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  • Shape memory composites composed of polyurethane/ZnO nanoparticles as potential smart biomaterials
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-27
    Yujie Wang; Pei Zhang; Yuchun Zhao; Ruixin Dai; Miaoming Huang; Wentao Liu; Hao Liu; Suqin He; Chengshen Zhu

    Polyurethanes are commonly used as shape memory materials due to their micro‐phase separation structure. The degree of micro‐phase separation is the key factor in the shape memory properties of materials. In this study, the shape memory polyurethane (SMPU) elastomer was prepared based on polycaprolactone diols, isophorone diisocyanate, and 1, 4‐butanediol. And the branched structure is introduced by glycerol and hexamethylene diisocyanate to increase the degree of micro‐phase separation. Moreover, nano‐ZnO is also used to enhance micro‐phase separation. Atomic force microscopy images clearly show that the nano‐ZnO disperses uniformly in the polymer matrix and leads to significant change in the phase structure of SMPU. Dynamic mechanical analysis results indicate that the SMPU/ZnO nanocomposites possess two phase transition above 0°C, one is the melting transition of the soft segments, which is near the body temperature, and the other is the glass transition of hard segments. And with the addition of nano‐ZnO, the difference in transition temperature between the hard and the soft segments is significantly increased. The relationship between shape memory properties and the micro‐phase separation is explored and discussed. In vitro biocompatibility studies show that the SMPU/ZnO nanocomposites have good biosafety. Therefore, the obtained bionanocomposites have the potential application prospect as smart biomaterials.

    更新日期:2020-01-27
  • Capacities of Z‐pinning in improving the bending performance of composite T‐joints
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-27
    Mengjia Li; Puhui Chen; Xiping Li; Jiajia Zheng; Weiping Dong

    The capacities of Z‐pinning in improving the bending performance of composite T‐joints were examined experimentally and numerically. It was found that Z‐pinning was not effective in enhancing the maximum bending load capacities of the T‐joints. Delamination at the interfaces of flange/filler, flange/flange, flange/skin, in the arc‐flange, as well as the fracture of the upper corner of the filler was observed. Among those failure patterns, the notorious delamination formed in the arc‐flange assumed the main responsibility of the disability of Z‐pinning in enhancing the maximum bending load capacity. Despite this, Z‐pinning was found to be highly effective in improving the residual plateau load‐carrying capacities of the T‐joints and the maximum bending displacement could also be dramatically increased, making the T‐joint maintain considerable bending load capacity under large deformation and preventing the T‐joint from catastrophe failure once the maximum bending load was attained.

    更新日期:2020-01-27
  • Low‐velocity impact behavior of glass fiber‐MWCNT/polymer laminates exposed to seawater and distilled water aging
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-27
    Carlos Rubio‐González; Eduardo José‐Trujillo; Julio A. Rodríguez‐González; Alexandre Mornas; Abderrahim Talha

    The influence of seawater (SW) and distilled water (DW) aging on low‐velocity impact behavior of glass fiber/polymer laminates with and without multiwalled carbon nanotubes (MWCNTs) is experimentally investigated. To this aim, unidirectional glass fiber fabrics were coated with 0.75 wt% MWCNTs by airbrushing, infused with resin (epoxy or vinylester), and cured. Then, composite laminates with and without MWCNTs were cut into specimens for low‐velocity impact testing and exposed to hydrothermal aging by immersing them to SW and DW at 60°C for ~2000 h. After that time of conditioning, dry and wet specimens were tested using a drop‐weight tower with an impact energy of 15 J. Results showed that the moisture absorption content of composite laminates exposed to SW and DW aging is considerably higher on epoxy‐based specimens with respect to vinylester ones. The impact tests revealed that the measured impact peak force and absorbed energy in wet specimens are significantly lower compared to dry specimens due to plasticizing effect of the matrix. With the incorporation of MWCNTs into the laminates, the absorbed energy is increased due to additional damage mechanisms induced at CNT‐rich regions during the impact loading. It was also found that the damage area of the laminates after impact tends to be more prominent for laminates fabricated using vinylester resin than for those using epoxy resin as a result of its brittle behavior during impact loading. Post impact damage analyses by ultrasonic C‐scan imaging and scanning electron microscopy showed that matrix cracking, fiber breakage, fiber/matrix debonding, and delamination are the main damage mechanisms induced in the dry and wet specimens during impact.

    更新日期:2020-01-27
  • Development of cashew nut shell carbon reinforced thiourea based biophenolic benzoxazine‐epoxy composites: High performance biobased coating materials
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-25
    Selvaraj Vaithilingam; Raghavarshini ThangavelRavivarman; Alagar Muthukaruppan

    The research work focused on the preparation of biobased eugenol benzoxazine (EUBz) using thiourea as amine resource and their conversion into EUBz‐epoxy (EUBz‐EP) blend matrix and EUBz‐EP blend composites. In the present work, thiourea‐based eugenol‐benzoxazine monomer was synthesized using eugenol as phenolic compound, thiourea as amine resource and paraformaldehyde. The molecular structure of monomer was confirmed by FTIR, NMR, and Maldi mass studies. The thiourea‐based EUBz properties were enhanced by the blending of EP resin and reinforced with varying weight percentages of amine functionalized cashew nut shell carbon (f‐CSC). The thermally cured f‐CSC/EUBz‐EP composites possesses a higher glass transition temperature of 202.9°C when compared to that of the EUBz matrix (104.2°C), which might arise due to the higher crosslinking density resulted from the reinforcement of EP resin with f‐CSC. In addition, the hydrophobic behavior of the prepared composite materials is improved by blending the EUBz with EP resin and reinforcing with f‐CSC. The enhancement of the value of contact angle from 80.3° to 105.9° infers the improvement of hydrophobic behavior of f‐CSC reinforced EUBz‐EP blend composites. The corrosion rate and protection efficiency of 5 wt% f‐CSC/EUBz‐EP composites exhibits 0.814 (mm/year) and 99.97%, respectively. Data obtained from different studies suggested that the f‐CSC reinforced EUBz‐EP blended composites can be used in the form of sealants, encapsulants, adhesives, and coatings for different industrial and engineering applications.

    更新日期:2020-01-26
  • Preparation of high‐efficiency perovskite solar cells via doping Ag into CuO nanofibers as hole buffer layer
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-24
    Zhishan Zhuang; Linlin Qiu; Lika Dong; Yue Chen; Zhudan Chu; Xiangyu Ma; Pingfan Du; Jie Xiong

    Ag/CuO nanofibers (Nfs) with a diameter of 650 nm were successfully prepared via electrospinning Ag doped CuO nanofibers and then calcined at 450°C for 2 hours. By using Ag/CuO Nfs and PEDOT:PSS as the hole transport layer, an optimum perovskite solar cell power conversion efficiency (PCE) of 11.6% was achieved, which was 33% higher than that of the original perovskite solar cells (8.7%). The devices showed a high PCE because of the high cavity mobility of the Ag/CuO Nfs/PEDOT:PSS films. At the same time, the Ag/CuO Nfs could also slow down the hydrolysis and corrosion of the perovskite by acidic PEDOT:PSS, and increase the environmental stability of the solar cells.

    更新日期:2020-01-24
  • Nonisothermal crystallization behavior of polylactide/polyethylene glycol/graphene oxide nanosheets composite films
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-22
    Jasim Ahmed; Giorgio Luciano; Sofia Maggiore

    The nonisothermal crystallization (NIC) behavior of solution‐cast polylactide (PLA)/polyethylene glycol (PEG)/graphene oxide (GO) nanosheets composite (PLA/PEG/GO) films was examined at the selected cooling rate. The crystallization temperature (Tc) of the PLA/PEG matrix improved with increasing the reinforcement of GO (0.5%‐2% w/w) at a constant cooling rate. Various conventional crystallization models, namely, Jeziorny, Ozawa, and Mo were employed to elucidate the NIC kinetics of the PLA/PEG/GO composite films. Results showed that the Mo equation was the best model to describe the NIC of the nanocomposite films. The activation energy (E) of crystallization was estimated by Friedman's method, and the values varied from 18 to 186 kJ·mol−1, however, the values were not systematic with the loading concentration of GO.

    更新日期:2020-01-23
  • Influence of thermal oxidation and maleinized liquid polybutadiene on dynamic and static performance of short aramid fiber‐reinforced carbon black‐ethylene propylene diene monomer composites
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-18
    Bo Yang; Peng Li; Zhu Luo; Jincheng Zhong; Lianpeng Yin

    Short aramid fiber (AF)‐reinforced rubber composites (SFRRs) possess better mechanical performance than carbon black‐filled rubber in many respects. However, the performance of an SFRR depends on interfacial adhesion to a large extent. In this article, AF was treated by thermal oxidation and then used to prepare AF‐reinforced carbon black‐ethylene propylene diene monomer (CB‐EPDM) composites in the presence of maleinized liquid polybutadiene rubber as the compatibilizer. The interfacial adhesion between the AF and matrix was evaluated by means of the relative debonding energy (RDE), and the corresponding dynamic and static performance was studied. The interfacial adhesion could be improved by a combination of fiber surface treatment and rubber compatibility, and the RDE was increased. Compared with those of the unmodified AF‐reinforced CB‐EPDM, the tensile moduli at 100% and 300% elongation and the tear strength increased by 27.4%, 16.7%, and 22.9%, respectively, and the stress‐controlled fatigue life of the notched sample increased by 140%. The results showed that the RDE decreased gradually with increasing average deformation after strain‐controlled fatigue for 30 000 cycles, and the RDE remained at a higher level in the AF‐reinforced CB‐EPDM when better interfacial adhesion was formed.

