Materials and Properties
YU Shikang, CHEN Ke, XUE Ping, JIA Mingyin, CAI Jianchen
Abstract (
559 )
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A type of high⁃strength， high⁃modulus， and lightweight polypropylene （PP）/CaCO3 composites was prepared using a die drawing method， and the effect of die drawing on the microstructure， crystalline structure， thermal properties， and density of the composites were analyzed. Their structural evolution and corresponding mechanism during the die drawing process were studied. XRD and DSC characterization results indicated that there was a transformation from the original spherulites to fibrous crystals for the composites， and meanwhile a grain refinement took place in the die drawing process. There was a phenomenon of stress⁃induced crystallization occurring due to an increase in crystallinity. Moreover， a significant increase in the size of micro⁃voids and a remarkable decrease in density mainly occurred in the free⁃stretching process after the composites were separated from the converging flow channel wall.
YANG Jin, CHEN Pengran, GAO Peixin
Abstract (
1147 )
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605
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10 )
A type of lightweight and high⁃strength epoxy resin foams was prepared through the foaming process at normal temperature using E⁃44 epoxy resin as a matrix， polymethylsiloxane （PHMS） as a foaming agent， and N⁃N⁃ethyl piperazine as a curing agent. The effects of formula components and foaming methods on the foaming behavior and compressive properties of the epoxy resin foams were studied. The results indicated that the PMHS content influenced the foaming behavior of the foams significantly， and therefore， there was a requirement for controlling its content strictly. The foams showed a remarkable increase in cell diameter but a decrease in cell density with the addition of 3 % PMHS， leading to the deterioration of cell structure. Moreover， the incorporation of nano silica， beet （CAB⁃35）， and poly（siloxane⁃co⁃oxyolefin） copolymer （DH212） also influenced the cellular structure and mechanical strength of the foams greatly.
ZHOU Yang, ZHAO Shikun, ZHAO Biao, LIU Huipeng, LI Jie, CAO Zhiwen, PAN Kai
Abstract (
770 )
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1164
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A semi⁃aromatic polyamide 6T/6I/6 （PA6T/6I/6） was synthesized using a two⁃step method through salt forming and high⁃temperature solution polycondensation. Its nonisothermal crystallization kinetics was investigated by differential scanning calorimetry （DSC）， and its nonisothermal crystallization behaviors of PA6T/6I/6 was studied using the Jeziorny′s method， the Oazawa′s method， and Avrami′s equation modified by the Mo′s method. The results indicated that there were two stages in the crystallization process of PA6T/6I/6， including primary crystallization and secondary crystallization. In the primary crystallization stage， the Avrami index varies from 1.08 to 1.09， resulting in the formation of crystals through heterogeneous nucleation and growth in a one⁃dimensional needle shape. In the secondary crystallization stage， the Avrami index was in the range of 2.13~2.21， leading to the two⁃dimensional sheet growth of crystals. The Ozawa′s method is not suitable for describing the nonisothermal crystallization process of PA6T/6I/6. The modified Avrami′s equation can describe the crystallization process better， with a value of （a） between 0.89 and 0.90 and a value of F（T） between 7.24 and 15.85. The activation energy for the nonisothermal crystallization of PA6T/6I/6 was calculated to be 294.17 kJ/mol using the Kissinger′s equation.
FU Yunzhao, ZHANG Qi, XIA Lidong, GAO Dali, ZHANG Shijun
Abstract (
916 )
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This paper reviewed the research progress in toughening modification for the carbon⁃fiber⁃reinforced thermoplastic composites and summarized the toughening methods such as the blending of toughening agent， co⁃toughening of multi⁃reinforcement， physical and chemical modification for the surface of carbon fiber， and processing and molding process control.
