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  • Strain rate dependent damage evolution in long glass fiber reinforced polypropylene
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2020-01-16
    J. Lienhard; D. Discher; J. Hohe

    Strain rate dependent characterizations of glass-fiber reinforced thermoplastic (LFT) under different multiaxialities show an increasing fracture strain and higher energy absorption capacity if the loading rate rises. The present paper gives a clue for the underlying micro-thermo-mechanical mechanisms of this effect. The method of correlating experimental field information of strain and heat generation provides data for advanced analysis. Strain and heat distribution of the deformation zone as well as a hot-spot occurrence display give hints on expanded damage zones at high strain rates. Quasi-static and dynamic interrupted tensile tests provided data to investigate the damage evolution. Scanning electron microscopic (SEM) images show differences in the area between fiber and matrix depending on the strain rate. Based on SEM images and correlated and analyzed field data a model representation was established that presents, in agreement with the literature, a perception of the damage mechanisms in the interface and its consequences for global deformation.

    更新日期:2020-01-17
  • Micromechanical modeling of barrier properties of polymer nanocomposites
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2020-01-15
    A.D. Drozdov; J.deC. Christiansen

    Observations in barrier tests on polymer composites with flake-like nanoparticles demonstrate one-step and two-step experimental dependencies of penetrant diffusivity on volume fraction of filler. Conventional models describe the one-step monotonic reduction in the effective diffusivity, but fail to predict the two-step decay. A model is developed for the effective diffusivity of polymer nanocomposites that takes into account clustering of nanoparticles induced by an increase in their content. An advantage of the model is that it (i) predicts both one-step and two-step experimental diagrams in an unified manner, and (ii) involves only two adjustable parameters with transparent physical meaning. The model is applied to the analysis of barrier properties of composites loaded with layered silicate clays, graphene, graphene oxide and reduced graphene oxide, boron nitride and molybdenum disulfide. Good agreement is shown between the experimental data and results of simulation. The influence of polymer matrices, types and chemical modifications of nanoparticles and preparation conditions on aggregation of filler is studied numerically.

    更新日期:2020-01-15
  • Enhanced electrical conductivity of polymer nanocomposite based on edge-selectively functionalized graphene nanoplatelets
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2020-01-13
    Jaehyun Cho; Hyeseong Lee; Ki-Ho Nam; Hyeonuk Yeo; Cheol-Min Yang; Dong Gi Seong; Doojin Lee; Seong Yun Kim

    Achieving high filler dispersion in a polymer composite is very important for effectively and efficiently imparting several advantages of functional fillers to the composite. To this end, we have suggested a synthesis of polyamide 6 via in situ ring-opening polymerization of ε-caprolactam and edge-selectively functionalized graphene nanoplatelets without defects on its basal plane synthesized by a ball-mill process with dry ice. As a consequence, the final graphene nanocomposite possesses highly dispersed filler and has enhanced electrical conductivity due to its undistorted sp2 hybridization after functionalization. This approach is a promising way of incorporating filler into polymer composites, effectively implementing highly electrical conducting graphene without its aggregation and damage to its inherent properties after functionalization.

    更新日期:2020-01-13
  • Cellulose nanofiber/elastomer composites with high tensile strength, modulus, toughness, and thermal stability prepared by high-shear kneading
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2020-01-12
    Toru Noguchi; Morinobu Endo; Kenichi Niihara; Hiroshi Jinnai; Akira Isogai
    更新日期:2020-01-13
  • 更新日期:2020-01-13
  • On the electrical conductivity of composites with a polymeric matrix and a non-uniform concentration of carbon nanotubes
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2020-01-11
    M.A.S. Matos; V.L. Tagarielli; S.T. Pinho

    We present a multiscale modelling approach to explore the effects of a non-uniform concentration of carbon nanotubes (CNTs) on the electrical conductivity of CNT-polymer composites. Realistic three-dimensional representative volume elements (RVEs) are generated from a two-dimensional CNT concentration map, obtained via microscopy techniques. The RVEs capture the measured probability density function of the CNT concentration and include a length-scale to represent the details of the spatial distribution of the concentration. The homogenized conductivity of the RVEs is computed via multiscale FE analyses for different values of such length-scale, and it is compared to measurements. The modelling strategy is then used to explore the effects of the microstructural features of these materials on their electrical conductivity.

    更新日期:2020-01-13
  • Covalent functionalization of aramid fibers with zinc oxide nano-interphase for improved UV resistance and interfacial strength in composites
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2020-01-10
    Lixiang Ma; Jingwei Zhang; Cuiqing Teng

    Improving the resistances of organic high-performance fibers to harsh environments and enhancing the interfacial interactions of fiber-reinforced composites have become crucial in various applications. In this report, ZnO nanoparticles (NPs) and ZnO nanowires (NWs) were successfully “grown” on the surfaces of aramid fibers (AFs) by grafting with γ-aminopropyl triethoxysilane (KH550) followed by the growth of nano-ZnO. The surface functionalized AFs exhibited improved UV-resistances. After 168 h of ultraviolet exposure, the tensile retention rates of the ZnO-NP- and ZnO-NW-grafted AFs reached 95.6% and 97.7%, respectively, which were significantly higher than the value of 79.1% of the bare fiber. Meanwhile, the introduction of the KH500 and ZnO formed a nano-interphase, enhancing the interfacial strength of the fiber-reinforced epoxy resin composites. The interfacial shear strengths (IFSSs) of the composites with AF-g-ZnO NPs and AF-g-ZnO NWs were 42.9 and 47.8 MPa, respectively, whereas that of bare AF-reinforced epoxy resin was only 31.2 MPa. Nano-ZnO was physically deposited on the AF surfaces without KH550. The IFSS was 36.4 MPa for the AF-ZnO NP and 38.8 MPa for the AF-ZnO NW, which were lower than those of the grafted composites. Therefore, the chemical grafting nano-ZnO on high-performance fibers provides a new strategy for improving the UV-resistances of advanced fibers and to enhance the mechanical properties of fiber-reinforced composites.

    更新日期:2020-01-11
  • A generalized distribution function of fiber orientation for injection molded composites
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2020-01-09
    Dayong Huang; Xianqiong Zhao

    The ability to predict fiber orientation accurately is critical for determining the improvement of mechanical properties of injection molded composites. Based on the cumulative distribution function (CDF) monotonically increasing, a smoothing model of piecewise linear approximation function is proposed by assuming that the first derivative is continuous. Taking into account the ability of Weibull distribution reducing to an exponential decay function, a generalized distribution function (GDF) of fiber orientation is proposed by introducing the core thickness ratio (hc) to describe the sandwich layered morphology. Compared with the experimental results in the literatures, the cumulative generalized distribution function fits well (R2 > 0.98), and there is a good correlation (RE<6%) between the experimental results and the elastic moduli computed based on the GDF's FOD and the modified Weibull distribution for FLD. In comparison to RSC model, the GDF improves more than 5% in prediction precisions of elastic moduli for long fiber-reinforced thermoplastics (LFT).

    更新日期:2020-01-09
  • An investigation into mechanical properties of the nanocomposite with aligned CNT by means of electrical conductivity
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2020-01-08
    Dayou Ma; Marco Giglio; Andrea Manes

    In the present study, a novel modelling approach based on electrical properties was proposed to replicate the mechanical behaviour of aligned carbon nanotube/polymer nanocomposites. Firstly, an electrical analytical model with Monte-Carlo method involved was established and validated by accurately predicted electric conductivity. The microstructure of the nanocomposite was then determined according to the electric property. Subsequently, a large-scale representative volume element model based on the predicted distribution of the carbon nanotubes was built to replicate the mechanical response of the nanocomposite under tension, which can be validated by existing experiments. To consider the crystalline structure of the matrix, two cases on the nanocomposites with crystalline and amorphous polymer were investigated, locating their difference on the bonding condition of the interface between CNT and matrix. Results evidenced that the electrical properties of nanocomposites can be used to identify the internal microstructure of nanocomposite. Moreover, the effects of the loading direction, the interfacial strength and the weight fraction were studied by numerical models. The reinforcement effect of the carbon nanotubes was significant when loaded along the aligned direction, but the effect was limited in the other directions. The modulus and the strength of nanocomposite were improved by the increase of the weight fraction of CNTs, while the increase of interfacial strength improves the strength of nanocomposite along CNT-aligned direction significantly, but had negligible effect on its modulus.