    更新日期:2020-01-21
  • Preparation and characterization of ultrahigh molecular weight polyethylene composites with high content of multiwall carbon nanotubes
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-17
    Anqi Li; Zexiong Wu; Zishou Zhang; Kancheng Mai

    In order to obtain the ultrahigh molecular weight polyethylene (UHMWPE) composites with high conductivity and mechanical property, an effective route of solution mixing and followed by hot‐pressing was investigated for UHMWPE composites with high content of multiwall carbon nanotubes (MWCNTs). The effect of MWCNT contents on the crystallization and melting behavior, crystal structure, electrical conductivity, and mechanical properties of MWCNT/UHMWPE composites was characterized by differential scanning calorimetry, four‐probe measurement configuration, X‐ray diffraction, and universal testing machine, respectively. The effect of MWCNTs on crystallization temperatures of UHMWPE is discussed by the heterogeneous nucleation of MWCNTs and the restriction of the macromolecular chain motion of UHMWPE by MWCNTs. The electrical conductivity of UHMWPE is significantly increased with increasing of MWCNT contents and the UHMWPE composite with the conductivity of 5649 S m−1 can be obtained at the MWCNT content of 60 wt%. The influence of MWCNTs on tensile strength and modulus of UHMWPE composites is explained by the reinforce effect of MWCNTs and the lower content of UHMWPE not enough to support the structure of composites.

    更新日期:2020-01-17
  • Preparation of β‐CD@ferrocene@hollow mesoporous silica microsphere and investigation of its flame retardant EP
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-17
    Xueying Shan; Ji Han; Jinchun Li; Yan Song; Yuan Hu

    For improving the flame retardancy of epoxy resin (EP), β‐cyclodextrin@ ferrocene@hollow mesoporous silica microspheres (β‐CD@FE@HMS) were prepared successfully by the self‐assembly method. Then, they were used as flame retardant to improve the fire safety of EP. EP/β‐CD@FE and EP/HMS composites were also prepared for comparative study. The results showed that β‐CD@FE@HMS could effectively improve the thermal stability of EP, in which the initial degradation temperature and the amount of char residue of EP were increased. The content of small molecule toxic gases produced by the combustion of EP composite was also reduced apparently. With the addition of 5 wt% β‐CD@FE@HMS, LOI value of EP was increased to 27.5% from 19.8%, and UL‐94 reached V‐1 rating. Comparing with pure EP, the peak heat release rate and total heat release values of EP were reduced by 11.0% and 12.3%, respectively, and the total smoke production was reduced by 30.6%. EP/β‐CD@FE@HMS composite formed a higher quality char layer. Therefore, β‐CD@FE@HMS microspheres could improve the fire safety of EP.

    更新日期:2020-01-17
  • Green chemistry mediated synthesis of cadmium sulphide/polyvinyl alcohol nanocomposites: Assessment of microstructural, thermal, and dielectric properties
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-17
    Peram Lokanatha Reddy; Kalim Deshmukh; Tomáš Kovářík; Narayanasamy Arunai Nambiraj; Khadheer Pasha Shaik

    In the present study, a green synthesis approach has been employed to prepare cadmium sulphide nanoparticles (CdS NPs). The prepared CdS NPs were used as nanofiller (0‐3 wt%) to produce polyvinyl alcohol (PVA)/CdS nanocomposite films via solution casting technique. The Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy, and atomic force microscopy were employed to investigate various properties of PVA/CdS nanocomposite films. An enhancement in the structural, thermal, and morphological properties of the PVA/CdS nanocomposite films was noticed confirming the successful incorporation of CdS NPs in the PVA matrix and good interaction between the polymer and the nanofiller. Further, an impedance analyzer was employed to evaluate dielectric properties of the PVA/CdS nanocomposite films at various frequencies (50 Hz‐1 MHz) and temperatures (40°C‐140°C). The dielectric constant (ε) and dielectric loss (tanδ) values of PVA/CdS nanocomposite films loaded with 3 wt% of CdS NPs were found to be 423.71 and 4.18, respectively, at 50 Hz and at 140°C. An improvement in the dielectric properties evidenced the homogeneous distribution of CdS NPs within the PVA matrix making the nanocomposite films useful for electrical charge storage devices.

    更新日期:2020-01-17
  • Electrical insulation performance of cross‐linked polyethylene/MgO nanocomposite material for ±320 kV high‐voltage direct‐current cables
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-16
    Ashish Paramane; Xiangrong Chen; Chao Dai; Honglu Guan; Linwei Yu; Yasuhiro Tanaka

    Polymeric nanocomposite insulations are receiving the widespread attention of the electrical cable industry. This paper presents the electrical insulation performance of as‐received commercial 320 kV high‐voltage direct‐current (HVDC) cross‐linked polyethylene (XLPE)/MgO nanocomposite material with reference to the pure XLPE. The results of this commercial‐grade electrical insulation material are not reported hitherto. The scanning electron microscopy confirms the well‐dispersed nanofiller inside the polymer matrix. The DC electrical insulation performance is investigated by DC breakdown strength, space charge, DC electrical conductivity, and surface potential decay measurements. The test samples are subjected to the thermal aging at 135°C for 30 days. The un‐aged nanocomposite exhibits 20% higher DC breakdown strength, negligible hetero space charge accumulation, and the lower DC conductivity by one order than the un‐aged pure XLPE. Moreover, thermally aged nanocomposite shows more restraint to the deterioration of its properties. After the thermal aging, the DC breakdown strength decreased by 38% and 20% in the pure XLPE and its nanocomposite, respectively. Thermally aged nanocomposite shows negligible hetero charges and an increase in the DC conductivity by one order. However, the pure XLPE shows higher hetero charge accumulation and the increased DC conductivity by one order. In un‐aged XLPE nanocomposite higher crystallinity, higher deep trap density, and the lower carbonyl index are found to be the primary attributes of its improved performance. It is postulated that these significantly unchanged attributes can be the reason for the better anti‐thermal aging properties of the XLPE nanocomposite.

    更新日期:2020-01-17
  • Two‐step fabrication of lignin‐based flame retardant for enhancing the thermal and fire retardancy properties of epoxy resin composites
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-14
    Shuai Zhou; Ran Tao; Peng Dai; Zhenyang Luo; Ming He

    Lignin is a biomass material that attracts more and more attention because of its extremely low utilization rate. In this paper, we have fabricated a lignin‐based flame retardant chemically grafted with PEI followed with polyphosphoric acid by a mild two‐step method. It is found that the nitrogen/phosphorus modified lignin exhibited a lower char forming temperature and enhanced thermal stability. After adding 7 wt% functionalized lignin, the maximum decomposition temperature of epoxy resin (EP) composite was reduced from 387°C to 364°C, while UL‐94 grade and limiting oxygen index was up to V‐0 grade and 31.4%, respectively, with excellent flame retardant effect. Moreover, the results of the characterization show that the carbon residue becomes much denser with the addition of multifunctional lignin‐based flame retardant. It is proposed that the phosphorus element acts to promote char formation in the EP composite, endowing the resin matrix with a dense char layer. And the dense char layer with released ammonia from the nitrogen element to block the entry of air during combustion achieves the purpose of high‐efficiency flame retardancy. This gentle and efficient multifunctional process enhances the driving force for a wide range of applications of lignin‐based flame retardants.

    更新日期:2020-01-14
  • Single polymer composite sheets from polypropylene nonwoven fabric and films. Influence of processing conditions on final properties
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-13
    Yamila V. Vazquez; Luciana A. Castillo; Silvia E. Barbosa

    Single polypropylene (PP) composites from a film/nonwoven fabric/film was obtained by hot calendering in order to develop recyclable, flexible, and low‐cost sheets. Processing temperature (Tp) influence on morphology and mechanical properties of developed single composites was analyzed. Two different values of roll temperature (140 and 150°C) were studied, keeping constant rotation speed and rolls distance. Results revealed notable differences in materials microstructure induced by a difference of only 10°C in Tp. Sheets obtained at 140°C presented a well‐defined film/nonwoven fabric/film structure, meanwhile the highest Tp led to a greater melting extent of external films which penetrate into the fabric, creating a more compact structure. Moreover, results confirmed that changes in Tp can induce a differential mechanical performance showing higher strength, and ductility in sheets processed at 150°C. Homogeneous sheets with good mechanical behavior, proper nonwoven fabric/films adhesion, and uniform thickness were obtained.

    更新日期:2020-01-13
  • Experimental investigation into the fabrication of green body developed by micro‐extrusion‐based 3D printing process
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-13
    Dipesh K. Mishra; Pulak M. Pandey

    In the present work, a micro‐extrusion‐based three‐dimensional (3D) printing process has been used to fabricate a metal‐polymer‐based green body. The fabricated parts consisted of carbonyl iron particles with a binder (polylactic acid) and a solvent mixture. From the pilot experiments, it was found that the process parameters, namely, Fe loading, layer thickness,and infill density, affect the green density, shrinkage, and surface roughness of the fabricated part. Moreover, to develop a statistical model with significant factors, experiments were performed based on the design of the experiment using a central composite design method. The experimental results revealed that green density and surface roughness of 3D printed parts increased with the increase in Fe loading and infill density. On the contrary, the shrinkage in the fabricated part decreased with an increase in Fe loading and increased with the rise in infill density. Further, with an increase in layer thickness, the green density decreased while shrinkage and roughness were observed to increase. To verify the accuracy of the developed model, confirmation experiments were also performed at the optimum set of process parameters obtained by the genetic algorithm optimization technique.

    更新日期:2020-01-13
  • High performance multi‐functional cyanate ester oligomer‐based network and epoxy‐POSS containing nanocomposites: Structure, dynamics, and properties
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-13
    Vladimir Bershtein; Alexander Fainleib; Pavel Yakushev; Demid Kirilenko; Larisa Egorova; Olga Grigoryeva; Valery Ryzhov; Olga Starostenko

    The aim of this research was the detailed analysis and estimation of CER oligomer‐based nanocomposites for applications under extreme high temperature conditions. Thermostable nanocomposites based on cross‐linked cyanate ester resin (CER), derived from PRIMASET PT‐30 multi‐functional oligomer and doped by 0.025wt% to 10wt% epoxycyclohexyl‐functionalized polyhedral oligomeric silsesquioxane (ECH‐POSS) nanoparticles, were synthesized and characterized using TEM, mid‐, and far‐IR spectroscopy, and by DMA, DSC, CRS, and TGA techniques. At nanoparticles contents less than 1wt%, basically their molecular level dispersion in the matrix is suggested, whereas their clusters of about 20 to 30 nm in diameter were observed at 2wt% and 10wt% ECH‐POSS. In correlation with the results of structural analysis, the ambivalent influence of the nanoparticles, depending on their content, on the dynamics and properties of nanocomposites was revealed. The “constrained dynamics” effects caused by post‐curing and covalent embedding ECH‐POSS units into the matrix were registered by DMA, far‐IR spectroscopy and CRS. Highly cooperative glass transition with Tg ≈ 400°C (DMA, 1 Hz) was observed, and at the limit total suppression of glass transition could be achieved. The obvious superiority of the studied nanocomposites over the CER nanocomposites synthesized from monomeric dicyanate ester of bisphenols, especially at high temperatures, was shown.

