Materials and Properties
ZHAO Rushuo, TAN Jing, YANG Weimin, MIAO Shunfu, MIN Yunjie, CHENG Lisheng, HE Xuetao
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410 )
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The thermotropic gelation process of a polyacrylonitrile （PAN）/dimethyl sulfoxide （DMSO）/H2O ternary solution system was investigated by molecular dynamics simulation at a microscopic level， and the microscopic promoting mechanism of water on the thermotropic gelation of the ternary solution system was determined. The results indicated that the ternary system with 4 wt% water exhibited a gel point temperature of around 332.75 K through the simulation. This result was consistent with the experimental results reported in literature. Water could increase the vibration amplitude of PAN molecular chain and the probability of cross⁃linking between cyanogen groups， thus promoting the rapid gelation of PAN solution. Within a certain range， the vibration amplitude of PAN increased with an increase in the water content. The introduction of water reduced the number of DMSO molecules around PAN and enhanced the aggregation degree of PAN molecular chains， causing a higher cross⁃linking degree between the cyanogen groups.
GUAN Guotao, LIU Chenze, HE Shiquan, SONG Chaoyang, ZHANG Xiang, ZHAO Na, WANG Chao
Abstract (
338 )
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In this study， an antibacterial degradable membrane was successfully prepared through electrostatic spinning using a mixture of quaternary ammonium salt and poly（lactic acid） （PLA）， and their structure and properties were characterized by using scanning electron microscope， electronic universal material testing machine， statistical distribution of fiber diameter， and antibacterial property measurement. The results indicated that the single chain quaternary ammonium salt improve the antibacterial performance of the PLA membrane to a certain extent but reduced its breaking strength and elastic modulus. The double⁃chain quaternary ammonium salt improved the antibacterial performance of the PLA membrane significantly. This ensures that the membrane achieves high tensile/breaking strength and elongation， good membrane formation uniformity， and good dispersity of antibacterial agents. Therefore， the PLA membrane filled with the double⁃chain quaternary ammonium salt is more suitable for industrial production and practical applications.
CHEN Hui, SUN Lingsheng, QIAN Weidong, TAN Bo
Abstract (
324 )
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Polyethersulfone （PES） resin/carbon fiber （CF）/carbon black （CB） composite powder⁃sintered parts were prepared through selective laser sintering （SLS）， and their microstructure， mechanical properties， electrical properties， and surface quality were investigated by using the sintered parts with a CB mass fraction of 2 wt% and a CF mass fraction varying from 0 to 3 wt%. The results indicated that the mechanical properties of the sintered parts were enhanced at a CF mass fraction of 1.5 wt%. The addition of CF enhanced the conductivity of the sintered parts， and their conductivity was increased from 5×10-3 to 15×10-3 S/m. In addition， the surface quality of the sintered parts exhibited a trend of deterioration with an increase in the CF mass fraction.
JIAO Yang, WANG Longzhen, CAI Zhuorui, LIU Ronghao, ZHANG Yuxia, ZHOU Hongfu
Abstract (
491 )
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In this paper， a green， simple， and feasible method was developed for solving the shrinking problem of poly（butylene adipate⁃butylene terephthalate） （PBAT） foams with a high volume expansion ratio. Firstly， a chain extender （CE） and a cell stabiliser （GMS） were melt blended with PBAT， and then supercritical CO2 was used to prepare PBAT foams. The rheological test results indicated that the addition of CE increased the energy⁃storage modulus by 3 orders of magnitude and the complex viscosity by 2 orders of magnitude. The dimensional stability of the PBAT foams increased gradually with an increase in the GMS content. The PBAT foams obtained an expansion ratio of 23.1 at a CE content of 2 wt% and a GMS content of 1.8 wt%， and their shrinkage rate and resilience rate was 8 % and 90 %， respectively. This indicated the successful preparation of the PBAT foams with a high expansion ratio， and excellent resilience， and good dimensional stability.
