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Composites Part B : Engineering
Journal Prestige (SJR): 2.039
Citation Impact (citeScore): 5
Number of Followers: 286  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1359-8368
Published by Elsevier Homepage  [3182 journals]
  • Surface modification of ammonium polyphosphate by supramolecular assembly
           for enhancing fire safety properties of polypropylene
    • Abstract: Publication date: Available online 9 November 2019Source: Composites Part B: EngineeringAuthor(s): Yaru Sun, Bihe Yuan, Sheng Shang, Hongming Zhang, Yongqian Shi, Bin Yu, Congrui Qi, Haoran Dong, Xianfeng Chen, Xinlei Yang Organically modified ammonium polyphosphate (APP) flame retardant is prepared by supramolecular assembly method using melamine formaldehyde (MF) resin and phytic acid (PA) as building blocks. Surface characteristics of APP are modified, resulting in the enhancements in water resistance, dispersion in the polymer matrix and their compatibility. This supramolecular assembly modified APP (APP@MF-PA) matches well with charring-foaming agent (CFA) to achieve excellent fire safety for polypropylene (PP), and the superiority over conventional APP is observed. Heat, CO and CO2 releases of PP are greatly decreased by the intumescent flame retardant (IFR) formulation containing APP@MF-PA and CFA. The modification of APP with MF-PA supramolecules are beneficial to improve the yield, insulation properties, graphitization degree and compactness of char. Flame-retardant mechanisms are demonstrated according to the investigations on gaseous and condensed phase products. This novel and facile modification method provides a new strategy for improving the flame-retardant efficiency of IFR.Graphical abstractImage 1
  • About the tensile mechanical behaviour of carbon fibers fabrics reinforced
           thermoplastic composites under very high temperature conditions
    • Abstract: Publication date: Available online 9 November 2019Source: Composites Part B: EngineeringAuthor(s): Y. Carpier, B. Vieille, A. Coppalle, F. Barbe The present work focuses on the thermomechanical behaviour of thermoplastic-based composite materials subjected to the combined action of a mechanical loading in tension and homogeneous temperature conditions. The investigations on the relationship between local temperature resulting from the local atmosphere and the mass losses are essential in understanding the influence of fire on the thermo-mechanical behaviours of polymers and polymer matrix composites. Regardless the testing atmosphere, the decomposition onset temperature is about 500 °C. From isothermal tensile tests conducted at temperatures ranging from ambient to 520 °C, it appears that the retention of the axial stiffness of quasi-isotropic carbon fibers reinforced polyphenylene sulfide (PPS) laminates is relatively high (about 70% of its initial value) beyond the decomposition temperature. At the same time, the ultimate strength dramatically decreases (about 25% of its initial value). The obtained results also show that melting is instrumental to rule the tensile behaviour of quasi-isotropic C/PPS laminates. Conversely, matrix melting significantly influences the damage mechanisms within the laminate. Finally, for testing temperatures close to the onset decomposition temperature, porosities appear and grow within the laminates, ultimately contributing to the degradation of the mechanical properties.
  • Sonochemical self-growth of functionalized titanium carbide nanorods on
           Ti3C2 nanosheets for high capacity anode for lithium-ion batteries
    • Abstract: Publication date: Available online 8 November 2019Source: Composites Part B: EngineeringAuthor(s): Sanghee Nam, Sima Umrao, Saewoong Oh, Kang Ho Shin, Ho Seok Park, Il-Kwon Oh Two-dimensional (2D) transition metal carbides (MXenes) have been considered a promising electrode material in energy storage devices due to their outstanding electrical conductivity, excellent electrochemical performance and unique surface terminations. Herein, with inspiration from the interesting functional structure of layered MXene, we report an efficient and facile sonochemical method to synthesize an anode material; functionally activated titanium carbide nanorods grown on Ti3C2 MXene nanosheets (FTCN-MXene) in deionized water and dimethylformamide mixture. In a striking contrast to pristine Ti3C2Tx MXene, FTCN-MXene exhibits outstanding specific anode capacity of 1,034 mAh/g, high coulombic efficiency (98.78%) after 250 cycles, and excellent reversible cyclic stability (retention of 96.05%). Functionalized nanorods grown on metallic conducting Ti3C2 sheets create more active sites and surface area, improving Li ion insertion/extraction capability. This study opens new avenues for developing functionalized MXene-based electrode materials with enhanced performance for electrochemical energy storage devices and systems.
  • Towards hemp fabrics for high-performance composites: Influence of weave
           pattern and features
    • Abstract: Publication date: Available online 7 November 2019Source: Composites Part B: EngineeringAuthor(s): Anne-Clémence Corbin, Damien Soulat, Manuela Ferreira, Ahmad-Rashed Labanieh, Xavier Gabrion, Pierrick Malécot, Vincent Placet Recent developments in the field of bio-based composite materials are mainly focused on the use of unidirectional reinforcements. The production of woven fabrics and required yarns or rovings is still complex for composite applications due to the finite length of plant fibers and to the high number of process parameters which can be tuned. This study focused on the influence of weave pattern and process parameters on the resulting material properties at different scales. Results from mechanical characterizations and X-ray nanotomography show that very competitive tensile properties can be obtained for woven hemp fabric composites made from low-twisted rovings, in particular when compared to the front-runner flax cross-ply laminate.
  • Automated quantification of reinforcement dispersion in B4C/Al
           metal matrix composites
    • Abstract: Publication date: Available online 7 November 2019Source: Composites Part B: EngineeringAuthor(s): Byeongjin Park, Donghyun Lee, Ilguk Jo, Sang Bok Lee, Sang Kwan Lee, Seungchan Cho This study proposes an automated quantification technique for reinforcement dispersion in metal matrix composites. While a fine and homogeneous dispersion of reinforcements is necessary to achieve an optimum reinforcing effect in metal matrix composites, there have been few studies on the quantitative measurement of reinforcement dispersion. The proposed technique extracts reinforcement information from a given microscopic image through image analysis with minimized human interruption and quantifies the reinforcement dispersion automatically using a statistical approach. The feasibility of the proposed technique is shown by analyzing the effect of the hot rolling process on the reinforcement dispersion in a B4C/Al metal matrix composite and comparing it with the as-cast state.
  • On the metal thermoplastic composite interface of Ti
           alloy/UHMWPE-Elium® laminates
    • Abstract: Publication date: Available online 6 November 2019Source: Composites Part B: EngineeringAuthor(s): Logesh Shanmugam, M.E. Kazemi, Zaiqing Rao, Lei Yang, Jinglei Yang Thermoplastic fiber metal laminate (T-FML) is a new hybrid composite material, which is a combination of sandwiched metal and complete thermoplastic fiber reinforced polymer (FRP). Due to its superior properties contributed from the unique combination of metal and FRP's, it has been applied in various advanced fields, like aerospace, and automotive. However, poor adhesion between inhomogeneous material surfaces of fiber, metal, and matrix in T-FML makes the whole system weaker. In this work, the Ti6Al4V (titanium alloy) and ultrahigh molecular weight polyethylene fiber (UHMWPE) reinforced thermoplastic (Elium®) polymeric composite were combined together to form a T-FML. Fiber surface functionalization by PDA (polydopamine) coating with MWCNT (Multiwalled carbon nanotubes) has been adopted to enhance the bonding between the fiber and matrix. Ti6Al4V metal surface treatment by anodization with postprocessing of etching and annealing process has been adopted to enhance the interfacial bonding between metal thermoplastic composite interface (MTCI). The double cantilever beam test was utilized to evaluate the G1C (Mode 1 interlaminar fracture toughness at MTCI) for the T-FML sample with fiber surface functionalization and metal surface treatment. The result shows, after metal surface treatment, the average G1C can be immediately increased from 0.25 kJ/m2 (pristine titanium alloy with pristine fiber) to 1.57 kJ/m2 for surface-treated titanium alloy with pristine fiber. The PDA only coating for UHMWPE fiber enhanced the G1C from 1.57 kJ/m2 to 1.84 kJ/m2. PDA fiber surface functionalization with MWCNT coating enhanced the G1C further to 2.54 kJ/m2.
  • Ionic liquid- modified lignin as a bio- coupling agent for natural fiber-
           recycled polypropylene composites
    • Abstract: Publication date: Available online 6 November 2019Source: Composites Part B: EngineeringAuthor(s): Hamed Younesi Kordkheili, Antonio Pizzi In this study, the influence of ionic liquid-treated lignin as a bio coupling agent on the various properties of bagasse fiber-recycled polypropylene composites was investigated. For this purpose, extracted lignin from Bagasse Soda black liquor was modified with 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) ionic liquid and then different ratios of unmodified and modified lignin (0, 1, 3 and 5 wt%) were added to the bagasse fiber/recycled polypropylene mixture. The composites were then manufactured by injection molding after mixing mechanically of the bagasse fiber, virgin or modified lignin and recycled polypropylene. Structural and thermal properties of lignin after modification by ionic liquid along with physical (water absorption and thickness swelling) and mechanical (flexural modulus, flexural strength, tensile strength and impact strength) properties of the manufactured composites were measured according to ASTM standard methods. The FTIR analysis indicated lignin rearrangements showing that some bonds changed or formed after its modification with IL. The DSC analysis showed that the glass transition temperature (Tg) of lignin decreased from 92 °C to 80 °C by increasing the weight ratio of ionic liquid to lignin from 20 to 30 wt%. The panel testing results indicated that all physical and mechanical properties of the composites were continuously improved by increasing the lignin content from 1 to 5 wt%. Thus, the composites with IL-treated lignin presented higher dimensional stability and mechanical strength compared to those prepared with unmodified lignin. Scanning electron microscopy (SEM) showed that treatment with ionic liquid improves the uniform dispersion of lignin in the polymer matrix.
