP/talc microcomposite foam shows significantly improved strength but seriously deteriorated toughness, compared with the pure PP foam. In contrast, the PP/talc nanocomposite foam shows simultaneously improved strength, rigidity and toughness. Notably, the tensile toughness and the Gardner impact toughness of the PP/talc nanocomposite foam are dramatically enhanced by 226.1% and 166.2%, respectively. Taking into account the flexible and scalable features of the processing methodology, the lightweight and strong PP/talc nanocomposite foam shows a promising future to replace the solid structural components in many industrial applications such as automotive and consumer electronics.
       
  • Hydrated aramid nanofiber network enhanced flexible expanded graphite
           films towards high EMI shielding and thermal properties
    • Abstract: Publication date: Available online 13 September 2018Source: Composites Science and TechnologyAuthor(s): Yuhang Liu, Kaiyi Zhang, Yanling Mo, Li Zhu, Bowen Yu, Feng Chen, Qiang Fu Expanded graphite (EG) films are known for high electric and thermal transportation properties, due to light oxidation preparation process compared with chemical converted graphene (cGE) films. However, the poor mechanical properties and brittle nature are the major limitations for commercial applications. To meet this challenge, in this work, hydrated aramid nanofiber (HANF) with excellent mechanical properties and flexibility is introduced into EG films to enhance their mechanical properties and flexibility. As a result, only the adding of 2 wt% HANF can endow EG films with good flexibility. The best comprehensive property is achieved by adding 10% HANF (EG-10). Compared with the pure EG films (EG-0), a 223% improvement of tensile strength from 7.5 Mpa to 24.2 Mpa and a 660% enhancement of elongation at break from 0.371% to 2.82% are observed for EG-10. Besides, EG-10 maintains good electric and thermal conductivities of 215 S cm−1, 208 W m−1 K−1. Moreover, the EMI shielding property of 34.9 dB is realized when the film thickness reaches only 30 μm. The EG/HANF films can be used up to the temperature of 300 °C and show good flame resistance compared with adding other polymers thanks to the good stability of HANF. And, the excellent flexibility can be maintained even after 1000 times direct folding. The comprehensive properties of light weight films, together with their advantages of simple, cheap and facile large-scale preparation process endow the films with promising applications in next generation foldable electronic devices.
       
  • Novel self-healing CFRP composites with high glass transition temperatures
    • Abstract: Publication date: Available online 11 September 2018Source: Composites Science and TechnologyAuthor(s): Lisha Zhang, Xuanzhe Tian, Mohammad H. Malakooti, Henry A. Sodano Carbon fiber reinforced polymer (CFRP) composites were fabricated using a novel intrinsically healable isocyanurate-oxazolidone (ISOX) thermosetting matrix. After multiple delamination events, repeatable strength recovery of the composites has been demonstrated with a first healing efficiency up to 85% after thermal treatment. The healing mechanism results from transformation of the isocyanurate with epoxide groups to yield new oxazolidone rings at the fracture surface. This novel ISOX polymer utilizes commercial diglycidyl ether of bisphenol F (DGEBF) and toluene diisocyanate to produce a high cross-link density thermoset with a glass transition temperature (Tg) up to 285 °C, and 99.5% of the composite weight remains at 300 °C. The strength and stiffness of the composites are comparable with an engineering grade polymer matrix composite typically used in aerospace applications and the thermal stability places the materials in the polybismaleimide performance region although with greater toughness. This polymer exhibits the highest Tg of any self-healing material reported and is composed of low cost reactants, which gives the polymer great potential to function as a major component of an advanced structural composite for extreme environments.
       
  • The effect of double grafted interface layer on the properties of carbon
           fiber reinforced polyamide 66 composites
    • Abstract: Publication date: Available online 10 September 2018Source: Composites Science and TechnologyAuthor(s): Jinchuan Chen, Huajie Xu, Chuntai Liu, Liwei Mi, Changyu Shen Given the advantages of polyethyleneimine (PEI) for interface modification of carbon fiber reinforced polyamide 66 composite (CF/PA66), an effective method was developed to fabricate CNT@PEI-CF. The XPS results confirmed CNT@PEI-CF was covered with a double grafted layer. Interface stability investigated showed thermal stability (under injection molding temperature, about 270 °C) and structural stability of CNT@PEI-CF/PA66 interface were both improved, but PA66 crystallization behavior affected by CNT@PEI-CF was identical with that of pure PA66. The contact angle tests exhibited that its compatibility with PA66 was also enhanced. Its interfacial shear strength, composite tensile strength and elastic modulus increased by 64.74%, 27.58% and 22.68% compared with that of untreated-CFs and composite, respectively. These best mechanical properties were ascribed to the formation of “fish-scale” layers on pull-out fibers resulted from CNT@PEI-CF modification. It could be concluded that CNT@PEI-CF would not only enhance its composite mechanical properties, but also exhibit much fiber pull-out and avoid the catastrophic failure for CNT@PEI-CF/PA66 composites. This CF surface modification study would be beneficial to expand application of thermoplastic composite with reusability.
       
  • Scalable one-step synthesis of hydroxylated boron nitride nanosheets for
           obtaining multifunctional polyvinyl alcohol nanocomposite films:
           Multi-azimuth properties improvement
    • Abstract: Publication date: Available online 8 September 2018Source: Composites Science and TechnologyAuthor(s): Wei Cai, Bibo Wang, Yongqian Shi, Ying Pan, Junling Wang, Weizhao Hu, Yuan Hu Introducing hydroxyl (OH) groups onto the surface of chemically inert hexagonal boron nitride (h-BN) is conducive to the exfoliation and functionalization of h-BN, meanwhile could enhance the intermolecular forces with polymer as well. However, chemical inertness generated by partially ionized B-N bonds makes the introduction of OH groups still remains a challenge. Here, we reported a scalable one-step thermal calcination method for the fabrication of OH-functionalized h-BN nanosheets (OH-BN). Then, transparent, strong, and flexible as well as flame retardant nanocomposite films of as-prepared OH-BN and PVA were prepared through a aqueous solution casting technique. Due to hydrogen-bond self-assembly and crystalline-region self-relief, elongation at break, tensile strength, and Young's modulus of PVA nanocomposite film were simultaneously increased by 109.3%, 73.6%, and 144.4% with as low as 0.2 wt % OH-BN. Besides, the self-stiffness phenomenon that damages the material elasticity during dynamic service process of PVA nanocomposite films was effectively hindered. Meanwhile, the superior visible light transmittance and higher absorption quality to UV-light were also confirmed, which promoted its practical use in artificial cornea materials. Attributing to the well-dispersed state and layered structure, incorporated OH-BN presented a barrier function to suppress the delivery of thermal degradation products of PVA matrix, thus enhancing thermal stability and fire safety. Herein, we come to a conclusion that the scalable one-step synthesis of OH-BN and environmentally friendly fabrication of PVA/OH-BN nanocomposite films as well as excellent properties greatly contribute to the development of the practical application of h-BN nanosheets, thus obtaining multifunctional composite materials.
       
  • Tailoring swelling to control softening mechanisms during cyclic loading
           of PEG/cellulose hydrogel composites
    • Abstract: Publication date: Available online 7 September 2018Source: Composites Science and TechnologyAuthor(s): A. Khoushabi, C. Wyss, B. Caglar, D. Pioletti, P.-E. Bourban One of the novel approaches for discogenic lower back pain treatment is to permanently replace the core of the intervertebral disc, so-called Nucleus Pulposus, through minimally invasive surgery. Recently, we have proposed Poly(Ethylene Glycol) Dimethacrylate (PEGDM) hydrogel reinforced with Nano-Fibrillated Cellulose (NFC) fibers as an appropriate replacement material. In addition to the tuneable properties, that mimic those of the native tissue, the surgeon can directly inject it into the degenerated disc and cure it in situ via UV-light irradiation. However, in view of clinical applications, the reliability of the proposed material has to be tested under long-term fatigue loading. To that end, the present study focused on the characterization of the fatigue behavior of the composite hydrogel and investigated the governing physical phenomena behind it. The results show that composite PEGDM-NFC hydrogel withstands the 10 million compression cycles at physiological condition. However, its modulus decreases by almost 10% in the first cycle and then remains constant, while cyclic loading does not affect the neat PEGDM hydrogel. The observed softening behavior has similar characteristics of the Mullins effect. It is shown that the reduction of modulus is due to the gradual change of NFC network, which is highly stretched in the swollen state. Moreover, the swelling degree of the matrix is correlated to the extent of softening during cyclic loading. Consequently, softening can be minimized by lowering the swelling of the composite hydrogel.
       
  • Modelling process induced deformations in 0/90 non-crimp fabrics at the
           meso-scale
    • Abstract: Publication date: Available online 31 August 2018Source: Composites Science and TechnologyAuthor(s): Adam J. Thompson, Bassam El Said, Jonathan P-H. Belnoue, Stephen R. Hallett The manufacture of non-crimp fabric composites typically requires the forming and consolidation of the reinforcement material. During this process the material is subjected to complex loading where the coupling of tensile, bending, shear and compressive forces result in deformations to the internal architecture of the textile. To determine the extent of these deformations a numerical modelling method has been developed to capture the kinematic behaviour of non-crimp fabric textiles. This method focuses on capturing the interactions between the fibrous tows and the stitch yarns which bind the tows together. Through modelling at a level of detail in which the meso-scale interactions are explicitly present, the macro-scale behaviour of the material proceeds naturally within the model, negating any requirement for detailed characterisation of the physical material. This also enables a detailed description of the internal architecture of the deformed fabric to be extracted for analysis or further modelling. The present study explores the method's ability to capture both local and global deformations which occur in non-crimp fabrics, specifically to capture the onset of deformations that appear due to tow-stitch interactions and the forming and compaction of multiple layers. Comparison with experimental results show good agreement for both meso-scale deformations, resulting from multi-layer compaction, and global in-plane shear deformations induced through forming over complex tooling.
       
  • Multifunctional performance of a carbon fiber UD lamina electrode for
           structural batteries
    • Abstract: Publication date: Available online 30 August 2018Source: Composites Science and TechnologyAuthor(s): Wilhelm Johannisson, Niklas Ihrner, Dan Zenkert, Mats Johansson, David Carlstedt, Leif E. Asp, Fabian Sieland In electric transportation there is an inherent need to store electrical energy while maintaining a low vehicle weight. One way to decrease the weight of the structure is to use composite materials. However, the electrical energy storage in today's systems contributes to a large portion of the total weight of a vehicle. Structural batteries have been suggested as a possible route to reduce this weight. A structural battery is a material that carries mechanical loads and simultaneously stores electrical energy and can be realized using carbon fibers both as a primary load carrying material and as an active battery electrode. However, as yet, no proof of a system-wide improvement by using such structural batteries has been demonstrated. In this study we make a structural battery composite lamina from carbon fibers with a structural battery electrolyte matrix, and we show that this material provides system weight benefits. The results show that it is possible to make weight reductions in electric vehicles by using structural batteries.
       
  • Quantifying fibre reorientation during axial compression of a composite
           through time-lapse X-ray imaging and individual fibre tracking
    • Abstract: Publication date: Available online 30 August 2018Source: Composites Science and TechnologyAuthor(s): Monica Jane Emerson, Ying Wang, Philip John Withers, Knut Conradsen, Anders Bjorholm Dahl, Vedrana Andersen Dahl The sudden compressive failure of unidirectional (UD) fibre reinforced composites at loads well below their tensile strengths is a cause of practical concern. In this respect and more generally, analytical and numerical models that describe composite behaviour have been hard to verify due to a lack of experimental observation, particularly in 3D. The aim of this paper is to combine fast in-situ X-ray computed tomography (CT) with advanced image analysis to capture the changes in fibre orientation in 3D during uninterrupted progressive loading in compression of a UD glass fibre reinforced polymer (GFRP). By analysing and establishing correspondence between a sequence of time-lapse X-ray CT images of the composite, we are able for the first time to follow each fibre and quantify the progressive deflection that takes place during axial compression in the steps leading up to fibre micro-buckling and kinking. Even at just 25% of the failure load, fibres have started to tilt in approximately the direction of the ultimate kink band. The rate of tilting increases as the composite approaches the collapse load. More generally, our approach can be applied to investigate the behaviour of a wide range of fibrous materials under changing loading conditions.
       