ZHOU Long, DU Guoyong, DENG Chunping
Abstract (
358 )
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A simple， efficient， and environmentally friendly method was adopted for oil⁃water separation by means of the improved Hummers method for preparing graphene oxide （GO）. The reduced GO （rGO） was first loaded on a melamine sponge （MS） by using a simple immersion method and a high temperature reduction method. Then， the MS was heated by a diesel oil， and the long chain alkanes were loaded on the MS. A superhydrophobic⁃superlipophilic sponge was successfully prepared. The addition of rGO increased the roughness of sponge surface， and the introduction of long⁃chain alkanes reduced the surface energy of sponge surface. The modified MS exhibited good performance in elasticity， thermal stability， and oil absorption. The oil⁃water separation performance test results indicated that a separation efficiency of over 97 % was achieved for various oil⁃water mixtures. When the pump provided dynamic external force， a static continuous oil⁃water separation could be realized without stirring and dynamic continuous oil⁃water separation under agitation. The modified MS presented good reusability and chemical stability after using for 20 times. Its separation efficiency for various oil⁃water mixtures reached more than 70 %. Even in the water at different pH values， the oil⁃water separation could be realized， and n⁃hexane in water emulsion could be effectively separated.
MEI Yuan, LI Zhen, XU Lubo, MA Yiming
Abstract (
352 )
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Transparent toughened recycled polyethylene terephthalate （rPET）/recycled poly（1，4⁃cyclohexylene dimethylene terephthalate glycol） （rPCTG） alloys was prepared through melt blending. The effect of rPCTG content on the mechanical properties， transparency and thermal properties of the alloys were investigated. The results indicated that the tensile and bending properties and transparency of the alloys decreased with an increase in the rPCTG content， whereas their impact properties increased significantly. When the rPCTG content was 15 wt%， the alloys obtained an increase in impact strength from 54.8 J/m to 68.0 J/m， increasing by 24.2 %. However， there was almost no influence on their tensile and bending properties， transparency， and haze.
ZHANG Zhiqi, LI Runtao, YANG Ruicheng, DAI Yunliang, ZHANG Xiaojuan, WEN Bianying
Abstract (
261 )
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A series of microwave absorbing and thermally conductive composites were prepared using polyvinylidene fluoride （PVDF） as a matrix resin， flaky FeSiAl and alumina （Al2O3） as functional fillers， and silane coupling agent as a surface modifier. The effects of filler content and coupling agent treatment on the wave absorption and thermal conductive performance of the composite samples were intensively investigated. The results indicated that when only 20 wt% of surface⁃treated FeSiAl and Al2O3 was incorporated as fillers， the PVDF/FeSiAl/Al2O3 composites exhibited good wave absorbing performance， and their lowest reflection loss value was -37.1 dB. When the contents of FeSiAl and Al2O3 were 20 wt% and 30 wt%， respectively， the composites obtained an increase in thermal conductivity by 168.2 % compared to pure PVDF. Through a combination of flake FeSiAl and Al2O3， followed by the surface treatment with a coupling agent， the wave absorption and thermal conductive performance were both improved at a low filler content.
Processing and Application
DENG Weijuan, WANG Qiao, HU Wei, YANG Fan, HUI Zhan
Abstract (
291 )
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To develop a high⁃performance adhesive suitable for retard⁃bonding prestressed steel strands， an adhesive based on the E51 epoxy resin/polyamide/filler system was studied through cone penetration， Shore hardness， mechanical property and durability measurements， and its optimal formulation was determined to meet the requirement of performance for retard⁃bonding prestressed steel strands. The results indicated that the initial penetration for optimum formulation was 53.6 （0.1 mm）， flexural strength was 23.82 MPa， compressive strength was 75.14 MPa， tensile shear strength was 18.92 MPa， damp heat aging resistance was 13.44 %， and the high⁃ and low⁃temperature alternating performance was 12.57 %. These properties can meet the requirements of industry standards and provides a reference value for the development of adhesive for retard⁃bonding prestressed steel strands.