  • A highly stretchable, super-hydrophobic strain sensor based on
           polydopamine and graphene reinforced nanofiber composite for human motion
    • Abstract: Publication date: Available online 5 November 2019Source: Composites Part B: EngineeringAuthor(s): Bei Li, Junchen Luo, Xuewu Huang, Liwei Lin, Ling Wang, Mingjun Hu, Longcheng Tang, Huaiguo Xue, Jiefeng Gao, Yiu-Wing Mai Much attention has been given to flexible electronic devices in recent years. Conductive polymer composites (CPCs) have been utilized to fabricate strain sensors owing to their lightweight and high flexibility. It is a great challenge to develop flexible and wearable strain sensors with light weight, good skin affinity and gas permeability, high sensitivity and excellent corrosion resistance. In this work, electrospun thermoplastic polyurethane (TPU) nanofibers were first decorated by graphene through ultra-sonication, followed by polydopamine (PDA) modification and then hydrophobic treatment with 1H, 1H, 2H, 2H-perfluorodecanethiol (PFDT). The obtained electrical conductive polymer nanofiber composites (CPNCs) have a hierarchical polymer core/graphene shell structure and exhibit super-hydrophobicity even under harsh environments. The introduction of PDA not only improves the interfacial interaction between individual graphene sheets but also the interaction between graphene and the TPU nanofibers. Their mechanical properties including Young's modulus, tensile strength and elongation at break are significantly improved, compared to those of TPU nano-fibrous membranes. When CPNC is used as a strain sensor, it displays high stretchability, controllable sensitivity, excellent cyclical stability and durability. Hence, the nanofiber composite based strain sensor can be attached on the skin for precise monitoring of different human motions, such as tiny and large body movements and thus has promising applications in wearable devices.
  • Facile strategy and mechanism of preparing high performance intrinsic
           flame retarding foams based on reactive end-capped liquid crystalline
           all-aromatic polyester without incorporating additional flame retardants
    • Abstract: Publication date: Available online 5 November 2019Source: Composites Part B: EngineeringAuthor(s): Yanfu Tang, Li Yuan, Guozheng Liang, Aijuan Gu It is still a big challenge to develop high performance polymer foams with outstanding flame retardancy and high thermal stability through a facile strategy. Herein, starting from synthesizing phenylethynyl end-capped all-aromatic liquid crystalline polyester with good processability, a new kind of flame retarding liquid crystalline thermosetting foam (LCTF) was fabricated without adding additional flame retardant and foaming agent. LCTF simultaneously shows outstanding flame retardancy (UL94‒V0 grade, 36.4% of limit oxygen index), excellent smoke suppression and high thermal stability, which are the best values reported so far among intrinsic flame retarding foams. The mechanism of outstanding flame retardancy is revealed by investigating chemical and morphological structures with the aid of three-dimensional reconstruction of morphology. Roles from gas phase and condensed phase are proved to be responsible for unique flame retardancy. The application of LCTF in thermal insulation was also evaluated.Graphical abstractImage 1
  • Enhanced composite plate impact damage detection and characterisation
           using X-Ray refraction and scattering contrast combined with ultrasonic
    • Abstract: Publication date: Available online 3 November 2019Source: Composites Part B: EngineeringAuthor(s): D. Shoukroun, L. Massimi, F. Iacoviello, M. Endrizzi, D. Bate, A. Olivo, P. Fromme Ultrasonic imaging and radiography are widely used in the aerospace industry for non-destructive evaluation of damage in fibre-reinforced composites. Novel phase-based X-ray imaging methods use phase effects occurring in inhomogeneous specimens to extract additional information and achieve improved contrast. Edge Illumination employs a coded aperture system to extract refraction and scattering driven signals in addition to conventional absorption. Comparison with ultrasonic immersion C-scan imaging and with a commercial X-ray CT system for impact damage analysis in a small cross-ply carbon fibre-reinforced plate sample was performed to evaluate the potential of this new technique. The retrieved refraction and scattering signals provide complementary information, revealing previously unavailable insight on the damage extent and scale, not observed in the conventional X-ray absorption and ultrasonic imaging, allowing improved damage characterisation.
  • Preparation of two-dimensional titanium carbide (Ti3C2Tx) and NiCo2O4
           composites to achieve excellent microwave absorption properties
    • Abstract: Publication date: Available online 2 November 2019Source: Composites Part B: EngineeringAuthor(s): Tianqi Hou, Bingbing Wang, Mingliang Ma, Ailing Feng, Zhengyong Huang, Yi Zhang, Zirui Jia, Guangxin Tan, Haijie Cao, Guanglei Wu The appearance and development of two-dimensional titanium carbide materials provide a new idea for our research on microwave absorption materials. Its excellent electrical conductivity and surface functional groups allow it to be used as a microwave absorber. In this study, Ti3C2Tx@NiCo2O4 composites were prepared by simple hydrothermal method and subsequent annealing process. With the change of annealing temperature, the state of composites is changed, so the structure and properties of samples are further adjusted. When the annealing temperature is 350 °C, an optimal reflection loss value of −50.96 dB can be obtained at 2.18 mm. The excellent microwave absorption performance is not only caused by polarization behavior, but also related to multiple reflections and multiple scattering produced by unique structures. Therefore, the prepared Ti3C2Tx@NiCo2O4 is expected to be a promising microwave absorber with thin thickness and high absorption intensity.Graphical abstractImage 1
  • Highly thermal conductive, anisotropically heat-transferred, mechanically
           flexible composite film by assembly of boron nitride nanosheets for
           thermal management
    • Abstract: Publication date: Available online 2 November 2019Source: Composites Part B: EngineeringAuthor(s): Zhi-Guo Wang, Wei Liu, Ya-Hui Liu, Yue Ren, Yan-Pu Li, Li Zhou, Jia-Zhuang Xu, Jun Lei, Zhong-Ming Li Fabricating thermally conductive yet electrical insulated composite films faces dilemmas of ineffective exfoliation of boron nitride (BN) platelets, unsatisfactory thermal conductivity (TC) and poor anisotropy ratio. Herein, few-layered and functionalized boron nitride nanosheets (BNNSs) were effectively exfoliated from BN platelets via eco-friendly biomolecule-assisted exfoliation. Then, BNNS/ethylene-vinyl acetate copolymer (EVA) composite films with the laminated structure were achieved by the green and scalable vacuum-assisted self-assembly. The as-prepared BNNS/EVA composite film showed superior in-plane TC of 13.2 W/mK and strong anisotropy ratio of ∼2500% at the BNNS loading of 50 wt%. It was mainly ascribed that the highly oriented BNNSs formed effectively thermally conductive pathways for heat transfer. Additionally, the oxygen-containing functional groups of BNNSs improved interfacial interaction with the EVA matrix and reduced phonon scattering. Thermal interface resistance of the 50 wt% BNNS/EVA film was reduced by 68% compared to the 50 wt% BN/EVA counterpart. Furthermore, the BNNS/EVA films exhibited an attractive flexibility and TC reliability. The retention ratio of in-plane TC was 98% after repetitive bending, 95% after repeated tensile test, and 97% after heating/cooling cycles. The obtained results offer valuable fundamentals to fabricate high-performance thermally conductive polymer composites as advanced thermal management materials.
  • Study the safeguarding performance of shear thickening gel by the
           mechanoluminescence method
    • Abstract: Publication date: Available online 1 November 2019Source: Composites Part B: EngineeringAuthor(s): Shuaishuai Zhang, Sheng Wang, Tao Hu, Shouhu Xuan, Han Jiang, Xinglong Gong This work reports the potential of a full-field, simple-setup and user-interactive method to study the safeguarding property of shear thickening gel (STG) by converting the invisible force/energy information to visible mechanoluminescence. Both the instantaneous intensity and force signals under impact prove the phase change of STG from viscous liquid state to rubbery state. The illumination images, presenting the energy maps, directly visualize the remarkably expanded impact area and phase change induced energy absorption, promoting the understanding of safeguarding mechanisms. The shear thickening property and viscoelastic deformation of STG significantly expand the impact area by almost 5 times, spreading and dissipating force/energy significantly. Moreover, the phase change accompanied by cracks is observed clearly, which is demonstrated to be beneficial to the energy absorption and contributes to the further enlargement of the impact area.
  • Experimental and numerical research on the mode I delamination of looped
           fabric reinforced laminate
    • Abstract: Publication date: Available online 1 November 2019Source: Composites Part B: EngineeringAuthor(s): Jian Yu, Chuwei Zhou, Shuguang Li The fabric structure of looped fabric reinforced laminate (LFRL) was investigated based upon braiding process and microscopy imaging. Fiber bridging in double cantilever beam (DCB) specimens manufactured of plain weave fabric laminate (PW) and LFRL was studied experimentally. An FE model for LFRL DCB specimen considering large-scale bridging was developed based on the experimental research and the numerical theory. The studied loop-bridging tractions were used with the cohesive model to describe crack growth, and a good agreement between numerical and experimental result was demonstrated. The proposed FE model was also applied to investigate the mode I fracture properties of various LFRL DCB specimens with different initial crack length, length of loops and density of loops, which could be referred by the composites design.
