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Journal Cover
Composites Part A : Applied Science and Manufacturing
Journal Prestige (SJR): 1.539
Citation Impact (citeScore): 5
Number of Followers: 260  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1359-835X - ISSN (Online) 1359-835X
Published by Elsevier Homepage  [3206 journals]
  • Homogeneously dispersed composites of hydroxyapatite nanorods and
           poly(lactic acid) and their mechanical properties and crystallization
           behavior
    • Abstract: Publication date: Available online 21 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Rong Zhang, Hailong Hu, Yang Liu, Junjun Tan, Wenqi Chen, Cheng Ying, Qingting Liu, Xudong Fu, Shengfei Hu, Ching-Ping WongAiming to disperse HA nanocrystals in a polymer matrix homogenously, uniform oil-soluble HA nanorods were synthesized via an oleic acid (OA)-assisted mixed-solvent thermal method, and then poly(lactic acid) (PLA)/HA nanorods nanocomposites were fabricated by using a solution method. The HA nanorods with an OA monolayer on the surface dispersed homogeneously in organic solvents and the dispersion in polymer solution was transparent and colloidally stable. TEM images showed that HA nanorods dispersed as single particles without aggregation in PLA matrix. The elongation at break of the composites increased from 4.24% to 8.79% by adding HA nanorods, whereas the tensile strength and Young's modulus were largely unchanged. HA nanorods accelerated evidently the PLA crystallization rate even at a low HA loading and induced a transition to an ordered crystalline morphology confirmed via non-iso/isothermal crystallization, the spherulitic morphology, calculations and wide-angle X-ray diffraction during heating and cooling cycles.Graphic abstractGraphical abstract for this article
       
  • Direct Bundle Simulation approach for the compression molding process of
           Sheet Molding Compound
    • Abstract: Publication date: Available online 21 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): N. Meyer, L. Schöttl, L. Bretz, A.N. Hrymak, L. KärgerAbstractThe manufacturing process of Sheet Molding Compounds (SMC) induces a reorientation of fibers during the flow, which influences local properties and is of interest for structural computations. Typically, the reorientation is described with an evolution equation for the second order fiber orientation tensor, which requires a closure approximation and multiple empirical parameters to describe long fibers. However, CT scans of SMC microstructures show that fiber bundles stay mostly intact during molding. Treating hundreds of fibers in such a bundle as one instance enables direct simulation on component scale. This work proposes a direct simulation approach, in which bundle segments experience Stokes’ drag forces and opposing forces are applied to the fluid field. The method is applied to specimens with a double-curved geometry and compared to CT scans. The Direct Bundle Simulation provides increased accuracy of fiber orientations and enables prediction of fiber-matrix separation with affordable computational effort at component scale.
       
  • Quantifying Nanodiamonds Assisted Exfoliation of Graphene and its Effect
           on Toughening Behaviour of Composite Structure
    • Abstract: Publication date: Available online 19 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Ankita Bisht, S.S. Samant, Satish Jaiswal, Kinshuk Dasgupta, Debrupa LahiriAbstractGraphene (Gr) is one of the most preferred reinforcement for polymer matrix, due to its large surface area. However, poor dispersion, due to stacking of Gr sheets, restricts their potential as reinforcement. In the present study, exfoliation of multi-layered graphene sheets is achieved in the presence of nanodiamond (ND), using ultrasonication. High-resolution electron micrographs clearly reveal the role played by ND in hindering restacking of graphene. SPM imaging further quantified exfoliation by measuring the thickness for different combinations of Gr:ND. Improved exfoliation of Gr increases both tensile strength and strain by ∼71% and ∼113%, respectively, for> 0.5wt% Gr content. Fracture toughness is improved by ∼150% with Gr, and an additional 44% with ND decorated Gr. Numerical analysis further confirms the effect of ND assisted exfoliation of Gr in toughening behavior of the composite, which can be explained in terms of improved total interface area, helping in better load transfer.
       
  • Squeeze-winding: a new manufacturing route for biomimetic fiber-reinforced
           structures
    • Abstract: Publication date: Available online 19 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Flavia Libonati, Andre E. Vellwock, Francesca E. Louizi, Randolf Hoffmann, Chiara Colombo, Gerhard Ziegmann, Laura VerganiAbstractNatural materials represent ideal biomimetic models for materials design. However, the sophisticated natural hierarchical architectures are rather difficult to be implemented in synthetic FRCs and components through classic manufacturing methods. We propose a new method, called squeeze-winding (SW), specifically designed for the fabrication of FRC-tubes with a bone-inspired internal structure. SW represents a modification to the classic filament winding (FW) and is aimed at implementing a bone-like structure characterized by axially-oriented cylindrical features and achieving a high reinforcement volume fraction (∼60%). The outcome of compression testing shows: a high repeatability of the mechanical characteristics achieved by SW, a higher fiber volume fraction of SW tubes compared to the conventional FW tubes, and improved mechanical properties. Moreover, we demonstrate how SW can be used to manufacture a sophisticated bio-inspired design, which mimics the cortical bone microstructure, ensuring enhanced mechanical properties compared to laminated tubes obtained by FW.
       
  • Ultra-strong and stiff randomly-oriented discontinuous composites: closing
           the gap to quasi-isotropic continuous-fibre laminates
    • Abstract: Publication date: Available online 17 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): M. Alves, D. Carlstedt, F. Ohlsson, L.E. Asp, S. PimentaAbstractConventional randomly-oriented Tow Based Discontinues Composites (TBDCs) are materials which combine good mechanical properties, lightweight and high manufacturability, and are therefore interesting for high-volume transport industries. This paper proposes, designs and successfully demonstrates a pathway to produce TBDCs with outstanding stiffness and tensile strength, by using ultra-thin tapes of (ultra-) high modulus carbon-fibres. Numerical models are used to explore the design space of discontinuous composite materials, in order to identify the optimal microstructural design to maximise stiffness and strength. Selected microstructures are manufactured and tested under tension; the experimental results show good agreement with the numerical predictions, and demonstrate a significant increase in the tensile strength and Young’s modulus of TBDCs by reducing the tow thickness and increasing the modulus of the fibres. Strength and stiffness increases of over 100% compared with the commercially available TBDC systems are achieved, resulting in mechanical properties that match the strength and overcome the stiffness of aerospace-graded continuous-fibre laminates.
       
  • Bilayer biodegradable films prepared by co-extrusion film blowing:
           mechanical performance, release kinetics of an antimicrobial agent and
           hydrolytic degradation
    • Abstract: Publication date: Available online 17 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Roberto Scaffaro, Andrea Maio, Fortunato E. Gulino, Claudio Di Salvo, Alessia ArcarisiAbstractBilayer biodegradable, eco-friendly films were prepared by co-extrusion film blowing, coupling polylactic acid (PLA) and Bio-flex ® (BIO). Furthermore, in the PLA layer, carvacrol (CRV) was added as a natural antimicrobial additive, whereas a nanoclay (D72T) was integrated to protect CRV from volatilization and to modulate release. The materials were analyzed by morphological, chemical-physical, mechanical testing. Furthermore, CRV release and degradation tests were performed. The results pointed out that coupling the two matrices allows gathering the stiffness of PLA with the ductility of BIO. Furthermore, the interlayer adhesion is promoted by CRV. D72T exerts a key-role in avoiding CRV volatilization, thus allowing more prolonged release. Degradation tests results highlight that bilayer films, while being particularly resistant in both acidic and neutral environments, showed a rapid degradation under alkaline conditions, which proved to be intermediate between those of the corresponding monolayers.
       
  • Large enhancement of discharge energy density of polymer nanocomposites
           filled with one-dimension core-shell structured NaNbO3@SiO2 nanowires
    • Abstract: Publication date: Available online 17 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Jianwen Chen, Dagui Ye, Xiaowei Wu, Wenbo Zhu, Xiucai Wang, Peng Xiao, Zhikui Duan, Xinmei YuAbstractDesign an architecture with the ability to improve breakdown strength has critical role to play for performance enhancement in energy storage capability. In this work, we report that the composite films with loaded with one dimension (1D) core-shell structured NaNbO3@SiO2 nanowires (NN@SiO2 NWs) are prepared and achieved significantly performance improvement in energy storage capability. The finite element simulation and experiment results both confirm the superiority of the 1D core-shell structured NN@SiO2 NWs in improving the energy density of the nanocomposite films. Especially, the nanocomposite films filled with 3 vol.% NN@SiO2 NWs show a large discharged energy density of 12.1 J cm-3, which is ≈ 243% over the bare PVDF (4.98 J cm-3) and ≈ 1008% greater than biaxially oriented polypropylenes (BOPP) (≈ 1.2 J cm-3 at 640 MV m-1). Therefore, this nanocomposite film can be considered as potential high-performance dielectric materials for next-generation pulsed power capacitor applications.
       