HUA Shaozhen, CAO Wei
Abstract (
284 )
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The calculation of viscoelastic flow is one of the challenges in the injection molding flow analysis. With regard to the viscoelastic characteristics and taking into account the inertia effect， a viscoelastic theoretical model for the melt flow in injection molding was developed based on the Giesekus constitutive model. The viscoelastic equation was integrated into a partial differential equation containing transient， convection and source terms， and the discretization method of the viscoelastic equation was proposed on the basis of the finite volume method. Taking a reference from the discrete elastic viscous stress splitting （DEVSS） in the finite element framework， a discrete splitting algorithm （FVM⁃DEVSS） based on the finite volume method was proposed， and a computational procedure for three⁃dimensional viscoelastic flow was developed. The validity of this algorithm was verified using the classically fully developed shrinkage flow at a shrinkage ratio of 4∶1. Then， the melt flow front， gate pressure and fusion line position were correctly predicted through combing with the mold filling flow experiments. The photoelastic experimental results proved the validity of the method again in the present study. The results indicated that the developed viscoelastic algorithm could effectively express the effect of melt viscosity and elasticity on the flow pressure and accurately predict the position of a fusion line and the formation process when two melt fonts met together. In addition， the flow⁃induced stress during the melt filling process could be calculated effectively and accurately through the developed viscoelastic algorithm.
Additive
ZHANG Cihai, LIU Song, ZHOU Dongqing, CHEN Yu, ZHANG Tingting, ZHONG Liu, LIU Zhiguo
Abstract (
693 )
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This article provides a comprehensive review on the synthesis and applications of 9，10⁃dihydro⁃9⁃oxa⁃10⁃phosphorophenanthrene⁃10⁃oxide （DOPO）⁃based reactive flame retardants based on phenolic， acrylic ester， amine， benzyl alcohol， fatty alcohol， epoxy compound， acid， and other compounds.
Plastic and Environment
CUI Chengzhi, CAO Jinxing, LIU Jianlan, ZHANG Hui
Abstract (
456 )
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This article reviewed the research progress in the interface， functionalization， and shape memory modification of poly（lactic acid）/thermoplastic polyurethane blends and prospected the future direction in the research and development of the blends.
ZHANG Shibo, YANG Yang, YAN Yong, FU Pengfei
Abstract (
285 )
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In this study， the effect of a catalyst DZ composed of a proportional mixture of 2，2'⁃dibenzoylaminodiphenyl disulfide （DBD） and zinc oxide （ZNO） on the desulfurization temperature of gum powders was investigated by using naphthenic oil as a desulfurization solvent. Based on this， the solubility of recycled gum in a trichloroethylene solution was taken as a core index， and the effects of catalyst admixture， desulfurization time， and gum⁃oil ratio were further evaluated to determine the optimal process parameters for the preparation of low⁃temperature desulfurization rubber powders. The mechanism and microscopic morphology of low⁃temperature desulfurization of the gum powder were investigated by using scanning electron microscopy and Fourier⁃transform infrared spectroscopy. The results indicated that the catalyst DZ has a positive effect on the desulfurization of rubber powders， and the recycled rubber treated by low⁃temperature desulfurization exhibited reduced roughness alone with a more obvious ‘groove’ structure on the surface. This is advantageous to the engineering applications. The solubility of recycled rubber reached 76.9 % when the desulfurization temperature of rubber powders was lower than 160 ℃， which was close to the solubility of recycled rubber prepared by a traditional dynamic desulfurization method. This indicated that there was almost no adverse effect on the solubility of rubber powders by lowering temperature. The preparation parameters of low⁃temperature desulfurization rubber powders were determined to be a rubber powder/naphthenic oil mass ratio of 4/6， a catalyst DZ⁃doping amount of 3 wt%， a stirring rate of 450 rpm， a desulfurization time of 2 h， and a desulfurization temperature of 160 ℃.