HU Yutao, WANG Lei, MA Ke, SONG Hongqin, WANG Li, LIU Qing, WAN Caixia, MENG Lingpu
Abstract (
581 )
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716
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The biaxially stretched wet separators were prepared at different stretching temperatures through systematically changing the stretching temperature in the longitudinal and transverse directions， and their internal pore appearance， pore structure， and air permeability were characterized using scanning electron microscope， the Gurley′s instrument， and pore size analyzer. In addition， differential scanning calorimetry was used to analyze the crystallinity of the micro⁃crystals inside the wet separators. The results indicated that there was no effect from the change of the longitudinal stretching temperature on the pore size of the wet separators. The pore size of the wet separators was only closely related to the transverse stretching temperature. As the transverse stretching temperature increased from 90 to 120 ºC， the pore size increased from 18.3 to 45.4 nm. Owing to a change in pore size， the air permeability of the wet separators decreased from 149.8 to 62.2 s， both of which exhibited a good linear relationship. When the transverse stretching temperature was 120 ºC， the melting and re⁃crystallization occurred inside of the wet separators， resulting in an increasing in the degree of crystallinity from 17 % to 20 %. Meanwhile， the interior of the separators showed a three⁃dimensional network structure comprising the shish⁃kebab crystals.
WANG Zhiping, CHEN Hao, LU Pengcheng
Abstract (
421 )
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In this paper， the damage mechanism of carbon⁃fiber⁃reinforced polymeric composites with an aviation structure was studied under the electro⁃wet coupling multiple fields. The electro⁃wet coupling environment⁃test platform was used to perform an electro⁃wet coupling treatment for the composites. The surface temperature of the composite samples was monitored in real time， and the evolution rule of the surface temperature with current intensity and electrification time was obtained. Moreover， a change in weightlessness rate under different current intensity was also obtained for the composite samples. The bending properties of the composite samples treated with different environmental conditions were measured， and their fracture morphology and surface morphology were observed and analyzed. The results indicated that the higher the energization current intensity， the higher is the stable surface temperature of the composite samples. The surface stable temperature of the composite samples increased with an increase in energization time at the same current value， and the moisture absorption tended to be greater than the dehumidification. After the 10 A electric⁃wet coupling treatment for 96 h， the composite samples reached the equilibrium of moisture absorption and dehumidification， and the samples after 12 A and 15 A electric⁃wet coupling treatment presented different mass losses. After the electro⁃wet coupling treatment at different current intensities， the sample interface was damaged to a certain extent. This makes the bending strength decrease， and the decrease range is positively correlated with the current intensity.
ZHAI Qianchao, LIU Guangyuan, WANG Fengwu, WANG Yihui, ZHANG Zhongjie, ZHENG Debao, CHEN Xiangying
Abstract (
604 )
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In this work， maleic anhydride （MAH） was first grafted onto polyethylene wax （PEW） using xylene （PX） as a solvent， benzoyl peroxide （BPO） as an initiator， resulting in the formation of a PEW⁃g⁃MAH grafting copolymer. The resultant grafting copolymer then slowly added to acetone to perform precipitation with acetone as a precipitant. The PEW⁃g⁃MAH micropowders were obtained from the above mixture through suction filtration， drying， grinding， and screening. The structure of the obtained product was characterized by Fourier⁃transform infrared spectroscopy and laser diffraction particle⁃size analyzer， and its adhesion was measured using an adhesion tester. The optimum reaction conditions were explored through investigating single factor and orthogonal design experiments. The results indicated that the optimal reaction parameters were determined to be a PEW amount of 10 g， an MAH amount of 0.6 g， a reaction temperature of 110 °C， an initiator amount of 0.2 g， and a reaction time of 4 h. Under this condition， MAH achieve the highest grafting efficiency of 58.57 % together with a grafting rate of 3.51 %， an average particle size of 15.54 µm， and adhesion of grade 0. The PEW⁃g⁃MAH micropowders exhibit great potential for the application in powder coatings.