  • Exfoliation and defect control of graphene oxide for waterborne
           electromagnetic interference shielding coatings
    • Abstract: Publication date: Available online 17 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Wenbo Zhang, Linfeng Wei, Jianzhong Ma, Shu-Lin BaiAbstractGraphene oxide (GO) prepared by Hummers’ method possesses many structural defects which decrease its conductivity and limit its application in electromagnetic interference (EMI) shielding. Highly exfoliated GO with less defects (LGO) was prepared by a combination of less oxidant dosage (only 1/3 of the original dosage) and ultrasound-assisted Hummers’ method. The sulfonated reduced LGO (S-rLGO) was compounded with P(St-BA) latex to serve as EMI shielding composite via a blending-casting process. After thermal and chemical reduction, reduced LGO (rLGO) possesses much higher conductivity than reduced GO. With a S-rLGO loading of 25wt%, a high EMI shielding effectiveness (SE) of 15.9 dB at only 0.25 mm is achieved. Meanwhile, the tensile strength of composite is improved by 1097% owing to the π-π interaction. LGO was demonstrated to possess both good structural integrity and exfoliation degree, proving its better potential than GO as precursor of graphene for broad application.
       
  • Recyclable Conductive Epoxy Composites with Segregated Filler Network
           Structure for EMI Shielding and Strain Sensing
    • Abstract: Publication date: Available online 17 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Dian Yuan, Haochen Guo, Kai Ke, Ica Manas-ZloczowerForming a segregated conductive filler network at polymer particle interfaces enables the fabrication of high-performance conductive polymer composites at low filler content. However, this method is not applicable to thermosets that are not melt processable. Here, we report a facile and effective strategy to build a segregated filler network at epoxy waste particles and convert the system into a high-performance conductive composite. First, the permanent network in the epoxy waste is converted into a dynamic one via catalyst infusion. Subsequently, using an interface design strategy, branched carbon nanotubes (CNS) are introduced in the recycled epoxy system to form a segregated structure at the epoxy particle interfaces by compression molding. The resultant composites have excellent tensile properties, very low electrical percolation threshold and high electrical conductivity at low filler loading. This strategy enables the recycling of epoxy waste for the fabrication of high-performance composites for strain sensing and EMI shielding.Graphical abstractGraphical abstract for this article
       
  • Adaptation of material deposition parameters to account for out-time
           effects on prepreg tack
    • Abstract: Publication date: Available online 17 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): A.W. Smith, A. Endruweit, G.Y.H. Choong, D.S.A. De Focatiis, P. HubertAbstractA single-stage peel method was employed to determine the relationship between key processing parameters and tack for a standard aerospace carbon/epoxy prepreg subjected to various levels of room-temperature out-time. The temperature-dependent viscoelasticity of the resin was studied using parallel plate rheometry and modelled using a simple Arrhenius equation. Differential scanning calorimetry and gel permeation chromatography results showed that, over a period of 35 days under ambient conditions, resin Tg increased, while no significant change in polymer chain length was observed. Time–temperature superposition was applied to construct tack master curves for each out–time interval, which were shown to approximately coincide when considering shift factors attributed to changes in Tg. Process maps considering prepreg out–time were generated using tack master curves to inform process parameters and achieve desirable tack levels. This type of tailored process control is anticipated to improve resource utilization when manufacturing large preforms which take several days to complete.
       
  • Enhanced mechanical properties and strengthening mechanisms of titanium
           matrix nanocomposites reinforced with onion-like carbons
    • Abstract: Publication date: Available online 15 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Kuowei Fan, Faming Zhang, Caiyun Shang, Farhad Saba, Jin YuAbstractNanodiamonds were annealed in a spark plasma sintering (SPS) furnace to synthesize onion-like carbon (OLC) powder, and thereafter, OLC-reinforced titanium (Ti) matrix composites with 0.1-1.0 wt. % OLCs were fabricated through SPS. Experimental results showed that OLCs were partially in-situ reacted with the Ti matrix forming nano- to submicron TiC particles and some OLCs were retained after the SPS processing. The content and morphology of TiC in sintered samples was determined by the amount of OLCs, which also affected the mechanical properties of the resultant composites. The Ti-0.35 wt. % OLCs composite possessed excellent compressive and tensile properties with acceptable ductility, which are 54% and 40% higher than those of pure Ti, respectively. The strengthening of the composites reinforced with the hybrid reinforcements of TiC/OLCs can be attributed to a group of mechanisms: solution strengthening, grain refinement, load transferring effect, and dispersion strengthening.
       
  • Damage assessment of NCF, 2D and 3D Woven Composites under Compression
           After Multiple-Impact using Acoustic Emission
    • Abstract: Publication date: Available online 14 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Milad Saeedifar, Mohamed Nasr Saleh, Hassan M. El-Dessouky, Sofia Teixeira De Freitas, Dimitrios ZarouchasAbstractThis study is devoted to the damage characterization of Non-Crimp Fabric (NCF), 2D plain-woven (2D-PW) and 3D orthogonal plain-woven (ORT-PW) carbon/epoxy laminates, subjected to compression after multiple-impact loading, using Acoustic Emission (AE). The ultrasonic C-scan images showed that the interlaminar damage area induced by the single and 3-impact in ORT-PW architecture is 3 and 2 times smaller than NCF and 2D-PW architectures respectively. The impacted specimens were then subjected to the in-plane compression load. Two indices, one based on the mechanical response and another one based on the AE behavior of the laminates, were proposed to compare the performance of different architectures. These indices showed that the ORT-PW had the best performance among all the architectures. Finally, AE was used to distinguish the different damage mechanisms including: matrix cracking, intra and inter-yarn debonding, defected-fiber breakage, intact-fiber breakage and z-binder fiber breakage in the CAI tests of the architectures.
       
  • Effect of functional mineral additive on processability and material
           properties of wood-fiber reinforced poly(lactic acid) (PLA) composites
    • Abstract: Publication date: Available online 13 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): T. Ozyhar, F. Baradel, J. ZoppeAbstractThis study examines the use of alkenyl succinic anhydride (ASA)-surface treated calcium carbonate as a functional mineral additive for application in wood fiber (WF)-reinforced PLA composites. The influence of addition quantity on the material properties of PLA composites with 40 wt.% fiber reinforcement was examined at mineral addition levels of 10 wt.%, 20 wt.% and 30 wt.%, respectively. The benefits of ASA surface-treated calcium carbonate over untreated mineral were exemplified by comparing the thermomechanical properties of PLA composites at an addition level of 10 wt.%.The results demonstrate that the addition of ASA-treated calcium carbonate has distinctive advantages over untreated mineral, in terms of both processability and material properties. First, it enables better control of the process by reducing the flowability of the PLA matrix. Furthermore, it improves the fiber adhesion with the PLA, allowing for a substantial reduction of PLA content in the composite formulation while maintaining material properties.
       
  • Facile Construction of Robust Super-hydrophobic Coating for
           Urea-formaldehyde Foam: Durable Hydrophobicity and Self-cleaning Ability
    • Abstract: Publication date: Available online 12 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Buyong Wu, Lin Ye, Zhao Zhang, Xiaowen ZhaoAbstractA robust super-hydrophobic coating was constructed on the surface of urea-formaldehyde (UF) foams through a facile immersion process in SiO2 nanoparticle-dispersed ethanol solution with dodecyltrimethoxysilane (DTMS) as compatibilizer. By introduction of DTMS, strong hydrogen bonding interaction formed between SiO2 coating and UF foam. The UF-g-SiO2/DTMS foam showed a water contact angle (CA) of 157.2° and a sliding angle (SA) of 3°, and after long-term immersion, very slight change of CA and SA was observed, while the water absorption ratio was 36.89% lower than that of pristine sample, displaying durable super-hydrophobicity. The UF-g-SiO2/DTMS foam showed excellent self-cleaning ability. Introduction of DTMS improved the dispersion of SiO2 in solution and thus lots of bamboo shoot-shaped granular protrusions of SiO2 nanoparticles at micro/nano-scale formed on the foam surface during treatment process, while the strong interfacial interaction prevented SiO2 nanoparticles from falling off the foam after long-term immersion, and thus durable hydrophobicity was achieved.
       
  • Oxide-fibre/molybdenum-alloy-matrix composites: A new way of making and
           some mechanical properties
    • Abstract: Publication date: Available online 11 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): S.T. Mileiko, A.A. Kolchin, S.N. Galyshev, O.F. Shakhlevich, V.M. ProkopenkoAbstractUltra-high temperature metal matrix composites are to be constructed using a sufficiently strong refractory matrix. Oxide fibres are primary candidates to reinforce molybdenum matrix by the internal crystallisation method. However, strong molybdenum alloys have not been used as the matrix until recently because the matrix preparation requires the alloys in form of foil and wire, which are not available. Hence, a way to strengthen pure molybdenum is now found through introducing reinforcing phases into it on the stage of matrix preparation prior to its reinforcement by oxide fibres. This communication presents the results of first experiments which show that such modification of the matrix yields composites of high strength at temperatures up to 1400°C. The composites are characterized by sufficiently high fracture toughness at room temperature.
       
