Materials and Properties
WAN Bangwei, YANG Yang
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156 )
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In this study， a novel type of methyl vinyl silicone rubber （VMQ）/multi⁃walled carbon nanotubes （MWCNT） composites were prepared by using an open⁃mill method， and the effects of MWCNT content on the dispersion， electrical conductivity and resistance⁃strain response of the composites were studied. The results indicated that MWCNT could be uniformly dispersed in VMQ at a certain amount to form a three⁃dimensional tunneling conductive network. This ensures the composites obtained a low percolation threshold of 2.51 wt%， a large sensing range higher than 200 %， and a high sensitivity with a gauge factor higher than 2 546.16）. The composites also present a stable resistance response signal in the process of multiple cycles， especially showing an excellent resistance signal stability without any shoulder peaks during 4 000 cycles. Through the theoretical model analysis of tunnel effect， the resistance⁃strain response mechanism was discussed. The composites exhibit the potential of real⁃time strain monitoring for large deformation isolation bearings.
TAN Jing, WANG Zhi, WANG Shuo, FU Hongyan, LI Changjin, LI Haoyi, YANG Weimin, ZHANG Yang
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110 )
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Poly（lactic acid） （PLA） was modified through melt blending with dendritic polymer CYD⁃T151 as a plasticizer. The effects of CYD⁃T151 content， spinning temperature and spinning voltage on the mean diameter， diameter distribution and tensile mechanical properties of PLA/CYD⁃T151 fibers in melt differential electrospinning were investigated. The results indicated that the addition of dendritic polymer CYD⁃T151 effectively improved the melt fluidity and reduced the fiber fineness. When the content of CYD⁃T151 was 1.25 %， the spinning temperature was 240 ℃， and the spinning voltage was 55 kV， the melt electrospinning fiber exhibited an average fiber diameter of 1.360 μm， which was 49.72 % lower than that of pure PLA. Dendritic polymer CYD⁃T151 as a plasticizer could effectively improve the toughness of the PLA⁃based melt electrospinning fiber membrane. When the content of CYD⁃T151 was 1.25 %， the spinning temperature was 240 ℃， and the spinning voltage was 55 kV. The PLA/CYD⁃T151 fiber membrane obtained tensile strength and elongation at break of 11.50 MPa and 92.33 %， respectively， which were 4.07 % and 13.99 % higher than that of pure PLA.
RUAN Fangtao, WU Hao, ZHU Jinwei, SU Yongsheng, CHEN Zhuolin, WANG Guofeng, WANG Hongjie
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91 )
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In this paper， tetraethyl orthosilicate （TEOS） and ammonia were used to prepare a solution gel to modify the surface of straw fibers （SF）. The changes in chemical composition， surface morphology and hydrophobicity of SF before and after the modification were investigated. Long⁃SF⁃reinforced polypropylene （PP） composites were prepared through hot pressing， and the mechanical strength of PP/SF composites before and after the solution gel modification of long SF were compared. The PP/SF composites were designed and prepared with five different straw orientations of 0 °， 15 °， 30 °， 45 ° and 90 °， and the effects of orientation angle on the mechanical strength of the composites were investigated. The experimental results indicated that the SiO2 particles deposited on the surface of the TEOS⁃treated SF could help to improve the hydrophobicity and roughness of the fiber surface， thus enhancing the infiltration and compatibility between SF and PP. Compared to PP composite with untreated SF， the tensile， flexural， and impact strengths of the composites with TEOS⁃treated SF were improved by 20.3 %， 11 %， and 35.7 %， respectively. The orientation angle of the fibers has a great influence on the mechanical strength of PP/SF composites. The smaller the angle between the orientation direction of SF and the direction of the applied stress， the more can the SF exert their reinforcing effect， and the higher are the tensile， flexural and impact strengths.
