Materials and Properties
HE Hezhi, XIONG Huawei, LAI Wen
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25 )
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In this study， hydrogenated hydrocarbon resin （H⁃HCR） was melt blended with POE using dicumyl peroxide （DCP） as a crosslinking agent and hexadecyl 3，5⁃di⁃tert⁃butyl⁃4⁃hydroxy⁃benzoate （UV2908） as a UV absorbers for fabricating a UV cut⁃off PV encapsulation film with high volume resistance. The transmittance of the blending films in the UV region （250~380 nm） was significantly reduced with an increase in the H⁃HCR content， and its high transmittance in the visible/near⁃infrared region of 380~1 100 nm was maintained. Meanwhile， UV2908 exhibited excellent UV cut⁃off performance in the range of 250~292 nm. The two components could generate a synergistic effect to prevent UV from entering PV modules， resulting in the formation of a PV encapsulation film with a high UV cut⁃off function. Meanwhile， the mechanical properties and volume resistivity of the blending films were significantly enhanced， and their volume resistivity reached the highest value at an H⁃HCR content of 15 wt%. When the POE/H⁃HCR/DCP/UV2908 mass ratio was 85/15/1.5/0.2， the average transmittance and UV cut⁃off wavelength of the blending films in the visible/near⁃infrared region are 91.6 % and 284 nm， respectively. Their tensile strength， elongation at break and volume resistivity reached 20.1 MPa， 904 % and 5.9×1015 Ω·cm， respectively. The blending materials demonstrated not only good volume resistivity and mechanical properties but also excellent UV cut⁃off performance.
LIU Xinlei, WEI Lianchuan, ZHANG Weizhen, LI Yuan, ZHANG Qi, ZHUANG Yi, ZHANG Shijun
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18 )
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Polyamide 10T （PA10T）/MoS2 composites were prepared by incorporating MoS2 into semi⁃aromatic polyamide PA10T through melt blending. Differential scanning calorimetry （DSC） was conducted to study the non⁃isothermal crystallization behavior of PA10T and its composites at different cooling rates. The effect of particle size of MoS2 on the crystallization behavior of PA10T was investigated. The non⁃isothermal crystallization kinetics of PA10T and its composites was studied by using the Jeziorny's and Mo's methods， and their non⁃isothermal crystallization activation energy was calculated by using Kissinger’s method. The results indicated that the crystallization rate of PA10T was fastened and its crystallization time was shortened. After being filled with MoS2， the PA10T composites demonstrated a larger crystallization temperature range， an extended half⁃crystallization time， a slowed crystallization rate， and a lower potential barrier required for nanoscale MoS2 to overcome in the crystallization process of PA10T. The analysis results obtained from the Jeziorny's and Mo's methods indicated that the MoS2 with different particle sizes had no significant effect on the non⁃isothermal crystallization rate of PA10T. In a certain range of cooling rates， incorporating nanometer or micron MoS2 into PA10T can be adopted as an effective means to control the crystallization rate of PA10T in its processing.
HOU Like, ZHAO Shikun, ZHAO Biao, GUO Hongyuan, DENG Jianping, PAN Kai
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19 )
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A series of furan⁃based polyamides （PAXFs）， including poly（tetramethylene furanamide） （PA4F）， poly（hexamethylene furanamide） （PA6F）， and poly（octamethylene furanamide） （PA8F）， were synthesized using 2，5⁃furandiformyl chloride and aliphatic diamines （C=4，6，8） as raw materials through interfacial polymerization. The characterization results obtained from FTIR， NMR and GPC tests confirmed the successful preparation of PAXFs with a high molecular weight. DSC and XRD analysis results indicated that PA4F was a semi⁃crystalline polyamide， whereas PA6F and PA8F were amorphous polyamides. This result may be due to the interaction between the furan ring and furan ring in the molecular chain as well as the coplanar structure of the furan ring and butylamine units， which resulted in a more regular molecular chain and a higher crystallinity degree of PA4F. TGA and UV⁃vis spectroscopy characterization results indicated that PAXFs had good heat resistance and transparency， and its maximum thermal decomposition temperature and transmittance at 760 nm of UV visible light reached 450 ℃ and 91.1 %， respectively.