ZHANG Wenlong, ZHANG Lin, CHEN Yu
Abstract (
464 )
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896
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The effects of ethylene⁃octene copolymer grafted acrylonitrile （POE⁃g⁃AN） oil⁃resistant compatibilizer on oil resistance， mechanical properties and electrical properties of EVA/PE⁃LLD cable materials were studied. The results showed that with the increase of the amount of POE⁃g⁃AN， the tensile strength， oil resistance and electrical properties of the material all showed a trend of increasing or decreasing first， while the elongation at break increased continuously. When the amount of the graft was 6 wt%， The interphase compatibility improvement effect is the best. At this time， the oil resistance of the modified cable material：the absolute value of the tensile strength， the absolute value of elongation at break， the absolute value of mass and volume change rate is the smallest， which are 35.7 %， 34.6 %， 15.69 %，15.35 %，and the tensile strength increased by 8.5 % to 13.02 MPa， and the elongation at break was 274.15 %； the maximum DC breakdown field strength was 199 kV/mm， and the maximum volume resistivity was 7.84×1012 Ω·m.
DONG Jingwei, YAN Haiyan, WANG Yi, ZHANG Bo, CHEN Shujuan, LI Minhao, ZHANG Yue
Abstract (
409 )
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501
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In this paper， a polyaniline （PANI） crystalline film was prepared using an interface template method， and then a PANI⁃film⁃based gas sensor was prepared using monocrystalline silicon as a substrate. The structure and properties of the resulting product were analyzed using FTIR， Raman， XRD， TEM， and a CGS⁃1TP gas sensing detection and analysis system. The effect of interface template inducement on the structure and gas sensing properties of PANI film were studied. The results indicated that the amphiphilic template induced PANI to polymerize at the gas⁃liquid interface and assemble onto the film. The crystallinity of PANI film was related to the reaction time， and its crystalline characteristics were evident when prepared at a reaction time ranging from 24 to 48 h. The film exhibited a value of gas response to 25 ppm NH3 between 15 and 60. The average response and recovery time were 36 s and 51 s respectively. The film showed rapid response recovery characteristics and excellent stability.
HUANG Jianwei
Abstract (
517 )
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351
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In order to explore the influence of curing temperature on the curing time and strength of an adhesive，the adhesive was cured at curing temperatures of 25， 45， 65， and 85 ℃. The curing rates of three types of adhesives at different curing temperatures were investigated through the Shore hardness test， and their tensile shear strength， flexural strength， and compressive strength of at different curing temperatures were measured. The results indicated that the higher the curing temperature， the shorter is the curing time. Taking 25 ℃ as a benchmark， the curing time at 45 ℃ was shortened by about 50 %. At a curing temperature at above 45 ℃，the curing time was shortened by about 10 % with an increase in temperature by every 20 ℃. In view of the strength at 25 ℃， the adhesives showed a change rate of tensile shear strength within 6 % under different curing temperatures. Their increase rates in flexural strength and compressive strength were distributed in the ranges of 6 %~45 % and 9 %~50 %， respectively.
Processing and Application
QIAO Shize, GUO Menghao, HE Yadong, XIN Chunling
Abstract (
582 )
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535
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In this paper， supercritical CO2 was used as a foaming agent to investigate its dissolution and diffusivity in PPO/PS blends through a weight decay method. The effects of process parameter and PPO/PS composition on the solubility and diffusion coefficient of CO2 were systematically studied under static conditions. The quantitative relationship between the temperature， pressure， and PPO content and the CO2 solubility was established. The results indicated that the solubility of CO2 in PPO/PS blends increased with an increase in the PPO content and pressure but a decrease in temperature. The diffusion coefficient decreased with an increase in the PPO content but increased with an increase in temperature and saturation pressure.
WANG Xing, JIA Zhixin, LIU Lijun, LI Jiqiang, ZHANG Chenchen, WANG Shaofeng
Abstract (
583 )
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1218
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4 )
To explore the effect of compression molding parameters on the comprehensive mechanical properties of sheet molding compound （SMC）⁃molded products. Dividing the compression molding process into three stages and taking the pressure and time of the three stages as totally six parameters for the influencing factors， the tensile strength， bending strength and impact strength of the products were characterized. Then， an orthogonal experiment was designed by taking the mechanical properties of the products as evaluation indicators. A range analysis method was used to analyze and discuss the effect of each process parameter of each stage on the mechanical properties of the SMC composite products. The reasons for the experimental results were analyzed by a combination of the change of material state during the molding process. Finally， the optimized process parameters were obtained.