    更新日期:2020-01-08
  • Reduced graphene oxide/zinc oxide coated wearable electrically conductive cotton textile for high microwave absorption
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2020-01-07
    Shivam Gupta; Ching Chang; Aswin Kumar Anbalagan; Chih-Hao Lee; Nyan-Hwa Tai

    Due to intensive development in smart electronics and energy devices, wearable electromagnetic interference (EMI) shielding materials such as conducting textiles have emerged to protect human as well as sensitive electronics from electromagnetic pollution. In this work, zinc oxide (ZnO) and reduced graphene oxide (rGO) coated wearable cotton fabrics have been prepared for the application of EMI shielding effectiveness in X-band (8.2–12.4 GHz). The uniform coating of ZnO nanoparticles is achieved by the easy and cost effective in-situ sol-gel method, whereas the uniform coating of rGO is achieved by simple spraying of graphene oxide solution followed by thermal reduction. It is observed that the total EMI shielding effectiveness increases with the rGO loading, however, the reflection loss decreases owing to improved conductivity of the cotton fabric. The as-prepared rGO/ZnO coated cotton (ZnO + 7 wt% rGO) achieves highest total EMI shielding effectiveness of ∼99.999% (54.7 dB), which is shared by ∼17.783% of reflection and ∼82.216% of absorption. Such high absorption dominant EMI shielding is attributed to highly dielectric ZnO nanoparticles, highly conductive rGO sheets and the core-shell structure of the coated cotton fabric. It is also concluded that the excessive loading of rGO can block all the pores of the cotton fabric which is not beneficial for high absorption of the electromagnetic waves. The high absorption of ∼90% is demonstrated when the ZnO coated cotton is loaded with 3 wt% rGO. In this work, the detailed mechanism of such absorption dominant EMI shielding has been discussed in details.

    更新日期:2020-01-07
  • Determination of gel point and completion of curing in a single fiber/polymer composite
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2020-01-07
    J. Hoffman; S. Khadka; M. Kumosa

    By embedding both a single fiber Bragg grating (FBG) sensor and a thermocouple during the cure cycle of a room temperature cure epoxy, a novel in-situ approach was developed to identify certain properties of the polymer. Residual strains during curing and cooling of the epoxy were determined as a function of time for three different ambient curing temperatures. Comparing the thermocouple based temperatures to those of the ambient environment allowed for the calculation of the degree of cure and the full cure time of the epoxy. Analyzing the wavelengths of the FBG sensor and compensating for the temperature measured by the internal thermocouple, the gel point was precisely identified and validated using Flory-Stockmayer theory. As expected the residual strains increased with the curing temperature while the gel time and the completion of curing time decreased with temperature. The integrated approach of using both FBG sensors and embedded thermocouples presented in this study could be used for other polymer systems and polymer matrix composites during their manufacturing.

    更新日期:2020-01-07
  • Flexible and durable cellulose/MXene nanocomposite paper for efficient electromagnetic interference shielding
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2020-01-07
    Dawei Hu; Xingyi Huang; Shengtao Li; Pingkai Jiang

    Flexible and multifunctional electromagnetic shielding (EMI) materials have attracted tremendous attention in the field of electromagnetic compatibility and civilian protection. However, these materials encounter an intrinsic contradiction between effective integration of multiple functions and simple, low-cost manufacture process. Herein, a highly electrically/thermally conductive MXene/cellulose nanocomposite paper was fabricated via a simple dip-coating method. Benefiting from the three-dimensional interconnected MXene (Ti3C2Tx) network, the resultant paper exhibits a marvelous electrical conductivity of 2756 S/m at a nanosheet loading of 1.89 vol%. Followed by a polydimethylsiloxane (PDMS) coating, the as-prepared freestanding nanocomposites with 0.2 mm thickness can reach an exceptional EMI shielding effectiveness of over 43 dB in the X and Ku band at the Ti3C2Tx loading of 1.07 vol%, and no apparent decline is observed after 2000 bending-releasing cycles in the durability test. In addition, an in-plane thermal conductivity of 3.89 W/(m⋅K) is achieved, which is 540% higher than that of PDMS coated neat filter paper. This work provides facile strategy to large-scale and green production of flexible and multifunctional EMI materials. Considering the prominent performance, the obtained nanocomposite paper has promising applications in aerospace, stealth weapon equipment, smart electronics and flexible devices.

    更新日期:2020-01-07
  • Super-low thermal conductivity fibrous nanocomposite membrane of hollow silica/polyacrylonitrile
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2020-01-07
    Dongzhi Tao; Xiang Li; Yubing Dong; Yaofeng Zhu; Yumin Yuan; Qingqing Ni; Yaqin Fu; Shaoyun Fu

    Global warming aggravates mainly due to human activities, such as the massive use of fossil energy and excessive deforestation. Thus, reducing energy waste becomes has gained more importance. Thermal insulation materials with superlow thermal conductivity show notable potential in energy saving. Herein, an adiabatic hollow silica/polyacrylonitrile (SiO2-PAN) fibrous nanocomposite membrane was prepared via electrospinning. Hollow SiO2 spheres were prepared by using tetraethyl orthosilicate as a silicon source and hydrothermal carbon spheres as the template. The thermal insulation property of PAN fibrous nanocomposite membrane can be enhanced by appending hollow SiO2 spheres. The solid conduction of the fibrous nanocomposite membrane was reduced by the addition of hollow SiO2 spheres. The composite fibrous nanocomposite membrane is flexible and achieves an optimal thermal conductivity of 16 mW/(m·K). The fibrous nanocomposite membrane can maintain its thermal insulation property and becomes hydrophobic after treatment with silicone oil. The developed membrane provides a new idea for the future development of thermal insulation materials.

    更新日期:2020-01-07
  • Mulberry-like polyaniline-based flexible composite fabrics with effective electromagnetic shielding capability
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2020-01-02
    Tong Pan; Yang Zhang; Chenhui Wang; Han Gao; Bianying Wen; Boqing Yao

    With the explosive development of wearable and foldable electronics, it is imperative to create novel flexible composite materials with excellent durability, reliability, and high electromagnetic interference shielding capabilities. However, the preparation of flexible polyaniline (PANI) based shielding composites with excellent mechanical deformation durability is still a huge challenge due to the inherent rigidity of PANI chains. Herein, porous and flexible artificial suede-like cloth (ASC) fabrics were chosen as the substrate. A facile approach was proposed to synthesize ASC/PANI composite fabrics. The mulberry-like polyaniline clusters coated ASC fabrics were successfully prepared by a facile in-situ polymerization technique. Therefore, a three-dimensional sandwich-like PANI conductive network was established. Extensive research has been carried out on structure, morphology, dielectrics and electromagnetic characteristics. The results indicate that the high dielectric loss mainly originates from the electrical conductivity. The fabricated ASC/PANI fabric exhibits an effective EMI shielding capability of 25.90 dB. The unique heterostructures and the skin depth effect were responsible for the enhanced shielding performance. Experimental and theoretical analysis demonstrated the absorption dominated shielding mechanism. Interestingly, more than 93.5% of SE can be retained after 1500 cycles of bending test with a bending radius of only 2.6 mm. Therefore, these ASC/PANI fabrics with effective shielding properties and robust durability can be delivered. Our results promise an efficient and powerful strategy to achieve flexible PANI-based composite for shielding application potentials.