  • Bioinspired Nacre-like GO-based Bulk with Easy Scale-up Process and
           Outstanding Mechanical Properties
    • Abstract: Publication date: Available online 11 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Huaiming Jia, Yongcun Li, Yunbo Luan, Yihao Zheng, Jinglei Yang, Luobin Wang, Zhangxin Guo, Xiaodong WuAbstractBionic structural material is a new type of high-performance material that has promising applications in the fields of aerospace, bio-medicine, etc. Herein, an investigation on the easy scale-up process and mechanical behavior of large-sized three-dimensional graphene oxide-based bioinspired nacre bulk materials with excellent mechanical properties was carried out. These bulk materials can be prepared by a lamination assembly strategy based on mass of two-dimensional graphene oxide nacre-mimetic films that fabricated by the continuous dry-spinning assembly technology. The mechanical mechanisms analysis shows that the lamination assembly process can control the interface bonding, and regulate the interface load transfer and failure models of the hierarchical structures, then optimize the combination of strength and energy absorption of the materials to meet different application requirements. These results may provide useful guidance for the efficient and controllable production of high-performance artificial nacre structure materials in application.
       
  • Thickness effect of carbon nanotube interleaves on free-edge delamination
           and ultimate strength within a symmetric composite laminate
    • Abstract: Publication date: Available online 11 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Lulu Shen, Ling Liu, Yexin Zhou, Zhanjun WuAbstractThis paper utilizes carbon nanotube (CNT) buckypaper (BP) as a modified interleaf and incorporates it into the potential delaminated interfaces within the [±θn]S laminates, and then how the CNT BP affects the interlaminar stress and induces free-edge delamination is considered. According to the measured in-put mechanical parameters, a numerical model is firstly developed. Results show that the thickness of the CNT-based interleaf has an obvious effect on the interlaminar stress and corresponding delamination. It just changes the relative value of stress or strength but doesn’t change the patterns of stress distribution or delamination. More importantly, the CNT-based interleaf with a reasonable thickness would significantly decrease the interlaminar stresses (less than 16 μm), delay initiation of delamination and enhance the ultimate strength (less than 40 μm) of the laminates. Simultaneously, the obtained experimental results are coherent with the numerical results, which further prove the thickness effect of the CNT-based interleaf.
       
  • Porosity Predictions during Co-cure of Honeycomb Core Prepreg Sandwich
           Structures
    • Abstract: Publication date: Available online 8 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Navid Niknafs Kermani, Pavel Simacek, Suresh G. AdvaniAbstractHoneycomb core sandwich structures are co-cured to bond partially cured thermoset prepreg facesheets with an adhesive layer to either side of the honeycomb core under a prescribed pressure and temperature cycle in an autoclave. Defects such as porosity and poorly formed fillets of the adhesive bond-line can compromise the mechanical properties of the sandwich structure. High defect levels during the co-cure are common as the process development cycle is strongly dependent on complex relationships among material properties, part geometry and process parameters. A process model to predict bond-line porosity is formulated based on the understanding gathered about the physics of the co-cure process and the physics of bond-line formation. A three-step approach is adopted to simulate the bond-line porosity. The first step uses the knowledge of the diffusion-induced void growth in the form of a stability map to guide the design of the co-cure cycle. The second step develops the void growth model accounting for the diffusion of volatiles within the adhesive and the prepreg resin. In the final step, the voids that escape into the core from the bond-line are taken into account to calculate the porosity of the bond-line. With the help of two examples, it is shown that in addition to the initial radius of voids and the initial porosity of the bond-line, the interplay between the stability map and the process cycle also play an important role in prediction of the final porosity within the bond-line. This process model should prove useful in reducing or eliminating voids by optimizing the co-cure cycle.
       
  • Grid nano-indentation as full-field measurements
    • Abstract: Publication date: Available online 8 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Y. Gaillard, F. AmiotAbstractThe use of grid nano-indentation as a full-field measurement tool to investigate the properties of heterogeneous materials is described. Contrarily to the reported approaches which rely on statistical analysis, the mechanical properties fields are analyzed herein relying on a topological description of the sample. The spatial convolution function is approached using Hertz contact theory, and the obtained convolution kernel is used to retrieve the mechanical properties of the different phases. This approach is exemplified on results obtained at very low contact force (and thus very high spatial resolution) on a composite material sample made of micrometer-sized fibers in a polymeric matrix.
       
  • Influence of component design on features and properties in thermoplastic
           overmoulded composites
    • Abstract: Publication date: Available online 8 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): M.A. Valverde, R. Kupfer, T. Wollmann, L. Kawashita, M. Gude, S.R. HallettAbstractThermoplastic composite overmoulding is an integrated process to manufacture components with combined continuous and short fibre reinforcements. These components benefit from high intrinsic mechanical properties, geometric complexity and low production cycle times. In this study, ribbed plates were manufactured by overmoulding short-fibre CF/PPS (carbon fibre/polyphenylene sulphide) material onto continuous woven-fibre CF/PPS flat preforms. Specifically, the effects of the rib geometry and flow length on the process-induced features were investigated using optical microscopy. The bonding at the overmoulded interface was evaluated via quasi-static tensile rib pull-off tests. Results indicate that both the bond strength and corresponding failure type vary with rib geometry. However, the effects of the specimen position along the flow length are only significant towards the end path. The implications of certain rib designs are discussed both qualitatively and quantitatively, based on feature development at the overmoulded interface during manufacture.
       
  • Design of continuous segregated polypropylene/Al2O3 nanocomposites and
           impact of controlled Al2O3 distribution on thermal conductivity
    • Abstract: Publication date: Available online 8 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Xi Zhang, Xiaochao Xia, Hui You, Toru Wada, Patchanee Chammingkwan, Ashutosh Thakur, Toshiaki TaniikeAbstractControl of nanoparticle distribution in polymer matrices is a key factor for designing highly conductive nanocomposites. Here, polypropylene (PP)/aluminum oxide (Al2O3) nanocomposites with a continuous segregated structure were designed. Al2O3 nanoparticles were initially distributed in the polyolefin elastomer (POE) phase of PP/POE/Al2O3 with a co-continuous structure. Selective extraction of the POE phase provided a porous PP scaffold, whose pore walls were covered by deposited Al2O3 nanoparticles. Subsequent compression molding made the porous scaffold tightly compacted to form uniform and dense thermal conductive networks. The thermal conductivity was compared among nanocomposites having three different types of Al2O3 distribution. It was found that the continuous segregated distribution was far the most effective for improving the thermal conductivity, where 1.07 W/m K was achieved at an Al2O3 loading of 27.5 vol%.
       
  • Simultaneously realizing ultra-high energy density and discharge
           efficiency in PVDF composites loaded with highly aligned hollow MnO2
           microspheres
    • Abstract: Publication date: Available online 7 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Lu Yang, Qiuying Zhao, Kaineng Chen, Yizhou Ma, Mingxia Shen, Haiyan He, Huajie Huang, Hongli Ji, Zhifeng Wang, Jinhao QiuAbstractEnhancing the energy density and discharge efficiency of dielectric poly(vinylidene fluoride) (PVDF) has long been a challenging task to realize their practical application as advanced electrostatic capacitors. Herein, in this work, we demonstrated a facile yet effective approach to simultaneously strengthen the energy density and discharge efficiency of PVDF through the synergy of optimized fabrication process and introduction of aligned MnO2 hollow spheres. First, using a nonequilibrium manufacturing approach involving electrospinning, hot-pressing and hot-rolling, reduced ferroelectric loss and improved breakdown strength was achieved in PVDF, which were advantageous to enhance the energy density and discharge efficiency. By further introducing oriented MnO2 microspheres, one could boost the discharge energy density up to 36J/cm3 while maintain the high discharge efficiency of 73% (500MV/m) due to the enhanced interfacial coupling effect and suppressed conduction loss. This work provides a new paradigm to explore high performance PVDF based composites as viable dielectrics for electrostatic capacitors.
       
  • Natural Fibre Thermoplastic Tapes to Enhance Reinforcing Effects in
           Composite Structures
    • Abstract: Publication date: Available online 7 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): M.H. Akonda, D.U. Shah, R.H. GongAbstractSemi-consolidated thermoplastic tapes were produced by spreading flax and polypropylene matrix fibres using a newly developed technology. This lightweight tape was structurally stable and contained 38% flax fibres by volume. The tapes were processed in unidirectional and woven fabric format for composite fabrication. We found that the flax/PP tape-based composites had 60-110% higher flexural modulus and 35-65% higher tensile modulus compared to flax/PP yarn based thermoplastics. Thermoanalytical results showed that the heating conditions used in the tape-making process did not degrade the flax fibres and PP matrix. We conclude that such semi-consolidated flax/PP tapes enable the achievement of properties not seen before for yarn-based composites, and therefore are an important step forward in optimising the reinforcing effect of natural fibres in composite applications.
       