WANG Zhigang, YANG Bo, ZENG Chen, LI Zhi, DENG Jianyi
Abstract (
578 )
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668
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The polyethylene gas pipe samples were aged in a water bath at 80 ºC and 1.1 MPa for 0， 165， 500， and 1 000 h. The isothermal oxidation induction time （OIT）， thermal decomposition temperature （Ts）， functional group composition， and elongation at break （ε） of each aged specimens were investigated using DSC， TG， FTIR， and tensile measurement. The change rule in the aging performance law of polyethylene gas pipes was analyzed under high temperature and inner pressure environment. The results indicated that the polyethylene gas pipes presented a gradual decrease in isothermal OIT， Ts， and ε with an increase in aging degree. The aging rate of the inner wall was significantly higher than that of the outer wall. FTIR analysis results indicated that there were two characteristic absorption peaks at 1 720 cm-1 and 3 400 cm-1 corresponding to C=O and O—H vibration， respectively， in the functional group diagram of polyethylene pipe material with an increase in aging time. This further confirmed the introduction of oxidation reaction products into the molecular chain of polyethylene pipes.
ZHANG Xuemin, HUANG Haohan, LI Houbu, QI Guoquan, ZHAO Yuanchao, DING Han, GAO Xiong, YANG Wenhui
Abstract (
644 )
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Based on the finite element method， a three⁃dimensional finite element model was established for the assembly of polyester fiber reinforced plastic composite pipe and its metal clamping joint， and the influence of clamping amount and joint structural parameters on the joint sealing performance was analyzed. The results indicated that the sealing performance of the joint was improved with an increase in the clamping amount. However， the plastic deformation occurred in the tube under a large clamping amount， leading to a decrease in sealing performance. As the serrated angle increased， the sealing performance of the joint increased at first and then tended to decrease. The tube suffered plastic deformation at an angle greater than 55 °. The higher the sawtooth height， the better was the sealing performance of the joint. When the sawtooth height increased up to 3 mm， the stress value at the end of the core tube reached the strength at break. It is not recommended to set too many serrated teeth in the joint. When the number of teeth reaches 14， the tube body was severely squeezed at the end of the joint. Considering of the sealing performance and joint strength， the optimum clamping quantity was determined to be 5.5 mm， and the optimum structural parameters were determined to be a serrated angle of 50 °， a tooth height of 2.5 mm， and a serrated number of 11.
WU Kun, FAN Yaqin, SHEN Qian, MIAO Zhuang, ZHOU Cheng
Abstract (
897 )
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In this study， a high⁃temperature accelerated aging test was conducted for the polytetrafluoroethylene （PTFE） material used in nuclear power station at temperatures of 315， 300， and 285 ºC. The microstructure and thermal properties of the PTFE material were characterized using Fourier⁃transform infrared spectroscopy， SEM， and thermogravimetric （TG） analyzer. Two aging life prediction models were established through thermal aging using a TG method. The results indicated that PTFE exhibited an evident red shift in its infrared frequency together with some obvious hole marks appearing on its surface， suggesting a deterioration in thermal stability and mechanical property with the aging time. The life prediction model demonstrated that the life prediction results obtained from the TG method thermal aging method were consistent， and the error decreased with an increased in service temperature. This indicated that the TG method was reliable to calculate the service life of the PTFE material and very suitable for the evaluation of the PTFE material as a simple and convenient life prediction method.