    更新日期:2020-01-02
  • Air-dried porous powder of polymethyl methacrylate modified cellulose nanocrystal nanocomposite and its diverse applications
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2020-01-02
    Yunxiao Liu; Lijuan Zhou; Li Wang; Xiaolong Pan; Kuntao Wang; Jie Shu; Lehuan Liu; Hui Zhang; Leyu Lin; Xinyan Shi; Alois K. Schlarb; Jianming Zhang
    更新日期:2020-01-02
  • When does nanotube grafting on fibers benefit the strength and toughness of composites?
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2020-01-02
    Qiang Liu; Stepan V. Lomov; Larissa Gorbatikh

    The answer to this question is revealed by our dual scale models, which say that the composite is the strongest and the toughest not when nanotubes themselves absorb energy but when they serve a supporting role in facilitating matrix to do the energy absorption instead. Toughening by means of only nanotube debonding/pull-out is not the most optimal strategy. The model concurrently considers five energy absorbing mechanisms acting at different scales. These mechanisms are nanotube debonding from the matrix, nanotube breakage, nanotube detachment from the (microscopic) fiber, fiber debonding and finally microdamage in the matrix. Our virtual experiments show that the benefit of CNT grafting largely depends on the tensile strength of CNTs and their interfacial cohesion with the matrix. A map of failure modes is constructed in the parametric space of these two CNT properties to help establish a window of properties beneficial for the strength and toughness improvement. The maximal enhancement is obtained when matrix is allowed to absorb energy through micro-scale damage and CNT debonding at the nano-scale has only partial contribution to it. Recommendations for the CNT tensile strength and CNT/matrix interfacial strength, necessary for creation of strong and tough hierarchical composites, are formulated.

    更新日期:2020-01-02
  • Synergistic improvement for mechanical, thermal and optical properties of PVA-co-PE nanofiber/epoxy composites with cellulose nanocrystals
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2020-01-02
    Mufang Li; Xu Zhao; Yingying Li; Wen Wang; Weibing Zhong; Mengying Luo; Ying Lu; Ke Liu; Qiongzhen Liu; Yuedan Wang; Dong Wang

    The rapid development of optoelectronic devices puts forward higher requirements for flexible transparent films with good mechanical and thermal properties. To further improve the mechanical, thermal and optical properties of the PVA-co-PE nanofiber reinforced epoxy composite film, cellulose nanocrystals (CNCs) was selected as modifier to enhance the interfacial adhesion between the reinforced nanofibers and matrix. Benefiting from excellent hydrophily, high strength, transparency and ultra-low thermal expansion coefficient (CTE) of CNCs, dramatic improvement in tensile strength, transparency and thermal stability of CNCs/PVA-co-PE/epoxy composites were observed over pure PVA-co-PE nanofiber/epoxy film. Typically, when the CNCs concentration was 3%, the transparency of CNCs/PVA-co-PE/epoxy film increased from 83.4% to 90.4%, the tensile strength increased from 11.4 MPa to 16.4 MPa, the CTE dropped from 33 to 10 ppm/K. Furthermore, as the reinforcement for matrix and the carrier for functional materials, the CNCs/PVA-co-PE nanofiber membrane was used to prepare the patterned photochromic and thermochromic film encapsulated with epoxy, indicating the potential application of CNCs/PVA-co-PE/epoxy composites in the light emitting devices.

    更新日期:2020-01-02
  • Integrated self-monitoring and self-healing continuous carbon fiber reinforced thermoplastic structures using dual-material three-dimensional printing technology
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-31
    Congcong Luan; Xinhua Yao; Chuck Zhang; Jianzhong Fu; Ben Wang

    Polymer-matrix composite structures with both self-monitoring and self-healing properties are proposed using a dual-material additive manufacturing technique. A double-nozzle three-dimensional (3D) printer system was adopted to fabricate these composite structures. A thermoplastic matrix with healing-agent containers was printed using one of the nozzles. The continuous carbon fibers, serving as both a sensory element and reinforcement, were embedded into the thermoplastic matrix using the other nozzle. The feasibility and effectiveness of the structures were verified through compression and three-point bending tests. Real-time self-monitoring of structural damage was performed using electrical resistance measurements. The results demonstrated that addition of 2120 Epoxy Cure agent and 2000 Epoxy Resin agent into the polymer matrix could help to repair the structural damage, with average healing efficiencies of 27.84% for non-reinforced specimens and 30.15% for fiber-reinforced specimens. In addition, digital image correlation (DIC) was utilized to analyze the reinforcing mechanism and failure behavior of the 3D printed thermoplastic composite structures reinforced with continuous carbon fibers. Integration of continuous carbon fibers and healing agents within the polymer matrix can create smart structures that can not only monitor their own structural health state, but also repair structural damage.

    更新日期:2020-01-01
  • Multiscale modeling of nano-SiO2 deposited on jute fibers via macroscopic evaluations and the interfacial interaction by molecular dynamics simulation
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-31
    Xuan Liu; Yihua Cui; Stephen K.L. Lee; Miao Zhang; Wenjun Nie

    To improve the interfacial combination of jute fiber reinforced polymer composites, sol-gel method was used to deposit nano-SiO2 layer on the surface of jute fibers. The macroscopic evaluations and molecular dynamics (MD) simulation were carried to characterize the deposition effect of nano-SiO2 layer on jute fibers. In addition, the multiscale modeling of nano-SiO2 deposited on jute fibers was established. The results showed that the deposition effect could be affected by the morphologies of nano-SiO2 layer including gel, array and aggregated particles. Compared with nano-SiO2 gel and aggregated nano-SiO2 particles, nano-SiO2 array may fill up the surface flaws of jute fibers efficiently, which would eliminate the stress concentration and lotus leaf effect on the jute fibers. The surface energy and tensile strength of jute fibers coated with nano-SiO2 array were increased by 9.79% and 16.47%, respectively. Additionally, MD simulation confirmed that non-bonding and C–O–Si chemical bonding interactions guaranteed the interfacial combination between the jute fiber and nano-SiO2 layer. C–O–Si chemical bonding could provide with a strong interfacial strength between the jute fiber and nano-SiO2 layer.

    更新日期:2019-12-31
  • Constructing multifunctional nanofiller with reactive interface in PLA/CB-g-DOPO composites for simultaneously improving flame retardancy, electrical conductivity and mechanical properties
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-31
    Xin Wen; Zhiqi Liu; Zhi Li; Jing Zhang; De-Yi Wang; Karolina Szymańska; Xuecheng Chen; Ewa Mijowska; Tao Tang
    更新日期:2019-12-31
  • 更新日期:2019-12-30
  • Hexagonal boron nitride-carbon nanotube hybrid network structure for enhanced thermal, mechanical and electrical properties of polyimide nanocomposites
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-29
    Ok-Kyung Park; Peter Samora Owuor; Ygor Morais Jaques; Joong Hee Lee; Nam Hoon Kim; Douglas Soares Galvao; Chandra Sekhar Tiwary; Pulickel M. Ajayan

    This study suggests the simple and effective synthesis method of chemically interconnected hexagonal boron nitride (h-BN)–carbon nanotubes (CNTs) hybrid materials (BN–Fe-CNT) with aminosilane functionalized iron oxide nanoparticles (NH2–Fe) via amide bond formations. Synthesized BN-Fe-CNT was acting as an effective filler that enhanced the mechanical, thermal, and electrical properties of polyimide (PI) nanocomposites and accelerated polycondensation reaction of poly(amic acid) (PAA) due to its high thermal conductivity and heat diffusivity. At a 2 wt% filler reinforcement, the in-plane thermal conductivity of the BN-Fe-CNT/PI reached 15 W m−1 K−1 at 200 °C, which represents an enhancement of approximately 11430% compared to that of pure PI. Moreover, thermal stability was enhanced from 400 °C to 570 °C. Furthermore, the connected CNTs between the individual h-BN produced electron pathways through the PI matrix, with the BN-Fe-CNT/PI exhibiting 106 times higher electrical conductivity than that of pure PI. The results in this study clearly suggested that the BN-Fe-CNT could be applicable as an effective multi-functional reinforcement in the fabrication of lightweight polymer nanocomposites with superior mechanical properties, high thermal properties, and high electrical conductivities.

