Materials and Properties
SHEN Yingzhou, LIU Lei, CHONG Jinxuan, ZHANG Kai, YIN Bo
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Syndiotactic polystyrene （sPS）/N，N'⁃diphenylterephthalamide （DPHT） blends were prepared through melt blending， and the conformation and crystallization behaviors of sPS were regulated by utilizing the π⁃π interactions between sPS and DPHT. The results indicated that there were two dispersion states for DPHT， i.e.， free molecule or as self⁃assemblies， existing in the sPS matrix. The addition of DPHT increased the content of the all⁃trans conformation （TTTT） of sPS and reached a maximum when the self⁃assemblies were formed for DPHT. Moreover， the self⁃assembled structures of DPHT effectively increased the content of β⁃crystals in sPS. The proportion of the β⁃crystals was higher than that of the α⁃crystals in the sPS/DPHT blends at a slow cooling rate of 5 or 2 ℃/min. However， the α⁃crystal content in sPS was higher when the cooling rate was increased to 10 ℃/min. When DPHT was molecularly dispersed in the sPS matrix， the π⁃π interaction between DPHT and sPS restricted the crystallization ability of sPS， resulting in a decrease in the degree of crystallinity from 41 % to 35.9 %）. When DPHT was in the self⁃assembly state， the self⁃assemblies of DPHT acted as a nucleating agent to promote the crystallization of sPS， leading to an increase in the degree of crystallinity from 36.1 % to 38.2 %. Therefore， the conformation and crystallization behaviors of sPS were successfully regulated during melt processing through the π⁃π interactions between DPHT and sPS.
WEI Ce, CHEN Tianyu, ZHANG Xiutao, ZHANG Yiyao, ZHANG Sibo, ZHANG Xiaoyu, HUANG Jing, DONG Weifu
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69 )
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This paper reviewed the research progress in the applications of dynamic covalent cross⁃linking networks in several major thermoplastic polymers， including polyolefins， polystyrene， poly（methyl methacrylate）， and polyesters. Through introducing dynamic covalent bonds， the resultant materials obtained an enhancement in melt strength， mechanical properties， heat resistance， and solvent resistance along with well maintainability of their inherent characteristics. However， there still have some challenges such as complex fabrication processes， high costs， and insufficient research on long⁃term stability and degradation in spite of significant advancements. Future research was suggested to focus on optimizing the preparation methods， enhancing the material properties， and investigating the long⁃term stability under various environmental conditions to promote the large⁃scale industrial applications of the dynamic covalent cross⁃linking technology.
LAN Qian, ZHU Ping, GUO Hongjiang
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74 )
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The paper introduced the advantages of a combination of the membrane separation technology and electrospinning technology in the field of oil⁃water separation and reviewed the latest research progress in the hydrophobic electrospinning oil⁃water separation membranes， hydrophilic electrospinning oil⁃water separation membranes， and intelligent electrospinning oil⁃water separation membranes based on the classification of oil⁃water separation nanofiber membranes. A detailed introduction about the methods was provided for improving the oil⁃water separation performance of nanofiber membranes， including the modification by adding nanoparticles and preparation of multilayer nanofiber membranes. Finally， the future focus in the field of oil⁃water separation was proposed for the development of environmentally friendly nanofiber membranes with abilities for both oil⁃water separation and functions such as antibacterial properties and removal of heavy metal ion.
SONG Ruiming, LYU Huaixing, ZHANG Wenlong, LI Bin, LI Hui
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75 )
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The paper reported an investigation on the degradation kinetics of ultra⁃high molecular⁃weight polyethylene （PE⁃UHMW） used for wet⁃process separator of lithium⁃ion battery under different conditions such as temperature， synthetic oil concentration， and shear force. A degradation rate curve was fitted to obtain a kinetic model suitable for the degradation behavior of PE⁃UHMW. The degradation kinetics of PE⁃UHMW at various temperatures and white oil concentrations was consistent with the first⁃order kinetic model； however， its degradation kinetics under a shear stress conformed to the second⁃order kinetic model. The degradation rate of PE⁃UHMW increased with an increase in the temperature and shear force； however， its degradation rate was reduced by the addition of white oil.