  • Prediction and validation of electromagnetic performance of curved
           radar-absorbing structures based on equivalent circuit model and ray
           tracking method
    • Abstract: Publication date: 20 October 2018Source: Composites Science and Technology, Volume 167Author(s): Dae-Sung Son, Jong-Min Hyun, Jung-Ryul Lee In this study, an equivalent circuit model and ray tracking method were used to predict the electromagnetic characteristics of curved radar-absorbing structures (RASs) applied with a frequency selective surface (FSS). After performing an electromagnetic analysis of FSS using a unit cell model, an equivalent circuit model reflecting the characteristics of the FSS was constructed. The equivalent circuit model of the FSS was applied to an equivalent circuit model for the RAS to evaluate the absorption performance as a function of the curvature and incident angle. Electromagnetic characteristics of the curvature structure were predicted by estimating the path of the electromagnetic wave using the ray tracking method. The calculated results were compared with the experimental results using free space measurements. Through this study, it was possible to estimate an equivalent circuit model reflecting the electromagnetic characteristics of the RAS with respect to the incident angle and curvature of the FSS. In addition, the electromagnetic performance of the entire curved structure was evaluated using the ray tracking method.
       
  • Thermal annealing induced enhancement of electrical properties of a
           co-continuous polymer blend filled with carbon nanotubes
    • Abstract: Publication date: 20 October 2018Source: Composites Science and Technology, Volume 167Author(s): Haixin Zhang, Jianwen Chen, Xihua Cui, Yuexin Hu, Liangcai Lei, Yutian Zhu, Wei Jiang In the current study, it is found that the electrical properties of a co-continuous polystyrene (PS)/poly(methyl methacrylate) (PMMA) blend containing with conductive multi-wall carbon nanotubes (MWCNTs) can be remarkably improved via the thermal annealing treatment. Utilizing the on-line (rheometer and optical microscope) and off-line (transmission electron microscopy) instruments, the evolution of the morphology and microstructure of PS/PMMA/MWCNTs composites are visualized. It is observed that thermal annealing can induce the coalescence of small phases into the more perfect co-continuous phase structure, which can significantly improve the electrical properties of the composites. Moreover, the re-aggregation of MWCNTs under thermal annealing also helps to improve the electrical properties of the composites. Furthermore, it is worth to note that parts of MWCNTs can be enriched at the interface of a co-continuous PS/PMMA blend to build up the conductive network during the thermal annealing, which further enhances the electrical properties of the composites.
       
  • Study the mechanism that carbon nanotubes improve thermal stability of
           polymer composites: An ingenious design idea with coating silica on CNTs
           and valuable in engineering applications
    • Abstract: Publication date: 20 October 2018Source: Composites Science and Technology, Volume 167Author(s): Yihe Wang, Xingna Qiu, Junping Zheng Silica nanotubes (SNTs) were coated on the surface of carbon nanotubes (CNTs) to form SNTs@CNTs core–shell hybrids, which is an ingenious and rigorous method to study the effect of CNTs for improving thermal stability of composites. SNTs@CNTs, CNTs, SNTs were introduced to silicone rubber (SR) and the different composites were tested and analyzed. The difference in the properties of SR-based composites leads us to get the specific mechanism that CNTs improve thermal stability of composites. This work reveals the mechanism on CNTs improving thermal stability of composites systematically and detailedly for the first time. The theoretical research provides an efficient guideline for further studying CNTs to improve properties of composites. Moreover, SNTs@CNTs/SR composites are also valuable in engineering applications. Experimental results show that the properties of SNTs@CNTs/SR are much better than CNTs/SR. Especially the initial thermal degradation temperature (Ti) of SNTs@CNTs/SR composites is 41 °C higher than that of SR.
       
  • Synergetic enhancement of mechanical and electrical strength in
           epoxy/silica nanocomposites via chemically-bonded interface
    • Abstract: Publication date: 20 October 2018Source: Composites Science and Technology, Volume 167Author(s): He Li, Feihua Liu, Huidong Tian, Chuang Wang, Zihao Guo, Peng Liu, Zongren Peng, Qing Wang While the incorporation of the inorganic fillers into polymers is envisioned to improve the properties of polymers, the organic–inorganic interface in the nanocomposite plays a prominent role in the modulation of the electrical, mechanical and thermal properties. Here, the epoxy chain-grafted silica nanoparticles were prepared and utilized as the fillers in epoxy matrix. The multiple physical properties such as the tensile strength, the elongation at break, the glass transition temperature, the dielectric strength of the nanocomposites with epoxy chain-grafted silica are simultaneously improved in comparison with those of the neat epoxy and the nanocomposites with unmodified silica. Moreover, substantial reductions in the water absorption ratio, dielectric loss and electric conductivity are obtained in the nanocomposites filled with epoxy-grafted silica even at relatively low filler loadings. These results verify the critical role of the chemically-bonded interface between organic and inorganic phases in determining the mechanical and dielectric strength of the polymer nanocomposites. The interaction zone models for the interface between nanoparticle and polymer matrix have been proposed to rationalize the experimental results.
       
  • Graphitic carbon nitride (g-C3N4) interfacially strengthened carbon fiber
           epoxy composites
    • Abstract: Publication date: 20 October 2018Source: Composites Science and Technology, Volume 167Author(s): Bo Song, Tingting Wang, Honggang Sun, Hu Liu, Xianmin Mai, Xiaojing Wang, Li Wang, Ning Wang, Yudong Huang, Zhanhu Guo In-situ synthesis of C3N4 on the carbon fiber surface was reported for enhancing interfacial properties of carbon fiber reinforced epoxy resin composite. The formed C3N4 on the carbon fiber surface can greatly increase the roughness, polar functional groups and wettability of carbon fiber surface, thereby leading to significant enhancement of interfacial properties of composites. After modification, interlaminar shear strength (ILSS) and interfacial shear strength (IFSS) of carbon fibers composites are increased from 44.3 to 60.7 MPa and from 43.1 to 75.9 MPa, respectively. Moreover, the surface free energy of carbon fibers is increased by 65.6%. The improved interfacial properties endow carbon fiber composites with better mechanical properties, leading to an increased tensile strength of composites from 1063 to 1279 MPa and total absorbed energy of impact experiment from 1.22 to 1.75 J. Meanwhile, the dynamic mechanical properties and hydrothermal aging resistance are also enhanced significantly. The storage modulus increases from 64.3 to 74.1 GPa. The markedly enhancement of interfacial mechanical properties and mechanical properties could be attributed to the improved resin wettability, enhanced mechanical interlocking and increased chemical bonding induced by the existence of C3N4 on the carbon fiber surface.
       
  • A novel model for determining the fatigue delamination resistance in
           composite laminates from a viewpoint of energy
    • Abstract: Publication date: 20 October 2018Source: Composites Science and Technology, Volume 167Author(s): Yu Gong, Libin Zhao, Jianyu Zhang, Ning Hu A previous study indicated that the normalized fracture controlling parameter (strain energy release rate G normalized by fatigue delamination resistance Gcf) in the Paris-type law has advantages of lower exponents and data scatter to evaluate the fatigue delamination growth (FDG) behavior. To accurately determine the critical Gcf, which characterizes the real changing resistance against delamination growth, a novel model is proposed from a viewpoint of energy. This model also allows the judgement on the numerical equivalence between the Gcf and fracture toughness Gc in a simple way. Well-designed delamination tests under mode I loading were carried out to validate the model. Significant R-curve effects on the FDG behavior due to fiber bridging and the bridging difference between static and fatigue delamination at the same delamination length were observed. The calculated result of Gcf has a really good agreement with that obtained by the compliance method, which indicates that fatigue delamination resistance can be accurately determined by using the present model.
       
  • Effects of aspect ratio and crystal orientation of cellulose nanocrystals
           on properties of poly(vinyl alcohol) composite fibers
    • Abstract: Publication date: 20 October 2018Source: Composites Science and Technology, Volume 167Author(s): Shikha Shrestha, Francisco Montes, Gregory T. Schueneman, James F. Snyder, Jeffrey P. Youngblood This work reports a study on the effects of different types and aspect ratios of cellulose nanocrystals (CNCs) on properties of poly (vinyl alcohol) (PVA) composite fibers. CNCs were extracted from wood pulp and cotton and reinforced into PVA to produce fibers by dry-jet-wet spinning. The fibers were collected as-spun and with the first stage drawing up to draw ratio 2. The elastic modulus and tensile strength of the fibers improved with increasing CNC content (5–15 wt. %) at the expense of their strain-to-failure. It was also observed that the mechanical properties of fibers reinforced with cotton CNC were higher than the fibers with wood CNC at the same amount of CNCs due to their higher aspect ratio. The degree of orientation along the spun fiber axis was quantified by 2D X-ray diffraction. As expected, the CNC orientation correlates to the mechanical properties of the fibers. Micromechanical models were used to predict the fiber performance and compare with experimental results. Finally, surface and cross-sectional morphologies of fibers were analyzed by scanning electron microscopy and optical microscopy.
       
  • Buckling load prediction of grid-stiffened composite cylindrical shells
           using the vibration correlation technique
    • Abstract: Publication date: 20 October 2018Source: Composites Science and Technology, Volume 167Author(s): Davoud Shahgholian-Ghahfarokhi, Gholamhossein Rahimi The vibration correlation technique (VCT) is one of the most important nondestructive methods to calculate the buckling load of imperfection sensitivity in thin-walled structures. VCT is widely used for beam and plate structures, but the technique is still under development for thin-walled shells. In this paper, an experimental and numerical validation of VCT approach was presented and discussed for the prediction of the buckling load of the grid-stiffened composite cylindrical shells loaded in compression. From the experimental point of view, three specimens were fabricated using a new silicone rubber mold, and specially-designed filament winding setup. The modal behavior of the grid-stiffened composite cylindrical shells was investigated by exciting the structures using modal hammer method in different applied compression load. Then, the variation of the first natural frequency of vibration with the applied compressive load was measured up to buckling during testing. Furthermore, a series of Finite Element Models (FEMs), including nonlinear effects such as geometric and thickness imperfection, are carried out in order to characterize the variation of the natural frequencies of vibration with the applied load and also compare it with the experimental results. Finally, the buckling test was performed to validate the experimental and numerical results of VCT approach. The results showed that the difference between the predicted buckling load using the VCT approach on the experimental results and numerical results with an experimental buckling load is 3.1% and 5.0%, respectively. Also, the current VCT approach has a very good correlation for grid-stiffened composite cylindrical shells when the maximum applied load is higher than 68% of the experimental buckling load.
       
  • Compression properties of composite laminates reinforced with rectangular
           z-pins
    • Abstract: Publication date: 20 October 2018Source: Composites Science and Technology, Volume 167Author(s): Julian Hoffmann, Gerhard Scharr This paper presents an experimental study investigating the static and fatigue compression properties of unidirectional and quasi-isotropic carbon fiber/epoxy laminates reinforced with rectangular and circular z-pins. The insertion of z-pins did not affect the compression modulus of the specimens, but all z-pinned laminates demonstrated a significantly reduced compression strength compared to unpinned specimens. Rectangular z-pins that were aligned lengthwise to the fiber direction of the laminate ply were observed to cause minor microstructural damages, such as in-plane fiber waviness. Therefore, the use of rectangular z-pins led to a minor reduction of the compression strength in both unidirectional and quasi-isotropic laminates. Especially for a small number of load cycles, the insertion of z-pins resulted in a decrease in the fatigue performance of the tested unidirectional and quasi-isotropic laminates. Since this deterioration was primarily caused by the initial knockdown of the static compression strength of the z-pinned laminates, rectangular z-pins showed superior fatigue performance in both unidirectional and quasi-isotropic laminates.
       
  • Fabrication of epoxy functionalized MWCNTs reinforced PVDF nanocomposites
           with high dielectric permittivity, low dielectric loss and high electrical
           conductivity
    • Abstract: Publication date: 20 October 2018Source: Composites Science and Technology, Volume 167Author(s): Saddiqa Begum, Hameed Ullah, Ayesha Kausar, Mohammad Siddiq, Muhammad Adeel Aleem Nanocomposites of Polyvinylidene Flouride (PVDF) with Multi-walled Carbon Nanotubes (MWCNTs) possess excellent thermal, piezoelectric and conductive behaviors. However, the potential of MWCNTs as filler in polymer composites is hampered by their poor dispersion into the matrix, corresponding to the strong inter-tubular and weak inter tubular-polymer chain interactions. This issue is successfully overcome by utilizing di-glycidyl ether of bisphenol-A (DGEBA) grafted MWCNTs (DG-MWCNTs) as reinforcement in PVDF matrix. To synthesize the desired nanocomposites, the easier to manipulate, solution casting technique was employed. The resulting PVDF/DG-MWCNTs nanocomposites have different loadings of filler ranging from 1.0 wt% to 10 wt%, and have shown variation in the phase transformation from α-phase to β-phase along with improvements in thermal and dielectrical behaviors. It was revealed by the impedance spectroscopy (IS) that the reinforcement of PVDF with DG-MWCNTs leads to an increase in the dielectric permittivity. This increase was found higher enough to reach up to ∼5288 (at ∼100 Hz) and 214 (at ∼102 Hz) for filler loading of 10 wt %. The increase is several hundreds of magnitude i.e., ∼204 at ∼102 Hz higher than the PVDF matrix, while retaining a low level conductivity (4.18 × 10−6 S/cm). This enhancement in the dielectric permittivity is attributed to the strong interfacial interaction between PVDF and DG-MWCNTs, and was explained by the Maxwell-Wagner-Sillar (MWS) effect.
       