CHEN Qingjiang, DONG Zhicong, LI Hongfa, WU Yijiang, GAO Song, NIE Wenxiang, LUO Yingwen
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93 )
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To improve the insulation performance of crosslinked polyethylene （PE⁃XL）， MgO⁃NH2/PE⁃XL nanocomposites were prepared by using polyethylene （PE） as a matrix and modified MgO （MgO⁃NH2） as a filler. The electrical insulation performance of the nanocomposites before and after thermal aging was investigated. The obtained results were compared with the unmodified MgO⁃crosslinked polyethylene composites （PE⁃XL/MgO）. The insulation properties of the nanocomposites were studied by DC breakdown strength， space charge， and DC conductivity. Compared to the non⁃aged PE⁃XL/MgO， the non⁃aged PE⁃XL/MgO⁃NH2 nanocomposites showed an increase in DC breakdown strength by 20 %， and the heterogeneous space charge accumulation could be negligible. After thermal aging， the breakdown strength of MgO /PE⁃XL and PE⁃XL/MgO⁃NH2 nanocomposites decreased by 38 % and 20 %， respectively， compared to those before thermal aging. In addition， the PE⁃XL/MgO⁃NH2 nanocomposites obtained from the surface modification of MgO have a lower DC conductivity than PE⁃XL/MgO. The PE⁃XL/MgO⁃NH2 nanocomposites exhibited better performance under non⁃aging conditions， and they also showed stronger inhibition to the deterioration caused by thermal aging.
ZHAO Chuantao, JIA Zhixin, LIU Lijun, LI Jiqiang, ZHANG Chenchen, RONG Di, GAO Lizhen, WANG Shaofeng
Abstract (
95 )
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The influence of molding process parameters on the mechanical properties of carbon fiber/epoxy sheet⁃molded products was studied through orthogonal experiments， and the influence trend of various process parameters on their tensile strength and flexural strength was analyzed. The influence of process parameters on the tensile strength was obtained by variance analysis in an increasing order of ： clamping speed > molding temperature > molding pressure > holding time， and the influence of process parameters on bending strength was obtained in an increasing order of： clamping speed > molding pressure > molding temperature>holding time. Moreover， the significance factors affecting the tensile strength and flexural strength were also obtained. The tensile failure mode and failure mechanism were studied， and the typical samples were selected for observation using the K⁃mean method. The results indicated that the bonding degree between the matrix and epoxy resin affected the tensile strength of the molding products.
DUAN Shuqian, LIU Shuya, LIU Jianghui, CHENG Xiaoqiong, MENG Dan, ZHANG Xianqun, CHEN Xiao, FU Hai
Abstract (
58 )
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In the preparation of polymer antistatic composites using conductive fillers， the addition amount of a conductive filler directly determines the conductivity of the resulting composites； however， the microscopic morphology of the conductive filler inventively affects the efficacy of the conductive channel. Polypyrrole （PPy） materials with different network structural features were prepared by using a soft template， and the PPy/polyurethane （PU） composites were prepared through solution blending. The effect of structural difference in PPy on the electrical conductivity of the composites was investigated. The electrical conductivity of PPy/PU composites at a PPY addition amount of 1 wt%~3 wt% was analyzed by using networked PPy materials with a line diameter in the ranges of 20~35 nm and 30~50 nm， and their electrical conductivities reached were an order of 10-7 S/m compaed to the PPy particles. The composites all showed a decrease in electrical conductivity under 100 %~500 % deformation. However， the electrical conductivity of the networked PPy/PU composites only decreased by one order of magnitude， and the electrical conductivies of the composites containing 1 wt% and 3 wt% PPy particles were identical. The results indicated that the native network of the networked conductive filler could maintain the integrity of conductive channels in the composites under deformation of the composites. This allows the materials to maintain a high conductivity under deformation.
LIU Gang, JIANG Xiong, LANG Tao, WANG Yi, ZHANG Lu, HU Songchao, CHANG Yijun, ZHANG Qilu
Abstract (
77 )
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In this study， the hydrolysis behavior of four types of polymer coatings， including three polyurethanes and one epoxy resin were evaluated with the assistance of Fourier⁃transform infrared spectroscopy， solid⁃state nuclear magnetic resonance， thermogravimetric analysis， and dynamic mechanical analysis. The results demonstrated that the polyether⁃based polyurethane coating exhibited superior water resistance and minimal impact on its chemical structure due to hydrolysis. However， the incorporation of ceramic particles can significantly accelerate the hydrolysis， resulting in an increase in water absorption and a decrease in coating performance. Both polyester⁃based polyurethane and epoxy resin coatings exhibited poor water resistance under the same conditions， and a chemical degradation might occur， resulting in an increase in storage modulus.