LIU Yaning, LIU Haiming, LIU Shao, CHEN Shihong, WANG Xiangdong
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61 )
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A variety of nucleating agents were introduced into long⁃chain branched polypropylene （LCBPP） to investigate the β⁃crystal nucleating effect of a nucleating agent WBG⁃Ⅱ in the LCBPP/isotactic polypropylene （iPP） blends as well as to evaluate their impact on the mechanical properties and foam structure of formed PP materials. The as⁃prepared samples were characterized by X⁃ray diffraction， differential scanning calorimetry， and rotational rheometer to identify the highly effective β⁃crystal inducer， WBG⁃Ⅱ. The results indicated that the addition of 5 phr WBG⁃Ⅱ resulted in an increase in the impact strength of LCBPP by 128 %， whereas its tensile strength decreased by above 20 %. Additionally， the nucleating agent had no significant adverse effect on the melt strength of LCBPP. Polarized optical microscopy （POM） observations further revealed that WBG⁃Ⅱ effectively induced the β⁃crystal orientation in iPP. Incorporating iPP into the LCBPP matrix significantly increased the β⁃crystal content in the blend. Compared to pure LCBPP， there was an increase in the crystallinity degree by 190 % for the LCBPP/iPP sample at a mas ratio of 1/1. Furthermore， the addition of iPP enhanced the storage modulus and complex viscosity of the PP blend under high⁃frequency conditions.
LI Yangyang, ZHANG Tao, QIAO Min, JIANG Jing, WANG Xiaofeng, LI Qian
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48 )
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Based on the self⁃built processing equipment for melt blending ⁃ high speed hot drawing， the effects of dispersed phase content of polylactic acid （PLA） on the microfiber morphology， the viscoelasticity， and crystallization behavior of poly（adipate⁃butylene terephthalate） （PBAT） matrix， PLA stereo⁃composite crystal （sc⁃PLA）， and the mechanical and thermal properties of PBAT/sc⁃PLA composites were investigated through a combination of in⁃situ fiber formation and stereo⁃composite technologies. The results indicated that the PBAT/sc⁃PLA microfiber composites with a minimum fiber diameter of 210 nm could be continuously prepared， and the PLA microfibers were intertangled in the PBAT matrix to form a network structure and also obtained a uniform dispersion. The presence of the sc⁃PLA microfiber network makes the viscoelastic behavior of the composites change from the “liquid⁃like” to “solid⁃like” state. Under the fiber induction， the relative crystallinity and crystal content of sc⁃PLA in the PBAT/sc⁃PLA composites were significantly increased. After adding 30 wt% PLA， the relative crystallinity of sc⁃PLA in the PBAT/ SC⁃PLA composite reached 46.4 %， and its yield strength and elastic modulus were higher than that of pure PBAT by 175.3 % and 404 %， respectively. Their Vica softening temperatures reached nearly 90 ℃. These research results provide a technical means for the large⁃scale preparation of reinforced and heat⁃resistant PBAT composites.
LIU Chenjun, XI Yuyang, REN Wei, YANG Xin, GE Zhenghao, WANG Chaobao
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58 )
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To address the brittle nature of polyphenylene sulfide （PPS） and further reduce its density， a series of PPS/polyamide 66 （PA66）/glass fiber （GF）/hollow glass beads （HGM） quaternary composites were prepared through melt blending with GF as a reinforcement， PA66 as a impact modifier， and HGM as a light⁃weight agent. The microstructure and mechanical and tribological properties of the composites were systematically investigated. The results indicated that the addition of a small amount of PA66 could significantly improve the toughness and water lubrication performance of the composites， and there was no change in their mechanical strength. The introduction of HGM significantly reduced the density of the PPS⁃based composites and effectively improved their mechanical strength and tribological properties. However， the excessive content of HGM resulted in a reduction in the toughness of the composites. The composites obtained the optimal performance at PA66 and HGM contents of 25 and 10 wt%， respectively. This study can provide a technical guidance for the development of lightweight and high⁃tough PPS composites and also extend the application range of PPS and its composites in high⁃end lightweight areas.