  • Use of computed tomography to determine penetration paths and the
           distribution of melamine resin in thermally-modified beech veneers after
           plasma treatment
    • Abstract: Publication date: Available online 7 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Richard Wascher, Florian Bittner, Georg Avramidis, Martin Bellmann, Hans-Josef Endres, Holger Militz, Wolfgang ViölAbstractIn this study, X-ray computed tomography was used to detect flow paths and the distribution of melamine resin in thermally-modified and subsequently plasma-treated beech veneers. By introducing iodide as a contrast agent, the melamine resin deposition in veneer samples could be visualized and quantified. The investigations showed that the deposition of melamine resin within the lumina and cell walls of the reference samples was limited to near-surface areas. In contrast to the reference, the plasma-treated samples showed a higher loading with the modifier, both in the near surface and in the deeper areas of the sample. Increased resin infiltration was observed in the production-related micro-cracks only in the plasma-treated samples. Plasma-treated samples displayed a significant increase in impregnated volume compared to non-plasma-treated samples, both in the lumina and cell wall areas.
       
  • Recent Researches of the Bio-inspired Nano-carbon Reinforced Metal Matrix
           Composites
    • Abstract: Publication date: Available online 6 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Rui Shu, Xiaosong Jiang, Hongliang Sun, Zhenyi Shao, Tingfeng Song, Zhiping LuoAbstractNatural materials usually have excellent performance for their special structures. Learning from the nature may catalyze the creation of artificial composites with unprecedented performance and functionalities. To realize this bio-inspired design idea on nano-carbon reinforced metal matrix composites, it is indispensable to understand and quantify the design principles of natural materials and consider the inherent characteristics of artificial materials and conditions of engineering applications. In this paper, recent researches of the bio-inspired nano-carbon reinforced metal matrix composites are reviewed to highlight the scientific and technological questions to obtain the bio-inspired structure artificial composites. These include the fabrication methods for solving the dispersion problem of nano-carbon and achieving the bio-inspired structure, characterization of microstructure and properties of bio-inspired composites. The interface and reinforcement mechanisms are emphatically investigated and discussed, in this way to help unveil natural design principles and provide reference for the future research of bio-inspired composites.
       
  • Influence of Dissolved Gasses in Epoxy Resin on Resin Infusion Part
           Quality
    • Abstract: Publication date: Available online 6 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Sam van Oosterom, Aigoul Schreier, Mark Battley, Simon Bickerton, Tom AllenAbstractThis study investigates the influences of dissolved gasses on vacuum assisted resin infusion, providing a methodology which can be applied to assist in the development of robust high-performance infusion manufacturing processes. Resin degassing pressure was found to be influential on the effectiveness of degassing. Pressures under 5mBar are recommended to ensure rapid and thorough removal of dissolved gasses. The saturation point of dissolved oxygen in resin was found to linearly correlate with resin pressure. The binary saturation condition of the resin during vacuum assisted resin infusion processes was found to directly impact void content within a cured laminate. Resin that was oversaturated with dissolved gas relative to the set post-fill fluid pressure was found to result in average void contents ranging from 1-2% across the laminate. Undersaturated resin resulted in consistently low void contents, being less than 0.2% across the laminate. This demonstrates the significance of resin dissolved oxygen content.
       
  • Reinforcing carbon fibers as sensors: the effect of temperature and
           humidity
    • Abstract: Publication date: Available online 6 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): N. Forintos, T. CzigányAbstractWe investigated how temperature and relative humidity affects the electrical resistance of reinforcing carbon fibers in polymer composites. We used hybrid composites in which a tight, carbon fiber roving was laminated inside glass fiber-reinforced epoxy specimens. The electrical resistance of the carbon fibers was monitored continuously while the temperature or relative humidity was varied. The specific resistance was calculated in order to compare the different effects acting on the resistance of the carbon fiber. We found a relationship between temperature or relative humidity and specific resistance. As a result, carbon fibers can be used in different applications (for example in cure process monitoring). On the other hand, the effects should be compensated for when the resistance of the carbon fiber is measured in a health monitoring application (e.g. as an elongation sensor).
       
  • Achieving excellent dielectric performance in polymer composites with
           ultralow filler loadings via constructing hollow-structured filler
           frameworks
    • Abstract: Publication date: Available online 5 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Jie Yang, Xiaotong Zhu, Huanlei Wang, Xin Wang, Chuncheng Hao, Runhua Fan, Davoud Dastan, Zhicheng ShiAbstractDielectric polymer composites are promising candidates for pulsed power capacitors. Enhanced dielectric performance is usually achieved at the expense of high filler loadings. Herein, we report the realization of significantly enhanced dielectric performances in epoxy composites with ultralow BaTiO3 loadings via constructing hollow-structured BaTiO3 frameworks with hierarchical interfaces in epoxy. An enhanced dielectric permittivity of 22 @10 kHz, which is about 5 times that of the epoxy matrix, is achieved in the composite with merely 5 vol% BaTiO3, while the dielectric loss keeps low (tanδ ≈ 0.032 @10 kHz). Meanwhile, a greatly improved energy density which is about 250 % that of the epoxy matrix and a high discharge efficiency (η = 89.7 %) are achieved simultaneously. It is believed that, the hollow-structured BaTiO3 frameworks with hierarchical interfaces leads to strengthened interfacial polarization and ensures continuous transmission of polarization, which collectively improve the dielectric energy-storage performance.
       
  • Special issue for Flow Processing in Composites Materials
    • Abstract: Publication date: Available online 5 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Staffan Lundström, Veronique Michaud
       
  • Enhanced magnetoelectric coefficient and interfacial compatibility by
           constructing a three-phase CFO@BT@PDA/P(VDF-TrFE) core-shell nanocomposite
           
    • Abstract: Publication date: April 2020Source: Composites Part A: Applied Science and Manufacturing, Volume 131Author(s): Weimin Xia, Jiahong Zhou, Tianle Hu, Penggang Ren, Guanjun Zhu, Yaling Yin, Jinglei Li, Zhicheng ZhangAbstractA ferroelectric ceramic barium titanate (BaTiO3, BT) layer and an interfacial agent polydopamine (PDA) as the shells are coated on the cobalt ferrite (CoFe2O4, CFO) nanoparticles successively to fabricate the interfacial compatibility of this magnetic oxide. Subsequently, the coated nanoparticles are compounded with ferroelectric poly(vinylidene fluoride-trifluoro ethylene) (P(VDF-TrFE)) matrix to obtain the CFO@BT@PDA/(P(VDF-TrFE) magnetoelectric nanocomposite films. We find these nanocomposites with three phases including a CFO magnetic core, a BT piezoelectric shell and the P(VDF-TrFE) piezoelectric matrix show a considerable dielectric permittivity of 85.7 and a maximum polarization of 49.5 μC/cm2. Attractively, after poling the saturated magnetization of this film increases from 52.1 emu/g to 61.7 emu/g, corresponding to a significant magnetoelectric effect. Through non self-consistent theory (NSC), the magnetoelectric coupling coefficient (αE33) of CFO@BT@PDA/(P(VDF-TrFE) film is calculated to reach 150.58 mV/cm·Oe, indicating that this flexible multiferroic film has a prospect of application on energy collector or new information storage devices.
       
  • The influence of carbon-encapsulated transition metal oxide microparticles
           on reducing toxic gases release and smoke suppression of rigid
           polyurethane foam composites
    • Abstract: Publication date: Available online 5 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Zhoumei Xu, Lijin Duan, Yanbei Hou, Fukai Chu, Shudong Jiang, Weizhao Hu, Lei SongAbstractThe rapid development and massive consumption of rigid polyurethane foams (RPUF) has drawn attention to their fire safety related problems, such as the heat release and notable generation of smoke and toxic gases in fire. Three novel types of carbon-encapsulated transition metal oxide microparticles, Cu@C, Fe2O3@C and Cu2O@Fe2O3@C, were prepared via a simple hydrothermal method in this research. Potential smoke and toxicity suppression by the as-prepared carbon-encapsulated hybrids in flame-retardant RPUF composites with ammonium polyphosphate (APP) and dimethylmethylphosphonate (DMMP) were investigated. Compared with pure RPUFs, the peak heat release rate (pHRR) value of RPUF/A5-D5/5.0Fe2O3@C decreased by 40.5%, indicating the obvious improved flame retardancy. Besides, the related mechanisms of smoke suppression and toxic based on the catalytic effect of transition metal oxide was also proposed on the basis of experiment results.
       
  • Flexure and flexure-after-impact properties of carbon fibre composites
           interleaved with ultra-thin non-woven aramid fibre veils
    • Abstract: Publication date: Available online 4 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Bingyan Yuan, Mingxin Ye, Yunsen Hu, Fei Cheng, Xiaozhi HuAbstractLaminar carbon fibre reinforced polymer (CFRP) composites contain inherent weak ply interfaces due to the lack of through-thickness fibre reinforcement. In this study, all ply interfaces were interleaved with ultra-thin (13 μm) non-woven short aramid fibre (SAF) veils to generate across ply fibre bridging, formed in-situ by movements of free fibre ends during the composite forming process. The toughening effect of ultra-thin SAF veils (13 μm and 29 μm in thickness) before and after impact was measured and compared. It was found that the 13 μm SAF veils increased the bulk flexural strength and modulus of CFRP by 16.9% and 19.8% prior to impact, challenging the common belief that interleaving with micro-length or short fibres is only beneficial to post-impact properties. X-ray micro-computed tomography and cross-section microscopy examinations were used to explain the mechanisms for improved flexural properties before and after low-velocity impact.
       