    更新日期:2020-01-13
  • Mechanical and thermal properties of Carpinas betulus fiber filled polypropylene composites
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-10
    Metehan Atagur; Yasemin Seki; Yigit Pasaoglu; Kutlay Sever; Yoldas Seki; Mehmet Sarikanat; Lutfiye Altay

    The aim of this study is to demonstrate whether Carpinus betulus L. (CB) powder can be used as an alternative filler/reinforcement material for polypropylene (PP). About 5, 10, 15, and 20 wt% CB loaded PP composites were prepared by a high‐speed thermokinetic mixer. In this article, the effects of weight fraction of CB within PP on thermal, viscoelastic, chemical, mechanical, crystallographic, and morphological properties of PP composites were investigated by tensile and three‐point bending test, dynamic mechanic analysis, thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared analysis, and scanning electron microscopy. Melting temperature of the composites decreased with the increase of CB content. The crystallization temperature of PP increased with the addition of CB into PP. When 10 wt% CB filler was loaded into PP, the tensile of PP increased by about 29 wt%. The storage modulus of PP were remarkably enhanced with increasing CB weight fraction. About 5 wt% CB addition into PP increased the flexural strength of PP by about 32%.

    更新日期:2020-01-10
  • Montmorillonite‐lecithin‐heparin/PDMS films with enhanced mechanical and antithrombogenic properties
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-09
    Na Meng; Ming Zhang; Man Qing Ge; Ninglin Zhou; Cheng Chi; Xiaohong Chu; Baohong Sun; Xiaojun Gao

    This study developed a polymer/layered silicate film as blood‐contacting devices. First, the lecithin‐heparin (LEC‐HEP) was used to modify pristine montmorillonite (MMT). LEC‐HEP was successfully exchanged in the MMT. The organically modified MMT was used for the synthesis of poly(dimethylsiloxane) (PDMS)/MMT‐LEC‐HEP films by intercalation solution technique. The morphological, structural of the prepared film were evaluated using X‐ray diffraction, scanning electron microscopy. LEC‐HEP‐MMT concentration of 0.5 wt% in PDMS systems enhanced mechanical properties. The hemocompatibility of PDMS/LEC‐HEP‐MMT films was evaluated by hemolysis assay, dynamic coagulation time, and plasma recalcification time (PRT). PDMS/0.5 wt% LEC‐HEP‐MMT films also exhibited higher blood anticoagulant indexes, longer the PRT and lower hemolysis rate than the corresponding PDMS film.

    更新日期:2020-01-10
  • The effect of aggregation of cured rubber particles on rheology of thermoplastic vulcanizates
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-09
    Ahmad Zohrevand; Fatemeh Goharpey; Jaber Nasrollah Gavgani; Reza Foudazi

    In this work, we study the effect of microstructure of rubber particle aggregates on linear and nonlinear viscoelastic properties of olefinic thermoplastic vulcanizates (TPVs) based on ethylene‐propylene‐diene rubber (EPDM) and polypropylene (PP). TPVs samples with identical rubber content and different extent of rubber particle aggregation are prepared through dynamic vulcanization of PP/EPDM blends (conventional method) with different compositions as well as dilution of PP/EPDM 40/60 TPVs. Morphological observations show larger aggregates of cured rubber particles in the diluted samples (D) compared to the ones prepared by conventional method (B). The difference between the microstructures of the two series of samples decreases with increasing rubber content. Linear viscoelastic measurements demonstrate higher elastic modulus and dynamic viscosity at low frequency for D samples compared to B ones, representing the effect of aggregation of the dispersed rubber phase. The higher extent of aggregation in D samples also leads to a lower percolation threshold and smaller linear viscoelastic region. From fitting of a structure‐dependent model on the stress growth results, longer characteristic relaxation times are obtained for D samples due to the presence of rubber aggregates. Additionally, A higher degree of orientation and less contribution of rubber aggregate destruction are found under shear flow in D samples.

    更新日期:2020-01-10
  • Cellulose nanocrystals from curaua fibers and poly[ethylene‐co‐(vinyl acetate)] nanocomposites: Effect of drying process of CNCs on thermal and mechanical properties
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-09
    Ana Carolina Corrêa; Kelcilene Bruna Ricardo Teodoro; José Alexandre Simão; Pedro Ivo Cunha Claro; Eliangela de Morais Teixeira; Luiz Henrique Capparelli Mattoso; José Manoel Marconcini

    Poly[ethylene‐co‐(vinyl acetate)] (EVA) and cellulose nanocrystals (CNCs) from curaua fibers were used to obtain nanocomposites. Due to polarity that acetate groups promote in EVA, they tend to present better affinity with cellulose nanostructures without compatibilizers. In addition, the influence of the drying conditions of CNCs suspension on their dispersion through the matrix was also evaluated. CNCs were obtained via acid hydrolysis in a mixture of sulfuric and hydrochloric acids. Part of CNCs in neutral suspension was freeze‐dried and part was dried in an oven with air circulation. The dried CNCs were incorporated into EVA at concentrations of 1, 3, and 5 wt% of each CNCs. The compositions were processed in a corotating twin‐screw extruder and injection molded. Morphological results showed better dispersion and adhesion of freeze‐dried nanocrystals into EVA, and these nanocomposites also presented increase in elastic modulus and elongation at break, resulting in more resilient and elastic materials.

    更新日期:2020-01-10
  • Mechanisms of inter‐ply void formation during vacuum bag‐only cure of woven prepregs
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-08
    Wei Hu; Timotei Centea; Steven Nutt

    The removal of inter‐ply air is critical for limiting porosity in laminates. In this study, an in situ monitoring technique was employed to observe inter‐ply air evolution during vacuum bag‐only cure. Observations showed that reduced vacuum resulted in inefficient inter‐ply air evacuation, a more rapid bubble expansion rate, and formation of new air bubbles. A modified tow impregnation model showed that resin infiltration was impeded at reduced vacuum conditions due to the presence of intra‐tow air. However, the cured laminates showed that tows were fully impregnated in all cases, indicating that the entrapped intra‐tow air migrated to inter‐ply regions during cure. The interactions between intra‐tow and inter‐tow air at deficient vacuum conditions were revealed. Findings led to the conclusion that air remaining in intra‐tow regions contributed more to the increase of inter‐ply voids than the reduction in consolidation pressure difference associated with reduced vacuum.

    更新日期:2020-01-08
  • Organic/inorganic hybrid nanostructured composites of liquid nitrile rubber‐based quaternary ammonium salt‐modified montmorillonite and epoxy resin: preparation and tribological behaviors
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-08
    Hongling Yi; Meiling Hu; Donggang Yao; Ting Wei; Heng Lin; Baicun Zheng

    A new type of polymer derivative, carboxyl‐terminated butadiene nitrile rubber‐based quaternary ammonium salt (CTBN‐QAS), has been synthesized and used for the functionalization of sodium montmorillonite (MMT‐Na) via a cationic exchange process. The resulting CTBN‐QAS‐modified MMT (CTBN‐QAS‐MMT) exhibits exfoliated and/or intercalated structures as indicated by X‐ray diffraction (XRD) analysis. Further CTBN‐QAS‐MMT was incorporated into diglycidyl ether of bisphenol A (DGEBA) with different loadings to produce organic/inorganic hybrid epoxy nanocomposites. Studies were conducted on tribological behavior and dynamic mechanical properties by ring‐on‐block wear tester and dynamic mechanical analysis, respectively. The results show that as‐prepared nanostructured epoxy has better wear resistance and lower friction coefficient than pure epoxy polymer (EP), and the best wear resistance is obtained at 6 phr (parts per hundred) CTBN‐QAS‐MMT‐modified EP. Wear surface morphology analysis shows that the friction mechanism is abrasive wear. Additionally, the good friction resistance and decreased wear loss are correlated with higher glassy storage modulus and lower tan δ. The improved tribological behavior is due to the formation of hybrid organic/inorganic nanostructured epoxy material.

    更新日期:2020-01-08
  • Optimization of graphene in carbon black‐filled nitrile butadiene rubber: Constitutive modeling and verification using finite element analysis
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-05
    Mohit Goswami; Bharat Singh Mandloi; Abhay Kumar; Sujit Sharma; Sanjoy Kumar Ghorai; Kajal Sarkar; Santanu Chattopadhyay

    Graphene nanoplatelet loading is varied in carbon black‐filled nitrile butadiene rubber (NBR) to form a hybrid system. The mechanical properties of the hybrid system are determined by performing tension and compression tests. It is found that graphene nanosheets are well dispersed possessing strong interfacial interaction with NBR and carbon black. There is an increment of 9% in tensile strength of the carbon black‐filled hybrid system with a graphene loading of 4 phr without hampering ultimate strain. Further addition of graphene resulted in degraded properties. Hyperelastic material models describing nonlinear mechanical behavior are fitted with experimental data to acquire material constants. Young's modulus is determined using various models, and a synergistic effect is observed with graphene loading of 4 phr. A comparison between experimental result and finite element analysis (FEA) result is presented for uniaxial tension and compression. Maximum principal stresses at break are also visualized with the help of FEA.