DONG Zhihui, QU Nan, ZHANG Xue, HAN Zhaolian, CHENG Zhiqiang
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44 )
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A type of polyacrylic acid sodium/Phellinus igniarius section composite superabsorbent resin （PISSR） was synthesized through microwave irradiation. A single⁃factor experiment was conducted to investigate the variable ratio scheme and optimize the preparation processes. The as⁃synthesized materials were characterized by FTIR， TGA， SEM， and EDS. The results indicated that the neutralization degree of acrylic acid reached 85 % when the dosage of Phellinus igniarius， initiator， and crosslinking agent was 20 %， 0.60 %， and 0.15 % of acrylic acid， respectively. PISSR presented the highest liquid absorption rates of 652.6 g/g in distilled water and 61.1 g/g in 0.9 % NaCl solution at a microwave power of 500 W. Ion type and electrolyte concentration are two important factors affecting the liquid absorption performance of PISSR. The surface of PISSR is rough， porous， and rich in Na， K and Ca elements， indicating good water retention and re⁃swelling performance.
MENG Chenghan, LUO Haowen, LIU Hao, FEI Jilong, YANG Jianfei, YANG Zhen, JIA Liangyuan
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45 )
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In this study， citric acid （CA） was used to modify ramie fiber （RF）， and then the polybutadiene succinate （PBS）/modified RF bio⁃composites were prepared. Changes in the thermal stability， crystallinity， and morphology of CA⁃modified RF were investigated. The mechanism for the interface interaction between the CA⁃modified RF and PBS was analyzed. The optimal content of CA⁃modified RF for the bio⁃composites was determined to be 8 wt% according to their tensile properties. The bio⁃composites obtained tensile strength and modulus of 44.1 and 563.3 MPa， respectively. Meanwhile， the mechanical properties were compared between the PBS/CA⁃modified RF bio⁃composites and the corresponding bio⁃composites with the acetic acid （AA）⁃ and sodium hydroxide （SH）⁃modified RF. The results indicated that PBS/AA⁃ and SH⁃modified RF bio⁃composites presented tensile strength of 40.2 MPa and 41.0 MPa， respectively， both of which were lower than those of the PBS/CA⁃modified RF bio⁃composites.
REN Siying, DU Jiahui, SUN Tao, WU Yifeng, GUO Jiushi, YUN Xueyan
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47 )
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Poly（lactic acid⁃co⁃glycolic acid butylenediyl ester） （PDBI） was synthesized by incorporating poly（butylene glycol itaconate） （PBI） into the main chains of poly（D⁃lactic acid） （PDLA）， and then the PLLA/PDBI blend films were prepared by melt blending the as⁃synthesized PDBI with poly （L⁃lactic acid） （PLLA） at different mass ratios. The results indicated that the total crystallinity degree of the blend films presented an increasing trend at first and then decreased with an increase in the mass ratio of PDBI to PLLA， and the most cubic composite crystals were formed at a PDBI/PLLA mass ratio of 1/1. At such a mass ratio， the blend films obtained a total crystallinity degree of 9.12 % with a melting point as high as 205 ℃， and their thermal properties were greatly improved. The elongation at break of the blend films exhibited an increasing trend at first and then decreased with an increase in the mass ratio of PDBI to PLLA， whereas their tensile strength and Young's modulus presented an opposite trend. The PDBI/PLLA blend film at a mass ratio of 1/1 presented a Young's modulus of 853.38 MPa and elongation at break of 285.07 %. There was no change in the tensile strength； however， its elongation at break was 59 times as much as that of PLLA and 21 times as much as that of PDBI， indicating a change from a brittle fracture to the ductile one. The barrier performance of the blend films also showed an enhancement at first and then became weakened. At a PDBI/PLLA mass ratio of 1/1， the blend film exhibited an O2 transmission amount of 309.4 cm3·m2/d and a maximum water contact angle of over 78 °， indicating good barrier performance and high hydrophobicity.
SONG Wenlan, SONG Wenxing, LI Bing, WANG Xuan, OUYANG Yuge, ZHANG Peiqi, TIAN Huafeng
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60 )
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This paper reviewed the catalyst， production， and polymerization technologies of polypropylene （PP） capacitor films in terms of their requirement of performance， and also discussed their current research status at home and abroad. The applications and performance requirements of the most widely used biaxially oriented PP capacitor films in the domestic and foreign markets were analyzed in particular. Finally， the future development of PP capacitor film materials in China was prospected.