  • Consolidation and compression of deformable impregnated fibrous
           reinforcements: Experimental study and modeling of flow-induced
           deformations
    • Abstract: Publication date: Available online 4 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): A. Hautefeuille, S. Comas-Cardona, C. BinetruyAbstractContinuous fiber-reinforced thermoplastic composites can be produced by compression or consolidation processes at a temperature above the thermoplastic melting temperature. High production rates or high fluidity thermoplastic (TP-HF) viscosities can lead to large in-plane displacements of the fibrous network during the process. The same mechanisms appear when viscous toughened thermosets resins are used. One can assume that the in-plane displacements occur when the liquid thermoplastic flow sets the deformable fibrous reinforcement in motion. The composite material being manufactured is therefore subjected to a hydro-mechanical coupling between a liquid flow and a deformable continuous fibre reinforcement. Within this context, the in-plane flow-induced deformations during transverse consolidation are investigated in this study. An experimental setup is used in order to localize and quantify fibre tow displacements and large strains as a transient full-field measurement. Then, in order to identify the driving forces occurring during consolidation, these induced deformations are taken into account in the modeling. The fibrous reinforcement properties are redefined locally based on the measured full-field strains. The comparison of experimental and modeling results shows that the local in-plane drag force peaks mainly drive the onset of the fibrous architecture deformation.
       
  • Percolative Polyurethane-Polypyrrole-Straw composites with enhanced
           dielectric constant and mechanical strength
    • Abstract: Publication date: Available online 4 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Ranjan Chaturvedi, Ritesh Kumar Gupta, Nikhil Rajendra Gorhe, Prashant TyagiAbstractPercolative polyurethane composites utilizing surface modified paddy straw particles as filler and exhibiting enhanced dielectric constant and tensile strength, low dissipation and reduced water absorption have been presented. A thin coating of Polypyrrole (PPy) conducting polymer over paddy straw (St) micro particles was accomplished via vapour phase polymerization. Composites were prepared by using a lab scale twin-screw compounder and injection moulding system to mimic the actual industrial processing conditions. At 30 phr, PPy coated particles filled composites exhibited 133 % and 26 % increment in dielectric constant (13.61, 1 KHz) and tensile strength (58.3 MPa) respectively with reduced water absorption by 51.3 % (264 hours) at room temperature as compared to their counterparts filled with uncoated particles. The successful preparation of these lightweight composites with improved performance paves the way for low cost, sustainable and eco-friendly materials for high end applications including electronics and sensors.
       
  • Bi-scale interfacial bond behaviors of CCF/PEEK composites by plasma-laser
           cooperatively assisted 3D printing process
    • Abstract: Publication date: Available online 4 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Luo Meng, Tian Xiaoyong, Shang Junfan, Yun Jingxin, Zhu Weijun, Li Dichen, Qin YingjieAbstract3D printed continuous carbon fiber reinforced PEEK (CCF/PEEK) composites have got much attention because of their excellent mechanical, thermal and chemical performance and the formability of complex structural components. However, there are always two different weak-bond interfaces limiting the application of the composites critically, which are the poor interlayer bond and the weak interface between carbon fibers and PEEK. A plasma-laser cooperatively assisted 3D printing process was utilized to improve the bi-scale interface. After optimizing, the interlaminar shear strength can be improved from 5.78MPa to 39.05MPa. After analyzing the failure mode and bi-scale interfacial bond mechanism, it’s found that the laser mainly improves the interlayer bond and crystallinity, while the plasma effectively improves the mechanical modulus by treating the surface of the carbon fibers chemically and physically. The work provides a really novel idea for developing the 3D printed CCF/PEEK composites for further application in aerospace and automotive industries.
       
  • Optically transparent tough nanocomposites with a hierarchical structure
           of cellulose nanofiber networks prepared by Pickering emulsion method
    • Abstract: Publication date: Available online 4 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Supachok Tanpichai, Subir K. Biswas, Suteera Witayakran, Hiroyuki YanoAbstractOptically transparent tough cellulose nanofiber (CNF) reinforced composites were successfully prepared through a simple Pickering emulsion method. The emulsions of CNFs, acrylic resin monomer and water were vacuum filtered to form mats, and the mats were hot-pressed, and UV-cured. Hierarchical CNF networks where the homogenously-dispersed CNFs formed a network surrounding resin droplets in the composites were observed. As the CNF content increased, thicker CNF networks were formed, which could bear greater loads. The strength, modulus, strain and toughness of the composites with 25 wt% CNFs increased to be 18.6, 56.7, 1.5, and 36.3 times as great as those of the neat acrylic films with the great reduction in the thermal expansion to 7.3 ppm K-1 (1/26th of the neat polymer) and only 3% degradation in optical transmittance. The composites prepared by Pickering emulsion approach showed higher performances than those from the impregnation method, which could be used in optoelectronic applications.
       
  • An accurate and easy to implement method for predicting matrix crack and
           plasticity of composites with an efficient search algorithm for LaRC05
           criterion
    • Abstract: Publication date: Available online 3 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Xiaodong Wang, Zhidong Guan, Shanyi Du, Geng Han, Zengshan LiAbstractA numerical method by combining extended Finite Element Method and anisotropic plastic model in ABAQUS is proposed to simulate matrix crack and plasticity of composites. The hydrostatic pressure sensitivity is introduced into the method by subroutine USDFLD based on Mohr-Coulomb theory. An efficient search algorithm is proposed for LaRC05 criterion, whose time cost is only 10% of that of original algorithm. Then, the accuracy of proposed method on anisotropic plasticity, hydrostatic pressure sensitivity, nonlinear response, failure strength and crack behavior are proved by simulation under multiaxial load. Thereafter, the failure behaviors of Iosepescu specimens with different fiber orientations and thickness are simulated. In all kinds of specimens, both failure modes and load curves match well with the experiment. The proposed method is accurate on predicting the matrix crack and plasticity of unidirectional composites, and is easy to be implemented in ABAQUS more importantly.
       
  • New tool for reduction of harmful particulate dispersion and to improve
           machining quality when trimming carbon/epoxy composites
    • Abstract: Publication date: Available online 3 February 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): N. Nguyen-Dinh, A. Hejjaji, R. Zitoune, C. Bouvet, M. SalemAbstractConventional machining of carbon fiber reinforced plastic composites (CFRPs) generates minute chips that get suspended in air causing a hazard compromising operator safety. This study investigates the influence of cutting parameters (feed speed, cutting speed, radial depth of cut, tool geometry and tool wear) during trimming of CFRP on the form and quantity of harmful particles dispersed. Also, performance of two classical PCD tool geometries (two straight flutes, two helix flutes) have been compared with newly designed (in collaboration with ASAHI Company) four serrated straight flutes for the purpose of dust emission reduction. The quantification of the number of harmful particles was estimated using laser spectroscopic dust monitor. The results reveal that, trimming with a combination of higher feed speed and lower cutting speed can reduce the dispersion of harmful particles. Further, the four serrated straight flutes recorded the least number of harmful particles compared to the conventional tools.
       
  • Thin-ply polymer composite materials: a review
    • Abstract: Publication date: Available online 30 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): A. Arteiro, C. Furtado, G. Catalanotti, P. Linde, P.P. CamanhoAbstractThe introduction of the spread-tow thin-ply technology enabled the development of composite plies as thin as 0.020 mm. The availability of composite plies with a broader thickness range makes the understanding of the effects of ply thickness more pertinent than ever, therefore, a comprehensive literature review is presented in this paper. The micro-structural effects of ply thickness and ply uniformity on the mechanical response of unidirectional laminae is described. Then, the effect of ply thickness scaling on several aspects of the mechanical response of composite laminates is reviewed. Finally, the current state-of-art and recent developments in manufacturing, design and application of thin plies on novel engineered composite laminates are presented. This review demonstrates that thin plies not only bring improvements to the plain strengths and design flexibility of composite laminates, but can also enhance the performance of primary structural applications, namely those driven by residual strength and damage tolerance requirements. This can be achieved by either combining thin plies with existing material technologies, or through novel design principles. Moreover, it is shown that thin plies provide increased flexibility for multifunctional optimisation and for adoption of more efficient manufacturing technologies, with great potential gains in terms of weight savings and cost reduction during conceptual and detailed design and operation.
       
  • High Performance Multiscale Glass Fibre Epoxy Composites Integrated with
           Cellulose Nanocrystals for Advanced Structural Applications
    • Abstract: Publication date: Available online 30 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Sandeep Kumar, Brian G. Falzon, Jeffery Kun, Emma Wilson, Georg Graninger, Stephen C. HawkinsAbstractRecently, considerable effort has been devoted to develop cellulose nanocrystal(CNC)/epoxy (EP) composites with improved properties. However, work on CNC-enhanced continuous fibre reinforced polymer (FRP) composites has received little attention. In this study, a CNC/epoxy mixture was infused through plain-woven glass fabric (GF) reinforcement to develop hierarchical CNC/GFRP composites. The results show that CNC/GFRP composites exhibit significantly enhanced mechanical properties compared to the GFRP control composite. The addition of 2 wt% CNC to GFRP yielded increases of 56% in storage modulus, 50% in flexural modulus, 55% in flexural strength, 14% in tensile modulus and 24% in tensile strength. Morphological studies (SEM) confirm the strong anchoring of CNCs with GF and the EP interphase thin layer around the GF. These results show that CNCs can be effective for strengthening the interface in fibre-reinforced composites for structural applications.
       