LI Zhaopu, WU Liwen, QIAO Liang, FAN Junming, ZHANG Yi
Abstract (
765 )
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In this review paper， the influencing factors of the hot⁃melt welded joints of polyethylene pipes were briefly described， and the research progress in the reliability testing methods of hot⁃melt joints at home and abroad was reviewed. The influence of welding parameters on the quality of the joint was summarized， and the failure mechanisms of the joint were analyzed. The change of welding parameters can significantly affect the performance of hot⁃melt joints， and the selection of optimal welding parameters can improve their reliability even across the whole piping system. The related research on the hot⁃melt joints was summarized from three aspects： mechanical properties， finite element simulation and nondestructive testing. It is expected that a comprehensive evaluation standard will be established for the mechanical properties of hot⁃melt welded joints in the future. This can reduce the experimental time and test cost. With the innovation of materials and the development of scientific and technological means， the finite element simulation and non⁃destructive testing technology are expected to replace mechanical experiments， and it will become the main method for reliability testing of hot⁃melt joints in the future.
Additive
YU Zhengfa, ZHAN Yue, CUI Yongyan
Abstract (
556 )
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878
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A flame retardant containing phosphorus， silicon and boron in its molecular structure （SiBP） was synthesized using 9，10⁃dihydro⁃9⁃oxa⁃10⁃phosphine⁃10⁃oxide， dimethoxymethyl vinyl siloxane， and boric acid as raw materials， and its chemical structure was characterized using Fourier⁃transform infrared spectroscopy and hydrogen nuclear magnetic resonance spectroscopy （1H⁃NMR）. The thermal stability of SiBP was also characterized by thermogravimetry （TG）. The SiBP exhibited an initial decomposition temperature of 110 ℃ in nitrogen atmosphere was， resulting in a residual char yield of up to 40 wt% at 800 ℃. A flame⁃retardant coating was prepared by using silicone acrylic lotion as a matrix， silicon powders as an inorganic filler， SiBP as a main flame retardant， and ammonium polyphosphate （APP） as a synergistic flame retardant together with dipentaerythritol （Di⁃PE） and melamine （MEL）. The fire⁃resistant performance was characterized and analyzed through limiting oxygen index （LOI）， UL 94 vertical combustion test， TG， and large board combustion test. The micro and macro morphologies of the char layer after combustion were observed using scanning electron microscope. The strength of char layer and the peel strength of coating were characterized using compression tester and electronic universal testing machine. The results indicated that when the addition amounts of APP， SiBP， Di⁃PE， MEL， and silicon powders were 10， 20， 8， and 25 phr， respectively， the flame⁃retardant coating achieved an LOI of 29.2 % along with a UL 94 V⁃0 classification and a carbon residue rate of 38.5 wt%， and its peel strength increased to 0.325 kN/m. In addition， the compressive strength of the char layer increased to 1.4 MPa along with an increase in hydrophilicity.
Standard and Test
YAO Yi, ZHANG Erjie, LU Changli, WANG Chaojun, JIAO Jian, ZENG Xiangbin
Abstract (
470 )
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This paper summarized the food contact regulations， especially for the special regulations on plastics. The current technical barriers of PBS were analyzed， and its development prospect in future was discussed.
DENG Yuming, TANG Lei, LUO Shipeng
Abstract (
425 )
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Aiming to evaluate the potential migration risk substances in PET⁃contained food contact materials， an ultra⁃high performance liquid chromatography tandem quadrupole time⁃of⁃flight high⁃resolution mass spectrometry （UPLC⁃Q⁃TOF） was used to implement screening tests and analyze the unknown non⁃volatile substances migrated from four different types of PET⁃contained food contact materials in 4 % acetic acid and 50 % ethanol simulants. The main migration substances are oligomers formed by polymerized monomers and processing aids such as antioxidants and smooth agents， as well as the NIAS substances formed in the processing and migration processes. Pure materials such as pure PET have less migration substances， while multilayer composite materials have much more migration substances. In the food contact composite materials， the PET materials can be modified by adding adipic acid， sebacic acid， neopentyl glycol or other substances during production. In addition， some of the migrated substances may undergo alcoholysis or addition reaction with ethanol in the simulant， leading to the generation of new risk NIAS.