QI Shijie, YOU Xiangyu, WANG Ruichen, ZHOU Linfei, ZHANG Huijie
Abstract (
87 )
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The escalating severity of environmental issues stemming from the poor degradability of conventional polymer materials has received an increasing concern. Biodegradable polymers such as poly（lactic acid） （PLA）， have garnered considerable attention. However， their extensive utilization is hindered by the high cost associated with their use. To address this issue， the present study focuses on the development of PLA/lignin blends using glycidyl methacrylate （GMA） as a compatibilizer. The epoxy groups on the GMA molecule could react with the hydroxyl groups of lignin and two end groups of the PLA molecule， thus enhancing the interfacial compatibility between lignin and PLA. The effect of lignin and GMA contents on the performance of PLA was determined through analyzing the encompassing microscopic morphology， mechanical properties， thermal behavior， and rheological characteristics of the PLA/lignin blends. The results indicated that GMA effectively enhanced the interfacial compatibility between lignin and PLA， consequently improving the mechanical properties of the blends. The blend containing 30 wt% lignin exhibited tensile strength of 42 MPa， a tensile modulus of 1 750 MPa， flexural strength of 60 MPa， flexural modulus of 3 460 MPa， impact strength of 26.2 J/m， and elongation at break of 2.4 %. Notably， when the lignin content increased to 60 wt%， the PLA/lignin blends exhibited better performance. This approach retained the biodegradable characteristics of PLA but reduced its cost significantly.
JIA Meng, XU Zhun, WEI Simiao, ZHANG Qinglei, XU Bo
Abstract (
132 )
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This paper reviewed the research progress in the flame⁃retardant foam materials for construction over the past five years， focusing on polyurethane foam materials， phenolic foam materials， and aerogel materials. Their flame⁃retardant mechanism was also analyzed. This paper finally pointed out that the realization of environmentally friendly flame⁃retardant foam materials was the development direction in future.
XU Zhiyang, ZHU Jun
Abstract (
170 )
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2，5⁃Furanedicarboxylic acid （FDCA） is an important monomer that can be used to synthesize bio⁃based polyesters， and it currently has broad application prospects in the field of new biodegradable plastics. How to efficiently and cheaply prepare FDCA has gradually become a hot topic. This article systematically reviewed the main research progress in the synthesis of FDCA through the 5⁃hydroxymethylfurfural （HMF） route in recent years. The connection and difference between the HMF route and other routes were introduced， and the advantages of the HMF route were explained. The methods for synthesizing FDCA using HMF were introduced and analyzed in detail， including direct oxidation method， precious metal catalysis method， transition metal catalysis method， photoelectric catalytic oxidation method， enzyme catalysis method， and whole cell biocatalysis method. In addition， based on the above⁃mentioned methods， the advantages and disadvantages of these methods were explained， and the challenges existing in the preparation of FDCA through the HMF route were discussed， including the selection， improvement and development of catalysts， optimization of reaction conditions， and treatment of intermediate products. The future prospects in the preparation of FDCA through the HMF route were also discussed.
Processing and Application
MA Xiuqing, LAO Zhichao, LI Mingqian, HAN Shuntao, HU Nan
Abstract (
89 )
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Poly（lactic acid） （PLA）/ethylene⁃butyl acrylate⁃methacrylic acid glycerin ester copolymer （PTW） blends were prepared by 3D print through a fused deposition modeling （FDM） process， and the effect of 3D printing process parameters， including nozzle temperature， printing platform temperature， and printing speed， on the mechanical properties of the PLA/PTW blends were investigated through a single⁃factor experiment. Based on this experiment， a 3⁃factor， 3⁃level orthogonal experiment was designed to optimize the 3D⁃printing process parameters. The results indicated that the impact strength and tensile strength of the blends exhibited an increasing trend at first and then tended to decrease with an increase in the nozzle temperature， and both of them increased with an increase in the printing platform temperature but decreased with an increase in the printing speed. The influence of various process parameters on the comprehensive mechanical properties of the PLA/PTW blends was in a descending order of nozzle temperature > printing speed > printing platform temperature. The printed PLA/PTW product exhibited optimal comprehensive mechanical properties at a nozzle temperature of 210 ， a printing platform temperature of 80 ， and a printing speed of 40 mm/s.