  • Fabrication of the silver modified carbon nanotube film/carbon fiber
           reinforced polymer composite for the lightning strike protection
    • Abstract: Publication date: Available online 1 November 2019Source: Composites Part B: EngineeringAuthor(s): Qianshan Xia, Hao Mei, Zhichun Zhang, Yaxin Liu, Yanju Liu, Jinsong Leng Carbon fiber reinforced polymer (CFRP) composites with low density, corrosion resistance and excellent mechanical properties are widely applied in the aircraft industry, instead of the traditional metallic material. Their poor electrical conductivity leads to the vulnerability to the lightning strike (LS). In this paper, highly conductive silver modified carbon nanotube film (SMCNF) was developed via the electrophoretic deposition (EPD) method for protecting CFRP structures and components of the aircraft. Lightning strike protection (LSP) efficiency of the SMCNF/CFRP composite was characterized from the micro-scale to the macro-scale, and its possible protective mechanism was discussed. The compressive strength of the SMCNF/CFRP composite after the simulated LS test maintains 91.05% and is higher than that of the Cu mesh/CFRP composite (83.28%). Compared to commercial copper mesh LSP material, it can reduce the weight by 27.4% with the better residual compressive strength ratio. Therefore, highly conductive and lightweight SMCNF as a LSP layer can effectively reduce the damage of the CFRP matrix caused by the LS.Graphical abstractImage 1
  • Crushing behavior and optimization of sheet-based 3D periodic cellular
    • Abstract: Publication date: Available online 1 November 2019Source: Composites Part B: EngineeringAuthor(s): Hanfeng Yin, Zhipeng Liu, Jinle Dai, Guilin Wen, Chao Zhang Sheet-based 3D periodic cellular structures attract great attentions due to their lightweight and excellent mechanical properties. Unlike other traditional honeycombs and lattice structures, sheet-based cellular structures consist of triply periodic minimal surface (TPMS) cores, which are continuous through space with a porous cavity surrounded by continuous surfaces. In this study, the crashworthiness of four types of TPMS sheet structures (i.e., Primitive, FRD, IWP, and Gyroid) under axial loading was investigated. According to the results obtained by the nonlinear finite element analysis, the level-constant in the implicit form of TPMS and the shell thickness of TPMS sheet structures were found to affect the crashworthiness significantly. To achieve an optimal design, a metamodel-based multi-objective optimization method was developed to optimize the four types of TPMS sheet structures. Three different metamodels, i.e., Kriging (KRG), polynomial response surface (PRS) and radial basis function (RBF), were compared to identify the most accurate model, which was then utilized for the optimization. Followed by the multiobjective optimization, four Pareto fronts of these TPMS sheet structures were plotted and compared, of which the FRD-sheet structure was found to have the best energy absorption capacity. Moreover, the crashworthiness of the TPMS sheet structures was compared with that of the other materials or structures in nature and engineering, and an Ashby plot was given. Overall, TPMS sheet structures possess excellent specific energy absorption and specific strength and show great potential for engineering applications.
  • Tailoring degradation-resistant thermal barrier coatings based on the
           orientation of spontaneously formed pores: From retardation to
    • Abstract: Publication date: Available online 1 November 2019Source: Composites Part B: EngineeringAuthor(s): Guang-Rong Li, Li-Shuang Wang, Wei-Wei Zhang, Guan-Jun Yang, Xue-Feng Chen, Wei-Xu Zhang Thermal barrier coatings (TBCs) endow metal components with exceptional endure capability to withstand high temperatures over their bearable limits. Thus, TBCs are indispensable in a wide range of applications related to high temperatures. However, the thermal barrier performance degrades by at least 50% during service, which remains a critical challenge for these coatings. Herein, degradation-resistant TBCs were achieved using composited structures. Thermal insulation 2D pores were spontaneously formed during thermal exposure. Moreover, the degree of resistance was optimized from 20% to 50% by tailoring the orientation of the 2D pores. Thus, the thermal barrier performance was self-improved. A detailed examination suggests that scale-progressive healing of the initial pores is primarily responsible for the degradation mechanism. Analysis of the orientation of the spontaneously-formed 2D pores on thermal resistance reveals that this accounts for the self-improved thermal barrier performance. These results will guide the advanced design of TBCs for future applications.Graphical abstractImage 1
  • Evaluation of carbon fiber composite repairs using asymmetric-frequency
           ultrasound waves
    • Abstract: Publication date: Available online 31 October 2019Source: Composites Part B: EngineeringAuthor(s): Feifei Liu, Zhenggan Zhou, Songping Liu, Yuseng Yang, Liangwang Zhang A novel asymmetric-frequency ultrasonic (AU) technique was developed for the nondestructive testing and evaluation of carbon fiber composite repairs. Experimental studies were conducted using the established AU system to repair specimens with and without natural debonding. The time-domain characteristics of the AU echo signals, cross-sectional imaging characteristics, and their variations from the repaired areas were analyzed. The results show that the echo signals from repaired zones had close to quasi-single period in AU-2F–5F mode. The cross-sectional geometric topologies of the repaired areas and morphologies of debonding in the specimens were visualized and evaluated well using the AU technique.
  • Influence of time-dependent phenomena on translaminar fracture of
           woven-ply C/PPS laminates above the glass transition temperature
    • Abstract: Publication date: Available online 31 October 2019Source: Composites Part B: EngineeringAuthor(s): D. Bouscarrat, M. Levesque, B. Vieille The time-dependency of damage development and translaminar fracture mechanisms were investigated in 5-harness satin weave carbon fabric reinforced polyphenylene sulfide composites above their glass transition temperature through an approach combining acoustic emission (AE) monitoring and fracture mechanics. Single edge notch specimens from two stacking sequences (quasi-istropic and angle-ply) were subjected to cyclic incremental tensile loading. Tensile tests were carried out for several loading rates or histories featuring creep and/or recovery stages. Both laminates’ failure mechanisms do not seem to be influenced by time-dependent phenomena. However, AE monitoring revealed AE activity during creep stages for both stacking sequences, thus highlighting possible time-dependent damage events. If those AE events are indeed related to time-dependent damage, this observation would mean that this damage is only subcritical. Those observations need to be investigated further with acoustic emission coupled to other monitoring tools, such as digital image correlation, in-situ microscopic observations or thermography, to provide a better insight of the physical phenomena associated with the monitored acoustic emission signals.
  • Controlling toughness and strength of FDM 3D-printed PLA components
           through the raster layup
    • Abstract: Publication date: Available online 25 October 2019Source: Composites Part B: EngineeringAuthor(s): Josef Kiendl, Chao Gao We investigate the influence of raster layup on the resulting material properties of FDM 3D-printed materials made of PLA. In particular, we investigate the resulting toughness, strength, and stiffness, with a special focus on toughness. We show that for standard layups with layer orientations alternating by 90°, stiffness and strength are almost isotropic, while a strong anisotropy is obtained for toughness. Moreover, we show that materials with such a layup can even switch their behavior from brittle to ductile depending on the loading direction. Finally, we propose a new layer stacking scheme which simultaneously provides increased toughness and increased strength compared to the standard approaches.
  • Flame retardancy and mechanical properties of glass fibre reinforced
           polyethylene composites filled with novel intumescent flame retardant
    • Abstract: Publication date: Available online 24 October 2019Source: Composites Part B: EngineeringAuthor(s): Junlei Chen, Jihui Wang, Anxin Ding, Aiqing Ni, Hongda Chen A novel intumescent flame retardant (IFR) system composed of ammonium polyphosphate and poly (1,3-diaminopropane-1,3,5-triazine-o-bicyclic pentaerythritol phosphate) (APP/PDTBP) was mixed with polyethylene to prepare the continuous glass fibre reinforced polyethylene (CGF/PE) unidirectional prepregs by melt impregnation process, and then the CGF/PE/IFR composite laminate were consolidated by hot compression moulding method. The flame retardancy, thermal stability and mechanical properties of CGF/PE/IFR composite laminates were investigated by limiting oxygen index, vertical burning test, cone calorimetric test, thermogravimetric analysis, tensile and flexural strength tests, mode I interlaminar fracture toughness test, and scanning electron microscopy (SEM). The flame retardancy of CGF/PE composite laminates increased with the increase of IFR system loading, which attributes to the formation of intumescent char layer from flame retardants and the weakening of wicking actions of glass fibres. The mechanical properties increased and then decreased with addition of flame retardants, except for the flexural strength with continuous increase. The SEM images showed that IFR system had toughening effect and could improved the strength of fibre-matrix interface. Based on the mechanical properties and the flame retardancy, when the matrix contains 30 wt% IFR system, the CGF/PE/IFR composite laminate had the best comprehensive performance.Graphical abstractImage 1
  • Flame retardant effect of cytosine pyrophosphate and pentaerythritol on
    • Abstract: Publication date: Available online 23 October 2019Source: Composites Part B: EngineeringAuthor(s): Guoxing Yu, Chao Ma, Juan Li Cytosine pyrophosphate (PPA-C) was prepared by using pyrophosphoric acid (PPA) and cytosine (C). The structure, morphology and thermal stability of PPA-C were analyzed by using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy and thermo gravimetric analysis (TGA). The PPA-C was used as acid and gas source and pentaerythritol (PER) as charring agent to form an intumescent flame retardant (IFR) system which was applied to improve the flame retardancy of polypropylene (PP). The flame retardancy and thermal degradation behaviors of PP/IFR composites were investigated by vertical combustion (UL-94), limiting oxygen index (LOI) and cone calorimeter (cone), TGA etc. The PPA-C and PER have good synergistic effects on improving the flame retardancy of PP which is better than that of commercial ammonium polyphosphate (APP) and PER system. The PP/IFR composites with 18 wt% PPA-C/PER (3:1) achieves the UL-94 V-0 rating and a LOI value of 28.8 vol%. The PPA-C reacts with PER to form -P-O-C and -P-C- during combustion which helps the formation of intumescent char layer. In addition, the IFR makes PP degrade in advance and form more char residues at high temperature. Proper ratio and amount of PPA-C/PER promotes the formation of intumescent char layer without defects during combustion, reduces the heat release rate and delays the thermal degradation of PP composites, thus improves the flame retardancy of PP.Graphical abstractCytosine pyrophosphate (PPA-C) and pentaerythritol (PER) show synergistic flame retardant effect on polypropylene (PP) composites.Image 1
  • Multi-role p-styrene sulfonate assisted electrochemical preparation of
           functionalized graphene nanosheets for improving fire safety and
           mechanical property of polystyrene composites
    • Abstract: Publication date: Available online 23 October 2019Source: Composites Part B: EngineeringAuthor(s): Zhixin Zhao, Wei Cai, Zhoumei Xu, Xiaowei Mu, Xiyun Ren, Bin Zou, Zhou Gui, Yuan Hu Polystyrene sulfonate functionalized graphene nanosheets (PSS@GNS) with high quality (ID/IG = 0.17) were fabricated through electrochemical exfoliation of bulk graphite followed by simple free radical polymerization in water solution, which is a promising strategy for mass production of polymer functionalized graphene. P-styrene sulfonate anions were used to intercalate into the bulk graphite under voltage and also as monomers of the macromolecule modification agents for the exfoliated graphene nanosheets. Besides, benzene rings and carbon double bonds are considered to be able to capture hydroxyl free radicals which produce defects on graphene sheets during electrochemical exfoliation process, thus improve the quality of the exfoliated graphene nanosheets. Then the graphene nanosheets were incorporated into polystyrene (PS) through a solution blending method to reduce the fire hazards and improve mechanical properties of PS resin. According to the results of cone calorimeter, the introduction of functionalized graphene nanosheets into PS reduces heat release rate (decreased by 40%), total heat release (decreased by 35%) and increases the amount of char residues. The flame retardant improvement is attributed to the barrier effect of well-dispersed graphene nanosheets, limiting the mass transfer of the volatile compounds and forming char layers which blocked polymers from heat and oxygen. Meanwhile, the introduction of PSS@GNS into PS also contributed to increase its strength and elongation rate thanks to the pristine properties of graphene nanosheets and their interfacial interaction with the PS matrix.