  • Analysis of the effect of manufacturing imperfections in the elastic
           properties of platelet nanocomposites
    • Abstract: Publication date: 20 October 2018Source: Composites Science and Technology, Volume 167Author(s): J.M. Munoz-Guijosa, G. Fernández-Zapico, H. Akasaka, E. Chacón We have developed and validated a conceptually simple model capable of predicting the macroscale elastic properties of a platelet nanocomposite. The model allows for studying the individual and combined effect of the parameters with influence on those properties, namely nanofiller weight fraction, misalignment, dispersion quality, size distribution and nanofiller-matrix interfacial characteristics. The model shows a very good correlation with experimental results. The interfacial characteristics under different strain states are evaluated at the nanoscale by means of a cohesive model which considers out-of-plane strains and angular distortions, so that the full, strain-dependent elastic tensor can be calculated, allowing for homogenization and subsequent study of the effect of filler orientation, dispersion quality and size distribution on the elastic properties at the macroscale. The use of a low complexity nanoscale model allows us to conceptually and quantitatively explain the causes underlying the divergences between the expected and experimental macroscale material stiffness experimentally found by different researchers.
       
  • Design of shape-memory materials based on sea-island structured EPDM/PP
           TPVs via in-situ compatibilization of methacrylic acid and excess zinc
           oxide nanoparticles
    • Abstract: Publication date: 20 October 2018Source: Composites Science and Technology, Volume 167Author(s): Chuanhui Xu, Wenchao Wu, Zhongjie Zheng, Zhiwei Wang, Jiada Nie It is a challenge to achieve considerable shape-memory (SM) effect for typical sea-island structured polymer blends. In this paper, we successfully realized the SM behavior for classical ethylene-propylene-diene rubber/polypropylene (EPDM/PP) thermoplastic vulcanizates (TPVs) through a strong rubber/plastic interface compatibilized by in-situ formed zinc dimethacrylate (ZDMA) which came from methacrylic acid (MAA) and excess zinc oxide (ZnO) nanoparticles. With MAA/ZnO, the average size of EPDM particles reduced to 400–500 nm, which significantly enlarged EPDM/PP interfacial contact surfaces. The enhanced interface improved the efficiency of stress delivery between PP and EPDM phases, which was critical to fulfill the SM behavior. At the same time, residual ZnO nanoparticles stressed a reinforcement on EPDM phase and PP phase, which further improved the shape recovery (SR) and shape fixing (SF) of TPVs. Enhanced tensile strength (∼9.1 MPa) and Young’ modulus (∼380 MPa), improved SF (∼99%) and SR (∼98%) of TPVs were achieved by tailoring the content of residual ZnO nanoparticles (MAA/ZnO = 2:1.3) and the shape deformation temperature (120 °C).Graphical abstractImage 1
       
  • Recyclable and heat-healable epoxidized natural rubber/bentonite
           composites
    • Abstract: Publication date: 20 October 2018Source: Composites Science and Technology, Volume 167Author(s): Chuanhui Xu, Rui Cui, Lihua Fu, Baofeng Lin Conventional crosslinking endows rubbers with excellent mechanical properties, at the same time, turn them to be thermosets with the impossibility of recycling and self-healing. From the perspective of sustainable development of material, it is crucial and meaningful to integrate these charming properties into crosslinked commercial rubbers. In this paper, we prepared a recyclable and healable epoxidized natural rubber (ENR)/citric acid-modified bentonite (CABt) composite. CABt with numerous carboxyls on surface served as cross-linker to covalently crosslink ENR through exchangeable β-hydroxyl ester linkages, as well as efficient reinforcer for ENR. Because of the transesterification reactions of β-hydroxyl ester linkages between CABt and ENR, ENR/CABt composites could alter the network topology at elevated temperature. Meanwhile, the low crosslink degree of network and inherent stickiness of ENR matrix facilitated chain diffusion and transesterification reactions of β-hydroxyl ester linkages, which made ENR/CABt composites recycled and healed. Thus, we envision that our work would open up new avenues to design more crosslinked rubber composites showing recyclable, healable and adaptable abilities.Graphical abstractImage 1
       
  • A viscoelastoplastic stiffening model for plant fibre unidirectional
           
    • Abstract: Publication date: 20 October 2018Source: Composites Science and Technology, Volume 167Author(s): F. Richard, C. Poilâne, H. Yang, F. Gehring, E. Renner At room conditions and standard strain rate (ε˙∼10−4s−1), unidirectional (UD) plant-based reinforced organic polymers often exhibit nonlinear mechanical behaviour in tension. A viscoelastoplastic model (VEP model) for the simulation of UD plant fibre composite mechanical behaviour in tension, previously validated from twisted flax yarn epoxy composite under room conditions and standard strain rate, is calibrated with new data obtained from flax fibre epoxy composite under repeated progressive loading and a wide range of strain rates (ε˙∼10−3 to 10−7s−1). The VEP model does not reproduce well the experimental observations. There seems to be a lack of stiffening in this phenomenological model.We propose an improved VEP model, developed within the frameworks of thermodynamics and limited to uniaxial tension and infinitesimal strains. An internal variable s representing the stiffening is added to create a VEP-stiffening model. This internal variable represents the coupled effects of reorienting cellulose microfibrils in kink band areas, spiral spring-like extension of cellulose microfibrils, and shear-stress-induced crystallization of the amorphous cellulose of flax fibres. The stiffening phenomenon was considered viscous, without a threshold, and was related to the tension energy in the direction of the fibres. Three viscosity coefficients drive the three phenomena: η (elastic), K (plastic), and Ks (stiffening). In the chosen formalism, this leads to two thermodynamic potentials φVEPs and ΩVEPs in which the stiffening phenomenon is strongly coupled with all the others.This VEP-stiffening model of the UD flax fibre epoxy composite correlates well with experimental observations. The paper also explores the evolution of the three viscous phenomena (elastic, plastic, and stiffening) by simulation of different loading conditions: monotonic, cyclic, and creep.This VEP-stiffening model can easily enrich existing multiaxial models of UD behaviour in the fibre direction. Implemented in a finite element model, it could be used at different length scales to numerically explore the origin of the mechanical behaviour of plant-based reinforced polymers.
       
  • Thermo-mechanical coupling analysis of transient temperature and rolling
           resistance for solid rubber tire: Numerical simulation and experimental
           verification
    • Abstract: Publication date: Available online 29 August 2018Source: Composites Science and TechnologyAuthor(s): Fanzhu Li, Feng Liu, Jun Liu, Yangyang Gao, Yonglai Lu, Jianfeng Chen, Haibo Yang, Liqun Zhang The achievement of low rolling resistance and long-term durability of tires on various vehicles is of great challenge. Tire performances heavily depend on rubber properties; however, the thermo-mechanical coupling characteristics of rubber composites are complicated rendering the design of high-performance tires time-consuming and costly. In our research, the transient temperature and rolling resistance of a solid rubber tire were performed based on the thermo-mechanical coupling approach and nonlinear viscoelastic theory by using finite element method. Particular attention was paid to the strain cycles as the tire rolling on the road presents non-sinusoidal deformation. First, a static three dimensional tire-road contact analysis was conducted to obtain the principal strain cycles. Second, the 100th-order Fourier sine series was used to approximate the strain amplitude. Third, the heat generation rate proportional to the product of the loss modulus and the square of strain amplitude was calculated. The loss modulus was updated as a function of strain amplitude, temperature and frequency. Loss modulus softening effect was also considered. A practical method was proposed to compute the rolling resistance and transient temperature distributions by establishing a 2-D axisymmetric model. A rubber rolling tester was used to verify the numerical results. The comparison between numerical data and test data reveals that the proposed analytical method is a reliable approach to predict rolling resistance and transient temperature distribution for rubber tires. At last, the dependence of rolling resistance and heat build-up on thermal conductivity and loss factor were investigated by the parametric numerical experiments.
       
  • Functional polycarbonates for improved adhesion to carbon fibre
    • Abstract: Publication date: Available online 29 August 2018Source: Composites Science and TechnologyAuthor(s): Jan Henk Kamps, Christina Scheffler, Frank Simon, Ruud van der Heijden, Nikhil Verghese In order to improve the fibre-matrix interaction in carbon fibre reinforced composites the polycarbonate (PC) matrix polymer was modified by the introduction of ethyl-3,5-dihydroxybenzoate as reactive sequences in the polycarbonate backbone. This promising strategy can be considered as an alternative approach to the modification of the carbon fibre surface to control and tailor the adhesion between carbon fibres and polymer matrix. The modification of the polycarbonate demonstrated improved adhesion to carbon fibre in pressed films, which was observed with microscopy-ATR-FTIR and SEM when compared to unmodified polycarbonate. Single fibre pull-out testing subsequently confirmed the improved adhesion, demonstrating higher interfacial shear strenght for the functionalized polycarbonate.
       
  • Electrically insulating, layer structured SiR/GNPs/BN thermal management
           materials with enhanced thermal conductivity and breakdown voltage
    • Abstract: Publication date: Available online 29 August 2018Source: Composites Science and TechnologyAuthor(s): Chang-Ping Feng, Shen-Shen Wan, Wei-Chun Wu, Lu Bai, Rui-Ying Bao, Zheng-Ying Liu, Ming-Bo Yang, Jun Chen, Wei Yang Layer structured high-performance thermal management materials via integrating the advantages of boron nitride (BN, electrically insulating) and graphene nanoplateles (GNPs, highly thermally conductive) as fillers were realized by a facile and scalable strategy. Outstanding thermal conductivity (TC) of 8.45 W m−1 K−1, the highest value among reported electrically insulating polymer-based materials, excellent electrical insulation (breakdown voltage∼5.33 kV/mm; volume resistance ∼1012Ωcm) and superior electromagnetic interface shielding performance are achieved at a filler loading of 17.88 vol%. Moreover, the mechanical properties and hardness are also in quite good range. Thus, a promising method is provided for large scale production of superior thermal management materials.
       
  • Natural weathering of hemp fibers reinforced polypropylene biocomposites:
           Relationships between visual and surface aspects, mechanical properties
           and microstructure based on statistical approach
    • Abstract: Publication date: Available online 27 August 2018Source: Composites Science and TechnologyAuthor(s): Célia Badji, Joana Beigbeder, Hélène Garay, Anne Bergeret, Jean-Charles Bénézet, Valérie Desauziers Two natural weathering of neat polypropylene (PP) and hemp fibers reinforced PP biocomposites were investigated. The objective was to emphasize the relationships between the properties of materials according to the fiber loading and the weathering time in order to bring new insights of degradation mechanisms understanding. For this purpose, a Principal Component Analysis (PCA) method was applied to the dataset. The treatment carried out by isolating materials loaded by the three different hemp fiber rates particularly outstand the link between mechanical properties and products issued from oxidation. The close correlation between whitening parameter and C=C bond level also confirmed the lignin degradation way. Finally, depending on the weathering duration, the properties characterized either fiber loading or weathering state (unweathered or weathered) whereas mechanical performance differentiated the three different non-weathered samples whatever the exposure time.
       
  • A rigid thick Miura-Ori structure driven by bistable carbon
           fibre-reinforced polymer cylindrical shell
    • Abstract: Publication date: Available online 27 August 2018Source: Composites Science and TechnologyAuthor(s): Zheng Zhang, Weili Ma, Helong Wu, Huaping Wu, Shaofei Jiang, Guozhong Chai Origami, the art of folding paper, has inspired the development of rigid foldable structures for various applications in aerospace, biomedical, and packaging applications. In order to drive and control origami structure with thick panels, a novel rigid Miura-Ori structure with bistable anti-symmetric carbon fibre reinforced polymer (CFRP) shells was proposed in this paper. Based on the membrane hinge technique, a theoretical model of the Miura-Ori structure with thick panels combined with bistable CFRP shells was established based on the principle of minimum potential energy. Bistable CFRP shells were used as the connection and driving parts of the whole structure instead of thin-walled materials or hinged structures. Finite element simulations were conducted to explore the deformations and trigger forces. The coincident boundary conditions were provided, which were the same as those used in the compression tests using the universal tensile testing machine. Experiments were conducted to validate the simulation results. The results showed that there is good agreement between the simulation and experimental results, indicating that the bistability of the origami structure is achieved under the control of the CFRP cylindrical shells.
       