    更新日期:2019-12-29
  • Damage evolution in braided composite tubes under torsion studied by in-situ X-ray computed tomography
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-28
    Yuan Chai; Ying Wang; Zeshan Yousaf; Nghia T. Vo; Tristan Lowe; Prasad Potluri; Philip J. Withers

    Here we present the first real-time three dimension (3D) observations of damage evolution in a composite tube under torsion. An in-situ torsion test of 1/1 45° (diamond) braided carbon fibre-epoxy circular composite tube was performed on a loading rig and the damage process was characterised by synchrotron X-ray computed tomography (CT). A number of damage modes and their damage sequence has been identified and monitored globally and in more detail within a representative region of interest. In particular, intra-tow cracks and inter-tow debonding have been found to occur almost simultaneously at low shear strains (1.5%). It is noteworthy that inter-tow debonding was initially trapped/limited within repeated braid units before propagating and connecting with other damage modes in 3D. The area fraction of inter-tow debonds was quantified at different stages and it was found to dramatically increase with increasing shear strain beyond 1.5%. The total volume fraction of the observed intra-tow cracks of various forms was seen to grow rapidly beyond shear strain of 2.0%. Beyond the peak shear stress (at shear strain of 2.5%), fibre micro-buckling and kink bands occur in the tows subjected to torsion induced axial compression at crimped regions close to tow crossovers. Tow crossovers control many aspects of damage propagation under torsion, positively by localising inter-tow debonds and negatively by initiating fibre micro-buckling.

    更新日期:2019-12-29
  • 3D printed shape-programmable magneto-active soft matter for biomimetic applications
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-28
    Song Qi; Hengyu Guo; Jie Fu; Yuanpeng Xie; Mi Zhu; Miao Yu

    Imitating from natural biology, shape-programmable materials play a significant role in biomimetic applications. Magneto-active soft materials (MASMs) with programmable shapes, which can assume desired shapes under external magnetic actuation as well as potential for applications in actuators, soft robotics, medical care, and bionics. Here, we propose a shape-programming strategy that can quickly design the desired magnetic moment and actuating magnetic fields for MASMs with fast, reversible, programmable, and stable shape transformation properties. This method allows us to program the magnetic moment in the soft matrix by printing diverse magnetic structural elements. The flexible matrix and soft-magnetic 3D printing filament enable the high-performance deformation of MASMs. With these capabilities, various biomimetic structures (inchworm, manta ray, and soft gripper) can be easily fabricated with walking, swimming and snatching functions. The proposed shape-programming strategy would provide an efficient way to fully capitalize the potential of MASMs, allowing researchers to develop a wide range of soft actuators that are critical in soft robotics, medical care, and bionics applications.

    更新日期:2019-12-29
  • In-situ grown hollow Fe3O4 onto graphene foam nanocomposites with high EMI shielding effectiveness and thermal conductivity
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-27
    Haoming Fang; Haichang Guo; Yiran Hu; Yanjuan Ren; Po-Chun Hsu; Shu-Lin Bai

    With the increasing packaging density and multi-functionality, thermal management and electromagnetic pollution in electronic devices are crucial. In this work, we propose a novel method to in-situ grow hollow Fe3O4 sphere (h-Fe3O4, inner and outer diameter of 870 nm and 975 nm, respectively) onto three-dimensional graphene foam (GF) surface and then filled it with polydimethylsiloxane (PDMS) to fabricate nanocomposites with high electromagnetic interference shielding effectiveness (70.37 dB from 8.2 to 12.4 GHz) and thermal conductivity (28.12 ± 1.212 W m−1 K−1) at room temperature. . Moreover, conductive networks inside composites show super-flexible performance with high electrical conductivity (84.02 ± 8.385 S cm−1). In order to reveal the mechanisms, the finite element method (FEM) simulation and theoretical modeling are carried out by considering the effect of content and morphology of Fe3O4 spheres with different preparation processing. Finally, the usage of GF/h-Fe3O4/PDMS composites as thermal interface materials (TIMs) for chip cooling is proved to be successful, and the corresponding temperature under usage power density is accurately predicted. These comprehensive properties of GF/h-Fe3O4/PDMS composite open a potential application for next-generation TIMs in chip packaging.

    更新日期:2019-12-27
  • Thermo-mechanical properties and creep modelling of wine lees filled Polyamide 11 (PA11) and Polybutylene succinate (PBS) bio-composites
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-27
    A. Nanni; M. Messori

    Solid wine wastes named wine lees (WL) have been mixed in different percentages (10, 20 and 40 phr) within Polyamide 11 (PA11) and Polybutylene Succinate (PBS) by twin-screw extrusion. Reactive extrusion has been also tested using 3-methacryloxypropyltrimethoxysilane tested as coupling agent. The obtained bio-composites have been characterized from a thermal (DSC, TGA, HDT), rheological (MFR), mechanical (tensile test) and thermo-mechanical (DMA, creep test) point of view. Micro-mechanics models of Voigt, Halpin-Tsai and Pukanszky have been fitted on tensile properties data meanwhile the creep behavior has been modeled and described through the models of Burger, Kohlrausch-Williams-Watts and Findley.

    更新日期:2019-12-27
  • Strain-rate independent small-strain-sensor: Enhanced responsiveness of carbon black filled conductive rubber composites at slow deformation by using an ionic liquid
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-26
    Jirawat Narongthong; Sven Wießner; Sakrit Hait; Chakrit Sirisinha; Klaus Werner Stöckelhuber

    Small-strain-sensors, based on conductive carbon black (CB) filled conductive rubber composites (CRCs), have been developed. An ionic liquid (IL) was used to improve the way that the piezoresistive response is independent of strain rate at small strains. Cyclic sensing behaviour at small strains was investigated under a sequential alteration of strain rates. At small strains, the CRCs without IL respond inefficiently to slow deformation cycles, giving a strain-rate dependent sensitivity. On the contrary, the presence of IL enhances the response to slow deformations. At elongations up to 3%, the loosely packed conducting parts and the sufficient rubber-filler interaction achieved with the use of an IL/CB ratio of 1.0 make the piezoresistive responses efficiently independent of the strain rates. Also, the sensitivity is at least threefold higher, compared with CRCs without IL. So, the IL enables the construction of strain-rate independent small-strain-sensor.

    更新日期:2019-12-27
  • Novel functional graphene and its thermodynamic interfacial localization in biphasic polyolefin systems for advanced lightweight applications
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-25
    Antimo Graziano; Christian Garcia; Shaffiq Jaffer; Jimi Tjong; Mohini Sain
    更新日期:2019-12-25
  • Polymer composites with high thermal conductivity optimized by polyline-folded graphite paper
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-24
    Chen Li; Li-Yuan Tan; Xiao-Liang Zeng; De-Liang Zhu; Rong Sun; Jian-Bin Xu; Ching-Ping Wong

    Owing to overheating of electronic components during work, more and more attention has been paid to the research of high thermal conductivity polymer composites in recent years. However, traditional way to improve the thermal conductivity of polymer is not ideal. Here, a high-performance polyline-folded graphite paper (PFGP)/epoxy resin (EP) composite was prepared by using polyline-folded graphite paper and liquid epoxy resin as fillers and matrix, respectively. Its out-of-plane thermal conductivity and the improvement efficiency per 1 wt% are as high as 24.19 Wm −1 K −1 and 349%, respectively. Most importantly, this approach is very simple and can be industrialized compared to traditional polymer compounding methods. The thermodynamic finite element analysis in this work simulated the thermal conductivity of PFGP/EP composite at different mass fractions, which can verify the accuracy of the experimental values. These results indicate that the PFGP/EP composites have great prospects in the field of thermal interface materials.

    更新日期:2019-12-25
  • A novel function-designed carbon fiber reinforced polymer with implanting expanded graphite/paraffin composite into interlayers: Mechanical, thermal and sustainable properties analysis
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-24
    Fei Cheng; Zhenfei Lv; Yunfei Xu; Zhaohui Huang; Xin Min; Minghao Fang; Yan'gai Liu; Xiaowen Wu

    In this study, an innovative carbon fiber reinforced polymer (CFRP) that obtains thermal storage property by implanting expanded graphite (EG)/paraffin (Pa) composite into carbon fiber interlayer (CFRP-EG/Pa composite) has been synthesized. In the CFRP-EG/Pa composite, EG/Pa composite plays a critical role in bringing about function of thermal storage for the whole composite, making CFRP composite with 9 wt% EG/Pa as an example, differential scanning calorimetry (DSC) result manifests it has melting enthalpy of 12.78 J/g and freezing enthalpy of 12.91 J/g. Besides, EG/Pa composite also contributes to improving the strength, the result demonstrates that flexural strength like CFRP-6wt%EG/Pa has been enhanced by 15.4%, and flexural strength achieves improvement at 65 °C even Pa stays in a molten state compared to CFRP without EG/Pa composite. The melting/freezing thermal cycles results reveal that CFRP-EG/Pa composites have stable and sustainable property, flexural strength have just varied in the ±1.8% interval and above two enthalpy values also change beyond 1.9% after 400 times and 800 times thermal cycles. The thermogravimetric (TG) result indicates CFRP-EG/Pa composite can be applied safely beyond 246.59 °C. Therefore, CFRP-EG/Pa composites have sustainable mechanical property and thermal property to broaden their application.