  • Corrigendum to “Simulation of manufacturing induced fiber clustering and
           matrix voids and their effect on transverse crack formation in
           unidirectional composites” [Compos. Part A: Appl. Sci. Manuf. 127 (2019)
           105620]
    • Abstract: Publication date: Available online 30 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Aswathi Sudhir, Ramesh Talreja
       
  • Ni@nylon mesh/PP composites with a novel tree-ring structure for enhancing
           electromagnetic shielding
    • Abstract: Publication date: Available online 28 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Songtao Li, Zibo Xu, Yu Dong, Dongyan Liu, Guoxin SuiTwo different composites one with a novel tree-ring structure and the other with a multi-layer structure were fabricated based on polypropylene (PP) film and Ni@nylon mesh by using the hot compressive molding. The Ni@nylon mesh prepared by electroless Ni plating generated continuously conductive networks for the composites to possess excellent electromagnetic shielding effectiveness (SE) along with the improvements of thermal conductivities. The maximum SE value of the composites with tree-ring structure achieved 50.6 dB, which was greater than that (25.8 dB) of the conventional multi-layer composites. There was not much difference in thermal conductivity (0.53-0.55 W/m·K) for both two composites with 3.07 vol.% Ni, while they were still about 1.2 times higher than that of composites without Ni inclusion. Moreover, the compressive strength (48.8 MPa) of composite with tree-ring structure was higher than that (45.7 MPa) of multi-layer composite at the same Ni content (3.07 vol.%).Graphical abstractGraphical abstract for this article
       
  • Self-sensing composite: Reinforcing fiberglass bundle for damage detection
    • Abstract: Publication date: Available online 28 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Gergely Hegedűs, Tamás Sarkadi, Tibor CzigányAbstractWe showed that the fiber bundle of the reinforcing E-glass fabric of the polymer composite structure can be used for damage monitoring without any special surface preparation. For the matrix of the composite, a carefully selected general-purpose resin system can be applied. We demonstrate a simple way to illuminate an arbitrarily chosen fiber bundle of the fabric, and the micro- and macroscopic damage caused by the load of the composite decrease the power of light transmitted by the bundle. With the microscopic examination of the ends of the illuminated fibers, fiber breakage and fiber-matrix debonding can be identified and distinguished as well. This way, a selected part of the reinforcement of the composite can be used as a structural health monitoring sensor making any further external sensors unnecessary.
       
  • Simultaneous improvements in fire resistance and alarm response of GO
           paper via one-step 3-mercaptopropyltrimethoxysilane functionalization for
           efficient fire safety and prevention
    • Abstract: Publication date: Available online 28 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Neng-Jian Huang, Qiao-Qi Xia, Zhao-Hui Zhang, Li Zhao, Guo-Dong Zhang, Jie-Feng Gao, Long-Cheng TangAbstractA flame-retardant graphene oxide (GO) based nanocomposite paper was prepared for efficient fire alarm response via a one-step and green 3-mercaptopropyltrimethoxysilane (MPTS) functionalization. Such MPTS modification not only improves thermal stability and flame resistance of GO network, but also produces ultra-fast flame detection and efficient fire early warning response. Typically, the MPTS-GO-10 wt% paper shows a flame detection response signal of about 1.0 s and improved fire early warning response time at a relatively temperature of 200 oC. The structural observation and analysis suggest that the thermal reduction behavior of GO network can be promoted by the sulfydryl groups of MPTS molecules at high temperature, thus producing the rapid and sensitive transition of electrical resistance form insulating GO into conductive reduced GO network. The MPTS functionalization developed here show promising to tailor fire early warning response of flame-retardant GO based fire alarm sensor for potential fire safety and prevention applications.
       
  • Swelling of natural fibre bundles under hygro- and hydrothermal
           conditions: determination of hydric expansion coefficients by automated
           laser scanning
    • Abstract: Publication date: Available online 28 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): William Garat, Nicolas Le Moigne, Stephane Corn, Johnny Beaugrand :, Anne BergeretAbstractThe effect of humidity conditions on the moisture content and dimensional variations of natural fibre bundles from several botanical origins with contrasting biochemical and structural characteristics is investigated. Results highlight wide variations in water uptake and swelling behaviour of fibre bundles as a function of plant species. Two main swelling mechanisms are identified: (i) a microscopic swelling due to the sorption of bound water in the cell walls and the middle lamella, and (ii) a macroscopic swelling related to the formation of free water in pores and lumens, which induces anisotropic deformation of bast fibre bundles. Surface hygro- and hydroexpansion coefficients are determined and studied in relation with the structural features of plant fibre bundles. These results constitute key data for the predictive modelling of “in-service” mechanical behaviour of biocomposites.
       
  • Interfacial performance of aramid, basalt and carbon fiber reinforced
           polymer bonded concrete exposed to high temperature
    • Abstract: Publication date: Available online 28 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Ao Zhou, Qiwen Qiu, Cheuk Lun Chow, Denvid LauAbstractExternally bonding fiber reinforced polymer (FRP) is an effective approach to strengthen/retrofit concrete structures. However, little is known on bond performance of FRP-bonded concrete under high temperature, impeding the application of FRP in buildings potentially subjected to fire. In this paper, the bond performance of aramid, basalt and carbon FRP-concrete subjected to high temperature (80-300 °C) have been investigated through acoustic-laser technique, macroscale fracture tests and microscale characterization. Results have shown that the deterioration percentages of both peel and shear interface fracture toughness of aramid FRP-bonded concrete are largest under high temperature, followed by carbon FRP-bonded concrete and basalt FRP-bonded concrete. The mechanisms behind different bond performance have been revealed with variations of microscale morphology and chemical decomposition. The results and findings can provide a fair comparison of thermal susceptibility and residual bond performance of various FRP-bonded systems, and contribute to designing FRP strengthening/retrofitting systems with better high temperature resistance.
       
  • Image-based characterization of fibre waviness in a representative
           vacuum-bagged corner laminate
    • Abstract: Publication date: Available online 27 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): N. Krumenacker, A. Madra, P. HubertAbstractThe ability to fully characterize design-induced defects in complex-shape laminates is indispensable to improving the design and out-of-autoclave processing of large integrated structures. To this end, two automated methods are proposed to characterize fibre waviness in a representative vacuum-bagged corner laminate. The first relies on optical microscopy of corner-flange sections to estimate the extent to which corner waviness progresses into flanges. The second relies on X-ray micro computed tomography of corner sections and advanced image-based techniques to measure the waviness magnitude in terms of representative, in- and out-of-plane angular components. The 3D structure of the waviness is then ascertained based on the examination of the combined imaging results. Finally, the usefulness of the magnitude measurements is illustrated by estimating the knockdown in corner stiffness via an Euler angle transformation. Both characterization methods can be adapted to other, more complex-shape cases and alternate processing routes.
       
  • Continuous Gradient Ceramic/Polymer Composite for Application in Large
           Temperature Gradient Connection by a Polymer-derived Ceramic Route
    • Abstract: Publication date: Available online 27 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Zhaocai Hu, Songhe Meng, Jinping Li Resource, Weihua Xie, Jiahong Niu, Yaoqiang ZhouAbstractThe need for combined high-temperature insulation and load-bearing functions under large temperature gradient conditions imposes new demands on functionally graded composite materials. Herein, a ceramic-polymer continuous gradient composite was prepared by a polymer-derived ceramic route using a custom-designed induction heating system. The gradient composite was subjected to six impregnation-crosslinking-pyrolysis cycles to obtain a 55-mm-long gradient layer with varying density (1.76–1.43 g/cm3). The compositions of the gradient matrix varied from amorphous SiCN ceramics to silicon resin from top to bottom, satisfying the gradient change rule. The gradient material had good thermal insulation and reusability with a heat flux of 0.3 MW/m2 for 10 min. The resin layer has the minimum compressive strength of 68 MPa. This material could serve as a transition material for connecting a high-temperature zone (≥1000 °C) with a low-temperature one (≤350 °C).
       
  • Vibration-based damage diagnosis of composite sandwich panels with
           bi-directional corrugated lattice cores
    • Abstract: Publication date: Available online 27 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Jin-Shui Yang, Zhi-Da Liu, Rüdiger Schmidt, Kai-Uwe Schröder, Li Ma, Lin-Zhi WuAbstractIn this paper we design and fabricate a series of carbon fibre composite bi-directional corrugated sandwich panels (BCSPs) with and without defects. A modified damage index (MDI) based on modal flexibility curvature variation (MFCV) is proposed to identify the damage location of composite BCSPs numerically. A good agreement of natural frequencies and modal shapes is obtained between the numerical and the experimental results, which demonstrates that the adopted numerical models are reliable for the present structures. Results show that the proposed MDI method can accurately detect almost all of damages and effectively eliminate the influence of false peaks as much as possible, which demonstrate the present MDI method is better than the DI method for the damage location of the present structures, which could be useful for the non-destructive evaluation (NDE) of such kinds of composite sandwich structures.
       