  • Carbon fibre reinforced thermoplastic composites developed from innovative
           hybrid yarn structures consisting of staple carbon fibres and polyamide 6
           fibres
    • Abstract: Publication date: Available online 24 August 2018Source: Composites Science and TechnologyAuthor(s): M.M.B. Hasan, S. Nitsche, A. Abdkader, Ch Cherif With the increased demand and usage of carbon fibre reinforced composites (CFRP), effective methods to reuse waste carbon fibres (CF), which are recoverable either from manufacturing waste or from end-of-life components, are attracting growing attention. In this paper, the development of innovative core-sheath hybrid yarn structures consisting of staple CF and polyamide 6 (PA 6) fibres of 60 mm lengths using a DREF-3000 friction spinning machine with varying machine parameters, such as core to sheath ratio and suction air pressure, is described. Furthermore, uni-directional (UD) CFRP were manufactured based on the developed hybrid yarns, and the influence of the processing parameters on tensile properties and CF content of the composites was analysed. UD composites manufactured from the developed hybrid yarns possess approximately at least 86% of the tensile strength and Young's modulus of composites produced from virgin CF filament yarn.
       
  • Comparison of different surface treatments of carbon fibers used as
           reinforcements in epoxy composites: Interfacial strength measurements by
           in-situ scanning electron microscope tensile tests
    • Abstract: Publication date: Available online 22 August 2018Source: Composites Science and TechnologyAuthor(s): Yu Liu, Delong He, Ann-Lenaig Hamon, Benhui Fan, Paul Haghi-Ashtiani, Thomas Reiss, Jinbo Bai In-situ characterization of the fiber/matrix interfacial failure behavior at microscopic scale is important to optimize the fiber surface treatment and to design high performance composites. In this study, in-situ tensile tests in scanning electron microscope (SEM) were used to investigate the interfacial adhesion strength of epoxy composites reinforced by four kinds of carbon fibers (CF)—raw CF, desized CF, carbon nanotube-grafted CF (CNT-CF) and oxidized CNT-CF. The crack initiation position and fracture failure mode were well recorded. The strains and the interfacial adhesion strength were obtained for these four kinds of composites. It was found that the interfacial strength decreased from 53 MPa to 48 MPa after removing the sizing on carbon fiber surface. However, by grafting CNTs on the CF surface, the interfacial strength reached 55 MPa and was further increased to 58 MPa after a simple thermal oxidation treatment. Moreover, energy dispersion X-ray analysis (EDX) was carried out using scanning transmission electron microscopy (STEM). The EDX mapping demonstrated that oxygen aggregated at the interfaces of raw CF/epoxy and oxidized CNT-CF/epoxy. Thus, a combination of CNT grafting with chemical functionalization should be necessary to achieve high performance carbon fiber reinforced polymer composites.
       
  • Highly sensitive and stretchable graphene-silicone rubber composites for
           strain sensing
    • Abstract: Publication date: Available online 21 August 2018Source: Composites Science and TechnologyAuthor(s): Heng Yang, XueFeng Yao, Zhong Zheng, LingHui Gong, Li Yuan, YaNan Yuan, YingHua Liu Flexible strain sensors made by conductive elastomer composites have attracted increasing attention. In this paper, the electromechanical properties of graphene-silicone rubber nanocomposites are studied systematically. First, the conductive nanocomposites composed of graphene and silicone rubber are prepared by means of co-coagulation, which shows a lower percolation threshold with 1.87 wt% (0.94 vol%). Second, the rubber nanocomposites with different graphene contents exhibit a very high strain sensitivity (gauge factor > 143) and a larger strain sensing range (>170%), also, the good recoverability and reproducibility have been found during the loading-unloading cycle. Finally, the analytical model based on the connectivity of the graphene nanosheets and the viscoelasticity of the rubber matrix is developed to describe the electromechanical properties and explain the ‘shoulder peak’ phenomenon, also a typical application example about monitoring the operate state of the rubber seal is given.
       
  • Mechanical reinforcement in poly(propylene carbonate) nanocomposites using
           double percolation networks by dual volume exclusions
    • Abstract: Publication date: Available online 21 August 2018Source: Composites Science and TechnologyAuthor(s): Shanshan Lin, Benke Li, Tingting Chen, Wei Yu, Xianhong Wang Poly(propylene carbonate) (PPC) nanocomposites with poly(lactic acid) (PLA) and sepiolite nanofibers (NF) double percolation networks were prepared according to the dual volume exclusions principle. A two-step melt mixing with annealing process was adopted to construct the double percolation networks, which were verified by rheological and morphological characterization. The formation of double percolation networks structure effectively increased both the mechanical properties and heat resistance of PPC due to the greatly improved efficiency of the formation of force transferring network of NF. As a result, the PPC/PLA/NF ternary nanocomposites with double percolation networks exhibited elastic modulus about three orders higher than that of the pure PPC at 100 °C. The thermal deformation temperature, evaluated from the modulus at the glass transition of pure PPC (0.1 GPa), was found to be above 100 °C.
       
  • Influence of chitin nanocrystals on the dielectric behaviour and
           conductivity of chitosan-based bionanocomposites
    • Abstract: Publication date: Available online 21 August 2018Source: Composites Science and TechnologyAuthor(s): A.M. Salaberría, R. Teruel-Juanes, J.D. Badia, S.C.M. Fernandes, V. Sáenz de Juano-Arbona, J. Labidi, A. Ribes-Greus A series of bionanocomposite films based on chitosan, reinforced with chitin nanocrystals, were developed, and assessed in terms of dielectric behavior and conductivity by using an experimental methodology that allows avoiding the conductivity contribution and the exclusion of contact and interfacial polarization effects. The dielectric relaxations at low and high frequency and temperatures were modeled by Havriliak-Negami functions. Below the glass transition temperature (Tg), the γ and β relaxations were observed, which were related to intramolecular and non-cooperative segmental movements. At higher temperatures, an intermolecular and cooperative macromolecular movement, related to the glass transition, gave rise to α-relaxation. In addition, two over-Tg ρI and ρII relaxations were found, which were related to the displacement of dipoles in the disordered structure of bionanocomposites. The addition of chitin nanocrystals did not affect the apparent activation energy Ea of the γ-relaxation. However, it decreased the Ea of the β-relaxation and increased the free volume at temperatures in the vicinities of the α-relaxation. Finally, the electric conductivity of the bionanocomposites was lower than that of neat chitosan and chitin due to the interaction between the -OH and -NH2 groups that reduced the ionic mobility, along with the increase of free volume, with the subsequent separation of phases.
       
  • Self-healing improves the stability and safety of polymer bonded
           explosives
    • Abstract: Publication date: Available online 20 August 2018Source: Composites Science and TechnologyAuthor(s): Xin Huang, Zhong Huang, Jian-Cheng Lai, Lei Li, Guang-Cheng Yang, Cheng-Hui Li Polymer-bonded explosives (PBXs) are often subjected to different external environmental conditions with various temperature and humidity during long-term storage, transportation, and usage process. The change in temperature and humidity will result in PBXs cracks formation and cause higher risk of explosion evolution when undergoing various stimulus including impact or friction. Herein, a self-healing polymer binder is developed to solve this problem. The fluoropolymer gel binder, a PVDF-co-HFP (copolymer of CH2-CF2 and CF2-CF(CF3))/EMIOTf (1-ethyl-3-methylimidazolium trifluoromethanesulfonate)/graphene ternary composite, has high density, high thermal conductivity, excellent interfacial adhesion property, and exhibits self-healing ability at room temperature. Highly filled PBXs composites with 95% of explosive 2, 6-diamino-3, 5-dinitropyrazine-1-oxide (LLM-105) and 5% of ternary composite are fabricated. The as-prepared PBX samples have high denotation parameter (7800 m s−1), low impact sensitivities (11–12 J), and low friction sensitivity (no sparks was observed even at friction energy load of 0.36 N). More importantly, our PBXs have effective crack healing ability within 48 h at room temperature. Therefore, the stability and safety of PBXs are improved through the self-healing polymer binder. Such PBXs can find widespread application in various military and civil fields.
       
  • Counterion design of TEMPO-nanocellulose used as filler to improve
           properties of hydrogenated acrylonitrile-butadiene matrix
    • Abstract: Publication date: Available online 19 August 2018Source: Composites Science and TechnologyAuthor(s): Shunsuke Fukui, Takuro Ito, Tsuguyuki Saito, Toru Noguchi, Akira Isogai A nanocellulose containing carboxylate groups was prepared from cellulose by catalytic oxidation with the 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO). The aqueous TEMPO-oxidized cellulose nanofibrils (TOCNs) with lithium (Li+), sodium (Na+) or tetraalkylammonium (+NR4) counterions (TOCN-X) were mixed with aqueous hydrogenated acrylonitrile–butadiene rubber (H-NBR) latex, and TOCN-X/H-NBR composite films were prepared by casting and drying. All of the composite films are transparent and flexible. The TOCN-Na/H-NBR (TOCN/H-NBR = 5/100, w/w) composite film has a high Young's modulus of ∼63 MPa, a high storage elastic modulus of 112 MPa at 25 °C, and a low coefficient of thermal expansion (CTE) of 122 ppm/K, whereas the neat H-NBR film has the values o 5.3 MPa, 2 MPa, and 2660 ppm/K, respectively. Microscopy images show that the hydrophilic TOCN-Na elements form grid-like network structures surrounding the hydrophobic H-NBR latex particles. Thus, the hydrophilic TOCN-Na elements cannot penetrate into hydrophobic H-NBR molecules, and the TOCN-Na elements are not homogeneously distributed in the TOCN/H-NBR composite films prepared under the conditions used in this study. Nevertheless, clear improvement of thermal and mechanical properties is achieved for the TOCN/H-NBR composite films at TOCN/H-NBR weight ratios of 1–5/100. TOCN-Li/H-NBR film has the highest Young's modulus, while the hydrophobic TOCN-NR4/H-NBR films have low CTE values 
       
  • All-organic dielectric nanocomposites using conducting polypyrrole
           nanoclips as filler
    • Abstract: Publication date: Available online 18 August 2018Source: Composites Science and TechnologyAuthor(s): Lin Zhang, Xu Lu, Xinyu Zhang, Li Jin, Zhuo Xu, Z.-Y. Cheng All-organic nanocomposites using conducting polypyrrole (PPy) nano-clips as fillers and poly(vinylidene fluoride-chlorotrifluoroethylene) (PVDF-CTFE) as the matrix are studied. The nanocomposites with a uniform microstructure were fabricated via a combination of a solution casting and a hot pressing process. Due to the uniform microstructure, the composites exhibit a single glass transition process, whose temperature decreases with increasing PPy content. The dielectric properties of the nanocomposites are systemically studied and analyzed over a wide temperature range from −60 °C to 140 °C and a broad frequency range from 100 Hz to 1 MHz. The nanocomposites have a low percolation threshold (∼7.4 wt.%) and exhibit a high dielectric constant and a low dielectric loss. For the composites with 7 wt.% of PPy at room temperature, the dielectric constant at 1 kHz is 23 times higher than that of the polymer matrix and the dielectric loss over a broad frequency range is less than 0.4 which is lower than the loss reported in other composites with the composition close to the percolation threshold. It is concluded that mixing PPy with P(VDF-CTFE) results in a new relaxation process that dominates the observed dielectric loss at low temperatures including room temperature. It is demonstrated that it is the DC conductivity rather than the dielectric constant that should be used to determine the percolation threshold.
       
  • Preparation of carboxylated nitrile butadiene rubber/fly ash composites by
           in-situ carboxylate reaction
    • Abstract: Publication date: Available online 18 August 2018Source: Composites Science and TechnologyAuthor(s): Shuyan Yang, Ping Liang, Kaihui Hua, Xiaokang Peng, Yanxue Zhou, Zhuodi Cai Fly ash (FA) is a byproduct of thermal power stations, which causes increasing environment pollutions in the last decade. The incorporation of FA would deteriorate the performance of polymer composites even modified by silane coupling agents. Thereby, the bulk utilization of FA in polymer industry is still a challenge in the world. In this work, by in-situ carboxylate reaction between carboxyl groups of carboxylated nitrile butadiene rubber (XNBR) and FA particles, an immobilized rubber layer is formed on the surface of FA particles, resulting in a better interface adhesion. As a consequence, the tensile strength of XNBR/20FA composite reaches 23.19 MPa, about 44.0% larger than pure XNBR. Even if the incorporation of FA is up to 40phr, the tensile strength is still about 20.60 MPa, about 28.0% larger than pure XNBR, which opens a new approach to lower polymer product cost and solve the environment pollution.
       