XIE Yingluan, ZHOU Bing, WANG James Hongxue
Abstract (
19 )
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Polyglycolic acid （PGA） usually has a high degradation rate， which leads to poor storage stability and short shelf life. In this study， the effects of different packaging materials， atmospheres inside the packages， and storage temperatures on the properties of PGA pellets were systematically investigated. The packaging materials evaluated in this work included low density polyethylene （PE⁃LD） and PE⁃LD/polyamide internal packaging materials and aluminum/plastic composite external packaging material. Air， nitrogen， and vacuum were used as packaging atmospheres. The storage temperatures were set to be ‒16， 5， and 25 ℃. The melt flow rates， molecular weights and molecular weight distributions， and thermal properties of PGA were assessed after different storage times， and the effect of packaging conditions on the degradation of PGA were analyzed. The results indicated that there was an increase in the melt flow rates of PGA with a variation of storage temperature along with a correspondingly decrease in its molecular weight. Both the moistures of the packaging atmospheres and the moisture barrier properties of the packaging materials influenced the degradation and properties of PGA.
GUO Yousheng, CHEN Yanming, WANG Haiyue, ZHANG Wenshuai
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17 )
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PET/ZnO nanocomposites were prepared through melt blending using polyethylene terephthalate （PET） and sodium oleate⁃modified nano⁃ZnO （4.73 nm） as raw materials for at nano⁃ZnO contents of 0， 0.02， 0.5， and 1.0 wt%. Differential scanning calorimetry was carried out to investigate the effect of cooling rate on the crystallization behavior of the nanocomposites. The results indicated that the crystallization temperature of PET/ZnO nanocomposites shifted to a low temperature， followed by a gradual increase in the width of crystallization peak， and their half crystallization time also tended to decrease with an increase in the cooling rate. In contrast pure PET， the crystallization ability and crystallization rate of the nanocomposites were improved at the same cooling rate with an increase in the nano⁃ZnO content. The non⁃isothermal crystallization kinetics was studied by the Jeziorny's method. The results indicated that the range of n value varied， indicating that the addition of nano⁃ZnO generated a certain effect on the original growing mode of PET. The crystallization rate constant （Zc） increased with an increase in the nano⁃ZnO content. However， the Zc value of the nanocomposites almost did not change at a nano⁃ZnO content of 1.0 wt%. The thermal stability and crystalline morphology of the nanocomposites were further analyzed by thermogravimetric analysis and hot⁃plate polarizing microscope. The results demonstrated that the incorporated nano⁃ZnO could act as a nucleating agent for the crystallization of PET， but it had little effect on the thermal stability of PET.
SONG Kunpeng, BAI Wei, XIE Meina, HE Jiyu, YANG Rongjie
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16 )
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In this study， Co⁃LDH@ZIF⁃67 composite structure was constructed in situ using Co⁃LDH as a carrier， which effectively improves the defects of low catalytic activity and low specific surface area of Co⁃LDH. The flame retardancy tests showed that the Co⁃LDH@ZIF⁃67 modified epoxy （EP） composites had significant advantages in suppressing heat， smoke， and toxic gases compared to Co⁃LDH. Specifically， the LOI value of the composites increased from 24.5 % to 28.2 % when Co⁃LDH@ZIF⁃67 was added at 2 wt%. The peak heat release rate， the total heat release， and the total smoke release of the EP/Co⁃LDH@ZIF⁃67 composites were reduced by 35.1 %， 16.3 %， and 15.8 %， respectively， compared with pure EP. And it has more obvious flame retardant and smoke suppression ability compared with Co⁃LDH.