    更新日期:2019-12-25
  • Concurrent use of Z-pins for crack arrest and structural health monitoring in adhesive-bonded composite lap joints
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-24
    Martin Kadlec; Roman Růžek; Petr Bělský

    Adhesive-bonded joints in carbon fibre-reinforced polymer laminates are cost effective, but their fatigue cracking potential currently limits aerospace certification. We investigated the concurrent use of Z-pins for crack arrest (including an analysis of underlying mechanisms) and structural health monitoring (SHM) in adhesive-bonded composite lap joints. The use of Z-pins resulted in a crack arrest capacity 33% higher than the joint's static limit load and produced a residual strength that far exceeded current ultimate loads (250 versus 150% of the limit load). The electrical resistance in the Z-pins was consistent with observed trends in crack growth, suggesting its viability for SHM.

    更新日期:2019-12-25
  • The interphase and thermal conductivity of graphene oxide/butadiene-styrene-vinyl pyridine rubber composites: A combined molecular simulation and experimental study
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-24
    Hailong Yang; Fei Cai; Yanlong Luo; Xin Ye; Chen Zhang; Sizhu Wu

    In this study, how the oxidation degree of graphene oxide (GO) affects the dispersion of GO and the interfacial adhesion in butadiene–styrene–vinyl pyridine rubber (VPR)/GO composites, as well as the interfacial thermal transport were investigated by molecular dynamics simulation. Subsequently, the composites containing different oxidation degrees of GO were prepared by the chemical reduction GO in situ to verify the theoretical predictions and explore the relationship between the microstructures and macroscopic performance. The results showed that with the increase of oxidation degree of GO, the compatibility between GO and VPR improved first and then reduced, while the interface interaction enhanced gradually. The best oxidation degree of GO was acquired at about 15%, for which case the optimal dispersion of GO, the best mechanical properties and highest thermal conductivity of the composites are achieved. Although increasing the oxidation degree of GO can reduce the interfacial thermal resistance, the decreased intrinsic thermal conductivity and re-aggregation of GO with high oxidation degree would limit the increase in thermal conductivity of the composites. This study may provide a valuable guidance for chemical modifying graphene surface to optimize the GO/rubber composite properties.

    更新日期:2019-12-25
  • On controlling interfacial heterogeneity to trigger bridging in secondary bonded composite joints: An efficient strategy to introduce crack-arrest features
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-24
    Ran Tao; Xiaole Li; Arief Yudhanto; Marco Alfano; Gilles Lubineau

    Secondary adhesive bonding of carbon fiber reinforced polymer laminates is of great interest for the aerospace and automotive industries. However, joint reliability is still a major concern because of fabrication-induced or service-related cracks that are difficult to monitor and can lead to catastrophic failure. In this work, we propose a patterning strategy where the careful design of spatially-varying interface properties enables the formation of an adhesive ligament that acts as a crack-arrest feature. Bi-dimensional finite element models of adhesively bonded double cantilever beams were employed to investigate the role of the main parameters of the pattern (i.e., geometrical parameters and interfacial properties) under mode I loading. The results show that an adhesive ligament can either bridge the separating arms, largely enhancing the dissipated energy, or fail, thereby limiting the attainment of a R-curve-like response. The precise scenario is heavily dependent on the contrast in interfacial properties rather than the geometrical details of the pattern.

    更新日期:2019-12-25
  • Permittivity transition from positive to negative in acrylic polyurethane-aluminum composites
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-24
    Zhongyang Wang; Kai Sun; Peitao Xie; Yao Liu; Qilin Gu; Runhua Fan

    The insulator-conductor percolative composites have been mostly constructed to achieve high permittivity and negative permittivity. In this work, permittivity transition from positive to negative is investigated in acrylic polyurethane-aluminum (APu/Al) percolative composites at radio frequency. Both the high permittivity and negative permittivity are accompanied with low loss due to the self-passivated nature of aluminum. The reactance and ac conductivity are studied to explain the dielectric properties, which provides an essential insight into the universal principles of high permittivity and negative permittivity behaviors in percolative composites. Meanwhile, when the conductive filler content exceeds the percolation threshold, a derived formula of permittivity has been put forward on the basis of the existing theoretical framework of percolation theory. Resourceful dielectric properties of APu/Al percolative composites will make them as potential alternatives for capacitors and metamaterials.

    更新日期:2019-12-25
  • Piezo/triboelectric hybrid nanogenerators based on Ca-doped barium zirconate titanate embedded composite polymers for wearable electronics
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-23
    Harishkumarreddy Patnam; Bhaskar Dudem; Nagamalleswara Rao Alluri; Ankireddy Mule; Sontyana Adonijah Graham; Sang-Jae Kim; Jae Su Yu

    Recently, hybrid nanogenerators (HNGs) based on the synergetic piezo/triboelectric effect have shown great promise for attaining high electrical output. In this work, microparticles (MPs) of calcium-doped barium zirconate titanate (Ca-BZT) are synthesized by a solid-state technique and subseqently dispersed into polydimethylsiloxane (PDMS) to prepare a composite film. This composite film is employed to develop an HNG device to efficiently harvest energy from various mechanical motion by individual piezoelectric or triboelectric effects, or a combined synergetic effect. The surface roughness, charge density, and dielectric permittivity of the composite films are are significantly enhanced, resulting in an increase in output performance of the HNG device. The effect of Ca doping concentration on the ferroelectric characteristics of the BZT MPs and the output performance of the HNG device are systematically investigated. The BZT MPs with 2 mol% of Ca dopant optimize the high remnant polarization and piezoelectric coefficient of the Ca-BZT/PDMS composite. Moreover, the HNG device with the corresponding composite film also exhibits a maximum electrical output performance, with open-circuit voltage, short-circuit current, and power density values of 550 V, 34 μA, and 23.6 W/m2, respectively. Additionally, the mechanical stability and durability of the HNG device are investigated. To verify the practical applicability of the HNG, the generated output power is employed to demonstrate its ability to harvest biomedical energy and to power several light-emitting diodes as well as portable electronic devices.

    更新日期:2019-12-23
  • Mechanical, electromagnetic shielding and gas sensing properties of flexible cotton fiber/polyaniline composites
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-23
    Weiyu Zhang; Xinpeng Zhang; Zhaofeng Wu; Karimay Abdurahman; Yali Cao; Haiming Duan; Dianzeng Jia

    Cotton fibers/polyaniline (PANI) composites were prepared by in situ polymerization acting as flexible sensors in order to avoid the waste brought by traditional sensing substrates. The uniform coating of PANI endowed the cotton strip loaded with PANI sensor (CSPS) and cotton yarn loaded with PANI sensor (CYPS) with good mechanical, electromagnetic shielding and gas sensing properties. Both CSPS and CYPS show high selectivity to NH3, high resistance to humidity and good repeatability between sensors. Compared with the strip shaped CSPS, quasi-one-dimensional CYPS shows higher sensitivity, faster response and recovery speed due to the higher surface exposure rate. The response of CYPS to 100 ppm NH3 increased from −32.1% of CSPS to −92.1%, and the recovery time was shortened from 30.1 s of CSPS to 20.1 s. In addition, quasi-one-dimensional CYPS also displayed the stability of sensing signals against mechanical bending from 0° to 60° and the change of effective sensing length. Importantly, the research has endowed cotton fibers with new diversified functions and expanded their application field.