    更新日期:2020-01-06
  • Synergistic effects of expandable graphite and ammonium pentaborate octahydrate on the flame‐retardant, thermal insulation, and mechanical properties of rigid polyurethane foam
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-05
    Emre Akdogan; Murat Erdem; Mustafa Erdem Ureyen; Metin Kaya

    The use of flame retardants (FRs) to improve the flame retardancy but also having good insulation and mechanical properties of rigid polyurethane foam (RPUF) has become significant due to the increasing demand in both the industry and academia. In the present study, a series of RPUF composites containing expandable graphite (EG), ammonium pentaborate (APB) octahydrate, and their binary blends were prepared with one‐shot and free‐rise methods. The effects of FRs on the FR and physical‐mechanical properties of RPUFs were investigated. The results show that both EG and APB could improve the flame retardancy of RPUFs and reduced the smoke production. The FR effect of EG was better than APB and more importantly, synergistic effect was found between EG and APB. The best results were obtained by the foam in the composition of 15E and 5A. The cone calorimeter test results showed that the peak heat release rate (pHRR) and total smoke release (THR) of 15E/5A foam were lower than the foams of 20E and 20A. The pHRR and THR values of 15E/5A foam decreased about 57.5% and 42.8% compared to the neat RPUF, respectively. Total smoke production (m2) also reduced about 77.0% by 20E and 83.6% by 15E/5A foams. Thermogravimetric analysis indicates that the char residue of 15E/5A foam increased to 39.5%, which provided better flame retardancy. The foam composites have high compressive strength (105‐150 kPa) and low thermal conductivity values (19.9‐21.3 mW/mK). While the thermal conductivity of 15E/5A foam increased by 0.5%, its compressive strength increased by 6.1%.

    更新日期:2020-01-06
  • Improvement of interfacial adhesion and mechanical properties of sisal fiber‐reinforced poly(lactic acid) composites with added bisoxazoline
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-05
    Lv Zhanglin; Wu Hong wu; Pei Yunmeng; Lan Bi

    In order to improve interfacial adhesion between poly(lactic acid) (PLA) and sisal fibers (SFs), bifunctional monomer bisoxazoline (BO) was introduced into melt‐blending process of fibers reinforced PLA composites via in situ reactive interfacial compatibilization. The morphology of fibers and their reinforced PLA composites, thermal, and mechanical properties of the composites were studied. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) results confirmed that PLA was successfully grafted onto the surface of fiber. BO played a hinge‐like role between PLA molecular chains and SFs. The interfacial reaction and the microstructures of the SF‐reinforced PLA composites were investigated by thermal analysis. The cold crystallization temperature of the composites increased by 6.5°C with the addition of 0.6 wt% BO and 20 wt% SF as compared with the composites without BO. Microdebonding test further confirmed that interfacial shear strength of samples with BO increased by more than 30.7% in comparison with unmodified samples. For composites with 20 wt% SF addition, tensile strength and modulus increased by 34% and 10%, respectively, with 1 wt% BO addition. Flexural strength and modulus increased by 25% and 8%, respectively, with the addition of 1.2 wt% BO. Impact strength of 1 wt% BO‐modified composites was 5.1 MPa, which is 17% higher than that of the composites without BO.

    更新日期:2020-01-06
  • Dual‐direction high thermal conductivity polymer composites with outstanding electrical insulation and electromagnetic shielding performance
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-05
    Yang Zhang; Bing Tang; Yang Liu; Rui Feng; Shaokun Song; Chuanxi Xiong; Lijie Dong

    The rapid dissipation of accumulated heat and efficient electromagnetic interference (EMI) shielding attract considerable attention due to the gradual integration and miniaturization of electronic devices. In an attempt to simultaneously overcome these issues, dual‐direction high thermal conductivity (TC) materials with outstanding electrical insulation and EMI shielding performance are urgently demanded. Herein, a tailor‐made sandwich network structure with insulated outer layer and EMI shielding middle layer is constructed by compression molding. The sandwich network structure endows the composite (#AB0.7/AM0.7/AB0.7) with high TC values of 3.051 and 3.365 Wm−1 K−1 at through‐plane and in‐plane directions, respectively, excellent electrical insulation (6.61 × 1013 Ω cm, 3.25 kV/mm) and superior EMI shielding performance (>27.68 dB from 8.2 to 12.4 GHz). All these results demonstrate that the prepared composite with tailor‐made sandwich network structure is a promising candidate as ideal thermal management material for electronic devices.

    更新日期:2020-01-06
  • Modified hemp fibers intended for fiber‐reinforced polymer composites used in structural applications—A review. I. Methods of modification
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-10
    Fulga Tanasă; Mădălina Zănoagă; Carmen‐Alice Teacă; Mărioara Nechifor; Asim Shahzad

    Natural fiber composites have experienced a renaissance in the last two decades as a response to societal demands for developing eco‐friendly, biodegradable and recyclable materials. They are now being extensively used in everyday products as well as in automotive, packaging, sports and construction industries. Hemp fiber is being used in most of these products because of its superior mechanical properties. Like other natural fibers, hemp fibers require modifications in order to improve their properties and interfacial bonding with polymer matrices, and to reduce their hydrophilic character. These modification methods can be grouped into three major categories: chemical, physical and biological. Chemical methods use chemical reagents to reduce fibers' hydrophilic tendency and thus improve compatibility with the matrix. They also expose more reactive groups on the fiber surface to facilitate efficient coupling with the matrix. Physical methods change structural and surface properties of the fiber and thereby influence the interfacial bonding with matrices, without extensively changing the chemical composition of the fibers. They are cleaner and simpler than the chemical methods. Biological methods use biological agents like fungi, enzymes and bacteria to modify the fiber surface properties. These methods are not toxic like chemical methods and are not energy‐intensive like physical methods. This paper presents an overview of recent developments in these methods. It is concluded that these methods almost invariably result in improvement in fiber/matrix interfacial bonding, resulting in increase in mechanical properties of the composites.

    更新日期:2020-01-06
  • Recent advances in mechanical properties of biopolymer composites: a review
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-07
    Kishor Kumar Sadasivuni; Prosenjit Saha; Jaideep Adhikari; Kalim Deshmukh; M. Basheer Ahamed; John‐John Cabibihan

    In recent years, biopolymers are getting wide attention with the perspective of developing high‐performance biocomposites with low environmental impact owing to their unique and useful features such as abundant availability, renewability, eco‐friendliness and lightweight. Biopolymer composites are expected to replace many conventional materials in optical, biological, and engineering applications as the investment and research on these materials increase substantially. The desired properties of biopolymer composites can be achieved by blending an appropriate biopolymer with suitable additives, which pave the way for polymer‐filler interaction. A variety of parameters such as chemical composition, degradation kinetics and mechanical properties of biopolymer composites can be tailored according to the application needs. The interfacial interactions between the biopolymer and the nanofiller have a significant effect on the mechanical properties of biopolymer composites. The present review is focused on the recent advances in the mechanical properties of various biopolymer composites. In the first part of this review, the unfamiliar mechanical characterization techniques such as fatigue test, nanoindentation and nondestructive testing of biopolymer composites have been discussed. In the later part, the various popular processing techniques of biocomposite fabrication have been discussed. In addition, in the conclusion section, few challenges associated with the processing and mechanical performance of biopolymer composites have been described.

    更新日期:2020-01-06
  • Balance between bonding and deposition during fused deposition modeling of polycarbonate and acrylonitrile‐butadiene‐styrene composites
    Polym. Compos. (IF 2.268) Pub Date : 2019-07-16
    Ying‐Guo Zhou; Jia‐Rui Zou; Hai‐Hong Wu; Bai‐Ping Xu

    To investigate the mechanical properties of fused deposition modeling (FDM) parts, a compatibilizer and nanoparticles were used as additions in Polycarbonate and Acrylonitrile‐Butadiene‐Styrene (PC/ABS) blends, and four PC/ABS composites were used to fabricate the FDM samples in this study. Two simplified deposition modes of the FDM process were proposed and used to investigate the bonding effect and deposition effect. The bonding effects of the four materials were first investigated using model I of the FDM process. Then, a linear relationship between the bonding strength and the porosity was found, and the optimal processing conditions that produced the best bonding strength were determined. These optimal processing conditions were then used in mode II of the FDM process to fabricate four samples. The mechanical properties and structural characterizations of these samples were studied using tensile tests, dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM). One interesting phenomenon observed from the tensile tests was that the necking of the PC/ABS FDM sample can spread throughout the total gauge length and measure more than 100% of the strain when the compatibilizer and the nanoparticles were added, which can be attributed to a balance between bonding properties and ductility. The results verify the applicability of PC/ABC composites to FDM technology and suggest that compatibilizers and nanoparticles are suitable candidates to improve the bonding strength and the deposition effect of PC/ABS FDM parts. In conclusion, the balance between bonding properties and ductility is key to improving the tensile behaviors of PC/ABS FDM parts by adjusting the compatibility and porosity of blended PC/ABS samples.

    更新日期:2020-01-06
  • A simulative overview on fiber predictions models for discontinuous long fiber composites
    Polym. Compos. (IF 2.268) Pub Date : 2019-07-29
    Christoph Kuhn; Enrico Koerner; Olaf Taeger

    During the molding of fiber reinforced plastics, complex behavior of long fibers are observed which lead to significant changes in fiber orientation and fiber content distribution as compared to short fiber reinforced plastics. In earlier publications, a direct fiber simulation approach with a mechanistic model has been presented to display the complex fiber behavior inside simple geometries, which is mainly influenced by fiber interactions during flow. In this article, the prediction with the mechanistic model is evaluated in a complex geometry and compared to commercially available direct fiber simulation as well as traditional simulation tools. In this overview, the fiber parameters of fiber orientation and fiber content distribution are analyzed and compared to experimental data. Conclusively, it is shown that the predictions with a mechanistic model show the most accurate results regarding fiber orientation and fiber content distribution, with the downside of a significantly longer computational time.