SHEN Bin, LIU Zhigang, LI Erxiang
Abstract (
21 )
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In this study， flame⁃retardant reinforced PBT compounds were prepared through a multi⁃component combination of halogen flame retardants with phosphorus， nitrogen， and phosphorus⁃nitrogen⁃based flame retardants， and their glow⁃wire ignition temperature （GWIT） was investigated. Brominated polystyrene， antimony trioxide， diethylaluminum hypophosphate， melamine cyanurate， melamine polyphosphate， and carbon⁃based composite halogen⁃free flame retardant were used as flame retardants to compound with the reinforced PBT for flame⁃retardant experiments. The enhanced PBT compound only with halogen flame retardant or with halogen⁃free flame⁃retardant system cannot meet the requirements of IEC60335⁃1 for the GWIT of current carrying components in unmanned electrical appliances. By a combination of different types of flame retardants and the use of bromine⁃nitrogen⁃phosphorus synergistic flame retardant， the enhanced PBT could ultimately achieve the best flame⁃retardant performance and simultaneously meet the requirements of flame⁃retardant standard at GWIT>825 ℃， GWFI>960 ℃， and UL 94 V⁃0.
ZHANG Jianfei, BAO Lulu, YANG Tingjie, LI Liang
Abstract (
17 )
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In this paper， The coal based high flow impact copolymerized polypropylene was successfully developed on a domestic polypropylene production unit using Innovene gas⁃phase process. At the same time， the modification of organic phosphate nucleating agents for the developed polymer materials was studied. The results showed that CH⁃39， FT⁃21 and TMP⁃6 nucleating agents can effectively promote the crystallization process and improve the crystallization rate of the materials， The bending modulus of TMP⁃6 modified polypropylene is slightly lower than that of polypropylene modified by other three nucleating agents， and the coal based impact copolymerized polypropylene modified by CH⁃39 and FT⁃21 is basically the same in tensile properties， bending properties and impact strength， which provides a certain industrial reference value for the development and performance optimization of new coal based polypropylene products.
Processing and Application
MA Chiyuan, XU Wenchong, PAN Yipeng, LIU Yuanyuan, HE Yadong, XIN Chunlin, REN Feng
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17 )
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The work done by a fiber bundle in the mold was analyzed for the wavy curved runner impregnation mold， and the fiber bundle broadening model including process and equipment structure parameters was constructed according to the principle of energy conservation. The influence of process and structural parameters on the width of the fiber bundle in the mold was explored by using the wavy curved runner impregnation mold designed in the laboratory. The results indicated that the process parameters generated a great influence on the fiber bundle broadening. Among these parameters， the traction tension was the main influencing factor， and the equipment structure parameters also had an impact on the width expansion to a certain extent. The model can effectively predict the unfolding width of the fiber bundle in the mold impregnation stage， which provides a theoretical basis for controlling and optimizing the fiber bundle broadening process in the mold.
YANG Fan, HOU Mengzong, SONG Lisha, HU Run, MA Yuhao, LIU Qiang, ZHANG Hong
Abstract (
15 )
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The gradual accumulation of the microplastics （MPs， <5 mm） and nanoplastics （NPs， <1 μm） produced by crushing， weathering， and aging of plastic products in the soil as well as their difficult degradation characteristics have received widespread attention. Although the interactions between the MPs/NPs and plants in plant⁃soil relationships have been reported， there are fewer review papers regarding the emerging knowledge in this area. This hinders the sustained progress in this emerging field. This paper summarized the sources of MPs/NPs in agriculture， hazards， effects on soil properties and plant growth， and research techniques to complement them， and also describes the possible mechanisms about the phytotoxicity of MPs/NPs.
YAN Xiang, DENG Jiao, LIU Wei
Abstract (
16 )
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The WJ⁃8 type fastening system is mainly used for high⁃speed railway tracks， and the gauge baffle is an important component of the WJ⁃8 type fastening system. This gauge baffle plays an important role in transmitting loads， maintaining and adjusting the gauge of two rails， and it also has a certain insulation in the fastening system. At present， the gauge baffle is produced using an ordinary injection molding technology， which makes the product prone to shrinkage， and the elastic strip buckle is prone to crushing during use. This article mainly optimized the structure of the gauge baffle and produced the corresponding products by selecting suitable foaming agents for tests to meet the performance requirements. The problems of shrinkage and pressure feedback at the clamping point of the track gauge baffle product was solved. This study provides an important reference for better engineering applications in the future.