    更新日期:2019-12-23
  • Enhanced energy storage capability of P(VDF-HFP) nanodielectrics by HfO2 passivation layer: Preparation, performance and simulation
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-23
    Chao Chen; Yunchuan Xie; Jingjing Liu; Jing Li; Xiaoyong Wei; Zhicheng Zhang
    更新日期:2019-12-23
  • Fabrication of Fe3O4 coated boron nitride nanoplatelets by liquid-phase exfoliation for thermally enhanced epoxy composites via magnetic alignment
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-20
    Youjin Kim; Jooheon Kim

    Boron nitride nanoplatelets coated with Fe3O4 nanoparticles (BNNP/Fe3O4) were fabricated via a liquid-phase exfoliation method using an ultrasonicator, and a composite was prepared by incorporating the resultant filler into an epoxy matrix. This fabrication method not only provided efficient exfoliation assisted by additional shear force from added Fe3O4 but also simultaneously made BNNP reactive toward magnetic force because of the coating of Fe3O4, which has superparamagnetic character. During the curing process, an external magnetic field was applied to vertically align the filler in the epoxy matrix, which led to an increase in thermal conductivity because of the generation of 3-dimentional thermal transport channels. The obtained thermal conductivity of the anisotropically aligned BNNP/Fe3O4 composites with a filler fraction of 20 wt% was 1.07 W/mK, which is higher than that of the raw boron nitride composites with 20 wt% filler (0.62 W/mK) because of the uniform dispersion resulting from the exfoliation and the efficient heat conduction path via filler orientation. Moreover, an enhanced storage modulus was recorded using DMA after magnetic alignment.

    更新日期:2019-12-20
  • Characterization of the adhesive properties between structural battery electrolytes and carbon fibers
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-20
    Johanna Xu; Wilhelm Johannisson; Marcus Johansen; Fang Liu; Dan Zenkert; Göran Lindbergh; Leif E. Asp

    Structural batteries can simultaneously store electrical energy and carry mechanical load, being similar to both laminated carbon fiber composites and lithium ion batteries. The matrix in a structural battery must both conduct ions and transfer load between the fibers, made possible with a phase-separated combination of a solid polymer and a liquid electrolyte. This leads to a trade-off between the polymer contact creating adhesion and liquid contact creating ionic conductivity. Here we investigate the fiber-matrix adhesion between carbon fibres with different sizing and two different matrix systems, using microbond testing supported by transverse tensile tests. The results show that the mechanical adhesion of the fiber-matrix interface is lower than that of a commercial non-ion conducting polymer matrix but sufficient for structural battery applications.

    更新日期:2019-12-20
  • Highly-efficient microwave absorptivity in reduced graphene oxide modified with PTA@ imidazolium based dicationic ionic liquid and fluorine atom
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-19
    Mohadese Mohamadi; Elaheh Kowsari; Vahid haddadi-Asl; Maryam Yousefzadeh; Amutha Chinnappan; Seeram Ramakrishna

    This study introduces fabrication of well-designed modified graphene oxide (GO) with highly microwave (MW) absorption performance, which includes covalently connection of the phosphotungstic acid-imidazolium based dicationic ionic liquid ([email protected] Imid diIL) and Fluorine atom on the surface of GO. The structure and morphology of as-prepared [email protected] Imidazolium based dicationic ionic liquid interlocked on the surface of fluorinated graphene oxide ([email protected] Imid diIL- FGO) were specified by XPS, FTIR, Raman spectroscopy, FESEM and TEM. The unique structure of GO after being connected to [email protected] Imid diIL and fluorine atom not only effectively reduced the agglomeration of GO, but also caused high polarity, high dielectric properties as well as multiple scattering and polarization. As an MW absorbing material the [email protected] Imid diIL- FGO/epoxy resin composites were created at various loading of [email protected] Imid diIL- FGO (10–60 wt %), and they absorbed strongly the MW in the 8.0–12.0 GHz range. For example the [email protected] Imid diIL- FGO/epoxy resin composite exhibited the reflection loss (RL) values of −39 dB at loading of 50 wt % [email protected] Imid diIL- FGO with absorber thickness of 2.0 mm and the bandwidth consistent with the RL less than −10 dB can reach 2.5 GHz (from 9.5 GHz to 12 GHz). This research showed that the [email protected] Imid diIL- FGO with polar dangling functional groups is useful to absorb the enhanced MW properties.

    更新日期:2019-12-20
  • Multi-modal strain and temperature sensor by hybridizing reduced graphene oxide and PEDOT:PSS
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-17
    Fan Zhang; Hailong Hu; Mohammad Islam; Shuhua Peng; Shuying Wu; Sean Lim; Yang Zhou; Chun-Hui Wang

    Mechanically stretchable sensors are responsive to multiple stimuli, such as strain and temperature, making it difficult to identify individual stimulus using a single senor. Herein, we present a hybrid sensor featuring dissimilar impedance frequency-responses under different stimuli. The sensor is made by infusing polydimethylsiloxane (PDMS) into an aerogel containing a hybrid of conductive materials consisting of PEDOT:PSS and reduced graphene oxide. Exhibiting positive and negative sensitivity to strain and temperature, respectively, this sensor makes it possible to determine both stimuli using an impedance method. By measuring the sensor's electrical impedance at two different frequencies, both strain and temperature can be readily determined using just one sensor. Test results under long-term cyclic loading confirm that the hybrid sensor also retains high sensitivity, stretchability, and cyclic stability. The new impedance method used in conjunction with the hybrid sensor enable simultaneous determination of multiple stimuli, such as strain and temperature.

    更新日期:2019-12-18
  • 更新日期:2019-12-17
  • Short fiber reinforced composites: Unbiased full-field evaluation of various homogenization methods in elasticity
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-16
    C. Naili; I. Doghri; T. Kanit; M.S. Sukiman; A. Aissa – Berraies; A. Imad

    This paper deals with the evaluation of several homogenization methods for short fiber-reinforced composites (SFRC) in isothermal linear elasticity. In order to have an unbiased assessment, only full-field finite element (FE) versions of the methods are developed and studied, no analytical mean-field models are considered. Firstly, the FE homogenization of unidirectional (UD) SFRC is performed using two computational models: representative volume elements (RVE) and unit cells, and comparing their predictions. Secondly, for the homogenization of misaligned SFRC, a model RVE seen as an aggregate of UD pseudo-grains (PG) is homogenized in two steps. In the first step, the effective response of PGs is obtained by FE analysis on UD unit cells. The second step is performed with one of three homogenization schemes: Voigt, Reuss and a FE-based version of the Mori-Tanaka (MT) model. The latter is equivalent to a direct MT homogenization of the RVE. The actual SFRC microstructure is 3D, but because of limited computer resources, the current article is restricted to 2D analyses, which nevertheless provide some guidance. A parametric study is conducted using several fiber volume fractions and orientation tensor components. Both the effective properties of RVEs and the mean strains inside individual fibers are assessed against reference results obtained by direct FE homogenization of the actual RVEs.

    更新日期:2019-12-17
  • Facile production of natural silk nanofibers for electronic device applications
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-16
    Qiusheng Wang; Shuqin Yan; Guocong Han; Xiufang Li; Renchuan You; Qiang Zhang; Mingzhong Li; David L. Kaplan
    更新日期:2019-12-17
  • Impact and damage behaviour of FRP-metal hybrid laminates made by the reinforcement of glass fibers on 22MnB5 metal surface
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-10
    Venkateswaran Santhanakrishnan Balakrishnan, Thawin Hart-Rawung, Johannes Buhl, Holger Seidlitz, Markus Bambach

    Hot stamping of 22MnB5 steel is know to yield very high strength of up to 1500 MPa depending on the final microstructure. In this work, different microstructures of 22MnB5 steel were produced by quenching with different cooling rates and then utilized to develop Fiber Reinforced Plastic (FRP)-metal hybrid laminates. By developing FRP-metal hybrid laminates using these hot stamped steels, the superior mechanical of it can be transferred to FRP-metal hybrid laminates. Two different types of FRP-metal hybrid laminates were developed in the study, one by reinforcing thermoplastic based glass/PA-6 FRP on steel surface using press-forming technique and other by reinforcing thermoset based glass/epoxy FRP using vacuum assisted resin transfer moulding process. By developing the FRP-metal hybrid laminates, optimal exploitation of the lightweight and high strength potential can be achieved. Both thermoplastic and thermoset based FRP-metal hybrid laminates developed by using heat treatment steel has better flexural properties compared to steel without heat treatment. In overall the PA-6 has better adhesion towards steel surface compared to epoxy polymer. The developed unsymmetrical hybrid laminates will consist of one side steel and other side with FRP and the influence of the damage behaviour with respect to the impacted side were investigated. Different failure behaviours were identified with respect to the impacted side. 22 J impact on the metal side of thermoplastic based FRP-metal hybrid laminates, developed by the hot stamped steel, requires 127.88% higher load compared to FRP laminates and 33.32% higher load compared to commercially available 22MnB5 steel.