  • Hierarchically structured PVP porous fibers derived from the embedding of
           NaY zeolite synergize the adsorption of benzene
    • Abstract: Publication date: Available online 23 October 2019Source: Composites Part B: EngineeringAuthor(s): Xianghua Wu, Xing Yang, Hu Yang, Zeping Guo, Jinpei Lin, Wei Wu, Xiaoguang Liang, Yun He Composite fibers synthesized via the electrospinning technique have been extensively investigated as the adsorbent for the volatile organic compounds (VOCs) because of their synergistic effect. Herein, the novel hierarchically structured polyvinylpyrrolidone (PVP) porous fibers embedded with microporous NaY zeolite are fabricated by employing the electrospinning method. The parameters such as the electrospinning voltage and flow rate as well as the particle sizes of NaY zeolite are optimized further for the preparation of composite fibers featured with homogeneous morphology and superior property. Consequently, the composite fibers with large specific area synthesized under the optimized process present an excellent benzene adsorption capacity of 667 mg/g, which can be attributed to synergistic effect originated from the hierarchical structure configured with porous PVP and microporous NaY zeolite. Our work does not only demonstrate the promising potential of the as-fabricated composite fibers for VOCs due to its advantages of low cost and large-scale production, but also provides valuable insights into the design and utilization of zeolite/polymer composite fibers for practical applications.
  • A synergistic combination of zinc oxide nanowires array with
           dual-functional zeolitic imidazolate framework-8 for hybrid
           nanomaterials-based gas sensors
    • Abstract: Publication date: Available online 23 October 2019Source: Composites Part B: EngineeringAuthor(s): In Su Jeon, Garam Bae, Moonjeong Jang, Wooseok Song, Sung Myung, Sun Sook Lee, Ha-Kyun Jung, Jinha Hwang, Ki-Seok An The complementary hybridization of nanomaterials enables to realize newly synergistic properties, which is a central concept in next-generation widespread applications. In particular, it is well-established that the hybridization of ZnO nanostructure with zeolitic imidazolate framework-8 (ZIF-8) allows the improvement of gas selectivity owing to molecular sieving capability caused by inherently size-defined porous structures of the ZIF-8. Here, we focused on a different viewpoint related with the preconcentration effect of ZIF-8 hybridized with ZnO nanowires (NWs) array on NO2, NH3, and H2 gas response. Hydrothermally-grown, structurally optimized ZnO NWs array are rationally employed for the nucleation sites of ZIF-8 nanocrystals as well as gas sensing channel. The chemical conversion of the surface of ZnO NWs to ZIF-8 was systematically implemented for the formation of core-shell hybrid structure, where morphological features of the ZIF-8 nanocrystals hybridized with the ZnO NWs array were optimized by simply adjusting synthetic conditions. The thickness of encapsulated ZIF-8 could be effectively manipulated by altering the concentration of 2-methylimidazole (HmIM), which strongly affects to determining gas response of ZIF-8@ZnO NWs-based gas sensors because of a variation in gas-loading capabilities related with the preconcentration effect. For the gas sensor based on ZIF-8@ZnO NWs synthesized using 8 mM HmIM solution, the gas response of NO2, NH3, and H2 gases were improved compared to those of the pristine ZnO NWs-based gas sensor. In addition, we consolidated the molecular sieving effect of the ZIF-8 by measuring the gas response of CH4 and C3H8 for suggesting the dual functionality of the hybrid system.
  • A fast modeling approach for numerical analysis of unreinforced and FRCM
           reinforced masonry walls under out-of-plane loading
    • Abstract: Publication date: Available online 23 October 2019Source: Composites Part B: EngineeringAuthor(s): Jacopo Scacco, Bahman Ghiassi, Gabriele Milani, Paulo B. Lourenço A new discretized homogenization approach is proposed in this study in order to predict the behavior of unreinforced and FRCM reinforced masonry structures. The proposed approach allows overcoming the common disadvantages of the existing homogenization approaches: (a) being difficult to implement and (b) not allowing to couple the in-plane and out-of-plane actions. Reference experimental results and detailed numerical modeling are used for validation of the proposed modeling strategy. In the proposed model, the elastic cells are linked by homogenized interfaces. The mechanical properties coming from the homogenization procedures are lumped at the interfaces by means of the generic Concrete Damage Plasticity model, allowing easy implementation and avoiding computational issues peculiar to other approaches available in the literature. The new approach shows accurate results in predicting the global behavior and the damage pattern for both unreinforced and FRCM strengthened masonry walls. The results are promising also with a view to be applied for more complex reinforced applications as double curvature masonry structures.
  • Activated carbon spheres@NiCo2(CO3)1.5(OH)3 hybrid material modified by
           ionic liquids and its effects on flame retardant and mechanical properties
           of PVC
    • Abstract: Publication date: Available online 22 October 2019Source: Composites Part B: EngineeringAuthor(s): Yong-Hui Wang, Wei-Hong Wu, Wei-Hua Meng, Hao Liu, Guang Yang, Yun-Hong Jiao, Jian-Zhong Xu, Hong-Qiang Qu In order to effectively reduce fire hazards while retaining excellent mechanical properties of flexible polyvinyl chloride (PVC), a novel core-shell-structured flame retardant, i.e., activated carbon spheres-supported NiCo2(CO3)1·5(OH)3 hybrid material (ACS@BNCC), was synthesized and dry-modified by 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquids ([BMIM] PF6) before mixing with PVC. The results of the limiting oxygen index (LOI) and cone calorimeter test (CCT) showed that 2 phr ILs-ACS@BNCC could endow PVC with outstanding fire-resistant and smoke suppression properties. The synergistic effect of ACS@BNCC and [BMIM] PF6 increased the LOI to 29.1%, and reduced the peak heat release rate, peak smoke production rate, and total smoke production of pure PVC by 37.0%, 62.0%, and 45.1%, respectively. The flame retardant mechanism was proposed. The 2 phr ILs-ACS@BNCC mainly had physical barrier, catalytic carbonization, endothermic and dilution effects. In addition, since [BMIM] PF6 enhanced the interface compatibility between PVC and ACS@BNCC, the tensile strength, elongation at break, and impact strength of 2 phr ILs-ACS@BNCC/PVC were significantly improved compared with those of ACS@BNCC/PVC. This kind of PVC composite with outstanding flame retardant, smoke suppression and mechanical properties will substantially expand the application of PVC.Graphical abstractImage 1
  • PLA/banana fiber based sustainable biocomposites: A manufacturing
    • Abstract: Publication date: Available online 21 October 2019Source: Composites Part B: EngineeringAuthor(s): Ujendra Kumar Komal, Manish Kumar Lila, Inderdeep Singh In the present experimental investigation, biocomposites based on short banana fiber (20 wt%) and poly-lactic acid were fabricated using three different processing techniques, namely direct injection molding (DIM), extrusion injection molding (EIM) and extrusion compression molding (ECM). The thermal and mechanical characterization as well as dynamic mechanical analysis has been performed to understand and compare the performance of the developed biocomposites. FTIR analysis has been conducted to investigate the presence and type of interfacial interaction in the biocomposites. XRD analysis was conducted to investigate the structure and to measure the crystallinity of the biocomposites. A significant improvement in the mechanical (tensile and flexural properties), dynamic mechanical properties (storage modulus, loss modulus, and tan delta) and crystallinity of the biocomposites fabricated by EIM were observed. A novel approach was used to examine the orientation and distribution of the fibers within the developed biocomposites. The fiber damage in terms of breaking, bending, twisting and formation of the clusters have been observed. Scanning Electron Microscopy (SEM) analysis revealed that the fiber pull-out and fracture are dominating the failure of biocomposite under loading.
  • Failure and complex crack patterns in hybrid laminates: A phase-field
    • Abstract: Publication date: Available online 22 August 2019Source: Composites Part B: EngineeringAuthor(s): R. Alessi, F. Freddi A powerful numerical instrument, which reproduces the complex failure mechanisms of hybrid laminates under in-plane loading conditions, is developed within the framework of phase-field modelling. The ruptures, strongly influenced by geometrical and mechanical properties of the plies and affected by the state of stress, are arranged as delamination of the adhesive interface and intricate crack patterns within the layers. Therefore, the mechanical response of a hybrid laminate is obtained by studying the simplified layup of two elastic-brittle solids connected by a cohesive interface. Explicit and well detailed simulations illustrate peculiar failure mechanisms, validated, when possible, against experimental results taken from the literature and compared to simplified analytical models. Different in-plane loading conditions are explored together with the possibility to include material anisotropy. The proposed model is a first attempt to provide an effective design tool for the understanding of the intriguing failure of hybrid laminates and the enhancement of their mechanical properties like ductility.