RONG Xin, LI Xiangpeng, WU Liang, LI Xujuan, XU Xiangbin
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18 )
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To explore the application value of a fully biodegradable film in tobacco planting and evaluate its suitability in crop growth with good thermal insulation and moisturizing effects， this paper analyzed the changes in chemical structure， surface micromorphology， and tensile strength of the fully biodegradable film during the degradation process through field service aging observation and infrared spectroscopy， scanning electron microscopy， tensile mechanical property test， and gel content test. The results indicated that when the fully biodegradable mulch film was served in the field for 51 days， the film surface at the root system of the crop was still intact. This could meet the requirements of the crop mulching cycle. In addition， after the crops were picked and ploughed， the biodegradable film could be degraded in the field under actual environments， and there was no residual film generated.
Additive
LEI Qifeng
Abstract (
16 )
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A mesoporous SiO2 aerogel was synthesized by using a surfactant⁃assisted templating sol⁃gel technique through graded ambient pressure drying. The effects of surfactants on the microstructure， thermal conductivity， and thermal stability of the as⁃synthesized SiO2 aerogel were investigated. The results indicated that the introduction of surfactants not only could avoid the solvent exchange process in the conventional sol⁃gel method but also could regulate the porous structure of the SiO2 aerogel. The SiO2 aerogel exhibited a low thermal conductivity of 0.018~0.035 W m-1 K-1， a high specific surface area of 469.56~692.07 m2/g， and good hydrophobicity with a contact angle of 136.7 °~151.8 °. This study provides an effective method for low⁃cost preparation of SiO2 aerogel with excellent performance， and the resultant aerogel can be used as thermal insulation and heat preservation materials in the building and industrial fields.
Plastic and Environment
ZHANG Liping, XIE Tong, GAO Yongping
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22 )
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Control of waste plastics is an important issue of the national strategy in China. As a substitute for plastics， biodegradable plastics can alleviate white pollution to some extent in specific application scenarios such as disposable， difficult to recycle， and prone to leakage. This article reviewed the performance， the application， and the full life cycle environmental impact of several major biodegradable plastics. Then， the global industry policies， development situation， and technological progress were summarized， and the problems and bottlenecks in the domestic industry were pointed out. Finally， several suggestions for China's biodegradable plastic industry were proposed.
CHU Xingyu, FANG Fang, XU Runze, WANG Suna, CAO Jiashun
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19 )
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Polyhydroxyalkanoate （PHA） as a biodegradable plastic has been gradually developed into an alternative to traditional plastics due to its similar physicochemical properties to traditional plastics together with environmentally friendly characteristics. Upon reaching the end of their lives， some consideration should be given to reasonably dispose PHA wastes to alleviate environmental pressures. This review paper introduced the categories， properties and applications of PHA. The biodegradation of PHA in different environments or processes， functional microorganisms， and enzymes， as well as the mechanism and standards related to biodegradation were also summarized. This paper aimed to provide theoretical references for improving the biodegradability of PHA products and optimizing PHA waste management and disposal strategies.
LI Jing, XIAO Dong, HE Yu, DAI Zaibo
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14 )
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To investigate the effect of plastic particles on the bending characteristics and fracture damage behavior of concrete， three⁃point bending fatigue fracture tests were conducted on the modified recycled polypropylene （PP） plastic particle concretes used for the concrete notched beams. The experimental results indicated that the load crack opening displacement curve of plastic particle concretes presented a single peak shape. With the addition of PP plastic particles， there is no change in the crack opening displacement. However， the downward section of the curve descended significantly， and the fatigue failure ductility of concrete was enhanced. The appropriate addition of PP plastic particles can effectively alleviate the fatigue damage of concrete； The shape of plastic particles has a significant impact on the fatigue performance of concrete. Short columnar PP particles play a bridging role in the tension， improving the toughness and deformation resistance of concrete. There is an increase in the fracture energy and energy absorption capacity of concrete after addition of PP plastic particles. This results in a significant extension in the fatigue life.