    更新日期:2020-01-06
  • The effect of the noncovalent functionalization of CNT by ionic liquid on electrical conductivity and electromagnetic interference shielding effectiveness of semi‐biodegradable polypropylene/poly(lactic acid) composites
    Polym. Compos. (IF 2.268) Pub Date : 2019-07-25
    Bluma G. Soares; Elisangela Cordeiro; Jorge Maia; Elaine C. L. Pereira; Adriana A. Silva

    Semi‐biodegradable polypropylene/poly(lactic acid) (PLA) (70:30 wt.%) blend with co‐continuous structure was used for the development of conducting composites. Multi‐walled carbon nanotube (CNT) and the noncovalently functionalized CNT with alkylphosphonium‐based ionic liquid (IL‐CNT) were used as conducting fillers. Relative high AC electrical conductivity was achieved by using 1 wt.% of CNT (around 10−3 S/m). This property increased four orders of magnitude when IL‐CNT was employed. The effect of the functionalization with IL on the rheological, morphological and thermal properties was investigated. The DSC analysis also suggested that the filler (CNT or IL‐CNT) exerted strong influence on the cold crystallization of the PLA phase and also on the melt crystallization of the PP phase. The effect of the IL on the dispersion of CNT was also confirmed by rheological measurements and transmission electron microscopy. An increase of the attenuation of the electromagnetic radiation, that is, an improvement of the electromagnetic interference shielding effectiveness (EMI SE) in the X‐band microwave region (8‐12 GHz) was achieved by using IL‐CNT, with an important influence of the absorption mechanism to this property.

    更新日期:2020-01-06
  • NiNb2O6‐BaTiO3/poly(arylene ether nitriles) composite film dielectrics with excellent flexibility and high permittivity for organic film capacitors
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-05
    Xu Huang; Jingjing Zeng; Hongtao Yu; Xianhua Wei; Linyu Pu; Jingsong Liu

    Nickel niobate (NiNb2O6) was used to modify the barium titanate (BaTiO3) ceramics, the obtained NiNb2O6‐BaTiO3 ceramics possess better dielectric performances than that of raw BaTiO3. By adding NiNb2O6‐BaTiO3 into poly(arylene ether nitriles) (PEN) polymer, a series of NiNb2O6‐BaTiO3/PEN composite films with different NiNb2O6‐BaTiO3 contents were prepared via solution casting method. The morphology, thermal, mechanical, dielectric properties, and flexibility of the obtained NiNb2O6‐BaTiO3/PEN composite films were investigated detailedly. As the filler content increases, the tensile modulus of NiNb2O6‐BaTiO3/PEN composite films increases gradually, while the tensile strength decreases. Thermal and flexibility analysis shows that the addition of the NiNb2O6‐BaTiO3 fillers does not affect the thermal and flexibility properties endowed by the PEN matrix. The dielectric constant of the composites almost linearly increases from 3.7 (1 kHz) to 15.3 (1 kHz) as the filler content increases from 0 to 40 wt%. Besides, results show that NiNb2O6‐BaTiO3/PEN composites exhibit higher dielectric constant than that of BaTiO3/PEN. The as‐prepared NiNb2O6‐BaTiO3 will be a more promising filler to prepare polymer‐ceramic composites for organic film capacitors.

    更新日期:2020-01-06
  • Synergistic effect of surface modification of carbon fabrics and multiwall carbon nanotube incorporation for improving tribological properties of carbon fabrics/resin composites
    Polym. Compos. (IF 2.268) Pub Date : 2019-07-23
    Beibei Wang; Qiangang Fu; Hejun Li; Lehua Qi; Yuanyuan Lu

    Surface modification of carbon fabrics (CFs) by nitric acid and multiwall carbon nanotube (MWCNT) incorporation into the resin matrix were simultaneously applied for CFs/resin composites to improve their tribological properties. The results show that surface roughness (Ra) of CFs increases from 8.20 to 15.10 nm after nitric acid treatment due to the remove of sizing agent on CFs surface. Surface hardness of the composites with 0.1 wt% MWCNT (CFR‐H‐0.1%T) is enhanced from 0.745 to 1.216 GPa compared with that of untreated CFs/phenolic resin composites (CFR), which is attributed to the toughening effect of MWCNT in resin matrix. The friction coefficient increases from 0.10 for CFR to 0.16 for CFR‐H‐0.1%T, while the wear rate significantly decreases from 5.75 × 10−14 m3 (N m)−1 to 2.05 × 10−14 m3 (N m)−1. The improvement of friction and wear properties is ascribed to the synergistic effect of the oxidation etching of nitric acid and the strengthening and toughening of MWCNT.

    更新日期:2020-01-06
  • Tribological behavior of glass/sisal fiber reinforced polyester composites
    Polym. Compos. (IF 2.268) Pub Date : 2019-07-26
    Gustavo S. Gehlen; Patric D. Neis; Liu Y. de Barros; Jean C. Poletto; Maurício Ebeling; Ney F. Ferreira; Sandro C. Amico; Clarissa C. Angrizani

    The present study addresses the tribological behavior of polyester composites reinforced with a natural fiber (sisal), a synthetic fiber (glass) and their combination (glass/sisal hybrid). The composites were obtained by compression molding with an overall fiber content of 20 or 40 vol%. The composites were rubbed against a steel counterface using a tribometer. Pure sisal composite exhibited superior wear resistance, mainly due to the formation of a concise tribofilm. It also showed the lowest coefficient of friction (CoF) because of the lubricating action of the water present in the natural fiber. Pure glass composite showed the lowest wear resistance due to the strong abrasive effect of the glass fibers. The increase in fiber content lead to an increase in CoF and its effect on wear was complex and discussed throughout the article.

    更新日期:2020-01-06
  • An investigation into resorcinol formaldehyde carbon aerogel/epoxy coatings: Exploring mechanical properties, ultraviolet stability, and corrosion resistance
    Polym. Compos. (IF 2.268) Pub Date : 2019-07-30
    Mehdi Naderi; Mohammad Aghabararpour; Mohammad Najafi; Siamak Motahari

    In the present study, carbon aerogels (CAs) are prepared through the pyrolysis of resorcinol‐formaldehyde aerogel and are then used as reinforcement in epoxy resin (ER) for coating applications. In order to reduce the viscosity of ER and enhance the dispersion and wetting of CA particles in the epoxy matrix, a reactive diluent is used. ER coatings containing different contents of CAs were synthesized and analyzed in terms of mechanical, morphological, ultraviolet (UV) resistance, adhesion, and anticorrosion properties. Applying only 3 wt% of CAs could significantly improve the mechanical properties, impact strength, and the joint shear strength of the ER. The Fourier‐transform infrared spectroscopy data before and after UV degradation were used for investigating the effect of CAs on UV stability; it was confirmed that CAs particles improved the UV resistance of the epoxy coatings. Moreover, the results of salt spray test and electro impedance spectroscopy proved that CAs enhanced the corrosion resistance of the epoxy coatings efficiently.

    更新日期:2020-01-06
  • Hybrid phthalonitrile‐based materials with advanced mechanical and nuclear shielding performances
    Polym. Compos. (IF 2.268) Pub Date : 2019-07-29
    Mehdi Derradji; Abdeldjalil Zegaoui; Aboubakr Medjahed; Wenbin Liu; Abdelkhalek Henniche

    Phthalonitrile resins as one of the leading high performance polymers are currently used in highly exigent applications. Herein, aiming to achieve the best combination of mechanical, thermal, and nuclear shielding performances, we prepared hybrid materials based on the typical phthalonitrile resin and the silane surface modified chopped carbon fibers and tungsten carbide nanoparticles. The obtained results suggested that a synergistic combination between the three constituent was clearly achieved leading to excellent mechanical and gamma rays shielding properties. For instance, the tensile and bending strengths reached up to 505 and 584 MPa for the composite containing 20 and 30 wt% of carbon fibers and tungsten carbide nanoparticles, respectively. Similarly, the gamma rays screening ratio also reached the exceptional value of 39% for the same 2 cm thick hybrid. Finally, the as such described hybrid materials proved that a multi‐approach strategy is often the best solution to achieve the requirements of highly exigent applications.

    更新日期:2020-01-06
  • Synthesis of organic‐inorganic hybrid nanocomposites based on the acrylate monomers and investigation of scratch resistance of these nanocomposites
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-06
    Shokufeh Bagheri; Maryam Kalantari; Samieh Fozooni; Hassan Hashemipour Rafsanjani

    Organic‐inorganic hybrid nanocomposites can be used as polymer coatings in order to improve their scratch resistance. These nanocomposites consist of a polymer matrix that provides flexibility and lightweight, and inorganic nanoparticles that are responsible for high thermal stability and improving scratch resistance. In this study, the polymer matrix, methyl methacrylate‐butyl acrylate (MMA‐BA) copolymer, was synthesized by conventional emulsion polymerization. To get the highest conversion percentage of the copolymer, various parameters, including reaction temperature, weight ratio of monomers, mechanical stirrer speed, type and amount of initiator, total amounts, and weight ratio of emulsifiers were investigated. For the synthesis of nanocomposites, nanoparticles of titanium dioxide, iron oxide, silver sulfide, and modified and unmodified nanosilica were added to the copolymer with the highest conversion percentage. According to the data, the best conditions for the synthesis of a copolymer with the highest conversion percentage were as follows: weight ratio of MMA:BA = 60:40 with a total amount of 10 g monomers, mechanical stirrer speed of 250 rpm, thermal initiator water‐soluble ammonium persulfate with amount of 0.12 g, emulsifiers such as sodium dodecyl sulfate and Triton X‐100 with a weight ratio of 1:3 and a total value of 1 g, and the reaction temperature of 80°C. According to the results of thermal gravimetric analysis, the samples with the highest thermal stability were selected for nanoscratch test. Nanoscratch test results suggested that Ag2S nanocomposite including 0.03 g AgNO3 and 0.0072 g thiourea had the highest scratch resistance with the lowest coefficient friction (0.48) and the lowest coefficient scratch (0.113 μN–1/2). Chemical structures of synthesized compounds were confirmed by Fourier transform infrared spectroscopy. The morphology of synthesized Ag2S nanocomposite was investigated by scanning electron microscopy and energy dispersive X‐ray spectroscopy analyses.