  • Mode II interlaminar fracture of hybrid woven carbon-Dyneema composites
    • Abstract: Publication date: Available online 27 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): H.X. Zhou, S.P. Li, K. Xie, X. Lu, Y. Zhao, T.E. TayAbstractRecently, there has been renewed interest in inter-woven hybrid composites. Hybridization of different fiber types within composite laminates provides opportunities to extend the design space and optimize properties such as strength and toughness. In this paper, the Mode II fracture behavior of a hybrid carbon-Dyneema fiber-reinforced composite is studied experimentally. The usual linear elastic fracture mechanics (LEFM) methods for measurement of interlaminar toughness are not readily applicable to hybrid composites due to the presence of large fracture process zones and extensive fiber bridging. Continuously increasing R-curves are obtained from standard data reduction approaches, resulting in poor estimates of Mode II interlaminar toughness values. A more general J-integral-based method coupled with digital image correlation technique is proposed here to obtain more consistent and accurate results. Specimens with different intralaminar and interlaminar hybridization schemes are explored, and the delamination process as well as toughening mechanisms is examined through a fractographic analysis.
       
  • Overmolded hybrid composites of polyamide-6 on continuous carbon and glass
           fiber/epoxy composites: ‘An assessment of the interface’
    • Abstract: Publication date: Available online 25 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Nursel Karakaya, Melih Papila, Güralp ÖzkoçAbstractIn this study, we investigated overmolding of thermoplastics on thermoset composites as an alternative joining method, in order to enable production of hybrid thermoset composites. Specifically, we explored the parameters affecting adhesion between overmolded polyamide-6 (PA6) and continuous glass or epoxy fiber-reinforced composites. Three main factors were studied: type of reinforcing fiber (carbon and glass), moulding temperature during overmolding process (30°C and 80°C), and application of peel-ply on composite surface. Overall, peel ply application, higher mould temperature (80°C) and composite surface with carbon fiber reinforcement resulted in better adhesion. Three point bending, dynamic mechanical analysis (DMA), roughness, and contact angle measurements reveal strong bonding. Scanning electron microscopy (SEM), micro-computed tomography (micro-CT) images and energy-dispersive X-ray spectroscopy (EDS) results support the improvement due to peel-ply application. Findings from thermal analysis confirm the effect of reinforcement material type on crystallinity of overmolded polymer and underline the essential role of contact surface chemistry.
       
  • Enhancing the mechanical and thermophysical properties of highly oriented
           graphite flake composites by formation of a uniform three dimensional
           tungsten carbide skeleton reinforcement
    • Abstract: Publication date: Available online 25 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Xiaoyu Zhang, Wenqi Xie, Bangzhi Ge, Ke Wang, Zhongqi Shi, Wanli Yang, Hongyan Xia, Jiping WangAbstractTungsten carbide (WC) reinforced highly oriented graphite flake composites were obtained using a combined process of surface-coating and spark plasma sintering techniques. Uniform and continuous three-dimensional WC skeleton was formed in the samples with WC concentration higher than 7 vol.%, rendering the resulting dense composites light, mechanical strong, high thermal conductive and with low thermal expansion. The skeleton architecture played a role of thermal expansion constraint which remarkably reduced the thermal expansion from 28×10-6 K-1 for highly oriented graphite matrix to ∼5×10-6 K-1 for the composite with 26 vol.% WC in the direction parallel to the sintering pressure. Concurrently, the composite with 26 vol.% WC exhibited bending strength up to ∼95 MPa, thermal conductivity up to ∼381 W∙m-1∙K-1 in direction perpendicular to the sintering pressure. The created highly oriented graphite-based composites with uniform 3D ceramic reinforcement are expected to be applied in thermal management of current demanding situation.
       
  • Experimental and analytical investigation of the bending behaviour of
           3D-printed bio-based sandwich structures composites with auxetic core
           under cyclic fatigue tests
    • Abstract: Publication date: Available online 25 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Khawla Essassi, Jean-luc Rebiere, Abderrahim El Mahi, Mohamed Amine Ben Souf, Anas Bouguecha, Mohamed HaddarAbstractIn the present paper, fatigue behaviour of sandwich composites with auxetic core under various stress ratios and for four different core densities is studied. Experimental and analytical analyses are performed on sandwiches subjected to cyclic bending tests in order to determine the influence of stress ratios on their fatigue properties. Experimental and analytical prediction result show good agreement. The analytical method predicts fatigue life as well as damage parameters of the structures and its reliability is verified by experiments. The acoustic emissions method is also used to monitor damage initiation and propagation up to failure. It is found that sandwiches with low core density present the maximum fatigue life.
       
  • In-situ observation of cutting-induced failure processes of single
           high-performance fibers inside a SEM
    • Abstract: Publication date: Available online 25 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Jinling Gao, Yizhou Nie, Boon Him Lim, Xuedong Zhai, Nesredin Kedir, Weinong ChenAbstractInsight into the detailed fracture processes of single high-performance fibers improves understanding for the nature of their unique resistance to external loads. Here, we show the in-situ observation of entire fracture processes of an uncoated single Kevlar® KM2 Plus and Dyneema® SK76 fiber cut by a razor blade at various angles in a Scanning Electronic Microscope (SEM), including initial contact, deformation, crack initiation and propagation until final failure. The effects of gauge length, sputter coating of the platinum, fiber type and cutting angle on the fiber failure were investigated and discussed. The mass-efficient cutting resistance of a single fiber was evaluated by the specific energy. The diversity of the failure modes and cutting resistance were analyzed and attributed to the specific fiber nanostructure and different cutting angles.
       
  • An experimental study on the influence of intralaminar damage on
           interlaminar delamination properties of laminated composites
    • Abstract: Publication date: Available online 24 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Ping Hu, Ditho Pulungan, Ran Tao, Gilles LubineauAbstractCoupling between intralaminar and interlaminar damage plays a significant role in accurately predicting delamination and final failure. However, insufficient experimental data are available for models of this phenomenon. In this paper, we proposed a two-step experiment on cross-ply laminates to quantitatively study the influence of in-plane strain on the interlaminar fracture toughness. First, we performed a tensile test on the [02/902]s cross-ply laminates to introduce various extents of intralaminar damage. Next, we bonded a backing adherend of [06] plies to the cross-ply, so we could probe the delamination properties through a subsequent double cantilever beam (DCB) test. We identified the effective fracture toughness Gc,eff by the compliance calibration method. We found that intralaminar damage promotes fiber bridging in the transverse direction, which finally influence the out-of-plane properties significantly.
       
  • Tensile properties and interfacial shear strength of recycled fibers from
           wind turbine waste
    • Abstract: Publication date: Available online 24 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Amirmohammad Rahimizadeh, Mazin Tahir, Kazem Fayazbakhsh, Larry LessardAbstractThe rapid growth of composites combined with imminent recycling legislation have increased the interest in reusing and recycling of composite waste. Tensile strength and interfacial shear strength (IFSS) of recycled fibers are critical factors contributing to the final properties of recycled products. Here, we focus on the tensile properties of recycled glass fibers from scrap wind turbine blades and their interface strength with polylactic acid (PLA). The single fiber tensile and pull-out tests are used to characterize the fibers recovered through mechanical and thermal processes. It is shown that while pyrolysis can significantly degrade the recovered fibers, ground fibers with a gage length of 20 mm feature characteristic strength comparable to that of virgin fibers. The effect of the fibers surface coating on the IFSS are investigated, with results showing an interface between ground fibers and PLA that is 14% and 26% stronger than pyrolyzed and virgin fibers, respectively.
       
  • Quantifying 3D-nanosized dispersion of SiO2 in elastomer nanocomposites by
           3D-scanning transmission electron microscope (STEM)
    • Abstract: Publication date: Available online 20 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Xiangyan Li, Qiuping Yang, Yi Ye, Liqun Zhang, Song Hong, Nanying Ning, Ming TianAbstractNanofiller/elastomer nanocomposites as strategically important materials have attracted intensive attentions due to high elasticity{Liu, 2011 #46}. However, due to the limitation of conventional two-dimensional characterization methods, the multi-scaled dispersion structure of nanofiller in elastomer nanocomposites hasn’t been comprehensively understood. Here, we established a highly-objective method to comprehensively quantify the three-dimensional (3D)-dispersion of nanoparticle in elastomer matrix. 3D-scanning transmission electron microscope (STEM) was applied to get the intrinsic 3D-dispersion structure of nano-silica (SiO2) in solution-polymerized styrene-butadiene rubber (SSBR). Equivalent sphere and fractal branch models were created to further quantify the poly-dispersity, inner connectivity and morphology of SiO2. A two-stage agglomeration evolution schematic was proposed to elucidate the development of nanosized dispersion structure of SiO2. With the increase of SiO2 volume fraction (Φsilica), the number, size and branching degree of SiO2 simultaneously increase (namely, self-agglomeration). Further increase Φsilica, adjacent SiO2 interconnect with each other, leading to sharp increases of connectivity and branching degree of SiO2 (namely, external agglomeration). This two-stage agglomeration mode interprets the well-known “Payne effect” well, which has not been quantified by 3D dispersion structure parameters before.
       