YANG Chen, ZHAO Lixue, LIN Yanping
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58 )
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Waterborne polyurethane （PU） was modified with flame⁃retardant polyester polyol as a phosphorus source， and the properties of the resultant modified waterborne PU emulsion， film， and coated polyester fabric were characterized. The results indicated that the flame⁃retardant polyester polyol as a modifier was completely participated in the flame⁃retardant modification of waterborne PU. When the phosphorus content was less than 5 wt%， the flame⁃retardant waterborne PU emulsion presented an aspect from translucent to milky white， its particle size was less than 100 nm， and its centrifugal stability was good. The waterborne PU film exhibited a decrease in the water absorption rate， mechanical properties and cracking temperature with an increase in the phosphorus content， but its mass retention rate increased. The coated polyester fabric reached a nonflammable level at a phosphorus content of 3 wt%. The mechanism analysis indicates that it was feasible to finish polyester fabric with the flame⁃retardant waterborne PU coating.
LI Mingkun, LIN Rongtao
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The fatigue⁃resistance performance of PC/ABS alloys under a high temperature of 90 ºC were investigated in the terms of acrylonitrile⁃butadiene⁃styrene terpolymer （ABS） phase， polycarbonate （PC） phase， and compatilizers. The results indicated that the rubber phase in the alloy was the main factor that weakens the fatigue resistance. It was beneficial to improve the property by increasing the mass ratio of styrene⁃acrylonitrile binary copolymer to polybutadiene in the alloy. Meanwhile， increasing the proportion of PC or reducing the viscosity of PC was capable of strengthening the fatigue⁃resistant property. There was an influence on the fatigue resistance from the addition of different types of compatilizer， in which polypropylene⁃grafted⁃maleic Anhydride （PP⁃g⁃MAH） exhibited optimal performance.
Processing and Application
XIAO Yuanhao, CHU Liqiu, CHEN Libo, ZHANG Shijun, ZHAO Xin, ZHANG Hao, LYU Yun, LIU Lei, ZHANG Kai, YANG Mingbo
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In this study， multi⁃melt multi injection molding （M3IM） was employed to construct a hierarchical structure for an incompatible system of poly（vinylidene difluoride） （PVDF） and high⁃density polyethylene （PE⁃LD）， and their interfacial properties were investigated. The results indicated that a unique interfacial interlocking structure was formed in these two incompatible polymers under the special external field of M3IM process， resulting in an increase in the peeling strength by 3.3 times. The experimental and numerical simulation analyses demonstrated that the formation of such an interfacial interlocking structure was attributed to an unstable flow generated at the breakthrough region when the secondary melt was injected into the primary melt as well as the elastic turbulence of the polymer melt at low Reynolds numbers. The Reynolds numbers in the thickness direction presented a bimodal distribution and tended to increase by more than one order of magnitude at the interface region. Compared to the regions before the breakthrough part， the turbulent kinetic energy and kinetic energy dissipation rate of the melt increased significantly after the breakthrough part.
MENG Jia, LIU Tongju
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This paper reviewed the research progress in the influence of process conditions， including temperature， pressure， residence time， solvent type， and mass ratio of solvent to plastics， on the distribution of degraded products from the aspect of its degradation mechanisms by taking a widely used thermoplastic， polyethylene， as the example. In addition， the industrialization devices reported currently for solvothermal liquefaction degradation were introduced， and the future research direction was prospected.
ZHANG Caili, ZHANG Chongxi, YU Yanlong, YANG Fenglei, MENG Qingying
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To address the problems of dim color and easy cracking on traditional colored road surfaces， a waterborne epoxy color coating was prepared by using waterborne epoxy resin， waterborne amine curing agent， film⁃forming agent， pigment， filler， and anti⁃skid sand as main components. The microstructure of the waterborne epoxy resin curing system was analyzed by Fourier⁃transform infrared spectroscopy and scanning electron microscopy. The effects of filler type and content of anti⁃skid sand on the road performance of color coating were investigated by tensile bond strength test， freeze⁃thaw cycles， and ultraviolet aging test. The results indicated that the stable cured products were formed during the curing process of waterborne epoxy resin. The incorporation of wetting agent improved the adhesion of the coating. The skid resistance and wear resistance of the coating increased with an increase in the addition amount of anti⁃skid sand but with a decrease in the mesh number. The impact resistance of the coating increased gradually with an increase in the addition amount of filler. The addition of an ultraviolet absorber improved the UV⁃aging resistance of the coating.