  • Effect of nano-silica filler on microstructure and mechanical properties
           of polydimethylsiloxane-based nanocomposites prepared by
           “inhibition-grafting” method
    • Abstract: Publication date: Available online 18 August 2018Source: Composites Science and TechnologyAuthor(s): Jian Liu, Yu Cheng, Kai Xu, Lulu An, Yuhang Su, Xiaohong Li, Zhijun Zhang Silica/polydimethylsiloxane nanocomposites (denoted as SiO2/PDMS) prepared by physical mixing exhibit poor processing flexibility and strength associated with the high viscosity effect and low addition amount of silica during the fabrication of room-temperature vulcanized PDMS elastomer. Thus a facile and scalable one-step “inhibition-grafting” method was established to graft polydimethylsiloxane (PDMS) onto the surface of DNS-2 (a kind of dispersible nano-silica with network structure) to yield nano-SiO2/PDMS high-performance nanocomposites. Their microstructure and chemical structure were characterized by TEM, GPC, FTIR and TGA. The viscosity and rheological properties were evaluated, and their mechanical properties of the as-prepared nano-SiO2/PDMS elastomers were measured as well. Findings indicate that PDMS chains are grafted on the silica surface via covalent bonding and the chains either grafted on the silica or in free state interpenetrated silica network thereby forming a kind of interpenetrating network. This kind of interpenetrating network and short PDMS chains can provide more crosslinking sites, leading to low viscosity and high mechanical properties of SiO2/PDMS composites. Besides, the nano-SiO2/PDMS elastomers containing over 16 phr (phr: parts of silica per hundred parts of PDMS by weight) of nano-silica exhibit shear thinning behavior, which corresponds to the transformation from Newtonian fluids to non-Newtonian fluids associated with the formation of whole interpenetrating network between nano-silica and PDMS chains. In summary, the nano-SiO2/PDMS elastomers exhibit a low viscosity and good mechanical properties, which is favorable for promoting their applications in the industry of high performance silicone materials.
       
  • The effects of polybenzimidazole and polyacrylic acid modified carbon
           black on the anti-UV-weathering and thermal properties of polyvinyl
           chloride composites
    • Abstract: Publication date: Available online 17 August 2018Source: Composites Science and TechnologyAuthor(s): Dandan Jin, Shiai Xu In this study, the effects of polybenzimidazole (PBI) and polyacrylic acid (PAA) modified carbon black (MCB) on the anti-UV-weathering and thermal properties of PVC composites were investigated. The optimal mass ratios of PBI and MCB to PVC are 0.1 wt% and 0.2 wt%, respectively, and the resultant 1PBI/2MCB/PVC composite membrane with a thickness of about 60 μm can block over 99% of UV light below 380 nm. The UV absorption mechanism was investigated by the optional band gaps (Eg) and the fluorescence spectra. The incorporation of PBI and MCB results in a decrease in Eg, from 4.96 eV for PVC membrane to 2.90 eV for 1PBI/2MCB/PVC composite membrane, and MCB can quench the fluorescence of PBI by photon-induced electron transfer to further protect PVC. The results of accelerated UV-weathering experiment indicate that the incorporation of PBI and MCB can improve the anti-UV-weathering property of PVC. The thermal degradation behaviors of PVC and its composite membranes in air and N2 atmosphere were also investigated. The highest char residue (13.7 wt%) is obtained in 1PBI/2MCB/PVC composite membrane at 800 °C in N2 atmosphere, with an increase of 73.4% compared with that of PVC membrane, which may be because PBI and MCB can synergistically accelerate the carbonization of PVC molecules to rapidly form stable char residue.
       
  • Extremely high thermal conductivity of nanodiamond-polydopamine/thin-layer
           graphene composite films
    • Abstract: Publication date: Available online 16 August 2018Source: Composites Science and TechnologyAuthor(s): Hui-Ching Yuan, Chi-Young Lee, Nyan-Hwa Tai The hybrid composite films containing nanodiamonds (ND) coated with polydopamine (pDA) (ND-pDA) and reduced graphene oxide (rGO) converted from graphene oxide (GO) films are designed for achieving extremely high thermal conductivity. The ND-pDA/rGO films are successfully fabricated using the vacuum-filtration process followed by a heat treatment at 800 °C. The thermal conductivities of the films in the in-plane (K//) and through-plane (K⊥) directions are measured by the laser flash method to better understand how the addition of dopamine, the amount of ND-pDA, and the test temperature affect the thermal properties of the hybrid films.The experimental results show that the addition of dopamine results in dense structure of the ND-pDA/rGO hybrid films, which is favorable for phonon transport, and thus remarkably increase the thermal properties of the film. Additionally, films with higher ND-pDA loading possess lower in-plane but higher through-plane thermal conductivity. K// and K⊥ of 1406 and 0.677 W m−1 K−1, respectively, for 20ND-pDA/20rGO measured at 25 °C are achieved. Both the K// and K⊥ of 20ND-pDA/20rGO increase with test temperature. Maintaining such high thermal conductivities at high temperature, the hybrid films are believed to be suitable for lightweight thermal management materials with high heat transfer properties in a specific direction.
       
  • Great toughness reinforcement of isotactic polypropylene/elastomer blends
           with quasi-cocontinuous phase morphology by traces of β-nucleating agents
           and carbon nanotubes
    • Abstract: Publication date: Available online 15 August 2018Source: Composites Science and TechnologyAuthor(s): Yanhui Chen, Zhiqiang Wu, Qian Fan, Song Yang, Erchao Song, Qiuyu Zhang Aiming at obtaining the polyolefin blends potentially applied in the field of the super-tough polymer products, in this work, isotactic polypropylene (iPP)/styrene-ethylene-butadiene-styrene block copolymer (SEBS) blends with great impact toughness were successfully fabricated by adding traces of β-nucleating agents (β-NAs) and carbon nanotubes (CNTs). The impact toughness of iPP blends with 30 wt% SEBS was as high as 62.4 kJ/m2, when simultaneously containing 0.1 wt% β-NAs and 0.05 wt% CNTs. Their toughness was about 13.1 kJ/m2 more than iPP blends with 30 wt% SEBS and 0.1 wt% β-NAs, 49.6 kJ/m2 more than iPP blends with 30 wt% SEBS and 0.05 wt% CNTs, and almost 22.3 times of pure iPP. The iPP matrix with abundant self-toughed β-crystals generated by β-NAs, the quasi-cocontiunous morphology of the SEBS dispersed phase as well as some small SEBS droplets induced by CNTs in the iPP matrix, and the good interfacial compatibility between SEBS and the iPP matrix all harmoniously took effect to synergistically enhance the toughness of iPP blends.
       
  • A new method to prepare composite powders customized for high temperature
           laser sintering
    • Abstract: Publication date: 20 October 2018Source: Composites Science and Technology, Volume 167Author(s): Bahareh Yazdani, Binling Chen, Luiza Benedetti, Richard Davies, Oana Ghita, Yanqiu Zhu Composites have the potential to enhance the mechanical properties of components fabricated by additive manufacturing; however, the bottleneck is the limited number of polymeric composite powders available for this manufacturing process. This paper describes a generically new method to create composite powders that are suitable for High Temperature Laser Sintering (HT-LS). C-coated Inorganic Fullerene-like WS2 (IF-WS2) nanoparticles and graphene nanoplatelets (GNPs) have been chosen to demonstrate their incorporation into a high performance polymer matrix: Poly Ether Ether Ketone (PEEK). The morphological and physical property investigations have confirmed that the resulting composite powders exhibit the desired particle morphology, size, distribution and flowability for HT-LS applications. Further preliminary sintering results have demonstrated that they are comparable to the currently available commercial grade of PEEK powder HT-LS applications in terms of powder packing properties and flow ability. The new strategy reported here brings in great potential for the additive layer manufacturing of high performance polymeric composite components with improved mechanical and added functionalities by choosing the proper matrix and filler combination.
       
  • Micro-mechanical damage model accounting for composite material
           
    • Abstract: Publication date: Available online 13 August 2018Source: Composites Science and TechnologyAuthor(s): Ghazi A.F. Abu-Farsakh, Haitham M. Al-Jarrah A new micromechanical damage model for predicting the effect of matrix-cracking on the mechanical behavior of the composite material is proposed. The model is based on the volumetric change that occurred due to the presence of cracks in a composite lamina due to uniaxial off-axis loading. It determines the volumetric crack-density (VCD) by combining the macro-mechanical and micro-mechanical principles. A representative volume-element is proposed that determines the material mechanical properties (E1, E2, G12 and ν12) in terms of crack-density, fiber and matrix properties and initial volume-fraction of fibers. The rule-of-mixture in combination with Halpin-Tsai model is used to determine the mechanical properties of a cracked composite lamina. It has been shown that, matrix-cracking is the main cause for composite-material nonlinearity. Moreover, the model has been shown to give a reliable and reasonable predictions of the VCD and the tangential damage-factor (TDF) for various fiber/matrix systems using the corresponding available data from literature. An alternative secant damage-factor is being proposed, which has a linear relationship with the VCD. In order to validate the model, two composite materials; Boron/Epoxy (Narmco-5505) and Graphite/Epoxy (4617/Modmor-II), have been considered using laminates at different fiber-orientation angles. The maximum volume-crack-density (MVCD) and maximum secant damage-factor (MSDF) are obtained using equations that depend on the fiber-orientation angle and the initial material mechanical properties.
       
  • Enhanced fracture toughness in architected interpenetrating phase
           composites by 3D printing
    • Abstract: Publication date: Available online 11 August 2018Source: Composites Science and TechnologyAuthor(s): Tiantian Li, Yanyu Chen, Lifeng Wang Interpenetrating phase composite (IPC), also known as co-continuous composite, is one type of material that exhibits an unusual combination of high stiffness, strength, energy absorption, and damage tolerance. Here we experimentally demonstrate that IPCs fabricated by 3D printing technique with rationally designed architectures can exhibit a fracture toughness 16 times higher than that of conventionally structured composites. The toughening mechanisms arise from the crack-bridging, process zone formation and crack-deflection, which are intrinsically controlled by the rationally designed interpenetrating architectures. We further show that the prominently enhanced fracture toughness in the architected IPCs can be tuned by tailoring the stiffness contrasts between the two compositions. The findings presented here not only quantify the fracture behavior of complex architected IPCs but also demonstrate the potential to achieve tailorable mechanical properties through the integrative rational design and the state-of-the-art advanced manufacturing technique.
       
  • Largely enhanced mechanical property of segregated carbon
           nanotube/poly(vinylidene fluoride) composites with high electromagnetic
           interference shielding performance
    • Abstract: Publication date: Available online 11 August 2018Source: Composites Science and TechnologyAuthor(s): Wan-Cheng Yu, Tao Wang, Guo-Qiang Zhang, Zhi-Guo Wang, Hua-Mo Yin, Ding-Xiang Yan, Jia-Zhuang Xu, Zhong-Ming Li Conductive polymer composites (CPCs) with segregated structure exhibit outstanding electromagnetic interference (EMI) shielding performance at low filler loadings. However, the mechanical performance is compromised due to poor interfacial adhesion resulting from the selective distribution of conductive fillers. Herein, a simple and effective approach, i.e. solid-phase extrusion (SPE), was proposed to fabricate segregated carbon nanotube (CNT)/poly(vinylidene fluoride) composites with high mechanical performance. Morphology examination revealed that both the matrix and segregated conductive network were highly oriented along the extrusion direction under the forceful flow field of SPE. The resultant SPE composites showed an excellent electrical conductivity of 74.5 S/m and a high EMI shielding effectiveness of 36.8 dB with only 4 wt% CNTs. More notably, simultaneous enhancement of the strength and fracture toughness was achieved. Compared to the counterparts with conventional segregated structure, tensile strength and elongation at break of SPE composites were significantly increased by ∼100% and ∼900%, reaching 120–140 MPa and 60%, respectively. This work demonstrates a valuable approach to prepare high-performance CPCs for EMI shielding applications.Graphical abstractImage 1
       
  • Ultra-strong, tough and high wear resistance high-density polyethylene for
           structural engineering application: A facile strategy towards using the
           combination of extensional dynamic oscillatory shear flow and
           ultra-high-molecular-weight polyethylene
    • Abstract: Publication date: Available online 9 August 2018Source: Composites Science and TechnologyAuthor(s): Tong Liu, An Huang, Li-Hong Geng, Xing-Han Lian, Binyi Chen, Benjamin S. Hsiao, Tai-Rong Kuang, Xiang-Fang Peng General purpose plastic materials with high strength and toughness are in great demand for structural engineering applications in recent years. Inspired by the relationship of excellent integration of mechanical performance and hierarchically ordered shish-kebab structure of polymeric materials, a facile and efficient strategy based on the combined effect of strong extensional dynamic oscillatory shear flow and ultra-high-molecular-weight polyethylene (UHMWPE) was developed to fabricate ultra-strong, super-tough and high wear resistance integrated high-density polyethylene (HDPE)-based materials. As a result, the maximum value of tensile strength, modulus and toughness were respectively 3.8, 5.9 and 6.8 times higher than that of neat HDPE, even superior to that of most common engineering plastics. Meanwhile, the wear rate of resultant HDPE-based materials could be reduced from 18.6 to 4.2 mg/MC. Overall, the HDPE-based material with extraordinary integrated strong, tough and high wear resistance properties would have a great potential for the replacement of engineering plastics and application in aerospace, military, tissue engineering, etc.
       