WU Zhifeng, JIANG Ruitao, DING Yongyue, PAN Xinfei, WANG Zhiwei
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77 )
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This article focused on evaluation of the aging rate of the steel⁃plastic⁃transition coating during the use. The methods employed for this evaluation include outdoor exposure and indoor ultraviolet accelerated aging tests on the fusion⁃bonded epoxy （FBE） coating and three⁃layers polyethylene coating （3PE） of the steel⁃plastic⁃transition. The tests were carried out in terms of encompass color difference， microscopic morphology， the adhesion strength for the FBE coating， and the tensile strength， elongation at break， and microscopic morphology for the 3PE substrate. The results indicated that the indoor ultraviolet aging was more effective than outdoor exposure aging for the FBE coating. The acceleration factor based on color difference testing was approximately 8.6~12.8 times， while the acceleration factor based on the holes and cracks formation tests for the coating was between 10.3 and 12.8 times. Regarding the 3PE substrate， the acceleration factor based on elongation at break was about 8.6 times， and the correlation between the acceleration factor and tensile strength was not significant.
Additive
LI Xianming, ZHANG Ning, LI Gaihua, LIU Shuang, LIU Zhengyuan
Abstract (
63 )
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Sodium dodecyl sulfate （SDS） was used to modify magnesium⁃aluminum⁃lanthanum carbonate hydrotalcite （LDHs）， and the effect of different modification conditions on the static thermal stability of poly（vinyl⁃chloride） （PVC） was investigated.The molecular structures of modified PVC samples were characterized by using X⁃ray diffractometry， scanning electron microscopy， and infrared spectroscopy. The thermal stabilities of the PVC samples with modified and unmodified LDHs were evaluated by means of Congo red test paper method， thermal aging oven method， torque rheometer， and thermogravimetric analysis. The results indicated the modification effect was best at a constant pH value of 7 and a mass ratio of SDS to LDHs of 1/10 in a water bath at 80 ℃ for 3 h. SDS did not change the crystal structure of hydrotalcite but was only adsorbed on the surface of LDHs， which enhanced its compatibility with PVC. The static and dynamic thermal stability times of the PVC/LDHs samples using the LDHs modified SDS for 65 and 28.5 min， respectively. Meanwhile， the later coloring of PVC samples was improved to make plasticize and form more easily. The temperature corresponding to the maximum weight loss rate of the modified PVC sample was 346 ℃， which increased by 55 ℃ compared to pure PVC. This could effectively inhibit the thermal degradation of PVC.
Plastic and Environment
TONG Yaxuan, GAO Hainan, CHEN Liping, WENG Yunxuan
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98 )
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This paper introduced the main methods of bio⁃based aerogels in flame retardant and hydrophobic properties as well as other functionalization modification and also reviewed the progress of the application of modified bio⁃based aerogel in the fields of flame retardancy， environmental remediation， energy storage， and biomedicine. Finally， the scientific and technological problems in the process of the development of bio⁃based aerogels and the development prospect of the functionalized bio⁃based aerogels were analyzed.
Review
ZHANG Xiaojuan, YANG Kexin, GUO Jiaqian, LEI Yang, FANG Changqing
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52 )
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Based on a brief introduction to the gas permeability mechanism of modified atmosphere packaging membrane and the fundamental properties of modified poly（ether ether ketone） （PEEK）， this paper provided a detailed review for the physical and chemical modification strategies and their mechanisms that can be used to improve the thermodynamic stability， gas permeability and antibacterial performance of PEEK⁃based modified atmosphere packaging membrane. The future research direction of modified PEEK in the field of modified atmosphere packaging membrane was prospected， and the possible problems and challenges were proposed.
KONG Zimeng, ZHANG Jian, DENG Yaxin, XU Xueling, CHEN Yajun
Abstract (
93 )
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This article reviewed the research progress in flame⁃retardant polybutylene succinate （PBS） and its flame⁃retardant mechanism in recent years. The commonly used flame retardants for PBS resin include phosphorus⁃nitrogen based flame retardants， nano flame retardants， biobased flame retardants， and their compound systems. Among them， phosphorus⁃nitrogen⁃based flame retardants have the most development and modification schemes. Especially， the flame⁃retardant system based on ammonium polyphosphate （APP） currently is the most studied and effective system， including the composite system of APP and nano flame retardants and the composite system of APP and bio⁃based flame retardants. Meanwhile， the article summarized the flame⁃retardant performance and typical flame⁃retardant mechanisms of various flame⁃retardant systems.
WANG Dong
Abstract (
68 )
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This paper introduced the applications of metal⁃organic frameworks and their derivatives in the fire⁃retardant polymer field in recent years. The design of metal⁃organic framework flame retardants and their effects on the fire⁃retardant properties of epoxy resins， polystyrene， polyurethane and other materials were highlighted. The possible flame⁃retardant mechanisms of metal⁃organic framework flame retardants were discussed， and their development direction in future was prospected.