LIU Xin, FEI Huaiyu, ZUO Hongmei, SU Yongsheng, HU Qiaole, YANG Li, RUAN Fangtao
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72 )
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This paper reviewed the research progress in the preparation principles and processes of surface coating treatment technologies for carbon （C）/carbon （C） composites from the aspects of ceramic precursors， SiC， transition metal⁃coated materials， and coating processing such as magnetron sputtering， chemical vapor permeation， chemical vapor deposition， reactive fusion infiltration， precursor conversion， and encapsulation. The future development prospects of surface⁃modified C/C composites for the improvement of material properties and extension of application areas were discussed.
XU Zhen, HUANG Zhigang, CHENG Yuanyuan
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44 )
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End curve is deduced and built in the method of relative motion for the 3 d model， after its meshing in Gambit software into the finite element simulation software Ansys， through the simulation process of motion are set up different slip boundary conditions to simulate the material in barrel inner surface and the screw on the surface of sliding phenomenon， The obtained physical field data were presented in the form of cloud chart and change curve by post⁃processing software for research and analysis. The volume flow rate of the extrusion process under different conditions was calculated， and the tracer particle method was used to explore the movement trajectory of the material in the flow channel. It is found that the wall slip condition is conducive to improving the pressure building ability and shear ability of the counter⁃rotating twin screw at the screw engagement， and the screw slip condition is conducive to the stability of the pressure in the flow channel during the extrusion process， so that the local high pressure phenomenon disappears and the service life of the machine is prolonged. The shear capacity of the counter⁃rotating twin screw decreases at the gap between the screw and the barrel under both sliding conditions. Both slip conditions will decrease the extruding flow rate of the hetero⁃twin screw， resulting in a longer residence time of the material during extrusion.
Additive
WANG Chen, LI Xiangyang, ZHOU Li
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The β⁃form crystallization⁃modified polypropylene （PP） was prepared through melt blending with homopolymerization⁃type PP⁃700+ as a matrix resin and 2，6⁃benzenedicarboxamide （TMB⁃5） as a β⁃form nucleating agent. The effects of TMB⁃5 on the application performance and crystallization behavior of the modified PP were analyzed by using polarizing microscope， differential scanning calorimeter， universal testing machine， digital impact testing machine， and heat deflection temperature tester. The results indicated that the α⁃form crystal of PP⁃700+ were gradually transformed to the β⁃form ones through induction by the TMB⁃5 nucleating agent. With an increase in the addition amount of TMB⁃5， the content of the β⁃form crystals， crystallization temperature and crystallization rate of the modified PP gradually increased. When 0.2 wt.% TMB⁃5 was incorporated into the PP⁃700+ matrix， the content of the β⁃form crystals in the modified PP increased to 84.9 %. As a result， its tensile strength， flexural modulus， and flexural strength were increased by 4.5 %， 14.6 %， and 13 %， respectively. However， there was no change in the impact strength. The modified PP obtained an increase in the impact strength by 9.8 % for the cantilever beam mode and by 5.9 % for the Charpy beam mode， and its heat deflection temperature was increased by 42.13 ℃. These results ensure PP⁃700+ obtain a wider application range. The modified PP developed in this work is especially suitable for the products that need to be used or sterilized at high temperature， such as plastic hot drink cups， microwave cookers， baby bottles， and disposable lunch boxes.
Standard and Test
LIU Lirong, CHEN Minjian, WANG Jiandong, ZHANG Yanjun, WANG Lun, LI Zhou, GAO Jianguo
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The paper reported a comparison of the GB/T 40006.2 standard with the ISO and EU standards for recycled plastics. The differences in the recycled plastics standards and relevant factors between China and other developed countries were intensively elaborated. This paper can provide a guidance for better understanding and utilization for recycled plastics standards.
Plastic and Environment
HU Peng, XU Hao, CAI Shaojun
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59 )
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To address the difficulty in waste epoxy resin （EP） recycling， EP was used as a filling material for the modification of polyamide 66 （PA66）. PA66 grafted with maleic anhydride （PA66⁃g⁃MAH） was prepared as a compatibilizer through melt grafting for enhancing the compatibility between PA66 and EP. Then， PA66/EP/PA66⁃g⁃MAH compounds were prepared through melt extrusion and characterized by using universal mechanical testing machine， thermogravimetric analyzer， and scanning electron microscope. The effects of different compatibilizer content on their mechanical properties， thermal properties and microscopic morphology were investigated. The addition of PA66⁃g⁃MAH enhanced the compatibility of the compounds， resulting in an increase in the tensile strength and elastic modulus. The PA66/20 wt% EP/3 wt% PA66⁃g⁃MAH compound exhibited the optimal comprehensive mechanical performance with tensile strength of 69.2 MPa and an elastic modulus of 678.3 MPa. Moreover， the addition of PA66⁃g⁃MAH also increased the initial decomposition temperature and the temperature corresponding to the maximum decomposition rate.