  • Simultaneous enhancement of toughness, strength and superhydrophilicity of
           solvent-free microcrystalline cellulose fluids/poly(lactic acid) fibers
           fabricated via electrospinning approach
    • Abstract: Publication date: 20 October 2018Source: Composites Science and Technology, Volume 167Author(s): Xianze Yin, Yun Li, Puxin Weng, Qiao Yu, Lu Han, Jing Xu, Yinshan Zhou, Yeqiang Tan, Luoxin Wang, Hua Wang In this paper, solvent-free microcrystalline cellulose fluids (MCCFs) with liquid-like behavior were synthesized for the first time through surface grafted polyethylene glycol-substituted tertiary amines into microcrystalline cellulose (MCC) followed by fabricating MCCFs based polylactic acid (PLA) fabric (PLA/MCCFs) via electrospinning method. Owing to low viscosity of MCCFs at room temperature, the addition of MCCFs not only hardly affected the viscosity of electrospinning solution, but also improved the thermal stability of as-prepared PLA fibers. Interestingly, it was amazingly found that surface micropore morphology of PLA fabric diminished, and even disappeared with the content of MCCFs increasing during solvent evaporation process, which may be ascribed to the rapid migration of MCCFs into micropore before solidification. More importantly, the tensile strengths of PLA/MCCFs fabric with 10 wt% content of MCCFs achieved as high as 13.68 MPa, which was 3.18 times as much as that of 4.3 MPa for pure PLA fabric meanwhile the elongation at break of PLA/MCCFs fabrics increased from 13.19% for pure PLA fabric to 48.84% for PLA/MCCFs fabric with 15 wt% content of MCCFs. Beyond above mentioned, the water contact angle for pure PLA fabric was 127° (hydrophobicity), whereas other samples were close to 0° with addition of MCCFs, displaying the super-hydrophilicity. It was possibly inferred that MCCFs quickly migrated towards to the surface of fibers rather than staying inside of the fibers during the electrospinning process, leading to positive effect on the hydrophilicity of the PLA fibers. Finally, it is anticipated that this strategy for fabricating PLA fiber using this novel MCCFs as filler will pave the way for developing high performance PLA composites with desirable properties in the future.
       
  • Characteristics and fabrication of piezoelectric GFRP using smart resin
           prepreg for detecting impact signals
    • Abstract: Publication date: Available online 7 August 2018Source: Composites Science and TechnologyAuthor(s): Mun Young Hwang, Lae-Hyong Kang To develop a composite that also functions as an impact sensor, a piezoelectric glass fiber-reinforced polymer (GFRP) was fabricated using a mixture of Pb(Ni1/3Nb2/3)O3-Pb(Zr, Ti)O3 (PNN-PZT) piezoelectric powder and epoxy as a smart resin. Prepreg sheets were prepared by impregnating glass fiber with the smart resin and the specimen was fabricated by autoclave molding. To utilize the composite as a sensor for detecting impacts, electrodes were added to the two sides of the composite, and the specimen was poled briefly at room temperature to activate its piezoelectric properties. A calibrated and instrumented impact test was conducted to demonstrate impact response and measure the sensitivity; a signal processing device was developed that matched the high impedance of the piezoelectric GFRP. The sensitivity of the piezoelectric GFRP sensor was measured by comparing the impact force signals from an impact hammer with the corresponding output voltage from the sensor. The threshold for detection of impacts was below 15 N. The tests confirmed that the piezoelectric GFRP itself could be utilized as an impact sensor.
       
  • Fabrication of polyketone-grafted multi-walled carbon nanotubes using
           Grignard reagent and their composites with polyketone
    • Abstract: Publication date: Available online 4 August 2018Source: Composites Science and TechnologyAuthor(s): Jeong Ung Nam, Eun Yeob Choi, Hye Jin Park, C.K. Kim A Grignard reagent containing pyrene, 1-pyrenylmethylmagnesium bromide (PMgBr), was explored as a novel reactive compatibilizer for producing aliphatic polyketone (PK) composites with multi-walled carbon nanotube (MWCNT) that had improved interfacial adhesion and mechanical strength. 1-Bromomethylpyrene (PBr) was adsorbed on MWCNTs and reacted with Mg to produce PMgBr on MWCNTs (MWCNT-PMgBr). PK-grafted MWCNT (PK-g-MWCNT) was prepared by reacting MWCNT-PMgBr with PK, and its composite with PK was fabricated by melt extrusion. The formation of PK-g-MWCNT was examined by spectroscopy, electron microscopy, and thermal analysis. The PK interfacial adhesion energies with MWCNTs were quantified, and the mechanical strengths of their composites examined. PK-g-MWCNT had the highest interfacial adhesion energy with PK among the MWCNTs. The PK/PK-g-MWCNT composite showed better MWCNT dispersion in PK and interfacial adhesion between MWCNT and PK than the PK/pristine MWCNT composite. Consequently, the PK/PK-g-MWCNT composite exhibited higher mechanical strength than the PK/pristine MWCNT composite when the composite contained the same amount of MWCNTs.
       
  • Enhanced mechanical and thermal performances of epoxy resin by oriented
           solvent-free graphene/carbon nanotube/Fe3O4 composite nanofluid
    • Abstract: Publication date: Available online 3 August 2018Source: Composites Science and TechnologyAuthor(s): Dongdong Yao, Ningkun Peng, Yaping Zheng In this work, we report a simple strategy for improving the mechanical and thermal performances of epoxy resin using a novel magnetic composite nanofluid as filler. The magnetic nanofluid, composed of multicomponent core of graphene oxide (GO)/carbon nanotube (MWCNTs)/Fe3O4 (GMF) and shell of polyether, is fabricated via a combination of ultrasonic assisted chemical coprecipitation process and post-modification. Subsequently, epoxy/GMF composite is prepared under magnetic field, in which the GMF nanoparticles are well dispersed in the epoxy resin matrix without obviously agglomeration and exhibit a directional arrangement along magnetic field. i.e., the GO sheets are induced to align parallel to the magnetic field direction, and the MWCNTs are uniformly dispersed on graphene sheets with the orientation along magnetic field, Fe3O4 nanoparticles are further encapsulated on GO/MWCNTs composites to form GMF core. The orientation degree of GMF is enhanced with an increase in the magnetic field strength. The results indicate that the Tg of composite material increases by 17 °C with increasing of GMF content. Moreover, the impact and bending performances of epoxy resin are apparently enhanced by 136.5% and 30.9% with the 1.5 wt% of oriented GMF nanofluid at 0.6 T. In addition, the epoxy/GMF composite exhibits an anisotropy in the thermal conductivity.Graphical abstractImage 1
       
  • Structure of the in situ produced polyethylene based composites modified
           with multi-walled carbon nanotubes: In situ synchrotron X-ray diffraction
           and differential scanning calorimetry study
    • Abstract: Publication date: Available online 1 August 2018Source: Composites Science and TechnologyAuthor(s): Mariya A. Kazakova, Alexander G. Selyutin, Nina V. Semikolenova, Arcady V. Ishchenko, Sergey I. Moseenkov, Mikhail A. Matsko, Vladimir A. Zakharov, Vladimir L. Kuznetsov Polyethylene based composites modified with multi-walled carbon nanotubes (MWCNTs) were produced via in situ polymerization of ethylene with the Ti-Ziegler–Natta catalyst preliminarily immobilized on MWCNTs. The composite structure was characterized with transmission and scanning electron microscopy, differential scanning calorimetry (DSC) and in situ synchrotron X-ray Diffraction (in situ XRD). For the first time the Ti-containing catalyst species of the size 2–3 nm were observed on the MWСNTs surface stabilized in the polymer matrix. A comparative study of the melting-crystallization cycles of neat polyethylene (PE) and MWCNT-PE composites with in situ XRD and DSC provide information on the nucleation of PE crystals. For the first time, the in situ XRD technique was used for estimation of the coherent scattering region of PE blocks during the melting-crystallization cycles. These experiments and molecular dynamic modeling showed that MWCNTs act as the template for the PE chain orientation and as the nucleating agent for PE crystallization. However, the nucleation of PE crystals in composites occurs on the nanotube surface and also within the space between nanotubes. Thus, the relative volume of PE nucleated on nanotubes depends on their content in the composite and can be significant only for the composites with high nanotube loading.
       
  • Effect of SWCNTs and graphene on the fatigue behavior of antisymmetric
           GFRP laminate
    • Abstract: Publication date: Available online 1 August 2018Source: Composites Science and TechnologyAuthor(s): Mostefa Bourchak, Abdullah Algarni, Adnan Khan, Usama Khashaba In this relatively unique study, the impact of adding nanoparticles (NPs) on the fatigue properties of antisymmetric glass fiber reinforced polymer (GFRP) laminate has been investigated. Antisymmetric GFRP laminates (+45/02/902/02/-45) were prepared and reinforced once with 0.1 wt.% of single walled carbon nanotubes (SWCNTs) and then with 0.1 wt.% of Graphene nanoplatelets (GNPs). The NPs reinforced GFRP laminates are termed here GFNRP nanocomposites. Ultrasonication method was used to disperse the NPs using carefully chosen process parameters. Fatigue tests were analyzed based on S-N curves, stiffness degradation and hysteresis loops. The results showed that the use of 0.1 wt.% of SWCNTs led to an increase in the fatigue strength coefficient (FSC) and the fatigue strength exponent (FSE) of GFNRP nanocomposite specimens by 51% and 24%, respectively, while the use of similar wt.% of GNPs enhanced the FSC and FSE by 33% and 25%, respectively. Consequently, fatigue life of GFNRP nanocomposites are surprisingly enhanced by about three and twelve times when GNPs and SWCNTs are used, respectively. The findings would give designers much more confidence in using antisymmetric composite laminates in specific elastic tailoring structures.
       
  • Combination of 1D Ni(OH)2 nanobelts and 2D graphene sheets to fabricate 3D
           composite hydrogel electrodes with ultrahigh capacitance and superior rate
           capability
    • Abstract: Publication date: Available online 1 August 2018Source: Composites Science and TechnologyAuthor(s): Chengen He, Shengqiang Qiu, Haiyan Peng, Qing Zhang, Xiaoyan Han, Yingkui Yang, Dean Shi, Xiaolin Xie Metal compound/graphene composites have been dominantly fabricated by in-situ intercalation of metal-containing precursors into graphene or graphene oxide (GO) followed by chemical and/or thermal treatment. This process usually leads to the formation of 0D oxide nanoparticles/2D graphene composites with the limited improvements in the supercapacitor performance. Herein a facile two-step method was reported to fabricate 3D porous Ni(OH)2/graphene composite hydrogels (NiGH) by incorporating the pre-synthesized 1D Ni(OH)2 nanobelts into a GO suspension followed by the hydrothermal process. The resulted hydrogels show large specific surface area (370.6 m2/g) and can be directly used as the self-supported electrodes. The NiGH electrode exhibits the specific capacitance up to 1738.3 F/g at 10 mV/s and 1701.5 F/g at 1 A/g, retains 1385.0 F/g at 100 mV/s and 1152.0 F/g at 8 A/g, respectively. The capacitance and rate performance of NiGH are far superior to those of Ni(OH)2 (841.2 F/g at 10 mV/s; 592.5 F/g at 1.0 A/g), graphene hydrogel (207.5 F/g at 10 mV/s), and the control Ni(OH)2 nanoparticle/graphene composite powder (NiGP: 1045.8 F/g at 10 mV/s; 950.8 F/g at 1.0 A/g) prepared by the one-pot hydrothermal processing of Ni salt and GO. Meanwhile, the NiGH electrode also shows lower resistance and higher cycling stability (retaining 100.8% of initial capacitance over 5000 cycles at 5 A/g) as compared to Ni(OH)2, graphene hydrogel, and NiGP due to the efficient combination of pseudo-capacitive 1D Ni(OH)2 nanobelts and conductive 2D graphene sheets to create 3D architectures. Such a facile two-step protocol enables the superiority of ultrathin oxide nanobelts to fabricate 3D graphene-based composite hydrogels for high-performance supercapacitor electrodes.Graphical abstract3D Ni(OH)2 nanobelt/graphene composite hydrogels were fabricated by incorporating the pre-synthesized Ni(OH)2 nanobelts into a suspension of graphene oxide followed by hydrothermal treatment. The resulting self-supported electrodes show much better electrochemical performance compared to the powdery Ni(OH)2 nanoparticle/graphene composites prepared by one-pot hydrothermal processing of Ni salts and graphene oxide.Image 1
       
  • In situ self-sensing of delamination initiation and growth in
           multi-directional laminates using carbon nanotube interleaves
    • Abstract: Publication date: Available online 31 July 2018Source: Composites Science and TechnologyAuthor(s): Lulu Shen, Ling Liu, Wei Wang, Yexin Zhou Self-sensing capability of carbon nanotube buckypapers (BPs), played as in situ sensor on delamination damage in multi-directional laminates, was investigated in this paper. BPs were interleaved into these interfaces of the laminates, where delamination tends to happen firstly under tensile loading. The inserted BPs are porous and conductive, which can benefit infiltration of epoxy resin and give contribution to damage monitoring. Systematic analysis of resistance variation (ΔR/R0%) against strain has demonstrated that BPs are sensitive to the initiation and growth of delamination. When delamination initiates, a sudden rise of the ΔR/R0% or the slope of the ΔR/R0%-strain curves is observed and corresponding delamination initiation stresses are simultaneously obtained. Moreover, effect of thicker laminates on the sensitivity is also examined and the self-sensing ability of BPs has been further proved. Finally, tensile properties of the BPs interleaved laminates slightly change compared with these of base laminates.
       