Plastic and Environment
ZHANG Jiale, BO Caiying, BEI Yu, SHA Ye, JIA Puyou, ZHOU Yonghong
Abstract (
1131 )
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Vitrimer is a type of polymer that combines the advantages of traditional thermosetting and thermoplastic polymers and is capable of network reorganization under the stimulation of external conditions to maintain good mechanical properties and allow repeatable molding processes. This has generated a great impact to the fields of self⁃healing of materials and corresponding design of shape⁃memory smart polymers. This paper introduced the history of vitrimer materials and the topological freezing transition temperature. The paper also gave an overview of the study on the dynamic mechanism of vitrimer based on the ester exchange， alkyl transfer， and transamination. In addition， the bio⁃based vitrimers based on lignin， vegetable oil， cellulose， and Vanillin were discussed in detail， and an outlook on vitrimer as a class of materials were prospected.
WANG Zhiwei, WU Mengge, CHEN Yan, GUO Shuaihua, LI Tiantian, ZHAO Junting, LI Hui, LEI Tingzhou
Abstract (
783 )
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According to the recent advances in co⁃pyrolysis of biomass and plastic technology， the synergistic effectiveness， thermogravimetric characteristic， kinetic mechanisms， and characteristics of gas， liquid and solid products during the co⁃pyrolysis process were summarized. The synergistic characteristics and advantages of co⁃pyrolysis derived from biomass and plastic were concluded. This paper can provide a theoretical basis for the co⁃pyrolysis technology of biomass waste and waste plastics as well as a scheme reference for environmental treatment. It is expected to create economic and ecological benefits and accelerate the realization process of sustainable development goals.
Review
ZHANG Xiang, WU Xian′an, LI Changjin, DU Changbiao, LI Haoyi, JIAO Zhiwei, YANG Weimin, ZHANG Yang
Abstract (
550 )
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775
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3 )
This paper briefly introduced the development of micro⁃nano laminated co⁃extrusion technology and reviewed the research progress in the nanofiber preparation based on the micro⁃nano laminated technology in recent years， which included polymer parameters， preparation methods， and fiber⁃forming mechanisms. The methods were classified and compared， and the properties of the fibers were analyzed. Moreover， the applications of micro⁃nano laminated nanofibers were introduced. Finally， the development direction and challenges of the micro⁃nano lamination technology for nanofiber preparation were discussed.
HE Yidan, ZHANG Xiaojuan, YANG Hongjuan, ZHAO Mengmeng, WEN Bianying
Abstract (
1017 )
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1457
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This paper first introduced the relevant mechanisms of microwave absorption and thermal conduction. Through a combination of the unique two⁃dimensional layered structure of MXene and its rich and tunable surface functional groups， the paper systematically reviewed the research progress in MXene and its composites applied in the field of microwave absorption and thermal conduction at home and abroad. This review paper can provide a reference for the subsequent design and development of integrated absorbing and thermal conductive materials. Finally， the problems and challenges of MXene materials with microwave absorbing or thermal conducting functions were pointed out， and its future research directions were forecasted.
HU Wanxin, YIN Hongfeng, YUAN Hudie, TANG Yun, REN Xiaohu
Abstract (
669 )
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This article introduced the electromagnetic shielding mechanisms， the classification of absorbers and microwave loss mechanisms， the division and applications of microwave bands， and the current research on the fiber⁃reinforced⁃resin microwave absorbing composites. The single⁃layer， multi⁃layer， multi⁃layer sandwich structure， and frequency selective surface of the composites were mainly discussed. Finally， the existing problems and outlook of the fiber⁃reinforced⁃resin microwave absorbing composites were proposed.
SUN Guohua, CUI Jiaqi, WANG Yang, ZHANG Xin, MA Jinsong, HOU Lianlong
Abstract (
673 )
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This paper reviewed the performance requirements of lithium⁃ion battery separators and the development status of heat⁃resistant polymer separators at home and abroad. The polymer separators based on polyetheretherketone， polyethylene terephthalate， polyvinylidene fluoride， and polyimide were mainly discussed. The characteristics， preparation methods， and properties of various polymer separators were introduced， and the future development direction of polymer separators was prospected.