  • Assessing Damage Mitigation by Silanized Milled Graphite Nanoparticles in
           Hybrid GFRP Laminated Composites
    • Abstract: Publication date: Available online 20 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Subhankar Das, Sudipta Halder, Nazrul Islam Khan, Bappi Paul, M.S. GoyatAbstractIn GFRP laminated composites, matrix-fiber delamination is almost unavoidable and a serious problem that significantly hampers the mechanical properties of the composites. This work presents the use of cost-effective silanized milled graphite nanoparticles (GrNPs) to mitigate matrix-fiber delamination in GFRP laminated composites. FESEM and TEM analysis of pristine GrNPs exhibit porous structure consisting of stacked and randomly oriented planes with a large number of defect sites. The silanization of GrNPs (SGrNPs) results in the covering of pores or defect sites and produces the rough surfaces. The SGrNPs (0.5 wt%) reinforced GRFP laminated composites reveal the enhancement in the mechanical properties such as tensile strength (∼33 %), tensile modulus (∼21 %), toughness (∼35 %), flexural strength (∼42.6 %), work of fracture (∼57 %), and short beam strength (∼23 %), respectively. The improvement in the mechanical properties of the composites is due to the mitigation of matrix-fiber delamination by SGrNPs.
       
  • Drop weight impact behaviour of viscoelastically prestressed composites
    • Abstract: Publication date: Available online 19 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Yang Qin, Kevin S. FanceyAbstractViscoelastically prestressed polymeric matrix composites (VPPMCs) are produced by subjecting fibres to tensile creep, the creep load being released prior to fibre moulding. Following matrix curing, the viscoelastically recovering fibres generate compressive stresses within the matrix which, from previous studies, can improve mechanical properties by up to 50%. This paper reports on the first study of thin flat-plate VPPMCs, using nylon 6,6 fibre-polyester resin to form cross-fibre composite plates (CCPs) with 0°/90° fibre layers and randomly distributed discontinuous fibre plates (RCPs). Drop-weight impact testing was performed on CCPs with impact velocities of 1.9 – 5.8 m/s and, compared with (unstressed) control samples, VPPMC damage depth was reduced by up to 29%; however, this difference decreased with impact velocity, indicating little improvement above 7.7 m/s. RCPs, tested at 3.0 m/s, showed a ∼30% reduction in VPPMC damage depth, compared with ∼20% for CCPs, but with no changes in debonded area.
       
  • Robust galactomannan/graphene oxide film with ultra-flexible, gas barrier
           and self-clean properties
    • Abstract: Publication date: Available online 19 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Chen Huang, Guigan Fang, Yongjun Deng, Samarthya Bhagia, Xianzhi Meng, Yuheng Tao, Qiang Yong, Arthur J. RagauskasAbstractThis study examines a facile technology to manufacture food packaging alternatives with superior mechanical, ultra-flexible, gas barrier and self-clean properties, based on green and benign starting materials. A novel galactomannan (GM) was isolated from the sesbania cannabina seeds, which was used as matrix for the fabrication of GM-based films. Inspired by the brick-and-mortar structure of natural nacre, a facile method was adopted to fabricate an artificial nacre based on the self-assembly of GM and borate crosslinked graphene oxide (GO). These GM/GO composites are ultra-flexibile, which can be folded into various shapes. The tensile strength reached 135.54 MPa which is 2.4 times that of the pure GM film. In addition, after coating with the poly(dimethylsiloxane) (PDMS), these films became hydrophobic (WCA around 120°) with self-cleaning properties. Our study further revealed that the oxygen and water vapor permeabilities were improved with the introduction of GO and PDMS coating.
       
  • High porosity cellulose nanopapers as reinforcement in multi-layer epoxy
           laminates
    • Abstract: Publication date: Available online 19 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Andreas Mautner, Wan M.F.W. Nawawi, Koon-Yang Lee, Alexander BismarckAbstractUtilizing high-performance cellulose nanopapers as 2D-reinforcement for polymers allows for realizing high-loading-fraction (80 vol.-%), high-performance (strength>150 MPa, modulus>10 GPa) laminated nanopaper reinforced epoxy composites. Such cellulose nanopapers are inherently dense, which renders them difficult to be impregnated with the epoxy-resin. High-porosity nanopapers facilitate better resin impregnation, truly utilizing the properties of single cellulose nanofibres instead of the nanofibre network. We report the use of high-porosity (74%) but low strength and modulus bacterial cellulose (BC) nanopapers, prepared from BC-in-ethanol dispersion, as reinforcement for epoxy-resin. High-porosity nanopapers allowed for full impregnation of the BC-nanopapers with epoxy-resin. The resulting BC-reinforced epoxy-laminates possessed high tensile modulus (9 GPa) and strength (100 MPa) at a BC loading of 30 vol.-%, resulting from very low void-fraction (3 vol.-%) of these papregs compared to conventional nanopaper-laminates (10+ vol.-%). Better resin impregnation of less dense nanocellulose networks allowed for maximum utilization of stiffness/strength of cellulose nanofibrils.
       
  • An Improved Progressive Failure Modelling and Damage Tolerant Design
           Methodology for Composite Scarf Joints with Bondline Flaws
    • Abstract: Publication date: Available online 17 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): J.M. Hayes-Griss, A.C. Orifici, A.A. KhatibiAbstractThere is a lack of understanding on the damage tolerant design of bonded scarf joints, specifically when an existing bondline flaw affects the performance. This paper presents an improved progressive damage modelling methodology for assessing the damage tolerant performance of composite scarf joints containing artificial flaws in the bondline. The developed methodology is validated using an experimental study investigating the influences of design parameters on the strength of scarf joints under quasi-static tensile loading. The presented work gives excellent predictions of joint strength, and significant insight into the initiation, interaction and progression of damage. A new damage tolerant design approach is subsequently proposed for the application of bonded composite scarf joints, particularly in primary aerospace structures. The proposed design approach assesses the state of the stress at the failure-critical regions of adhesive and adherend to inform on damage-tolerant safe design loads, thus improving the future application of bonded composite scarf joints.
       
  • Carbon Fiber-Based Polymer Composite via Ceramization toward Excellent
           Electromagnetic Interference Shielding Performance and High Temperature
           Resistance
    • Abstract: Publication date: Available online 14 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Ying-Ming Li, Cong Deng, Ze-Yong Zhao, Lin-Xuan Han, Peng Lu, Yu-Zhong WangAbstractIt is greatly important to shield the X-band electromagnetic radiation and meanwhile possess a high temperature resistant performance for the outer sealing materials of hypervelocity air aircrafts. In this work, novel ceramifiable electro-conductive polymer composites were prepared by incorporating glass powder (GP), mica powder (MP), organo-modified montmorillonite (OMMT), and short carbon fiber (SCF) into ethylene-vinyl acetate (EVA). The prepared EVA/GP/MP/OMMT/SCF displayed excellent electromagnetic interference (EMI) shielding performance before and after treating at 1000 ℃ and also had a high temperature resistant feature via the ceramization. For the EVA/GP/MP/OMMT/SCF composite with a weight ratio of 35/23/17/5/20, its EMI shielding effectiveness (SE) reached 36.0 dB at 2.6 mm thickness, and its ceramic formed at 1000 °C possessed about 30.0 dB of EMI SE. Moreover, the formed ceramic did not show any change during a vertical burning test. Mechanism for the high SE before and after high temperatures were revealed.
       
  • Highly enhanced performance of epoxy composites via novel
           phthalazinone-bearing hybrid system as matrix
    • Abstract: Publication date: Available online 13 January 2020Source: Composites Part A: Applied Science and ManufacturingAuthor(s): Fengfeng Zhang, Lishuai Zong, Zhihuan Weng, Feng Bao, Li Nan, Jinyan Wang, Xigao JianAbstractA novel phthalazinone-bearing epoxy resin, namely TEPZ, was designed and synthesized as functional modifier and prepreg agent for carbon fiber TGDDM epoxy composites by a “one pot two steps” method. Three-dimensional TEPZ/TGDDM/DDS system was constructed and optimized by modulating curing procedure and concentration of DDS to give thermosets with excellent thermal resistance and mechanical strength. The storage modulus and glass transition temperature (Tg) increased significantly with composition of 100 phr TGDDM, 30 phr TEPZ and 40 phr DDS as compared to those of TGDDM/DDS. The tensile strength, impact strength and flexural strength increased simultaneously. Afterwards, continuous unidirectional carbon fiber reinforced laminates were fabricated, followed by systematical investigation of their mechanical and interfacial properties. The interfacial study indicated that the polarity and wettability of TEPZ played an important role during the modification.
       
 
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