  • Loading rate dependency of Mode I interlaminar fracture toughness for
           unidirectional composite laminates
    • Abstract: Publication date: Available online 30 July 2018Source: Composites Science and TechnologyAuthor(s): Huifang Liu, Hailiang Nie, Chao Zhang, Yulong Li This study was conducted to investigate the effect of the loading rate on the Mode I interlaminar fracture toughness of unidirectional carbon/epoxy laminates. Double cantilever beam (DCB) test geometry was employed for both quasi-static and dynamic fracture tests. A novel dual electromagnetic Hopkinson bar was employed to load the DCB specimens dynamically and symmetrically with velocities in the range of 10–30 m/s. A hybrid experimental-numerical method was used to determine the interlaminar fracture toughness for both quasi-static and dynamic loading conditions using the virtual crack closure technique (VCCT). The results indicate the presence of a critical loading rate for interlaminar fracture, below which the fracture toughness remains constant and beyond which the fracture toughness increases rapidly. Fractography results suggest that the failure mechanism transitions from a fiber/matrix interface failure under quasi-static loading to a brittle cleavage fracture of the matrix material with microbranching under dynamic loading.
       
  • Accurate evaluation of failure indices of composite layered structures via
           various FE models
    • Abstract: Publication date: Available online 30 July 2018Source: Composites Science and TechnologyAuthor(s): A.G. de Miguel, I. Kaleel, M.H. Nagaraj, A. Pagani, M. Petrolo, E. Carrera The objective of the current work is to perform a failure evaluation of fiber composite structures based on failure indices computed using the Hashin 3D failure criterion. The analysis employs 1D and 3D finite elements. 1D elements use higher-order structural theories from the Carrera Unified Formulation based on Lagrange expansions of the displacement field. The 3D model analysis exploits ABAQUS. Attention is paid to the free-edge effects, the mode of failure initiation - matrix or fiber tension, delamination -, and the loads at which first ply failure occurs. The results underline the paramount importance of out-of-plane stress components for accurate prediction and the computational efficiency of refined 1D models. In fact, 1D models lead from one to twofold reductions of the CPU time if compared to 3D models.
       
  • Preparation of self-healing, recyclable epoxy resins and low-electrical
           resistance composites based on double-disulfide bond exchange
    • Abstract: Publication date: Available online 29 July 2018Source: Composites Science and TechnologyAuthor(s): Fengtao Zhou, Zijian Guo, Wenyan Wang, Xingfeng Lei, Baoliang Zhang, Hepeng Zhang, Qiuyu Zhang Vitrimers have been emerged as a new class of polymers with many attractive properties of material processing such as reshaping, recycling and repairing. Herein, a new type of vitrimers (BDSER) based on thermosetting dynamic epoxy network with double disulfide bonds was synthesized by the reaction of a difunctional epoxy monomer containing disulfide bonds with 4,4′-disulfanediyldianiline (4-AFD). Our results demonstrated that the relaxation time of BDSER at 200 °C was as short as 9 s without any catalyst. The storage modulus of BDSER was up to about 2.2 GPa and its glass transition temperature was higher than 130 °C. Additionally, the thermodynamic and chemical properties of BDSER were no significant loss after 3 cycles of continuous breaking/compression molding. Furthermore, the resistance of CNT/PPy/Vitrimer composites (CPV), synthesized by doped BDSER with the polypyrrole (PPy) decorated multi-walled carbon nanotubes (WMCNTs), was decreased to 109 Ω even the mass ratio was only 1%wt, which could be used a promising candidate as self-repairing materials in the field of antistatic.
       
  • Multi-functional interface sensor with targeted IFSS enhancing, interface
           monitoring and self-healing of GF/EVA thermoplastic composites
    • Abstract: Publication date: Available online 29 July 2018Source: Composites Science and TechnologyAuthor(s): Bin Yang, Fu-Zhen Xuan, Zhenqing Wang, Liming Chen, Hongshuai Lei, Wenyan Liang, Yanxun Xiang, Kang Yang Developing the fiber/matrix interface with combined structural and functional performances is of tremendous importance in ensuring the service safety of fiber reinforced plastic composites (FRPs) and expanding the capabilities of FRPs to perform multiple parallel tasks. Herein, a multi-functional interface sensor that can improve the interfacial shear strength, and simultaneously monitor and heal the interfacial damage between glass fiber yarn and thermoplastic ethylene-vinyl acetate copolymer resin (GF/EVA) is reported. The basic idea is introducing muiti-walled carbon nanotube into GF/EVA interface. By this proposed method, the interfacial shear strength (IFSS) of GF/EVA composites is enhanced by 48.9%. The resistance of the interface sensor is recorded during the pull-out tests, and results show that the relative resistivity change could reflect the interfacial damage information very well. Electric heating of the sensor is adopted to heal the interfacial damage. The applied electrical power is discussed to evaluate the self-healing efficiency of the interfaces at different damage degrees. Successful interfacial self-healing ability is achieved and confirmed using different characterization techniques. Moreover, to verify the feasibility of our method in GF/EVA composite laminates, in-situ monitoring of the laminates under complicated stress and healing of delamination are performed. The results show that the developed sensor could monitor and heal the GF/EVA composite laminates with high sensing/healing ability. The proposed method and the obtained results could help to get a multi-functional sensor to ensure the service safety of composite structures.
       
  • Structural performance and photothermal recovery of carbon fibre
           reinforced shape memory polymer
    • Abstract: Publication date: Available online 29 July 2018Source: Composites Science and TechnologyAuthor(s): H.M.C.M. Herath, J.A. Epaarachchi, M.M. Islam, W. Al-Azzawi, J. Leng, F. Zhang The shape-memory polymers (SMPs) have an interesting capability of keeping a temporary shape and then recovering the original shape when subject to a particular external stimulus. However, due to SMP's relatively low mechanical properties, the use of SMP in wider range of engineering applications is limited. As such SMP's needs to be reinforced before use in engineering applications. This paper presents the mechanical properties, thermomechanical characteristics, photothermal behaviour and light activation of 0/90 woven carbon fibre reinforced shape memory epoxy composite (SMPC) made out of prepreg material. Prepreg is widely used manufacturing technique for large-scale engineering applications. The experimental results have demonstrated that the structural performance of the SMP has increased significantly due to carbon fibre reinforcement as anticipated. According to ASTM standard D 3039/D 3039M-00, the mode of tensile failure was identified as “XMV”, where the failure is explosive type. The dynamic mechanical analysis has revealed that the shape fixity and recovery ratios of the SMPC are 100% and 86% respectively. Under constrained strain, the stress has been recovered up to 5.24 MPa. The SMPC was exposed to five different power densities of 808 nm and the resultant activation has been systematically investigated. Interestingly, the SMPC has been heated over its glass transition temperature, once it exposes to a power density of 1.0 W/cm2. Furthermore, the applicability of carbon fibre reinforced SMPC for a deployable solar panel array, intended for remote and localized activation is demonstrated. The SMPC will be a potential candidate for space engineering applications, because of its enhanced mechanical properties and ability of photothermal activation.
       
  • Damage detection and self-healing of carbon fiber polypropylene
           (CFPP)/carbon nanotube (CNT) nano-composite via addressable conducting
           network
    • Abstract: Publication date: 20 October 2018Source: Composites Science and Technology, Volume 167Author(s): Sung-Jun Joo, Myeong-Hyeon Yu, Won Seock Kim, Hak-Sung Kim In this work, damage sensing and self-healing of carbon fiber polypropylene (CFPP)/carbon nanotube (CNT) nano-composite were performed based on addressable conducting network (ACN). To increase damage sensing resolution of CFPP/CNT nano-composite, through-thickness electrical conductivity was improved by adjusting press condition and spraying carbon nanotubes (CNT) between prepregs. From the results, electrical resistivity in thickness direction was reduced to 19.44 Ω·mm under 1.0 MPa and 1.0 wt% of CNT condition. Also, self-healing efficiency was examined with respect to the temperature and time via resistive heating of CFPP/CNT nano-composite. As a result, the optimized fabrication and self-healing condition exhibited high resolution of damage sensing with outstanding self-healing efficiency (96.83%) under fourth cycle of repeated three-point bending test.
       
  • Al2O3/graphene reinforced bio-inspired interlocking polyurethane
           composites with superior mechanical and thermal properties for solid
           propulsion fuel
    • Abstract: Publication date: 20 October 2018Source: Composites Science and Technology, Volume 167Author(s): Xiao Zhang, Jian Zheng, Haoming Fang, Yafei Zhang, Shulin Bai, Guansong He Nature always provides intelligent strategy for developing advanced materials with superior properties. In this study, by cloning the reinforcing mechanisms in nacre, a nacre-inspired Al2O3/graphene/polyurethane (PU) composite with hybrid hierarchical structure, was successfully fabricated. The structural interlocking interface, together with its excellent force bearing property, leads to exceptional mechanical performance. Compared with pure PU, the bio-inspired, Al2O3/graphene reinforced PU composite demonstrates a unique improvement in Young's modulus (211%), tensile strength (41%), and compressive modulus (145%). Moreover, the thermal conductivity of Al2O3/graphene/PU composite reaches to 0.502 W m−1 K−1, enhanced by 141% compared with pure matrix, showing very high enhancement efficiency, which is attributed to the multilevel aligned structure and multi-contact conductive pathway inside the composite. This design strategy offers a promising approach to handling high mechanical and thermal performance of solid propulsion fuel by synthesizing bio-inspired architecture.
       
  • Tribo-performance enhancement of PAEK composites using
           nano/micro-particles of metal chalcogenides
    • Abstract: Publication date: 20 October 2018Source: Composites Science and Technology, Volume 167Author(s): Jitendra Narayan Panda, Jayashree Bijwe, Raj K. Pandey While designing the ambitious advanced composites based on PAEK (50 wt%), glass fibers (30 wt %) and natural graphite (10 wt %), it was proposed to include one more solid lubricant (10 wt %) from the category of metal chalcogenides. Particles of MoS2 and WS2 in micron and nano-sizes were selected for inclusion in combination with natural graphite. The themes for investigations were; which one is the better performer amongst MoS2 and WS2, and nano-particles can impart beneficial effect or not; and the last how efficient would be these tribo-composites in terms of friction, wear resistance and PVlimit values. The composites were characterized in detail for physical, mechanical, thermal and tribological performance. The WS2 proved more beneficial till moderate PV conditions but not for severe conditions as compared to MoS2. The composites proved excellent tribo-materials in terms of low friction (∼0.04), wear rate (2.2 × 10−16 MPa m/s) and PVsafe values (84 MPa m/s). The chemistry of the counterface surface was studied using X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy (RS) while the morphology of the worn pins surface and counterface surface was observed using a combination of 3D profilometer and scanning electron microscopy.
       