    更新日期:2020-01-06
  • Effect of yerba mate (Ilex paraguariensis) residue and coupling agent on the mechanical and thermal properties of polyolefin‐based composites
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-05
    Irene Bavasso; Maria P. Bracciale; Francesca Sbardella; Jacopo Tirillò; Fabrizio Sarasini; Luca Di Palma

    In this study, the feasibility of giving added value to spent yerba mate residues by manufacturing thermoplastic composites, and their potential benefits, is investigated. Experimental tests performed on yerba mate residues demonstrated that such residue, after a simple extraction procedure by water/ethanol solution, showed an acceptable level of interfacial compatibility with polyolefins. Biocomposites at different yerba mate residue amount in polypropylene and high‐density polyethylene (HDPE) were produced by a two‐stage process, involving extrusion and injection molding, and their mechanical and thermal properties were evaluated through tensile, TGA, and DSC tests, respectively. The addition of yerba mate residues resulted in a significant improvement (up to 23% when 20 wt% of filler was added to HDPE) of tensile properties compared to the neat matrices. This result was obtained without showing a positive effect on their crystallization behavior, as found from DSC results. Composite materials modified with maleic anhydride as coupling agent exhibited an even greater reinforcing efficiency due to enhanced interfacial compatibility. Basing on the results of this study, yerba mate residue/thermoplastic composites appear to be a viable alternative to wood composite materials, with associated environmental benefits related to the valorization of such agro‐food waste.

    更新日期:2020-01-06
  • Influence of zinc oxide nanoparticles on the mechanical and thermal responses of glass fiber‐reinforced epoxy nanocomposites
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-02
    Sridhar Thipperudrappa; Achutha Ullal Kini; Anupama Hiremath

    The present article investigates the effect of incorporation of zinc oxide (ZnO) nanoparticles in varied weight percentages into glass fiber‐reinforced (GFR) epoxy composites through the evaluation of mechanical properties such as flexure strength, impact strength, and ultimate tensile strength of the composite. Thermo‐gravimetric analysis for the fabricated composites has been taken up to evaluate the effect of ZnO nanoparticle on the thermal stability of the composite. The ZnO nanoparticle is loaded in different weight percentages ranging from 1 to 5 wt% and is dispersed uniformly in the epoxy resin through ultrasonication method. The required GFR epoxy‐ZnO nanocomposites are fabricated through hand layup technique and cured through vacuum bagging method. The analysis of the obtained result indicate that ZnO has a negative impact on the mechanical properties such as flexure and tensile strengths, while it had a positive impact on the impact strength of the GFR epoxy‐ZnO nanocomposites. These results indicate that ZnO has a greater affinity with the epoxy resin, which results in increase in matrix‐dominated properties. The presence of ZnO nanoparticles result in the reduction of active sites for bond formation between the matrix and the glass fibers which tends to reduce the fiber‐dominated properties such as tensile and flexure strength. The thermal responses of GFR epoxy‐ZnO nanocomposites increased up to 2 wt% addition of ZnO nanoparticles, while at 5 wt% there was a reduction in the thermal response of the nanocomposite due to an increased steric hindrance.

    更新日期:2020-01-06
  • Constitutive modeling of nonlinear compressive behavior of fiber reinforced polymer composites
    Polym. Compos. (IF 2.268) Pub Date : 2019-10-17
    Guangwei Chen; Xiaojuan Suo

    An elastic‐plastic constitutive model to describe the nonlinear compressive stress‐strain behavior of fiber reinforced polymer composites was developed under the plane stress condition. Model predictions are based on the tensile properties and a tensile/compressive asymmetry coefficient. A variety of tensile and compressive tests were carried out on 0°, 15°, 45°, and 90° unidirectional and ±30° and ±45° angle‐ply thermosetting and thermoplastic polymer composite laminates to obtain the material parameters and validate the model, while the finite element implementation and applications to three‐point bending loading are discussed in the next investigation.

    更新日期:2020-01-06
  • Adaptive hinged fiber reinforced plastics with tailored shape memory alloy hybrid yarn
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-05
    Moniruddoza Ashir; Andreas Nocke; Uwe Hanke; Chokri Cherif

    Currently, there is an urgent need to reduce the CO2 footprint and simultaneously improve resource efficiency. Hence, conventional construction materials are increasingly being replaced by fiber reinforced plastics, which can be used more efficiently by integration of actuator materials for the formation of adaptive fiber reinforced plastics. This paper presents the development of adaptive hinged fiber reinforced plastics based on shape memory alloys, which were structurally integrated into reinforcing fabrics by weaving technology. Prior to weaving, the SMA was converted into hybrid yarns in the form of core‐sheath structures by means of friction spinning technology. The produced functionalized fabrics were varied by the distance between two adjacent SMAs and their hinged width. Subsequently, the deformation behavior of adaptive fiber reinforced fabrics was tested, and results were evaluated in terms of quasi‐static and dynamic aspects. Results revealed that the maximum deformation of adaptive FRP was tripled by increasing the hinged width from 50 to 150 mm and doubled by reducing the distance between two adjacent SMAs from 20 to 10 mm.

    更新日期:2020-01-06
  • Improvement of water vapor barrier and mechanical properties of sago starch‐kaolinite nanocomposites
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-14
    Jareerat Ruamcharoen; Ruszana Munlee; Polphat Ruamcharoen

    The composite films of sago starch were prepared by incorporation of various amount of kaolinite (K) and kaolinite intercalated by dimethyl sulfoxide (DMSO) (KD) via solution blending method in order to reduce the water vapor transmission and enhance mechanical properties of starch based films. The kaolinite intercalation by DMSO and the composite films were characterized by using X‐ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscope techniques. The result showed that well‐dispersed kaolinite layers were delaminated in the starch matrix attesting to intercalate and exfoliate composite films. The effect of kaolinite content on the water vapor transmission and tensile properties of the composite films was investigated. The water vapor transmission of the starch film (neat starch film ca. 0.132 g.cm3/h) decreased with the addition of K and KD to the starch. It was also observed that the maximum tensile strength (5.18 MPa) was attained for the composite film with 4% by weight of clay content. The improvement in the tensile strength and modulus of starch‐based composites was due to the strong interfacial interaction between matrix and kaolinite clay, correlating to the change of morphology of the starch composite films as revealed by scanning electron microscopy.

    更新日期:2020-01-06
  • Flammability, thermal stability and mechanical properties of polyvinyl alcohol nanocomposites reinforced with delaminated Ti3C2Tx (MXene)
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-07
    Ying Pan; Li Fu; Qingwei Zhou; Zhenan Wen; Cheng‐Te Lin; Jinhong Yu; Weiming Wang; Hongting Zhao

    Herein, Ti3C2Tx (MXene) was synthesized and mixed with polyvinyl alcohol (PVA) to fabricate PVA/MXene nanocomposites. The results confirmed that delaminated MXene was successfully synthesized. The nanocomposites were obtained via casting/evaporation method. The thermal stability was evaluated by thermogravimetric analysis (TGA). For the PVA composites with content of 2 wt% MXene (PVA‐MXene2), the thermal decomposition was retarded by approximately 20°C when the temperature was lower than 350°C compared with that of pure PVA. Moreover, the evolved gas products of the PVA/MXene composite were lower than those of pure PVA. For the first time, the flame retardancy of PVA/MXene nanocomposite was investigated using a microscale combustion calorimeter. The peak heat release rate (PHRR) and total heat release of the PVA composite were reduced by 25.7% and 25.5%, respectively, with 1 wt% of MXene. The temperatures at PHRR of PVA/MXene composites were improved with the addition of MXene. Moreover, the addition of MXene resulted in PVA composites with a higher tensile strength and elongation at break than those of a pure PVA film. The improvements in the flame retardancy, thermal and mechanical properties of PVA/MXene composites should enable a wide range of potential applications of MXenes in polymer matrices.

    更新日期:2020-01-06
  • Surface modification of cellulose nanofiber aerogels using phthalimide
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-11
    Sima Sepahvand; Mehdi Jonoobi; Alireza Ashori; Florent Gauvin; H.J.H. Brouwers; Qingliang Yu

    The present work studied the possibility of using phthalimide for surface modification of cellulose nanofibers (CNF). The modification was carried out in 96/4 (v/v) water/acetic acid with CNF to phthalimide ratio of 1:0, 1:0.5, 1:1, and 1:1.5 wt%, respectively. Morphological, physical, chemical, and thermal properties of prepared aerogels were characterized by scanning electron microscopy, transmission electron microscopy, X‐ray diffraction spectroscopy, and thermogravimetric analysis. The mechanical characterization such as the stress‐strain behavior was measured by compression testing. The results showed that surface modification and addition of phthalimide increased the surface area and pore volume but decreased the overall pores size. The presence of phthalimide onto CNF was confirmed by attenuated total reflectance‐Fourier transform infrared spectroscopy as the characteristic peaks of NH2, CN, and ester bonding ( COO−) appeared. Since more energy is needed for breaking hydroxyl bonds than ionic bonds, by taking into account the reduced hydrogen bonds as the result of the chemical modification, the thermal stability of the CNF‐Ph is lower than the pure CNF aerogel. Besides, the modulus of elasticity increased that could be due to the high densities.

    更新日期:2020-01-06
  • Computation and modeling of microwave absorbing CuO/graphene nanocomposites
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-09
    Yuksel Akinay; Abdullah O. Kizilcay

    In this study, the microwave absorption properties of single‐ and double‐layer composites were investigated for experimental and numerical solution in the 8.2 to 12.4 GHz for different thickness (t m) of composites. Herein, the single‐layer composites (R1: CuO and R2: CuO‐containing graphene nanoparticle [GNP]) and double‐layer composites that composed of R1 and R2 layers were fabricated. The first double‐layer composite labeled as D1 contains R1 as a matching layer and R2 as an absorbing layer and the second double‐layer composite labeled as D2 contains R2 as a matching layer and R1 as an absorbing layer. D1 and D2 produced composites were also designed numerically and denoted as M1 and M2, respectively. The measured and simulated reflection loss (R L) of double‐layer composites shows similar performance, and it was observed that the microwave absorbers obtained with experimental studies can be modeled using computer design. The M2 double‐layer design based on 5 mm of the matching layer and 2 mm of the absorbing layer shows a minimum R L value of −33.7 dB at 10.06 GHz and an absorption bandwidth of about 1.13 GHz below −10 dB compared to single‐layer composites.