  • Polyethylene glycol supported by phosphorylated polyvinyl alcohol/graphene
           aerogel as a high thermal stability phase change material
    • Abstract: Publication date: Available online 19 October 2019Source: Composites Part B: EngineeringAuthor(s): Jia Shen, Ping Zhang, Lixian Song, Jiapeng Li, Bingqiang Ji, Jiajun Li, Lin Chen Polyethylene glycol (PEG) as a phase change material (PCM) is limited in practical applications due to the three major drawbacks of low thermal conductivity, poor thermal stability, and easy leakage. In this study, a new shape-stabilized PPVA/GA/PEG PCM based on Phosphorylated polyvinyl alcohol (PPVA) and graphene aerogels (GA) as a “double-network” support material was obtained using a one-step method, and the three major obstacles of PEG as a PCM were well resolved in this composite material. 15%-PPVA/GA/PEG composite PCMs still exhibit high energy storage capacity while having high thermal stability and high shape-stabilized property. 15%-PPVA/GA/PEG composite PCMs (0.610 W m−1 K−1), with only 1.60 wt% GA, showed an enhanced thermal conductivity than that of PEG (0.493 W m−1 K−1), and it still exhibited an acceptable latent heat of fusion of 119.6 J g−1. Furthermore, the peak heat release rate of 15%-PPVA/GA/PEG composite PCMs decreased by 19.2% compared with PEG. The above experimental results indicate that the prepared PPVA/GA/PEG composite PCMs have application prospects in thermal energy storage field.Graphical abstractImage 1
  • Digital light processing 3D printing of graphene/carbonyl iron/polymethyl
           methacrylate nanocomposites for efficient microwave absorption
    • Abstract: Publication date: Available online 18 October 2019Source: Composites Part B: EngineeringAuthor(s): Yuxin Zuo, Zhengjun Yao, Haiyan Lin, Jintang Zhou, Jiong Lu, Jun Ding Digital light processing (DLP) 3D printing can enhance the microwave absorption performance of absorbers from the material composition and structure design. For the first time, graphene/carbonyl iron powder(CIP)/polymethyl methacrylate(PMMA) nanocomposites with various compositions of graphene and CIP were successfully prepared by DLP 3D printing technology. These newly prepared composites show enhanced microwave absorption properties. Specifically, the nanocomposite (labelled as CG4) containing 1.0 wt% graphene and 47.8 wt% CIP possesses the maximum reflection loss (RL) of −54.4 dB at a thickness of 2.1 mm, along with effective absorption (RL<–10dB) bandwidth of as wide as 3.41 GHz 3D printing technology can enhance the higher efficiency of microwave absorbers preparation due to the rapid prototyping and little post-treatment. The superior microwave absorption performance benefits from interface polarization and proper impedance matching.
  • Synergistic effect enhanced shape recovery behavior of metal-4D printed
           shape memory polymer hybrid composites
    • Abstract: Publication date: Available online 18 October 2019Source: Composites Part B: EngineeringAuthor(s): Yang Liu, Fenghua Zhang, Jinsong Leng, Liyun Wang, Chase Cotton, Baozhong Sun, Tsu-Wei Chou The four-dimensional (4D) printing technology enables the convergence of three-dimensional (3D) printing and shape memory polymer (SMP). The aim of this research is to demonstrate the synergistic effect between a spring steel strip (SSS) and a 4D printed thermoplastic SMP on enhancing the shape recovery properties. The recovery time of the SMP/SSS hybrid composite was shortened by 39% as compared to that of the SMP specimen. The corresponding recovery force of the SMP/SSS hybrid specimen at 64 °C was 9 N, 199 times of that of the non-hybrid SMP specimen. For optimizing the design of hybrid composite specimens, the structural parameters, such as hybrid stacking configuration, SMP infill percentage and SSS thickness, have been also investigated and their influences on the shape recovery properties of the hybrid composite specimens have been identified. The present results signify a promising approach to improve the performance of SMP based sensors and actuators using hybrid composites.
  • Hierarchical assembly of polystyrene/graphitic carbon nitride/reduced
           graphene oxide nanocomposites toward high fire safety
    • Abstract: Publication date: Available online 18 October 2019Source: Composites Part B: EngineeringAuthor(s): Yongqian Shi, Chuan Liu, Libi Fu, Fuqiang Yang, Yuancai Lv, Bin Yu Developing polymer nanocomposites with high thermal stability and excellent flame retardant performances at low loadings still remains a great challenge. Here, we constructed multilayered polystyrene (PS) nanocomposites consisting of graphitic carbon nitride nanosheets (g-C3N4 NSs) and reduced graphene oxide (RGO) using the layer by layer assembly technique. Microstructure analysis demonstrated the successfully alternative assembly of g-C3N4 NSs and RGO onto PS spheres through electrostatic interaction. The ternary PS nanocomposites showed the highest thermal stability. For instance, the temperature at maximum decomposition rate and the residual yield were increased by 15 °C and 5.89 wt%, respectively for PS nanocomposite with one number of g-C3N4/RGO bilayers (PS/CG1). Furthermore, the PS/CG1 exhibited dramatically lowest release of total pyrolysis gaseous products and the peak of heat release rate, indicative of the highest fire safety. Fire safety enhancement was attributed to the formation of compact network barriers that retarded the heat and mass transfer between combustion zone and underlying PS matrix.Graphical abstractImage 1
  • Synthesis of bio-based fire-resistant epoxy without addition of flame
           retardant elements
    • Abstract: Publication date: Available online 17 October 2019Source: Composites Part B: EngineeringAuthor(s): Jinyue Dai, Na Teng, Jingkai Liu, Jianxiang Feng, Jin Zhu, Xiaoqing Liu Blending with flame retardants or introducing fire resistant elements into their skeletons is a routine method to obtain the fire resistant epoxy resins. Herein, we report a novel epoxy monomer diglycidyl ether of genistein (DGEG) synthesized from the renewable genistein, and after it was cured with 4, 4-diaminodiphenylmethane (DDM), the intrinsically flame-retardant resin (DGEG/DDM), which contains only C, H and O elements, was obtained. The DGEG/DDM system demonstrates a total heat release (THR) as low as 6.3 kJ/g measured by microscale combustion calorimetry (MCC), a high limiting oxygen index (LOI) of 33.1%, and the flammability rating of V-0 in UL94 test. In addition, when compared with the bisphenol A epoxy resin system (DER332/DDM) cured under the same condition, DGEG/DDM exhibits higher glass transition temperature (223 °C vs. 175 °C) and shows a 12%, 19%, 33% and 183% increment in storage modulus (25 °C), tensile strength, flexural strength and residual char value at 800 °C, respectively. The results in this work provide us a new strategy to synthesize high performance flame retardant epoxy resins by taking advantages of the unique structures of renewable compounds.Graphical abstractImage 1
  • 3D printing to enable multifunctionality in polymer-based composites: A
    • Abstract: Publication date: Available online 17 October 2019Source: Composites Part B: EngineeringAuthor(s): D.G. Bekas, Y. Hou, Y. Liu, A. Panesar The employment of 3D printing for the fabrication of advanced multi-functional composites is attracting increased interest of the research community due to the opportunities offered by this technology (i.e. the wide range of materials that can be printed, short time, low costs). Numerous attempts are being presented every year regarding the incorporation of specific functionalities such as conductive, magnetic, embedded circuitry, thermal, sensing and self-healing to composites by employing different 3D printing processes and materials. This review provides an overview of the main functionalities that have been incorporated, homogeneously or locally, to polymer based composite materials via 3D printing. A strong emphasis is laid on the two main pillars enabling functionalisation: additives and printing methods. Finally, promise offered by the maturation of technology and recommendation on research efforts that are imminently needed to fulfil the untapped potential of functional 3D printing is given.
  • Flexural strength enhancement in carbon-fiber epoxy composites through
           graphene nano-platelets coating on fibers
    • Abstract: Publication date: Available online 17 October 2019Source: Composites Part B: EngineeringAuthor(s): Alok K. Srivastava, Vidit Gupta, Chandra S. Yerramalli, Aparna Singh Carbon-fiber epoxy composites show extremely high modulus and strength in the uniaxial direction. However, they fail relatively easily under flexural loading due to the weak nature of the interface between the carbon-fiber and epoxy. In the current study, the desizing and oxidation treatment of carbon fibers and the coating of graphene nano-platelets (GNPs) on the carbon-fibers has been done with an aim to strengthen the interface/interphase between the fiber and the matrix. GNPs were coated on the carbon fibers before making the final laminates through vacuum assisted resin transfer molding. The flexural strength of the laminates has been found to improve significantly with GNP addition. Scanning electron microscopy equipped with energy dispersive X-ray spectroscopy have been used to examine the nature of interface/interphase between the fiber and the matrix as well as the mechanism of failure of the composite.Graphical abstractImage 1
  • Experimental evaluation of residual tensile strength of hybrid composite
           aerospace materials after low velocity impact
    • Abstract: Publication date: Available online 16 October 2019Source: Composites Part B: EngineeringAuthor(s): Mahdi Damghani, Nuri Ersoy, Michal Piorkowski, Adrian Murphy Although much work has considered hybridised Carbon and Glass Fibre Reinforced Polymers to positively influence the performance of composite structures when subjected to transverse impact loading, there is limited understanding considering low energy impact levels (≤10J) - in particular how variation in impact energy influences damage formation and post impact tensile strength. Herein, low velocity impact and residual tensile strength after impact tests are completed on four laminate designs (one pure Carbon laminate layup and three hybrid Carbon and Glass layups). Three repeat tests and three graduated low energy level impacts (≤10 J) are considered along with pristine laminate performance. The impact response was evaluated in terms of surface damage size by visual inspection, and the evolution of peak force and stiffness with impact energy level. The contribution of this paper is the first presentation of a detailed experimental study on the tensile performance of hybrid composite materials subjected to a graduated range of low energy level impacts. The methodical experimental work demonstrates how the hybrid layup influences the scale and form of damage. By distributing the glass plies through the laminate, as opposed to clustering the glass plies at the inner or outer mould surfaces, more favourable residual tensile strength and strain to failure is demonstrated.