  • Thermal conductivity and tortuosity of porous composites considering
           percolation of porous network: From spherical to polyhedral pores
    • Abstract: Publication date: Available online 27 July 2018Source: Composites Science and TechnologyAuthor(s): Wenxiang Xu, Mingkun Jia, Zheng Gong Understanding the effect of percolation behavior of complex geometrical pores on the tortuosity and thermal conductivity of porous composites is very crucial to the design and optimization of porous composites. In this work, we adopt the continuum percolation theory to accurately determine the nonlinear thermal conductivity and tortuosity of porous composites composed of homogeneous solid matrix and three-dimensional pores of geometrical morphologies from the isotropic sphere to anisotropic polyhedra. Through extensive Monte Carlo simulations and the finite-size scaling analysis, the percolation threshold of spherical and polyhedral pores is obtained. Two continuum percolation-based models are respectively presented to derive the tortuosity and thermal conductivity of porous composites over the whole porosities range, including near the percolation threshold. Comparison with extensive experimental, numerical and theoretical results confirms that the present models are capable of accurately determining the percolation threshold and tortuosity of complex geometrical porous networks and the effective thermal conductivity of porous composites as conductor-superconductor and insulator-conductor media. Furthermore, we use the proposed models to probe the influences of pore shape and porosity on the tortuosity and thermal conductivity of porous composites. The results elucidate the intrinsic interplay of component, structure, and thermal conductivity of porous composites, which can provide sound guidance for porous composite design and evaluation.
       
  • Effect of composite bone plates on callus generation and healing of
           fractured tibia with different screw configurations
    • Abstract: Publication date: Available online 27 July 2018Source: Composites Science and TechnologyAuthor(s): Ali Mehboob, Seung-Hwan Chang In this paper, finite element analysis of a fractured tibia with a glass/polypropylene composite implant is introduced. A rejection coefficient algorithm (for callus development) that is sensitive to interfragmentary movement is programmed, calibrated (using experimental in vivo statistics), and successfully implemented on a 3D fractured tibia model. A biphasic mechano-regulation algorithm is implemented to verify healing status under five different screw configurations (C1–C5) using glass/polypropylene composite bone plates and the development of tissue phenotypes in calluses is estimated. A 300% increase in circumferential callus volume is obtained when using the composite bone plate. Furthermore, the C5 configuration of the composite bone plate results in a maximum interfragmentary movement of 4.33% on day one with faster and stronger healing through 95% of bone growth during the final day of healing.
       
  • Thermo-magneto-mechanical long-term creep behavior of three-phase
           nano-composite cylinder
    • Abstract: Publication date: Available online 25 July 2018Source: Composites Science and TechnologyAuthor(s): Ahmad Reza Ghasemi, Komeil Hosseinpour This article investigates the history of long-term radial and circumferential creep strains and radial displacement for a three-phase nano-composite exposed to an internal pressure and placed uniform temperature and magnetic field. Three-phase nano-composite made of single-walled carbon. The results in this paper were achieved by presuming a non-linear viscoelasticity, based on Shapery's integral model, classical laminate theory, Prandtl-Reuss's relation and Mendelson's approximation method. The distribution of the radial creep strain, circumferential creep strain and radial displacement in two states of with and without magnetic field and three temperature conditions for two lay-ups [0/45/0/45] and [0/90/0/90] described for 10 years. It has been found that the values of creep strain and radial displacement in magnetic field are lower than without a magnetic field, for two lay-ups.
       
  • Multi-scale toughening of epoxy composites via electric field alignment of
           carbon nanofibres and short carbon fibres
    • Abstract: Publication date: Available online 25 July 2018Source: Composites Science and TechnologyAuthor(s): Anil R. Ravindran, Raj B. Ladani, Shuying Wu, Anthony J. Kinloch, Chun H. Wang, Adrian P. Mouritz The present paper demonstrates that multi-scale fillers such as carbon nanofibres (CNFs) and short carbon fibres (SCFs) can significantly improve the mode I fracture toughness of epoxy composites by various toughening mechanisms. A comparative assessment on the toughening performance promoted by CNFs and SCFs is presented along with the effects of aligning the filler normal to the crack growth using an applied alternating current (AC) electric field. For SCF concentrations of up to 1.5 wt%, with a concentration of CNFs of 1.0 wt%, the multi-scale, hybrid reinforcements additively toughen the epoxy polymer, with the measured fracture toughness being up to about fourteen times the value of the unmodified epoxy polymer. When subjected to an external AC electric field, these two reinforcements rapidly align along the direction of the electrical field in epoxy resin, with the CNFs concentrating between the ends of, and depositing on, the SCFs. For the same concentrations of SCFs and CNFs, the electric field induced alignment of the CNFs and the SCFs further increased the fracture toughness of the multi-scale toughened or hybrid epoxy polymer by up to twenty times that of the unmodified epoxy polymer. The intrinsic and extrinsic toughening mechanisms spanning the nano-to-millimeter length scale have been identified, based upon which an analytical model has been proposed.Graphical abstractImage 1
       
  • Novel phase separated multi-phase materials combining high viscoelastic
           loss and high stiffness
    • Abstract: Publication date: Available online 24 July 2018Source: Composites Science and TechnologyAuthor(s): A.P. Unwin, P.J. Hine, I.M. Ward, M. Fujita, E. Tanaka, A.A. Gusev In a previous study we showed that a unique combination of high stiffness and high viscoelastic loss could be achieved by filling a polystyrene matrix with rigid inorganic spheres coated with a thin (∼200 nm) layer of a viscoelastic material. The sandwiching of this ‘lossy’ layer between the two rigid components was found to give a significant amplification of the tanδ loss peak associated with this material, without significantly compromising the sample stiffness. This was an experimental validation of the effect originally proposed by Gusev using finite element numerical studies. Following on from this, in the current study we have developed this concept further and shown that a similar amplification of viscoelastic loss can be achieved by incorporating rigid, but uncoated, particles into a phase separated matrix blend of polystyrene (PS) and a polystyrene/polyisoprene/polystyrene triblock co-polymer (SIS). The inspiration for this choice of the PS/SIS blend as the matrix came from some previous work where we studied, and modelled, the viscoelastic properties of these materials. In this work we show that in the filled PS/SIS blends, the loss amplification effect can been seen for different PS/SIS ratios, for different SIS polymers with different glass transition temperatures and also for glass fibres as well as for spherical particles. The key to seeing this effect is the fact that the SIS rubber phase was found to form a thin coating on the surface of the embedded particles during processing, effectively producing a surface coating layer on the particles (as well as phase separating within the PS matrix). As with our previous studies, it is shown that the experimentally measured effects are closely predicted by numerical micromechanical modelling based on the measured bulk properties of the three discrete components.
       
  • Reaching maximum inter-laminar properties in GFRP / nanoscale sculptured
           aluminium ply laminates
    • Abstract: Publication date: Available online 24 July 2018Source: Composites Science and TechnologyAuthor(s): Björn Bosbach, Melike Baytekin-Gerngross, Emil Heyden, Mark-Daniel Gerngross, Jürgen Carstensen, Rainer Adelung, Bodo Fiedler The aim of the present work is to reach maximum inter-laminar properties in fibre metal laminates (FML) consisting of glass fibre reinforced polymer (GFRP) and aluminium (Al) plies. The Al plies are AA5019 and AA5754 alloys and pre-treated by nanoscale sculpturing before the FMLs are manufactured by resin transfer moulding. The nanoscale sculpturing of the Al plies leads to the formation of cubical hook-like structures on the surface giving rise to a three-dimensional mechanically interlocking surface. The inter-laminar properties of the FML are investigated by double-notch shear as well as double cantilever beam (Mode I) and end notched flexure (Mode II) testing methods and compared to untreated Al plies and conventional GRFP laminates as reference. As result the nanoscale sculptured Al plies show drastically increased inter-laminar mechanical properties due to highly improved inter-ply bonding between metal surface and resin. For all FMLs with nanoscale sculptured Al plies the delamination appears in the transition zone between glass fibres and matrix due to the lower adhesion of the glass fibre/matrix interface compared to the nanoscale sculptured Al ply/matrix interface. This proves that the maximum necessary inter-laminar properties are achieved.
       
  • Thinner and better: (Ultra-)low grammage bacterial cellulose
           nanopaper-reinforced polylactide composite laminates
    • Abstract: Publication date: Available online 24 July 2018Source: Composites Science and TechnologyAuthor(s): Martin Hervy, Frederic Bock, Koon-Yang Lee One of the rate-limiting steps in the large-scale production of cellulose nanopaper-reinforced polymer composites is the time consuming dewatering step to produce the reinforcing cellulose nanopapers. In this work, we present a method to reduce the dewatering time of bacterial cellulose (BC)-in-water suspension by reducing the grammage of BC nanopaper to be produced. The influence of BC nanopaper grammage on the tensile properties of BC nanopaper-reinforced polylactide (PLLA) composites is also investigated in this work. BC nanopaper with grammages of 5, 10, 25 and 50 g m−2 were produced and it was found that reducing the grammage of BC nanopaper from 50 g m−2 to 5 g m−2 led to a three-fold reduction in the dewatering time of BC-in-water suspension. The porosity of the BC nanopapers, however, increased with decreasing BC nanopaper grammage. While the tensile properties of BC nanopapers were found to decrease with decreasing BC nanopaper grammage, no significant difference in the reinforcing ability of BC nanopaper with different grammages for PLLA was observed. PLLA composite laminates reinforced with BC nanopaper at different grammages possessed a tensile modulus of 10.5–11.8 GPa and tensile strength of 95–111 MPa, respectively, at a vf,fibres  = 39–53 vol.-%, independent of the grammage and tensile properties of the reinforcing BC nanopaper(s).
       
  • Mechanical interlock effect between polypropylene/carbon fiber composite
           generated by interfacial branched fibers
    • Abstract: Publication date: Available online 21 July 2018Source: Composites Science and TechnologyAuthor(s): Kailin Zhang, Yijun Li, Xuewei He, Min Nie, Qi Wang Weak interface is a limiting factor to prepare polymer composite with excellent properties. Here, we report an interfacial interlocking strategy to improve interfacial strength of polypropylene (PP)/carbon fiber (CF) by manipulating interfacial diffusion and aggregation of amide-based self-assembling nucleating agent (WBG) and studied the effect of CF surface nature on the interfacial structures. The experimental results showed that when the interfacial energy between CF and WBG became low, it was favorable that the preferential localization of WBG toward the CF surfaces from polymer matrix, leading to the laterally growth of WBG fibers and the formation of interlocking interface. Single fiber fragmentation testing proved that there was a critical size of the laterally grown WBG fibers for the interfacial improvement. Only when the size exceeded 100 μm, the interfacial interlocking was strong enough to enhance the interfacial interaction, as evidenced by the substantial increases of 97% in interfacial shear strength compared to conventional PP/CF composite.
       
  • Extraordinary improvement of ablation resistance of carbon/phenolic
           composites reinforced with low loading of graphene oxide
    • Abstract: Publication date: Available online 20 July 2018Source: Composites Science and TechnologyAuthor(s): Yuanyuan Ma, Yu Yang, Chunxiang Lu, Xiaodong Wen, Xingchen Liu, Kuan Lu, Shijie Wu, Qianxiu Liu The effectiveness of graphene oxide (GO) on improving the ablation resistance of composite is investigated by incorporating a low concentration of GO (0.1wt%) into the carbon/phenolic (CF/PR). The X-ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy analyses reveal that the superiority of GO-filled composite over the neat in terms of thermal resistance is associated with the promoted char yield of PR and graphitization of fibers by the addition of GO. Molecular dynamics simulations identify the GO inside the matrix, even a small concentration, as a nuclei agent for the graphitized crystal growth of carbonized PR. And the GO at the fiber-matrix interface can bond to the fibers at extreme ablation temperatures, which promotes the formation of the Stone-Thrower-Wales defect (xy plane) and sp2 hybridization (z direction) at the graphene-fiber interface, and further increases the graphitization degree of fibers.
       
  • Smart cord-rubber composites with integrated sensing capabilities by
           localised carbon nanotubes using a simple swelling and infusion method
    • Abstract: Publication date: Available online 18 July 2018Source: Composites Science and TechnologyAuthor(s): Yinping Tao, Yi Liu, Han Zhang, Christopher A. Stevens, Emiliano Bilotti, Ton Peijs, James J.C. Busfield Smart self-sensing composites with integrated damage detection capabilities are of particular interests in various applications ranging from aerospace and automotive structural components, to wearable electronics and healthcare devices. Here, we demonstrate a feasible strategy to introduce and localise conductive nanofillers into existing elastomeric coatings of reinforcing cords for interfacial damage detection in cord-rubber composites. A simple swelling and infusion method was developed to incorporate carbon nanotubes (CNTs) into the elastomeric adhesive coating of glass cords. Conductive CNT-infused glass cords with good self-sensing functions were achieved without affecting the bonding provided by the coating with rubber matrix. The effectiveness of using these smart cords as interfacial strain and damage sensors in cord-rubber composites was demonstrated under static and cyclic loading. It showed the possibility to identify both reversible deformation and irreversible interfacial damage. The simplicity of the proposed swelling and infusion methodology provides great potential for large-scale industrial production or modification of CNT functionalised elastomeric products such as cord-rubber composites.
       
 
 
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: 54.166.207.223
 
About JournalTOCs
API
Help
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-