    更新日期:2020-01-06
  • Preparation and properties of melt‐spun poly(fluorinated ethylene‐propylene)/graphene composite fibers
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-11
    Jinfeng Pan; Changfa Xiao; Yan Huang; Zhengtao Zhu

    The matrix of poly(fluorinated ethylene‐propylene) (FEP) was modified with graphene (GE) as filler, and then the composite fibers were prepared by melt spinning method with a twin‐screw extruder. The effects of both the draw ratio and GE content on the structures and properties of FEP/GE composite fibers were investigated. The results showed that the addition of nanoparticles reduced the crystallization of molecular chains and the orientation of crystalline units in the fibers, while the drafting and heat setting process could effectively improve the crystallinity and orientation of composite fibers. Moreover, the addition of GE improved the mechanical properties of the composite fibers and had no effect on the chemical resistance of the composite fibers. A significant enhancement of mechanical properties of the composite fibers was obtained at low GE content, that, a 35.5% improvement of tensile strength and a 19.5% increase of Young's modulus were achieved at a GE content of only 0.3 wt%. Compared with pure FEP fibers, the oil affinity of composite fibers was also significantly improved. The prepared FEP/GE composite fibers that showed excellent chemical resistance have potential application in oil‐water separation, especially in high temperature resistant fibrous materials.

    更新日期:2020-01-06
  • Thermomechanical postbuckling of pressure‐loaded CNT‐reinforced composite cylindrical shells under tangential edge constraints and various temperature conditions
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-14
    Pham Thanh Hieu; Hoang Van Tung

    Buckling and postbuckling behavior of carbon nanotube‐reinforced composite (CNTRC) cylindrical shells with tangentially restrained edges exposed to preexisting temperature conditions and subjected to uniform external pressure are presented in this analytical study. Three temperature conditions considered are that uniform temperature rise, through‐the‐thickness temperature gradient, and in‐plane linear temperature distribution. Carbon nanotubes (CNTs) are reinforced into matrix phase through uniform or functionally graded distributions. The properties of CNTs and matrix are assumed to be temperature‐dependent and effective moduli of CNTRC are determined according to extended rule of mixture. Governing equations are based on the classical shell theory taking into account Von Karman‐Donnell nonlinearity and elasticity of tangential constraints of edges. Multi‐term solutions of deflection and stress function are assumed to satisfy simply supported boundary conditions and Galerkin method is applied to derive closed‐form expression of nonlinear pressure‐deflection relation from which critical buckling pressures and postbuckling paths are determined. A variety of numerical examples are given and interesting remarks are achieved. Due to practical situations of boundary edges and various temperature conditions, this paper aims to analyze separate and combined influences of tangential edge constraints and preexisting temperatures on thermomechanical postbuckling behavior of pressure‐loaded nanocomposite cylindrical shells.

    更新日期:2020-01-06
  • Experimental and numerical study on the tensile properties of T‐joints with low Z‐pin volume density
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-14
    Mengjia Li; Puhui Chen; Xiping Li; Ningning Gong

    Experiments and simulations were carried out to study the tensile performance of unreinforced and Z‐pinned composite T‐joints with low Z‐pin density (Z‐pin spacing larger than 5 mm). It was found that the initial load drop of the Z‐pinned specimen was obviously smoother than that of the unpinned specimen, and the improvement to the ultimate strength of the T‐joint was over 45% by Z‐pinning. Besides, the tensile performance of the Z‐pinned T‐joint was significantly related to the distance of the Z‐pin to the symmetry plane of the T‐joint and Z‐pin diameter, while was independent of the column spacing. Regarding the numerical study, the proposed macro T‐joint model was found to be capable of successfully predicting the tensile performance of Z‐pinned and unreinforced T‐joints in terms of both load‐displacement response and damage mode.

    更新日期:2020-01-06
  • Printable self‐heating coatings based on the use of carbon nanoreinforcements
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-22
    Silvia G. Prolongo; Rocío Moriche; Alberto Jiménez‐Suárez; Andrea Delgado; Alejandro Ureña

    Graphitic nanofillers reinforced epoxy coatings have been manufactured using UV‐photopolymerized resin. These materials present effective low‐power resistive heating, which can be potentially useful for deicing and anti‐icing devices. During the optimization of UV‐3D manufacturing printing process, it was confirmed that the coating thickness strongly depends on the nature and content of graphitic nanofillers. Carbon nanotubes (CNTs) strongly inhibit the photopolymerization because of the UV light dispersion, which competes with the light absorption of the photoinitiator, decreasing the coating thickness. Thermo‐mechanical behavior of the doped coatings has been analyzed together with their efficiency as de‐icing materials. The highest self‐heating achieved by Joule's effect was measured for the coating doped with the lower studied content of CNTs, close to electrical percolation. This is explained by its high‐electrical conductivity and the higher contribution of tunneling effect regard to the electrical conduction by direct contact.

    更新日期:2020-01-06
  • Fabrication of ternary composites with controlled surface microstructure using a cascaded suspension deposition method
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-30
    Maya Pishvar; Mehrad Amirkhosravi; M. Akif Yalcinkaya; M. Cengiz Altan

    Fabrication of multifunctional materials via incorporation of the third component into structural composite laminates is of great interest, especially for manipulating surface properties. However, achieving a uniform, well‐dispersed surface microstructure in ternary composites is quite challenging by using the traditional fabrication processes. In this article, a novel cascaded suspension deposition method is presented to introduce well‐dispersed short fibers into the molded laminates, allowing the control of the surface properties of the resulting ternary composite. Towards this goal, the micron‐sized, nickel‐coated carbon (NiC) fibers are uniformly deposited on a glass fabric surface by the proposed method. The deposited fabric is then used to fabricate NiC/glass/epoxy composite laminate by vacuum assisted resin transfer molding (VARTM). The deposition morphology on the glass fabrics and the fabricated laminates is investigated by assessing: (i) spatial uniformity of fiber volume fraction; (ii) degree of dispersion; and (iii) process‐induced orientation and degree of alignment. To demonstrate the flexibility of the proposed method, the effects of fiber concentration, fabric architecture, and resin flow are studied. The experimental results reveal that, in all fabrication cases, the cascaded suspension deposition technique is capable of depositing short fibers on the fabric surface with a uniform fiber volume fraction and excellent dispersion with random orientation. In addition, it is observed that the resin flow during VARTM does not considerably disturb the deposition‐induced microstructure of the NiC fibers, which allows the successful fabrication of ternary composites by VARTM.

    更新日期:2020-01-06
  • Functionalized graphenes as nanofillers for polylactide: Molecular dynamics simulation study
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-20
    Khongvit Prasitnok; Orrasa In‐noi

    This simulation studied graphene functionalized with methyl (CH3), hydroxyl (OH), carboxyl (COOH), and amine (NH2) groups as potential nanofillers for polylactide (PLA) biodegradable polymers. Key properties including the structure and dynamics of polymer chains, interaction energy and interfacial shear force between the polymer matrix and the filler, and glass transition temperature (Tg) of the nanocomposites were investigated. Results indicated that graphene functional groups play important roles in the interfacial bonding characteristics between polymer matrix and the filler. Among the fillers studied, graphene modified by COOH groups provided the strongest enhancement of interfacial interaction and shear force between the PLA matrix and the filler. The presence of nanofillers resulted in a moderate shift of the composite Tg compared to the unfilled polymer. The system with stronger interfacial interaction possessed higher Tg due to lower mobility of chain segments induced by the interaction strength between the polymer and the filler.

    更新日期:2020-01-06
  • Sub‐nanometer titanium‐oxo cluster‐polymer nanocomposites for elastic, transparent UV‐resistant films and nano‐coatings
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-22
    Yuyan Lai; Mingxin Zhang; Haitao Yu; Weiyu Wang; Panchao Yin

    Core‐shell inorganic‐organic hybrid nanocomposites, Ti‐PMMAs are constructed applying the titanium‐oxo cluster (Ti6O4(BrC[CH3]2COO)8(OiPr)8, TiO; iPr = isopropyl) as quasi‐spherical initiator for ATRP (atom‐transfer radical polymerization). Confirmed by UV‐Vis measurements and mechanical test, Ti‐PMMAs inherit the properties of both TiO cluster and polymers and show outstanding UV‐proof performance, high visible light transmittances, and excellent mechanical properties and processabilities. The elasticity and toughness of TiO‐polymer nanocomposites can be further optimized by simply tuning the polymer composites during the ATRP reactions. The admirable processability of the hybrid materials render us the capability to produce uniform nano‐coatings of Ti‐PMMAs and TiO2 with thickness approaching to a challenging length scale, 10 nm.

    更新日期:2020-01-06
  • Effect of surface treatments on interfacial properties of natural intralaminar hybrid composites
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-23
    Rosemere de Araujo Alves Lima; Daniel Kawasaki Cavalcanti; Jorge de Souza e Silva Neto; Hector Meneses da Costa; Mariana Doina Banea

    The objective of this work was to analyze the influence of the alkalization and alkalization + silanization (mixed) treatments on the interfacial adhesion and mechanical properties of intralaminar hybrid composites (jute + sisal, jute + curauá, jute + ramie, and jute + glass fiber). Single‐fiber tensile tests, fragmentation, and short beam tests were performed. Finally, a SEM analysis was used to study the influence of surface chemical treatments on the morphology of the natural fibers used. SEM images showed that the chemical treatments altered the morphology of the natural fibers. The chemical treatments improved the tensile strength of the fibers studied. It was found that the alkaline treatment is the best suited for jute, ramie, and curauá fibers, while the sisal fiber presented the best results after the mixed treatment. The superficial chemical treatments also affect the interfacial/interlaminar adhesion of the hybrid composites studied here. The best superficial treatments for each type of hybrid composite were: alkaline treatment for jute + ramie and jute + sisal, while for jute + curauá the best results were obtained for the untreated specimens.

    更新日期:2020-01-06
  • Erosive wear characteristics of E‐glass fiber reinforced silica fume and zinc oxide‐filled epoxy resin composites
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-20
    Bülent Öztürk; Hasan Gedikli; Yavuz S. Kılıçarslan

    In the present study, the effect of addition of silica fume, also known as microsilica, and zinc oxide fillers on the erosive wear behavior of bidirectional E‐glass fiber‐based epoxy resin composites has been investigated. The amount of silica fume and zinc oxide fillers in the composites was changed in the interval from 0 to 16 wt.%. The erosive wear of the composites has been evaluated at different impingement angles from 20° to 90° and at four different impact velocities of 70, 100, 150, and 200 m/s. The erodent particles used were silicon carbide (SiC) with the average particle sizes of 72 μm, 175 μm, and 348 μm, respectively. The results show that the erosion rate increases with increasing impingement angle, impact velocity, exposure time, and erodent particle size in all the composites. By comparing the two types of fillers, the composites filled with silica fume showed better erosion resistance than those of zinc oxide‐filled composites at the same filler loading. The composite filled with 16 wt.% silica fume presented the best erosion resistant while the highest erosion rate was obtained at the composite filled with 16 wt.% zinc oxide. The morphology of eroded surfaces was examined by using scanning electron microscopy, and possible erosion mechanisms were discussed.