    更新日期:2019-12-11
  • Enhanced thermal conductivities of epoxy nanocomposites via incorporating in-situ fabricated hetero-structured SiC-BNNS fillers
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-10
    Yixin Han, Xuetao Shi, Xutong Yang, Yongqiang Guo, Junliang Zhang, Jie Kong, Junwei Gu

    Novel hetero-structured silicon carbide-boron nitride nanosheets (SiC-BNNS) by sol-gel and in-situ growth method were performed as thermally conductive & insulating fillers, and the SiC-BNNS/epoxy thermally conductive nanocomposites were then prepared by blending-casting approach. Synthesized hetero-structured SiC-BNNS fillers have synergistic improvement effects on the thermal conductivities of the SiC-BNNS/epoxy nanocomposites. When the amount of hetero-structured SiC-BNNS fillers is 20 wt% (SiC-BNNS, 1/1, w/w), the thermal conductivity coefficient (λ) value of the SiC-BNNS/epoxy nanocomposites (0.89 W/mK) is 4.1 times that of pure epoxy resin (0.22 W/mK), and 2.1, 1.4, and 1.7 times of SiC/epoxy (0.43 W/mK), BNNS/epoxy (0.62 W/mK), and (SiC/BNNS)/epoxy thermally conductive nanocomposites (0.52 W/mK) with the same amount of fillers (20 wt% single BNNS, SiC, or SiC/BNNS hybrid fillers), respectively. Meantime, the obtained (SiC-BNNS)/epoxy thermally conductive nanocomposites also demonstrate favorable electrical insulating properties, and the breakdown strength, volume resistivity as well as surface resistivity is 22.1 kV/mm, 2.32 × 1015 Ω cm, and 1.26 × 1015 Ω cm, respectively.

    更新日期:2019-12-11
  • Epoxy resin composites reinforced and fire-retarded by surficially-treated carbon fibers via a tunable and facile process
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-10
    Xiao-Hui Shi, Li Chen, Qing Zhao, Jia-Wei Long, Ying-Ming Li, Yu-Zhong Wang
    更新日期:2019-12-11
  • Reinforcement and Payne effect of hydrophobic silica filled natural rubber nanocomposites
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-10
    Huilong Xu, Xinpeng Fan, Yihu Song, Qiang Zheng

    Nanoparticles significantly reinforce rubber and enhance nonlinear rheological behaviors while the underlining mechanisms are not yet clear. Herein a time-concentration superposition (TCS) principle is employed for constructing master curves of high-frequency linear rheology of hydrophobic silica filled natural rubber compounds with reference to the matrix. The effect of dynamics retardation of the matrix disclosed by the TCS principle is explained by the time-dependent diffusion double reptation model that predicts linear rheology well covers the TCS mater curves in the nonterminal region. With aid of the convective constrain release model, the Payne effect of the compounds is shown to originate mainly from the filler-promoted disentanglement of chains in the matrix whose local strain amplitude is amplified by the filler. Furthermore, the filler is shown to be able to enhance both the elastic and viscous nonlinearities of compounds under large strain amplitudes.

    更新日期:2019-12-11
  • Interfacial reinforcement of hybrid composite by electrophoretic deposition for vertically aligned carbon nanotubes on carbon fiber
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-09
    Lizhi Li, Wenbo Liu, Fan Yang, Weicheng Jiao, Lifeng Hao, Rongguo Wang
    更新日期:2019-12-11
  • Nanocomposites with size-controlled nickel nanoparticles supported on multi-walled carbon nanotubes for efficient frequency-selective microwave absorption
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-09
    Francisco Mederos-Henry, Sébastien Depaifve, Arnaud Wolf, Yann Danlée, Arnaud Delcorte, Christian Bailly, Isabelle Huynen, Sophie Hermans

    Two types of nanocomposites based on multiwalled carbon nanotubes (MWCNTs) decorated with metallic nickel nanoparticles (NiNPs) possessing very different size distributions (13 vs. 130 nm) were produced using novel synthetic techniques. The obtained nanocomposites were dispersed in a polycarbonate (PC) matrix to produce thin (∼500 μm) composite films. For the first time, we show that such films possess clear ferromagnetic resonances in the ultra-high frequency (UHF) and L microwave regions. Furthermore, we prove that their natural ferromagnetic (FMR) frequency is lowered when using nanocomposites with smaller NiNPs. These results could be exploited to design selective dual-band filters for telecommunications applications.

    更新日期:2019-12-11
  • Ternary thermoelectric composites of polypyrrole/PEDOT:PSS/carbon nanotube with unique layered structure prepared by one-dimensional polymer nanostructure as template
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-09
    Lirong Liang, Jueshuo Fan, Miaomiao Wang, Guangming Chen, Guoxing Sun

    Recently, organic polymer-based thermoelectric (TE) hybrids or composites have received significant attention. Here, a unique layered morphology of polypyrrole/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)/single-walled carbon nanotube (PPy/PEDOT:PSS/SWCNT) ternary TE composites are designed using 1D nanostruture of PPy as template. The nanowires of PPy/PEDOT:PSS binary composites are obtained via coating PEDOT:PSS on the surfaces of 1D PPy nanowires. Interestingly, the PPy/PEDOT:PSS/SWCNT ternary composites reveal unexpected layered morphology and dramatically-enhanced TE function with an optimal power factor of 45.3 ± 1.4 μW m−1 K−2 at room temperature. This study will enrich the structure design and preparation strategy of novel TE composites by judicious combing 1D polymer nanostructure with 3D layered networks of composites.

    更新日期:2019-12-11
  • Effect of microcrystalline cellulose [MCC] fibres on the morphological and crystalline behaviour of high density polyethylene [HDPE]/polylactic acid [PLA] blends
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-06
    Siddharth Mohan Bhasney, Kona Mondal, Amit Kumar, Vimal Katiyar

    The present study describes the fabrication and characterization of eco-friendly composites based on high density polyethylene (HDPE), poly (lactic acid) (PLA) with microcrystalline cellulose (MCC) fibres via melt extrusion followed by injection moulding. The morphology of PLA in both HDPE/PLA blends and HDPE/MCC fibres composites was irregular and immiscible. The tensile strength at max load and % elongation at break of all polyblend composites were reduced to ∼17%, ∼15%, and ∼84%, ∼89% than pure HDPE matrix, respectively. The toughness of HDPE and its polyblend composites were decreased to ∼92% and ∼91%, respectively. As higher number indicates greater resistance, the hardness of HDPE was improved by ∼7% and ∼10% after adding PLA followed by MCC fibres. As revealed from DSC analysis, the crystallinity of composites was considerably influenced by the MCC fibres content due to the transcrystallization effect. The crystallinity of HDPE/PLA with MCC fibres polyblend composites was decreased by ∼41% as compared to the HDPE matrix because of disorientation of fibres as seen in X-ray diffraction analysis. Eventually, the results revealed that the presence or absence of MCC fibre loading had significant effects on the mechanical, morphological, and thermal properties of HDPE/PLA blends.