Machinery and Mould
ZHANG Weihe, FENG Jing, ZHAO Liping, XU Yonglin, YAN Lijing, FEI Qiang, TAO Yongjie, CHEN Zhuohang
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In this study， a large injection mold with a sequential valve hot runner was designed for the left⁃front door panel of a vehicle， and the forming defects such as poor filling and fusion marks in the horn mesh were effectively eliminated by using the formed parts made of a type of powder metallurgy breathable steel. The problem in the inclined inner reverse buckle demolding was effectively solved by using an inclined guide groove. The difficulty in filling large mold cavities was effectively addressed by using a sequential valve hot runner control technology. The injection cycle was shortened by about 8 %， and the dimensional accuracy reached the MT3 level （GB/T 14486—2008） by using a fast and balanced temperature control system.
XIE Maoqing, WANG Leigang
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A hot runner two plate mold was designed for injection molding of plastic parts for an automotive glove box body. In this mold， a hot runner + cold runner composite gating system was adopted for gating according to the non⁃equilibrium characteristics of the plastic mold cavity. There were three cold gates at the beginning of the mold cavity， which were fed in a timely and sequential manner by two hot nozzles， ensuring the filling balance of the mold cavity. In terms of a difficulty in implementing automated demolding for plastic parts with multiple demolding directions， an integrated classification design method was applied for demolding directions. Based on the determination of the main demolding direction， 14 secondary demolding directions were obtained， and corresponding 4 sliders and 11 lifters were set up for the side core demolding of these difficult demolding models. This design method is effective to solve the problems in automated demolding for complex plastic parts in automobiles. There were 11⁃lifter mechanisms， and three different types of lifter mechanisms were set up according to the design space， including a square top rod mechanism， a cylindrical lifter rod + lifter block mechanism， and a cylindrical lifter rod + inclined guide column extended range lifter mechanism. In the extended range lifter mechanism， the inclined guide column was used to extend the range of the lifters seat plate on the basis of the cylindrical lifter rod+lifter block mechanism， thus realizing the lateral core pulling stroke extension of the lifters block. For the formation of plastic part skin patterns， a skin pattern depth of 30μm and a draft angle of 2.4 ° were adopted as a solution. The forming material was S136 alloy steel， and the skin pattern was polished with a 1000 # sandpaper.
Review
WANG Shilong, WEI Xingyue, ZENG Xiankui, YANG Weimin, JIAN Ranran
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107 )
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This paper introduced the classification of organic phase⁃change heat⁃storage materials as well their preparation methods for composites， including microencapsulation method， porous carrier adsorption method， melt⁃blending method and electrostatic spinning method. The advantages and limitations of these preparation methods were discussed. The future development direction of organic phase⁃change heat⁃storage materials was prospected.
LI Shuangyan, LU Xinyu, SU Qiong, ZHAO Mengchi, Alidan Ruzha Hong, WANGYupu , ZHAO Libin
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54 )
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This paper introduces four types of biomass materials， including cellulose， lignin， starch and chitosan. A variety of new properties were imparted to these four types of biomass materials after the modification. The foaming methods for three types of foamable biomass materials， including supercritical CO2 foaming， freeze⁃drying foaming， and extrusion foaming method， were summarized. Finally， a detailed overview on the future applications of biodegradable biomass materials in the fields of packaging， construction and medical treatment was proposed.
LIN Liangbin, ZHOU Weiming, XUE Hun, QIAN Qingrong, YANG Songwei, CAO Changlin, CHEN Qinghua
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The recent advances in the photocatalytic degradation of microplastics are reviewed， including the mechanisms of photocatalytic degradation and the design of catalysts. The important parameters for evaluating the efficiency of photocatalytic degradation and the factors influencing its efficiency are discussed. From the perspective of the aggregation state of microplastics， the reasons for the low degradation efficiency is analyzed. Finally， future research directions of this technology are prospected.