    更新日期:2020-01-06
  • Mechanical, microstructural, and thermal characterization insights of pyrolyzed carbon black from waste tires reinforced epoxy nanocomposites for coating application
    Polym. Compos. (IF 2.268) Pub Date : 2019-09-03
    Akarsh Verma; Kriti Baurai; M. R. Sanjay; Suchart Siengchin

    Pyrolysis is a viable technique to convert waste tires into recyclable products, as the dumping of these scrap tires pose a serious environmental threat. In the present investigation, a detail methodology to fabricate and characterize the carbonaceous filler (in the form of nanocarbon black obtained from pyrolysis of waste tires) modified epoxy resin composites has been retrieved. The composites with varying carbon filler content (0, 5, 10, and 15 wt%) were fabricated using the manual hand lay‐up and compression molding techniques. The morphological analysis (field‐emission scanning electron microscopy test) revealed that the synthesized pyrolytic carbon black was in nanoscale and uniformly dispersed in the epoxy matrix. Various physical (density and water absorption), mechanical (tensile, compression, flexural, hardness, and impact), electrical and thermal (differential thermal analysis and thermogravimetric analysis) tests were done to completely examine the nanocomposite developed. We found that the 5 wt% of carbon black in epoxy resin exhibited the best mechanical properties and was complemented by the microstructural (scanning electron microscopy and X‐ray diffraction) tests analysis. High tensile strength and hardness than neat epoxy resin makes this composite a potential candidate for polymer coatings in automotive industries.

    更新日期:2020-01-06
  • The effect of two‐dimensional d‐Ti3C2 on the mechanical and thermal conductivity properties of thermoplastic polyurethane composites
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-23
    Xiaolong Wang; Libo Wang; Yan He; Meng Wu; Aiguo Zhou

    In this study, Ti3C2 was delaminated into monolayer or few‐layer d‐Ti3C2 nanosheets, followed by preparation of d‐Ti3C2/thermoplastic polyurethane (TPU) composites. The products were characterized by X‐ray diffraction and field emission scanning electron microscopy. The effects of d‐Ti3C2 loading on the thermal and mechanical properties of the composites were investigated and the fracture morphology was analyzed. Results showed that the prepared d‐Ti3C2 was a monolayer or few‐layer nanosheets and the monolayer thickness is about 1.2 nm. The two‐dimensional d‐Ti3C2 was uniformly dispersed in the TPU matrix. The addition of d‐Ti3C2 nanosheets increased the thermal conductivity of TPU and also improved the mechanical properties of the matrix. When d‐Ti3C2 loading was 1 wt%, the specific strength and specific elongation were improved by about 29% and 53%, meanwhile the dissipated energies increased by 0.3 kJ/m3.

    更新日期:2020-01-06
  • Dielectric properties of epoxy resin impregnated paper insulation in different stages of partial discharge development
    Polym. Compos. (IF 2.268) Pub Date : 2019-08-28
    Yongqiang Wang; Yu Luo; Jie Guan; Renjie Ding

    To investigate the variation of dielectric properties of epoxy resin impregnated paper insulation in different stages of partial discharge (PD) development, a PD experimental platform was established and epoxy resin impregnated paper insulation samples were prepared. According to the discharge amount, the number of discharges and discharge phenomena during the PD process, the PD process is divided into an initial stage, development stage, burst stage, and near‐breakdown stage. The variations of dielectric constant and dielectric loss factor of the sample during different PD development stages were measured by frequency domain dielectric spectrum tester. Scanning electron microscopy was used to observe the microscopic morphological changes of the samples at different stages of PD development. The surface characteristic functional groups at different stages of PD development of the sample were determined by Fourier transform infrared spectroscopy. The results show that: as the PD progresses, the insulation performance deteriorates; under continuous bombardment by high‐speed electrons, the network structure of the fiber surface and the epoxy molecular chain are destroyed, causing the weakening of the binding force between the molecular chains, and the short‐chain structure formed by cracking has a stronger steering ability. Under the continuous action of PD, the inside of the long‐chain molecule breaks and oxidizes, and a large number of small molecules, such as free radicals and monoglucose, are formed. The decrease in the molecular weight of the polymer leads to the weakening of the interaction between the molecules, resulting in an increase in polarization, a large dielectric constant, and an increase in the dielectric loss factor.

    更新日期:2020-01-06
  • Natural rubber nanocomposites with MWCNT@POSS hybrid filler: Preparation and properties
    Polym. Compos. (IF 2.268) Pub Date : 2019-09-04
    Lakshmipriya Somasekharan; Priti Xavier; Suryasarathi Bose; Ajesh K. Zachariah; Nandakumar Kalarikkal; S. Anil Kumar; Sabu Thomas

    The use of hybrid fillers can replace conventional nanoparticles in the area of fabrication of nanocomposites due to their superior properties owing to the synergistic action from the individual components. Here we prepared for the first time, polyhedral oligomeric silsesquioxane and multiwalled carbon nanotube hybrid filler based natural rubber nanocomposites by two‐roll mill mixing method. The filler‐polymer interactions were studied from frequency sweep and strain sweep rheological measurements. The cure characteristics of the nanocomposites threw light into the effect of the nanofiller on vulcanization reactions and crosslinked networks. The transmission electron microscopic images provided information about the filler dispersion in the polymer matrix and could be correlated with the material properties. The mechanical properties of the composites were also examined which showed the extent of reinforcement provided by the hybrid filler on the NR matrix.

    更新日期:2020-01-06
  • Improvement in thermal, mechanical, and barrier properties of biocomposite of poly (3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate)/modified nano‐SiO2
    Polym. Compos. (IF 2.268) Pub Date : 2019-09-03
    Dongna Li; Jirui Fu; Xiaojun Ma

    A biocomposite of poly (3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBH)/nano‐SiO2 modified with silane coupling agent KH570 (KH570‐SiO2/PHBH) were prepared by solution‐casting method. SiO2 modified with KH570 exhibited improved uniform dispersion than that of pure nano‐SiO2, and maximum thermal decomposition temperature range and crystallinity (Xc) of KH570‐SiO2/PHBH are 8.6°C and 119.7% higher than that of neat PHBH. Compared to the neat PHBH, a 75.4% and 70.8% improvement in Young's modulus and tensile strength were obtained. The water‐vapor transmission and oxygen permeance of KH570‐SiO2/PHBH decreased by 46.2% and 618.6%, respectively. The oxygen barrier property is equivalent to that of polyvinylidene chloride. Simultaneous enhancements on the thermal stability, mechanical, crystallizing, and barrier properties were mainly caused by uniform dispersion of modified nano‐SiO2 and solid interfacial bonding between filler and matrix.

    更新日期:2020-01-06
  • Two‐dimensional Ti3C2Tx/poly(vinylidene fluoride) metacomposites with weakly negative permittivity
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-03
    Yuliang Zhang; Kuan Yin; Kai Sun; Shengjia Cao; Fujun Tao; Binbin Wang; Li Li; Xueting Chang; Liangjun Huang; Runhua Fan

    In recent years, random metacomposites with tunable negative permittivity have aroused widespread attention because of their distinctive properties and broad potential prospects. It is indicated that an enormously negative permittivity with a large value is not conducive to performance optimizing and impedance matching. In this article, the 2D Mxene Ti3C2Tx was selected as the conductive phase instead of metal and carbon materials to fabricate Ti3C2Tx/poly(vinylidene fluoride) metacomposites. The results of dielectric properties indicated that the conductive Ti3C2Tx networks were formed by Ti3C2Tx contacting with each other near the percolation threshold (ƒc). The as‐obtained metacomposites containing 75 wt% Ti3C2Tx generated percolating phenomenon. Additionally, when the fraction of Ti3C2Tx was below ƒc, the frequency dispersion behaviors of conductivity were in accordance with the Jonscher's power law, which proved that conducting mechanism was dependent on hopping conduction. While above ƒc, the conductivity conformed to the Drude model and Lorentz model, which demonstrated a conductive behavior. Furthermore, the real part of permittivity transformed to negative value at 75 wt%, which can be explained as the existence of the low‐frequency plasma oscillation and electric‐dipole‐induced resonance. The dielectric loss of the metacomposite was also analyzed by the imaginary permittivity spectra. Small negative permittivity values in the range of −550 to −400 were observed, owing to the low free carrier concentration in composites. The appearance of weakly negative permittivity opened up a new direction in negative dielectric materials by 2D layered Ti3C2Tx nanomaterials.

    更新日期:2020-01-04
  • An effective surface modification of UHMWPE fiber for improving the interfacial adhesion of epoxy resin composites
    Polym. Compos. (IF 2.268) Pub Date : 2020-01-03
    Shicheng Wang; Jinyang Ma; Xia Feng; Jinxue Cheng; Xiao Ma; Yiping Zhao; Li Chen

    Ultra high molecular weight polyethylene (UHMWPE) fiber composite was reinforced by coating a functional layer on the surface of the UHMWPE fiber to improve interfacial adhesion between the fiber and the resin matrix. In this work, tannic acid (TA)‐Na+ composite modified UHMWPE fiber was used to improve moisture wettability and adhesion between the fiber and the resin. This approach had the advantages of being green, sustainable, lossless, low‐cost, and industrialized. The surface characteristics of UHMWPE fiber were investigated by Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and scanning electron microscopy. The results show that the TA coating can improve the surface roughness, wettability, and adhesion of UHMWPE fiber, thereby improving the interface properties between fiber and resin. The tensile strength of interfacial shear strength and macro‐composites of TA coating UHMWPE fiber increased by 43.3% and 28%, respectively.

    更新日期:2020-01-04
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