    更新日期:2019-12-07
  • A reconfigurable, self-healing and near infrared light responsive thermoset shape memory polymer
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-06
    Yongkang Bai, Jiwen Zhang, Didi Wen, Peiwei Gong, Jiamei Liu, Junping Ju, Xin Chen
    更新日期:2019-12-07
  • Retraction notice to “Abrasive wear of zircon sand and alumina reinforced Al-4.5 wt% Cu alloy matrix composites - A comparative study” [Compos. Sci. Technol. 67 (2007) 746–751]
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-06
    Sanjeev Das, Siddhartha Das, Karabi Das

    This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of Editors. The article duplicates significant parts of papers that had already appeared in J Mater Sci 41 (2006) 5402–5406. https://doi.org/10.1007/s10853-006-0243-0 and J Mater Sci 41 (2006) 4668–4677. https://doi.org/10.1007/s10853-006-0056-1. One of the conditions of submission of a paper for publication is that authors declare explicitly that their work is original and has not appeared in a publication elsewhere. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

    更新日期:2019-12-06
  • 3D microwave printing temperature control of continuous carbon fiber reinforced composites
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-12-05
    Nanya Li, Guido Link, John Jelonnek

    Continuous carbon fibers show dramatic promise as reinforcement materials to improve the stiffness, strength properties and design ability of 3D printed polymer parts. Current 3D printing methods have a low printing speed because the intrinsic slow and contact needed heat transfer disadvantages of the traditional resistive heating approach. We present a 3D microwave printing method by using the microwave for instantaneous and volumetric heating the continuous carbon fiber reinforced polymer (CCFRP) filament. This allows fabricating CCFRP components with much higher speed compared to traditional 3D printing technologies. To utilize the benefit of high printing speed, the speed-variation 3D microwave printing is applied to adapt the diverse printing path and reduce the printing period. In this paper, a new 3D microwave printing temperature control method by combining the prediction-model and step-proportional-integral -derivative control is researched to reduce the printing temperature difference of the CCFRP filaments during the speed-variation printing process. Three different CCFRP specimens with variation printing speed are tested, including a spanner, an aircraft and a spider from Nazca lines. The experimental results indicate that the new printing temperature control method for 3D microwave printing process dramatically reduces the temperature deviation. Further mechanical testing results indicate that the CCFRP printed with this method has a high tensile strength up to 358 MPa. This technology solved a key problem of 3D microwave printing of continuous carbon fiber reinforced polymer composites and can be used to manufacture complex polymer-matrix composite materials.

    更新日期:2019-12-05
  • A stretchable and transparent strain sensor based on sandwich-like PDMS/CNTs/PDMS composite containing an ultrathin conductive CNT layer
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-11-30
    Jianwen Chen, Yutian Zhu, Wei Jiang

    Stretchable and transparent strain sensors based on conductive polymer composites (CPCs) possess potential applications in a variety of fields, including electronic skin, wearable electronics, and human motion detection. However, it is still a challenge to prepare CPC-based strain sensors with both good transparency and broad sensing range by a low-cost, facile, and scalable fabrication method. Herein, we report a simple spray deposition and transfer method to fabricate a stretchable and transparent strain sensor based on the sandwich-like polydimethylsiloxane (PDMS)/carbon nanotubes (CNTs)/PDMS composite containing with an ultrathin and uniform conductive layer. The fabricated strain sensors exhibit superb stretchability, good optical transparency, and excellent sensing performances, which can detect both the subtle and large strains with outstanding stability and repeatability. For example, the strain sensor based on PDMS/CNTs/PDMS composite (containing 0.16 mg/cm2 CNTs on the conductive layer) presents a good optical transmittance of 53.1% at 550 nm, broad sensing range of over 130%, and the ability to monitor both the subtle motions of facial expressions and the large motions of human joints, which has great potential applications in human motion detection, wearable electronics, and electronic skin.

    更新日期:2019-11-30
  • Flexible nanopositioning actuators based on functional nanocomposites
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-11-25
    Hairong Chen, Wanwan Liu, Hong Xia, Yiping Qiu, Qing-Qing Ni, Yaqin Fu

    Nanopositioning actuators play a vital role in nanofabrication technologies, but existing nanopositioning actuators are typically made of rigid materials. Here, considering the advantages of soft actuators such as lightweight and good adaptability, we developed a kind of flexible actuators which could realize nanopositioning in a simple way. These actuators were made of functional nanocomposites which were compounded by lead zirconate titanate, shape memory polyurethane and silver nanoparticles. The results showed the ability to generate displacements with positioning errors within ±5 nm and the ease to be deformed into desired shapes. Moreover, no special requirement for the realization of nanopositioning also revealed the promising potential for decreasing the costs.

    更新日期:2019-11-26
  • 4D printed anisotropic structures with tailored mechanical behaviors and shape memory effects
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-11-25
    Tianzhen Liu, Liwu Liu, Chengjun Zeng, Yanju Liu, Jinsong Leng

    Four-dimensional (4D) printing as a new generation additive manufacturing of smart materials has shown great potential for the intelligent development of multi-functional and customized structures. The microarchitecture design of printing infill patterns could bring flexible and diversified structural performances by combining the geometry design, thus opening up more possibilities for practical application. This work investigates the anisotropic characteristics of mechanical and shape memory performances induced by different infill strategies via both experimental and theoretical methods. Uniaxial tensile tests and compressive tests are performed to study the effect of infill patterns on mechanical properties. Both classical laminate plate theory and honeycomb equivalent modulus theory take into account the actual shape and dimensions of printed cross-section to improve the prediction accuracy. The viscoelasticity of each printing pattern is described by generalized Maxwell-Wiechert model and Prony Series are fitted to provide references to implement in Abaqus. With the purpose of exploring the shape memory properties including recovery speed, recovery ratio and shape fixity ratio, deformation-recovery tests are conducted under different temperatures and a 2D and 3D convertible structure with programmable Poisson's ratio are demonstrated. This work may potentially provide pattern design guidance for 4D printing structures to meet different application requirements.

    更新日期:2019-11-26
  • All-carbon multi-scale and hierarchical fibers and related structural composites: A review
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-11-22
    József Karger-Kocsis, Haroon Mahmood, Alessandro Pegoretti

    Recent advancements in the preparation of all-carbon multi-scale fibers and their use in carbon fiber (CF)-reinforced polymer composites are reviewed. A multi-scale or hierarchical structure is the result of a combination of micro-scaled fibers and nano-scaled fillers which are in intimate contact by physical or chemical interactions. Carbonaceous nanofillers, such as carbon black, carbon nanotubes and nanofibers, graphene and its oxidized derivatives, can be deposited on CFs by different strategies. In particular, preformed nanoparticles (indirect methods) or in situ prepared nanoparticles (direct methods) can be used. Multi-scale structuring of the interlaminar region via various deposition techniques is also discussed. An overview of multi-scale fibers and multi-scale structured interlaminar layers to improve the load transfer between the matrix (namely thermoset-, thermoplastic- and carbon-based) and the reinforcing (CFs) phase is considered for this review. Moreover, their use to add new functionalities (electric conductivities, sensing, thermal conductivities) to structural composites is also reviewed. Finally, the recent efforts in modeling the mechanical behavior of the interphase and interlaminar regions of all-carbon composites with multi-scale fibers are discussed, along with some notes on future challenges.

    更新日期:2019-11-22
  • Facile one-step preparation of laminated PDMS based flexible strain sensors with high conductivity and sensitivity via filler sedimentation
    Compos. Sci. Technol. (IF 6.309) Pub Date : 2019-11-22
    Rong Zhang, An Lv, Cheng Ying, Zikang Hu, Hailong Hu, Hai Chen, Qingting Liu, Xudong Fu, Shengfei Hu, Ching Ping Wong

    Rubber based conductive composites with laminated structures are promising approaches to prepare flexible sensors with high performance abilities. Herein we report a facile one-step method to prepare polydimethylsiloxane (PDMS) based flexible strain sensors with a laminated structure via filler sedimentation. Nickel coated graphite (NCG) conductive fillers were homogenosly dispersed into a PDMS solution and then allowed to form a sedimention layer by allowing the mixture to stand for 2 h to obtain composite sensors. PDMS/NCG composites presented a two dimensional conductive network with a low percolation value of 2.52 vol% and high conductivity of 148 S/m at 11.11 vol% NCG. Due to the laminated structure, the Younge's modulus of the composites increased from 0.88 MPa for pure PDMS to only 1.98 MPa for 11.11 vol% NCG indicating high flexibility. Under applied stress, composite resistances increased from 8 to 20 Ω (varied by vol% NCG) to 4 × 108 Ω and presented a gauge factor (GF) of 5.6 × 108, amongst the highest values when compared with published results. Composite resistance under strain is explained by constriction, tunneling, and hopping mechanisms, and experimental results agree well with theoretical values. Filler sedimentation is demonstrated to be a valuable method to produce highly conductive and sensitive rubber based, laminated flexible sensors requiring only one preparation step.

    更新日期:2019-11-22
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