  • Shape memory effect of dynamically vulcanized ethylene-propylene-diene
           rubber/polypropylene blends realized by in-situ compatibilization of
           sodium methacrylate
    • Abstract: Publication date: Available online 15 October 2019Source: Composites Part B: EngineeringAuthor(s): Chuanhui Xu, Rui Cui, Yukun Chen, Jianping Ding In this paper, the shape memory (SM) effect of dynamically vulcanized ethylene-propylene-diene rubber/polypropylene (DV-EPDM/PP) blends with typical sea-island structure is successfully fabricated by using sodium methacrylate (NaMAA) as compatibilizer and proper programming. The powerful EPDM/PP interface generated by in-situ compatibilization of NaMAA, as confirmed by FTIR, DMA, SEM and TEM, is the key to orchestrate the overall cooperation of EPDM and PP components to fulfill the SM behavior. The crystalline PP continuous phase holds the highly elongated EPDM particles via strong interface to fix the temporary shape perfectly, while the elongated EPDM particles restore elastic resilience as the driving force for the shape recovery. After a proper SM programming, e.g. shaping at 130 °C and triggering at 165 °C, the shape fixity ratio (Rf) and the shape recovery ratio (Rr) of DV-blends with NaMAA could exceed ∼95% and ∼95%, respectively.Graphical abstractImage 1
  • 3D pollen-scaffolded NiSe composite encapsulated by MOF-derived carbon
           shell as a high-low temperature anode for Na-ion storage
    • Abstract: Publication date: Available online 15 October 2019Source: Composites Part B: EngineeringAuthor(s): Chiquan Su, Qiang Ru, Shikun Cheng, Yuqing Gao, Fuming Chen, Lingzhi Zhao, Francis Chi-Chung Ling As a novel sodium ion battery anode material, 3D pollen-scaffolded NiSe composite encapsulated by metal-organic framework-derived (MOF-derived) carbon shell is synthesized, denoted as P–NiSe@C. The results depict that well-crystallized NiSe particles were in-situ grown on 3D pollen framework, preventing the particles aggregation effectively. Meanwhile, the pyrolytic MOF-derived shell from 2-methylimidazole further strengthens the adhesion between NiSe particles and pollen skeleton, which would enhance the structural stability and mitigate the volumetric changes during sodium intercalation/deintercalation. Compared with the inferior sodium storage capability of raw NiSe, the P–NiSe@C electrode delivers a sustainably reversible capacity of 598.2 mAh g−1 (200 mA g−1 after 100 cycles) and excellent rate performance of 488.9 mAh g−1 even at a large current density of 2000 mA g−1. The P–NiSe@C electrode also has an impressive high-low temperature adaptability with durable and controllable capacities of 343.8–792.6 mAh g−1 from −5 to 70 °C.Graphical abstractImage 1
  • Modeling strategy for dynamic-modal mechanophore in double-network
           hydrogel composites with self-growing and tailorable mechanical strength
    • Abstract: Publication date: 15 December 2019Source: Composites Part B: Engineering, Volume 179Author(s): Haibao Lu, Ziyu Xing, Mokarram Hossain, Yong-Qing Fu Smart materials with self-growing and tailorable mechanical strength have wide-range potential applications in self-healing, self-repairing, self-assembly, artificial muscle, soft robots and intelligent devices. However, their working mechanisms and principles are not fully understood yet and mathematically and physical modeling is a huge challenge, as traditionally synthesized materials cannot self-grow and reconstruct themselves once formed or deformed. In this study, a phenomenological constitutive model was developed to investigate the working mechanisms of self-growing and tailorable mechanical strength in double-network (DN) hydrogel composites, induced by mechanochemical transduction of dynamic-modal mechanophore. An extended Maxwell model was firstly employed to characterize the mechanical unzipping of hydrogel composites, and then mechanochemically induced destruction and reconstruction processes of brittle network in the hydrogel composite were formulated. The enhanced mechanical strength of brittle network has been identified as the key driving force to generate self-growing and tailorable mechanical strength in the hydrogel composite. Finally, a stress-strain constitutive relationship was developed for the dynamic-modal mechanophorein the hydrogel composite. Simulation results obtained from the proposed model were compared with the experimental data, and a good agreement has been achieved. This study provides an effective strategy for modelling and exploring the working mechanism in the mechanoresponsive DN hydrogel composites with self-growing and tailorable mechanical strength.
  • High-entropy alloy@air@Ni–NiO core-shell microspheres for
           electromagnetic absorption applications
    • Abstract: Publication date: Available online 14 October 2019Source: Composites Part B: EngineeringAuthor(s): Hongjing Wu, Di Lan, Bo Li, Limin Zhang, Ying Fu, Yi Zhang, Hui Xing Core-shell microspheres with high-entropy alloy (HEA: FeCoNiCrCuAl0.3) as core and metal oxide (Ni–NiO) as shell have been successfully constructed via a two-step hydrothermal method. The chemical composition, microstructure, electromagnetic (EM) properties and EM wave absorption properties were characterized in detail. We find that the magnetic loss originated from high-entropy alloy and the dielectric loss caused by Ni–NiO can promote the consumption of EM energy through synergistic effect. The effective absorption bandwidth (fE, RL  
  • Net-like SiC@C coaxial nanocable towards superior lightweight and
           broadband microwave absorber
    • Abstract: Publication date: Available online 13 October 2019Source: Composites Part B: EngineeringAuthor(s): Meng Zhang, Hui Lin, Shiqi Ding, Ting Wang, Zhenjiang Li, Alan Meng, Qingdang Li, Yusheng Lin In this study, a practical lightweight and broadband microwave absorber, namely, the net-like amorphous carbon-coated silicon carbide coaxial nanocables (SiC@C NCs), which had low density and excellent physicochemical stability, was successfully fabricated according to the hydrothermal-carbonization strategy. Typically, the microwave absorption performance exhibited broad effective absorption bandwidth (EAB) of up to 7.2 GHz (9.12–16.32 GHz) at a small matching thickness of 2.58 mm. Meanwhile, the minimal reflection loss (RL) value of −51.53 dB with the corresponding EAB across the whole Ku-band (11.68–18 GHz) appeared at 2.08 mm, which suggested that, the as-prepared SiC@C NCs displayed extensive application prospects as a superior lightweight and broadband microwave absorber. Moreover, the systematic characterization results indicated that, the superior microwave absorption performance was ascribed to the interfacial polarization and multiple reflections on the heterogeneous interface between the SiC nanowires (SiC NWs) core and the amorphous carbon shell, together with the electron polarization and Debye dipolar relaxation resulted from the stacking faults of SiC NWs core, and the abundant defect and disorder within the amorphous carbon shell.Graphical abstractImage 1
  • A novel four-linear cohesive law for the delamination simulation in
           composite DCB laminates
    • Abstract: Publication date: Available online 11 October 2019Source: Composites Part B: EngineeringAuthor(s): Shihao Yin, Yu Gong, Wangchang Li, Libin Zhao, Jianyu Zhang, Ning Hu Large-scale fiber bridging usually presents in the wake of the crack tip in multidirectional composite DCB laminates, resulting in a significant R-curve phenomenon on the fracture toughness. In order to consider the influence of the fiber bridging on the delamination behavior in FE modelling, a novel four-linear cohesive law is proposed in this study, which is physically established based on the realistic failure mechanism during the delamination process. The required parameters in this law can be determined by experiments, expect for the fracture toughness ratio, which is introduced to present the non-linear softening behavior of the bridging fibers in a simple way and make the cohesive law easy to be implemented in FEM. The numerical results predicted by the proposed law have good agreements with the experimental results for two kinds of multidirectional laminates, illustrating the applicability of the new four-linear cohesive law. The advantages of this new cohesive law are the less parameters required to be numerically determined and the simplicity for practical application than existing methods. In addition, the new cohesive law is physical-based rather than a direct superposition by two linear cohesive zone models, which is lack of physical basis.
  • Versatile 3D porous recycled carbon garments with fully-loaded active
           materials in the current collector for advanced lithium-ion batteries
    • Abstract: Publication date: Available online 11 October 2019Source: Composites Part B: EngineeringAuthor(s): Hyunjin Cho, Yeonho Kim, Yong Ju Yun, Kyu Seung Lee, Jaeho Shim, Chil-Hyoung Lee, Jin Won Seo, Won G. Hong, Hae Jin Kim, Hak Yong Kim, Dong Ick Son We have developed a new and versatile three-dimensional (3D) porous and the conductive carbon spun fabric (CSF) structure and applied it to the current collector for advanced lithium-ion batteries (LIBs). The 3D porous CSF are manufactured from recycled oxidized polyacrylonitrile (Oxi-PAN) staple fibers via the spinning, the knitting, stabilization, and carbonization process in order. Furthermore, we have demonstrated the conductive T-shirts and gloves and investigated the structural, electrical, mechanical, and thermal properties of the CSF through various analytical methods including Joule heating simulation as well as the deformation simulation. The CSF with its 3D porous structure is applied as a current collector for advanced lithium batteries in order to replace the conventionally used metal-based current collector. During battery performances, the porous 3D network structure of the CSF provides effective diffusion pathway for lithium ions during the charge/discharge processes. Consequently, the CSF shows not only the improved cycling stability than that of the conventional aluminum current collector but also demonstrating high-rate performances at high percentage loading of active materials in the current collector. The pouch-type LIBs with the CSF/LiFePO4 composites electrode exhibits excellent mechanical stability and flexibility with showing a discharge capacity of 148.7 mA h g−1 at 2 C over 250 cycles over the 1200 times bending with a radius of 12 mm.Graphical abstractA new and versatile three-dimensional (3D) porous and the conductive carbon spun fabric (CSF) structure have been developed and have been applied it to the current collector for advanced lithium-ion batteries (LIBs).Image 1
  • Highly stretchable liquid metal/polyurethane sponge conductors with
           excellent electrical conductivity stability and good mechanical properties
    • Abstract: Publication date: Available online 9 October 2019Source: Composites Part B: EngineeringAuthor(s): Nanying Ning, Wei Huang, Suting Liu, Qi Zhao, Hua Zou, Bing Yu, Ming Tian, Liqun Zhang An all-soft, highly stretchable liquid metal (LM) conductor with high electrical conductivity, excellent electrical conductivity stability under various mechanical deformations and good mechanical properties was achieved. The stretchable conductor was prepared by infiltrating Gallium-indium-tin (GIT) LM into porous polyurethane sponge (PUS) with large porosity and small pores using a vacuumizing method followed by encapsulation with Polydimethylsiloxane (PDMS) to prevent the leakage of GIT-LM and to improve the mechanical properties. The as-made PDMS/PUS/LM composite shows a high tensile strength (1.11 MPa), high elongation at break (419%), excellent electrical conductivity (104 S/cm) and electrical conductivity stability under various mechanical deformations. The normalized resistance is of highly repeatability in stretch-release and bend-release cycle experiments.Graphical abstractImage 1
  • Examining conductivity, current density, and sizings applied to carbon
           fibers during manufacture and their effect on fiber-to-matrix adhesion in
           epoxy polymers
    • Abstract: Publication date: Available online 8 October 2019Source: Composites Part B: EngineeringAuthor(s): Andreas Hendlmeier, Filip Stojcevski, Richard Alexander, Sunil Gupta, Luke C. Henderson This study provides a comprehensive study of carbon fiber surface treatment conditions for epoxy resins. A set of 27 fibers, derived from DowAska precursor, with alterations to manufacturing conditions only occurring at the electrochemical oxidation and sizing bath. Electrolyte (NH4HCO3) conductivity was varied between 8, 16 and 24 μS/cm while oxidative current density was varied between 0.5, 1.0 and 1.5 A/m2. Subsequent to oxidation, fibers were coated with either epoxy, polyamide or polyurethane compatible sizing. This study is the first to consider electrolyte conductivity, oxidative current density and sizing variables simultaneously and links them to interfacial shear strength (IFSS). Extensive chemical, physical and mechanical characterization was conducted to quantify the changes to fiber properties as a result of treatment variation. Results reveal that varying combinations of electrolyte and applied current density not only vary the degree of oxidation on the fiber, but the types of surface chemistry installed (e.g. ratio of COH, CO, and COOH). Somewhat counter-intuitively, at high conductivities and current densities the degree of oxidized carbon species on the fiber surface is decreased. Indeed, this study shows combinations of surface treatment variables which could be used to promote the formation of surface bound functional groups in preference (e.g. phenolic groups in preference to COOH) to enhance interfacial bonding for a given resin. Determination of fiber roughness for all samples showed no statistical difference between samples, suggesting that mechanical interlocking effects do not play a role in the variations in interfacial adhesion observed herein.