ZHOU Lei, ZHANG Lihua, CHEN Gingming, MAO Xu, CHEN Shuguang, QIU Jiancheng
Abstract (
343 )
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This paper focused on the irregular and wavy⁃like wrinkle problems in the surface of the sheets extruded by using a degradable plastic extrusion head. The extrusion process of a degradable plastic sheet was simulated by means of Polyflow， and the distribution of speed， pressure and shear rate in the extrusion process were calculated and analyzed. The flow channel structure of the extrusion head was optimized according to the numerical simulation results and compared with the original organic head flow channel. The results indicated that the optimized head flow channel not only improved the melt flow velocity but also enhanced the melt flow performance of the inlet. The pressure drop of the forming section in the runner was improved， resulting in an improvement in the mold filling speed and melt flow rate. The shear rate of the extrusion head was improved. This was advantageous to the uniform mixing of materials in a runner. As a result， the problems in irregularity and surface wrinkle of the sheets were solved.
Machinery and Mould
QIN Sen, HE Hezhi, ZHANG Tao, HUANG Zhaoxia, QU Jinping
Abstract (
324 )
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According to the volume pulsation injection⁃molding technology and equipment， the effects of pulsation force field on the flowability， cavity pressure response， and microstructure of polymeric materials were analyzed by means of the experimental data. The strengthening effects of pulsation force field on injection and packing processes were clarified. The self⁃toughening and self⁃reinforcement of immiscible polymer blending systems under a pulsation force field were revealed. The advantages and potential applications of the pulsation force field in optimizing the injection⁃molding process and improving the service performance of injection⁃molded products were clarified through introducing the research progress in the volume pulsation injection⁃molding technology.
YE Weiwen, CHEN Zhensen, JIANG Bingchun, WU Guangming
Abstract (
353 )
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According to the design characteristics and production requirements of the mold for an oblique orifice air chamber in the automotive heat exchange system. A more detailed molding process scheme was proposed for the PA66/30 %GF plastic parts， which included the characteristic process analysis of plastic parts， structural design， working principle， and product pre⁃variation technology. The core technologies for the three⁃time slider mechanism of the inclined orifice air chamber mold and product pre⁃variation were intensively studied， and the structural design and application investigation of the molding process for the plastic parts were conducted. Through verifying the preform of the orifice chamber repeatedly， the optimal mathematical model of the orifice chamber was designed， and an orifice chamber mold was developed to directly meet the requirement of production assembly. The research results indicated that the developed mold was more compact with fewer molding defects， which improved productivity and stable operation significantly through three slider designs. Owing to the use of an open mold design solution for the PA66/30 %GF parts， the product was converted from a metal part to a plastic part. This significantly reduced the material costs and obtained a lightweight design for automotive parts. As a result， the overall weight of the vehicle was reduced and the fuel economy was improved.
Review
LI Dan, ZHAO Biao, CHEN Ke, WANG Fan, ZHANG Jingyu, ZHANG Fengbo, PAN Kai
Abstract (
458 )
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This review paper mainly summarized the preparation process and modification methods of hollow polypropylene fibers， and their development direction in future was prospected.
WANG Yuwei, XIAO Runxiang, ZHANG Hongkai, GUAN Wenjin, DENG Yafeng
Abstract (
475 )
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This paper analyzed the source of microparticle pollutants in the air and the harm to human body and introduced the air filter material filtration mechanism. The different structures of nanofiber⁃based air filtration materials， electrospinning preparation process， and other preparation processes were summarized， and their applications were introduced. Finally， the research direction of air filtration technology in the future was presented.
XIANG Lixue, TANG Bo, ZHOU Gang, DAI Xumin, WANG Erke, JIANG Tao, WU Xinfeng
Abstract (
417 )
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The development process of 3D printing technology in the preparation of thermally conductive composites was analyzed， and the different types of highly thermally conductive composites prepared by the 3D printing technology were introduced， which included the carbon fiber type， graphene type， carbon nanotube type， boron nitride type， and aluminum nitride type， etc. The different types of forming process were outlined， and their thermal conductivity properties were summarized and concluded. Finally， the summary and outlook on the preparation of thermally conductive compo⁃sites by the 3D printing technology were presented.