LI Dongpo, HAN Hua, WANG Li, YANG Jian, ZHAO Dan, JING Hongjun, ZOU Xiaolong, ZHANG Yongfei
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14 )
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To improve the pavement performance of recycled asphalt mixtures， the preparation schemes of recycled asphalt were designed by using a response surface method with the contents of waste cooking oil and styrene⁃butadiene⁃styrene （SBS）⁃modified asphalt， and the shear temperature as independent variables. The influence of these independent variables on the properties of regenerated asphalt were analyzed through basic physical and rheological measurements to determine the optimization scheme of recycled asphalt. On this basis， the pavement performance was verified. The results indicated that the optimal optimization scheme for recycled asphalt was determined to be a content of waste cooking oil of 8.4 wt%， a content of SBS⁃modified asphalt of 152 wt%， and a shear temperature of 166 ℃. The maximum error between the predicted values and actual results of performance indicators of recycled asphalt was 4.5 %， which was within the acceptable limits. With an increase in the content of the reclaimed asphalt pavement （RAP）， the cracking resistance and water stability of recycled asphalt mixtures decreased but their high⁃temperature stability was improved. Compared to the recycled asphalt mixtures without waste cooking oil， the recycled asphalt mixtures containing waste cooking oil showed a significant improvement in the low⁃temperature crack resistance and water stability.
Machinery and Mould
ZHANG Wenchao, WU Di, ZHANG Han, MIAO Lei, CUI Enming, WANG Mingwei, YE Xinghui, YU Junwei
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18 )
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In view of the complicated structure of the trim panel on the front A⁃pillar of a car with many internal reinforcement bars， inverted buckle features， snap seats and support structure base， and other structures， and the exterior surface needs to be covered with fabrics. In this case， a low⁃pressure injection overmolding process is adopted， and a pair of one⁃mold and a two⁃cavity valve hot runner low⁃pressure injection overmolding inverted molds were designed. Owing to the low⁃pressure injection overmolding， the hot runner could not feed the glue from the cavity side. Therefore， a direct gate was opened on the B⁃side （the core side） of the molded part， and the Moldex 3D mold flow analysis software was used to verify the reasonableness of the pouring system and analyze the possible defects in the molding process. For the inverted feature， a “spring+slider” side core extraction mechanism was adopted. The “inclined top bar+inclined top block” and “cylinder+slider” mechanisms were adopted for the support structure base and snap seat structures， respectively. The “oblique top bar+oblique top block” and “oil cylinder+slider” mechanisms were designed for the support structure base and snap seat structures， respectively， and used for lateral core extraction and demolding. The ejector mechanism was driven by an oil cylinder to eject the molded parts by the “straight top block+straight top bar+ejector pin” mechanism together with other components. Before the mold starts to work， it is necessary to lay the fabric flat on the one side of the cavity at first and then close the mold and injection molding. When the mold is opened， the lateral core⁃extraction mechanism moves to both sides under the action of cylinders and springs. After the core extraction， the ejector cylinder can provide a power to drive all the ejector parts to eject. As a result， the plastic parts， cold runners， and excess overflow material can be smoothly demolded from the mold. The mold structure is reasonable and can be operated stably and safely， and the obtained products produced can meet the design standard.
Review
JIANG Xinpei, HUANG Tianyu, WEI Xingyue, ZHANG Peng, WANG Shilong, WANG Shilin, YANG Weimin, JIAN Ranran
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Polymer materials such as rubber and plastic exhibit poor thermal conductivity and significant viscous dissipation， leading to a significant rise in temperature during the extrusion molding process. Excessive temperatures may increase the thermal history of polymers， cause chain scission due to high⁃temperature oxidation， damage their original properties， and increase energy consumption， thereby affecting the molding quality of polymer products. Based on these issues， this article analyzed the causes of temperature rise during the polymer extrusion process， reviewed the contributions made by domestic and foreign scholars in the direction of low⁃temperature extrusion technology from the aspects of barrel cooling devices， temperature control systems， screw structure optimization， and measures taken in energy consumption management. Finally l the future development trend of low⁃temperature extrusion technology was prospected.
LI Xiaoqian, CHEN Hao, GE Zhenghao, SONG Haojie, GAO Yanjun
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This article overviewed various molding processes for carbon⁃fiber⁃reinforced polymer composites （CFRPs） applied in the automotive field and compared various schemes for improving the performance of CFRPs. Based on the actual documentation of industrial applications， the existing modification methods and design schemes were discussed. The development prospects of green technology for CFRPs used in automobiles were proposed， and the opportunities and challenges faced by the research on lightweight materials for the automotive industry were analyzed.