  • Failure characteristics of UHPFRC panels subjected to projectile impact
    • Abstract: Publication date: Available online 7 October 2019Source: Composites Part B: EngineeringAuthor(s): M. Beppu, S. Kataoka, H. Ichino, H. Musha This study investigates the failure characteristics of ultra-high performance fiber-reinforced concrete (UHPFRC) panels subjected to a steel projectile impact. Impact tests for 60–120-mm-thick UHPFRC panels were conducted to examine the failure state and impact resistant performance of the panels by using an 8.3-kg-mass projectile with a diameter of 90 mm at a velocity approximately corresponding to 42 m/s. Experimental parameters included the arrangement of pre-stressing steel wires and enforcement of pre-stress. Although the effect of arranging the pre-stressing steel wires on the damage restraint of UHPFRC panels was observed, the enforcement of pre-stress was not significantly effective in mitigating the damage. The impact response characteristics of UHPFRC panels were investigated by comparison between the impact force, reaction force, and strain response.
  • 2D closed form solutions for exact elastic analysis of multilayered shells
           with imperfect bonding
    • Abstract: Publication date: Available online 7 October 2019Source: Composites Part B: EngineeringAuthor(s): Hossein Darban, Francesco Fabbrocino, Raimondo Luciano, Rosa Penna Plane elasticity problem of a simply supported laminated cylindrical shell with imperfectly bonded orthotropic or isotropic layers subjected to static loading is considered. Imperfect bonding of layers is modeled by a linear uncoupled interfacial law which relates the tangential and normal interfacial tractions to the sliding and opening displacement jumps at the interface. The problem is solved in closed form through a matrix formulation and novel explicit expressions are presented for displacements and stresses. The expressions are valid for shells with any numbers of layers under plane-strain or plane-stress conditions, can be readily applied to generate benchmark solutions and perform parametric analyses. The expressions recover the solution to the plane elasticity problem of plates for the limiting case of shells with infinite curvature. Results are presented in tabular and graphical forms for a sandwich shell.
  • Large-scale production of simultaneously exfoliated and Functionalized
           Mxenes as promising flame retardant for polyurethane
    • Abstract: Publication date: Available online 3 October 2019Source: Composites Part B: EngineeringAuthor(s): Lingxin He, Junling Wang, Bibo Wang, Xin Wang, Xia Zhou, Wei Cai, Xiaowei Mu, Yanbei Hou, Yuan Hu, Lei Song The low yield of MXenes nanosheets and its poor interfacial compatibility with polymer matrix have been an unavoidable obstruction for the fabrication of related polymer nanocomposites. Here, we reported a facile and large-scale route for the simultaneous organic modification and exfoliation of MXene by utilizing the wet ball milling process. Due to the electrostatic attraction effect, positively charged poly(diallyldimethylammonium chloride) (PDDA) long chains would attach to negatively charged MXene, which prevented the newly peeled-off MXene sheets from agglomerating and reduced the collision from the steel balls. Also, the attached PDDA molecule may act as protective shield for MXene nanosheets, leading to the delay of oxidation on the surface of MXene nanosheets in atmosphere. Notably, with the incorporation of 3 wt% PDDA modified MXene in thermoplastic polyurethane (TPU) matrix, the peak heat-release rate (decreased by 50%) and total smoke production (decreased by 47%) were significantly decreased. Moreover, mechanical performance (tensile strength at break was raised by 31.2%) and thermal conductivities (increased by 88.6%) of TPU nanocomposites were evidently enhanced. This novel strategy provide a simple and effective way to obtain exfoliated and functionalized MXenes nanosheets, enriching the application of MXenes in polymeric material field.Graphical abstractImage 1
  • Intrinsically flame-retardant bio-based epoxy thermosets: A review
    • Abstract: Publication date: Available online 3 October 2019Source: Composites Part B: EngineeringAuthor(s): Xin Wang, Wenwen Guo, Lei Song, Yuan Hu At present most of epoxy thermosets is dependent on petroleum-based resources especially diglycidyl ether bisphenol A (DGEBA)-type epoxy monomers produced from epichlorohydrin (ECH) and bisphenol A (BPA). Owing to the limitation of the greenhouse gas emission, development of the bio-based epoxy thermosets is gaining increasing attention to substitute the petroleum-based ones. However, the bio-based epoxy thermosets possess similar high flammability to their petroleum-based counterparts. It is thereby necessary to endow them with flame retardancy. This review article aims to summarize the most relevant and up-to-date advances in intrinsically flame-retardant bio-based epoxy thermosets. First, the approaches to synthesis of bio-based intrinsically flame retardant epoxy monomers are introduced briefly. Subsequently, the review focuses in particular on partly bio-based intrinsically flame retardant epoxy thermosets from either bio-based epoxy monomers or bio-based curing agents in terms of their flame retardant property as well as mechanical property and thermal stability. Additionally, the fully bio-based intrinsically flame retardant epoxy thermosets are also reviewed. Finally, we will provide a brief comment on opportunities and challenges for future growth of bio-based intrinsically flame retardant epoxy thermosets.
  • Design of core/active-shell NaYF4:Ln3+@NaYF4:Yb3+ nanophosphors with
           enhanced red-green-blue upconversion luminescence for anti-counterfeiting
    • Abstract: Publication date: Available online 2 October 2019Source: Composites Part B: EngineeringAuthor(s): Guo Gong, Ya Song, Haihu Tan, Shaowen Xie, Changfan Zhang, Lijian Xu, Jianxiong Xu, Jie Zheng Lanthanide-doped NaYF4 upconversion luminescent nanophosphors have attracted great interest for anti-counterfeiting applications. However, low luminescent intensity caused by surface defects and low extinction coefficients of lanthanide dopants greatly limits their practical applications. Herein, we developed core/active-shell NaYF4:Ln3+@NaYF4:Yb3+ (e.g. NaYF4:Er3+/Tm3+@NaYF4:Yb3+, NaYF4:Yb3+/Er3+@NaYF4:Yb3+, and NaYF4: Yb3+/Tm3+@NaYF4:Yb3+) nanophosphors with enhanced near-infrared (NIR)-to-visible upconversion luminescence by coating Yb3+-doped NaYF4 shell (active-shell) on NaYF4:Ln3+ upconversion core nanoparticles. The structure, morphology, and elemental composition of NaYF4:Ln3+@NaYF4:Yb3+ core/active-shell nanoparticles (CASNs), NaYF4:Ln3+@NaYF4 core/inert-shell nanoparticles, and NaYF4:Ln3+ core nanoparticles were characterized and compared systematically to reveal their structure-property relationship. Collective data showed that coating of a NaYF4:Yb3+ active shell on NaYF4:Ln3+ cores significantly enhanced upconversion luminescent intensity by ∼21 times, while an inert (pure NaYF4) shell coated on the surface of NaYF4:Ln3+ core only resulted in 5.2 times luminescence enhancement. The enhanced upconversion luminescence intensity was mainly attributed to (i) the NaYF4 shell-reduced quenching effect and (ii) the promoted transformation of the absorbed NIR light from the pump source to the core nanoparticles by Yb3+ sensitizer in the active shell. Moreover, by tailoring dopant pairs and molar ratios of lanthanide ions in the core nanoparticles, three CASNs with enhanced red, green, and blue upconversion luminescence were obtained and fabricated into environmental benign luminescent inks. The inkjet printing of RGB CASNs inks on papers produced multiple-color, high-resolution, complex luminescent patterns under 980 nm laser. This work expands the lanthanide-doped NaYF4 materials for anti-counterfeiting applications.
  • A review of recent research on bio-inspired structures and materials for
           energy absorption applications
    • Abstract: Publication date: Available online 1 October 2019Source: Composites Part B: EngineeringAuthor(s): Ngoc San Ha, Guoxing Lu It is widely known that the availability of lightweight structures with excellent energy absorption capacity is essential for numerous engineering applications. Inspired by many biological structures in nature, bio-inspired structures have been proved to exhibit a significant improvement over conventional structures in energy absorption capacity. Therefore, use of the biomimetic approach for designing novel lightweight structures with excellent energy absorption capacity has been increasing in engineering fields in recent years. This paper provides a comprehensive overview of recent advances in the development of bio-inspired structures for energy absorption applications. In particular, we describe the unique features and remarkable mechanical properties of biological structures such as plants and animals, which can be mimicked to design efficient energy absorbers. Next, we review and discuss the structural designs as well as the energy absorption characteristics of current bio-inspired structures with different configurations and structures, including multi-cell tubes, frusta, sandwich panels, composite plates, honeycombs, foams, building structures and lattices. These materials have been used for bio-inspired structures, including but not limited to metals, polymers, fibre-reinforced composites, concrete and glass. We also discussed the manufacturing techniques of bio-inspired structures based on conventional methods, and adaptive manufacturing (3D printing). Finally, contemporary challenges and future directions for bio-inspired structures are presented. This synopsis provides a useful platform for researchers and engineers to create novel designs of bio-inspired structures for energy absorption applications.
  • Corrigendum to “Interfacial reaction induced efficient load transfer in
           few-layer graphene reinforced Al matrix composites for high-performance
           conductor” [Compos Part B: Eng 167 (2019) 93–99]
    • Abstract: Publication date: Available online 24 September 2019Source: Composites Part B: EngineeringAuthor(s): Weiwei Zhou, Pavlina Mikulova, Yuchi Fan, Keiko Kikuchi, Naoyuki Nomura, Akira Kawasaki
  • Thermo-mechanical behavior prediction of particulate reinforced shape
           memory polymer composite
    • Abstract: Publication date: Available online 20 September 2019Source: Composites Part B: EngineeringAuthor(s): Wei Zhao, Liwu Liu, Jinsong Leng, Yanju Liu A micromechanics model based on thermal viscoelasticity constitutive relation is presented to investigate the thermal-mechanical behavior of particulate reinforced shape memory polymer composite (SMPC). Based on the thermomechanical constitutive relation assumption and linear elastic constitutive relation assumption, the effective properties of SMPC are studied by using a micromechanics method. Through analyzing the constitutive theories of polymer and multi-walled carbon nanotubes (MWCNTs), as well as the filling quality of particles, the generalized Maxwell model (GMM) combined with Mori-Tanaka theory is developed, and the thermo-mechanical cycle behavior of SMPC is studied emphatically. Moreover, a set of uniaxial tensile experiments, stress relaxation tests and thermal-mechanical cycle tests are performed to verify the developed model. Eventually, the developed model is validated using a simulated example and experiment to ensure its creditability.
  • A closed-loop recycling process for discontinuous carbon fibre polyamide 6
    • Abstract: Publication date: Available online 18 September 2019Source: Composites Part B: EngineeringAuthor(s): Rhys J. Tapper, Marco L. Longana, Ian Hamerton, Kevin D. Potter The effects of a closed-loop recycling methodology are evaluated for degradation using a discontinuous carbon fibre polyamide 6 (CFPA6) composite material. The process comprises two fundamental steps: reclamation and remanufacture. The material properties are analysed over two recycling loops, and CFPA6 specimens show a total decrease of 39.7% (±3.5) in tensile stiffness and 40.4% (±6.1) in tensile strength. The results of polymer characterisation and fibre analysis suggested that the stiffness reduction was likely due to fibre misalignments primarily caused by fibre agglomerations, as a result of incomplete fibre separation, and by fibre breakages from high compaction pressures. The ultimate tensile strain was statistically invariable as a function of recycling loop which indicated minimal variation in polymer structure as a function of recycling loop. To the authors’ best knowledge, the mechanical performance of the virgin CFPA6 is the highest observed for any aligned discontinuous carbon fibre thermoplastic composites in the literature. This is also true for recycled specimens, which are the highest observed for any recycled thermoplastic composite, and, for any recycled discontinuous carbon fibre composite with either thermosetting or thermoplastic matrices.
  • Fabrication of durable and roughness-regeneration superhydrophobic
           composite materials by hot pressing
    • Abstract: Publication date: Available online 11 September 2019Source: Composites Part B: EngineeringAuthor(s): Mingdong Yu, Zhongyu Cui, Feng Ge, Cheng Man, Li Lei, Xin Wang The practical applications of superhydrophobic materials are still limited due to the fragile micro-nano scale rough structures. Here a novel preparation method based on a new roughness-regeneration model is reported to fabricate durable and non-fluorinated superhydrophobic materials, through combining organosilicon functionalized Al2O3 (SiF–Al2O3) microparticles and low-cost bakelite powder (solid-resin). The effect of the blend ratio of SiF–Al2O3/solid-resin on superhydrophobic properties of composite material was investigated in this paper. The material surface can retain superhydrophobicity after a series of rigorous durability testing, such as broken area test, sandstorm test, sandpaper abrasion test, knife scratch test and cold-resistant test. Even if the fine sandpaper (5000 Cw) is applied, a higher surface roughness can still be maintained (Sa = 2.1 μm) and the superhydrophobicity (WCA = 151°) of the surface is reserved.Graphical abstractA preparation method based on a new roughness-regeneration model is used to fabricate durable superhydrophobic composite materials.Image 1
  • Electrostatic self-assembly synthesis of ZnFe2O4 quantum dots (ZnFe2O4@C)
           and electromagnetic microwave absorption
    • Abstract: Publication date: Available online 5 September 2019Source: Composites Part B: EngineeringAuthor(s): Zhenguo Gao, Binghui Xu, Mingliang Ma, Ailing Feng, Yi Zhang, Xuehua Liu, Zirui Jia, Guanglei Wu Making effective usage of quantum size effect is a foregrounded strategy to design and fabricate excellent electromagnetic microwave absorption materials. In this research, ZnFe2O4 quantum dots were coated by hybrid amorphous carbon to form a sea islands structure by a facile electrostatic self-assembly synthetic technology. Simultaneously, the rejection of heterogeneous charges leads to the formation of quantum dots, by which the quantum size effects on dielectric and magnetic characteristic were investigated. Consequently, multiple hetero-interface and interfacial polarization was originated from polycrystalline feature of ZnFe2O4 with spinel and inverse spinel structures. In particular, the electromagnetic microwave absorption properties of ZnFe2O4 were greatly optimized, as the minimized reflection loss reached −40.68 dB at the frequency 11.44 GHz and thickness 2.5 mm, while the effective bandwidth corresponding was 3.66 GHz (from 9.87 to 13.52 GHz). The largest effective bandwidth was 4.16 GHz (from 8.08 to 12.24 GHz) with a thickness of 3 mm. It is suggested that high performance of microwave absorption of ZnFe2O4 quantum dots was well guided by the optimized impedance matching and attenuation constants.Graphical abstractImage 1
  • Multiscale modeling of the viscoelastic response of braid-reinforced
           polymers: Model formulation and experimental assessment considering
           different rheological models
    • Abstract: Publication date: Available online 28 August 2019Source: Composites Part B: EngineeringAuthor(s): U. Hofer, M. Luger, R. Traxl, R. Lackner Multiscale modeling is routinely employed to obtain the effective properties of hierarchically-organized materials. Departing from the definition of observation scales, upscaling is employed to obtain the effective (homogenized) properties at each scale. In this paper, unit-cell based upscaling procedures are used for homogenization, providing the basis for a multiscale model for the viscoelastic behavior of braid-reinforced composites. Elastic fiber and viscoelastic matrix properties are upscaled over three distinct observation scales, accounting for yarn and braid geometry. Two rheological models, i.e., the fractional Zener model and the extended Lomnitz model are employed to describe the viscoelastic matrix behavior. The proposed multiscale model is experimentally validated by compressive creep tests on braid-reinforced tubes, with the model results agreeing well with the experimentally-obtained results. Moreover, the experimentally-observed influence of the braid geometry is correctly reproduced by the proposed multiscale model, providing access to the sensitivity of geometrical properties on the mechanical performance of braid-reinforced polymers.
  • Experimental and numerical studies on the bending collapse of multi-cell
           Aluminum/CFRP hybrid tubes
    • Abstract: Publication date: Available online 11 October 2019Source: Composites Part B: EngineeringAuthor(s): Zhixin Huang, Xiong Zhang, Chongyi Yang Wrapping the structures with composites and adopting multi-cell sections are two typical methods to improve the crashworthiness of thin-walled beams. However, the effects of combining these two methods on crashworthiness are not clear. This paper aims to investigate the bending collapse and crashworthiness of the multi-cell aluminum/carbon fiber reinforced plastic (Al/CFRP) hybrid tubes under quasi-static and dynamic loading. Three-point bending tests are firstly conducted for the CFRP, Al and Al/CFRP square tubes with single or multi-cell sections. The deformation characteristics and crushing force responses of the tubes are analyzed, and the energy absorption performances are evaluated. The bending resistance of the Al tubes is increased by up to 41% attributed to the CFRP enhancement. The non-linear finite element software ABAQUS/Explicit is then employed to simulate the tests and help analyze the deformation mechanisms. Parametric studies are performed to investigate the influence of the Al wall thickness, the number of CFRP plies, loading velocity, partial wrapping and sectional shape on the crashworthiness of Al/CFRP tubes. Results show that the Al wall thicknesses, partial wrapping, and sectional shapes have a significant influence on the deformation pattern and force response of Al/CFRP tubes, while the number of CFRP plies and the loading velocity have a relatively small influence. The specific energy absorption of Al/CFRP tubes can be increased by 11% by introducing partial CFRP wrapping, and in all cases, the multi-cell Al/CFRP tubes outperform the single-cell counterparts in crashworthiness performances.Graphical abstractImage 1
  • Fabrication and anti-crushing performance of hollow honeytubes
    • Abstract: Publication date: Available online 11 October 2019Source: Composites Part B: EngineeringAuthor(s): Sha Yin, Huitian Wang, Jianxing Hu, Yaobo Wu, Yongbin Wang, Shiqing Wu, Jun Xu Honeytubes were architectured materials formed by the hybrid of honeycomb and lattice microstructures, which exhibited great energy absorption capability. In this work, thin-walled hollow honeytubes (HHTs) were further designed, and fabricated using different 3D printing methodologies and electro-chemical deposition technique. The compression results indicated that HHTs could possess smaller relative density and their specific strength be 2.4 and 1.5 times greater than that of solid-walled honeytubes and honeycombs, respectively. Geometrical effects on compressive performance of HHTs were examined, and tube configurations that determined the interactions with ribs were proved to be vital for the specific performance. Meanwhile, foam filled honeytubes could exhibit additional enhancement after properly designed. The specific energy absorption of HHTs especially steel HHTs was proved to have superiority among cellular materials. Hollow honeytubes (HHTs) in the present study had indicated the guidelines to tailor mechanical properties by microstructure design, which would also provide opportunities for artificial intelligence to speed up the development of novel materials.
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