Materials and Properties
FENG Yingjian, HU Dongdong, WEI Shaolong, QIAN Jun, XIONG Wei, YAO Shun, ZHAO Ling
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208 )
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Long⁃chain⁃branched poly（ethylene terephthalate） （PET） was controllably prepared through reactive extrusion by a combination of in⁃situ polymerization of polyol⁃modified PET with a branched structure as a raw material and pyromellitic dianhydride （PMDA） as a chain extender. Rheological test results indicated that the melt viscoelasticity of long⁃chain⁃branched MPET was greatly improved， and its strain hardening factor was also enhanced with an increase in the long chain branched degree. During the supercritical CO2 extrusion foaming process， the long⁃chain⁃branched modified MPET exhibited excellent extrusion foamability. The MPET foam prepared with 0.3 wt% PMDA （MPET⁃P3） presented the best extruded foaming performance， which obtained an expansion ratio of 14.0 at 265 °C， a cell density of 4.81×106 cells/cm3， and an average cell diameter of 153.9 μm.
CHEN Hui, QIAN Weidong, SUN Lingsheng, TAN Bo
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149 )
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Polyethersulfone resin （PES）/nano⁃SiO2 composite sintered parts were prepared through selective laser sintering using PES as a matrix and nano⁃SiO2 as a filler. The effect of nano⁃SiO2 content on the surface quality and mechanical properties of the composite sintered parts were investigated. The results indicated that the composite sintered parts presented a little change in the arithmetic mean in the nano⁃SiO2 content range of 0.1~1.0 wt% and then their deviation increased significantly at a nano⁃SiO2 content above 1.0 wt%. The tensile strength and flexural strength of the composite sintered parts increased first and then tended to decrease with an increase in the nano⁃SiO2 content. The tensile strength and bending strength of the composite sintered parts reached a maximum at a nano⁃SiO2 content of 0.5 wt%. Compared to pure PES sintered parts， the composite sintered parts exhibited an increase in tensile strength and bending strength by 22.66 % and 41.51 %， respectively. Their impact strength reached a maximum at a nano⁃SiO2 content of 0.7 wt%， which was increased by 12.10 %.
HE Boyuan, LEI Hexiang, CAO Ning, CHEN Xi, YAO Lifei, JIA Weiyi, LIAN Huiqin, WANG Xiaodong, CUI Xiuguo
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159 )
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A series of sulfonated polysulfone （SPES） was prepared through controlling the reaction temperature and time with polyethersulfone as a raw material and chlorosulfonic acid as a sulfonating agent. Further， proton exchange membrane composites were fabricated through solution casting using 2D black phosphorus as a functional filler and SPES as a matrix. The structures of the as⁃prepared materials were characterized by Fourier transform infrared spectrometer， X⁃ray diffractometer， and scanning electron microscope， and their properties in terms of water absorption， proton exchange and alcohol resistance were studied. The results indicated that the sulfonation degree of SPES increased with increasing the reaction temperature， time， and sulfonation agent concentration. The addition of black phosphorus enhanced the comprehensive properties of the composite membranes， which included thermal stability， oxidation stability， proton exchange ability， and alcohol resistance. Under the same test conditions， the SPES substrate membrane exhibited a methanol permeability of 1.185×10-6 cm2/s， whereas the SPES/BP composite membrane containing 5 % BP only present a methanol permeability of 2.88×10-7 cm2/s.
PAN Hongyang, CHEN Zongyong, LIAO Tingmao, YUAN Hong
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191 )
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In this paper， polyolefin elastomer （POE） was selected as the core material for the mattress. Through the static and fatigue durability tests towards POE specimens， the loading deformation curves of each specimen were compared and analyzed， and the influencing factors of POE on their anti⁃fatigue compression and support performance were discussed. Meanwhile， the nonlinear mechanical behavior of POE was characterized by choosing the 2nd⁃order Ogden model and the 3rd⁃parameter Mooney⁃Rivlin model to simplify the human⁃bed interface contact process. The pressure⁃reducing performance of the POE mattress was evaluated through finite elements. The results indicated that there was no apparent geometric relationship between the thickness and hardness loss of POE， which seems not to increase significantly with an increase in the density. The density had little effect on the minimum static buffer coefficient. The compression coefficient of POE was greater than 2.8， and the hardness pressure reached 0.77 N/cm2. These results can meet the support requirements of people with different weights for mattress materials. The 2nd⁃order Ogden model and the 3⁃parameter Mooney⁃Rivlin model have an ability to predict the large deformation of POE materials. However， the 3⁃parameter Mooney⁃Rivlin model is insufficient in describing the small deformation range. The POE mattress with two densities was more uniform and hierarchical in stress transmission than the natural latex/palm fiber mattress. The peak pressure decompression percentage was as high as 94.11 % and 94.23 %， which was enough to meet the requirement of daily production and life.
WAN Yanhong
Abstract (
224 )
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This paper reviewed the reaction mechanism， synthesis methods （suspension chlorination method， gas⁃solid chlorination method）， and four application fields of chlorinated polyethylene （CPE） obtained from polyethylene. The CPE special materials required for producing CPE and the catalysts for preparing the special materials were introduced. Finally， the technological development of CPE， CPE specific materials， and catalysts for producing specific materials were prospected.
Processing and Application
ZHAO Hejin, WAN Xian, LU Jiahui, ZHANG Hongyu, GUO Baohua
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290 )
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In this paper， the classification for phase⁃change energy⁃storage materials was summarized on the basis of the domestic and foreign development of building energy conservation and energy consumption in construction field in our country as a background， and the selection of phase⁃change materials for building use was analyzed. Meanwhile， the application of phase⁃change energy⁃storage technology in the field of building energy conservation and the existing deficiencies were investigated. Finally， the application prospect of phase⁃change energy⁃storage materials in the construction field was prospected.
ZHANG Chao, XU Shuangping, JIA Hongge, ZHANG Mingyu, QU Yanqing, XU Jingyu
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183 )
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This paper introduced the origin， development， structure， and properties of graphene⁃like carbon nitride （g⁃C3N4） and summarized the preparation methods of g⁃C3N4. The research progress in g⁃C3N4 used in the field of gas membrane separation was reviewed， and the preparation， separation performance， and separation mechanisms of the membranes were introduced in detail. Finally， the future research direction of g⁃C3N4 in the field of membrane separation was prospected.
WANG Luowei, YANG Jianjun, ZHU Jialei
Abstract (
132 )
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Polydimethylsiloxane （PDMS）⁃based material has a feature of spreading （flow infiltration） in the uncured state， and the traditional bottom heating curing method can not meet the requirement of timely curing. To solve this problem， a PDMS/silicon carbide （SiC） powder⁃mixed functional gradient material was taken as an example， and a two⁃step 3D printing precision forming method for border area and filling area was proposed by using a dual heating method on the top and bottom plate. The effects of the printing speed， air pressure， effect of laser power density， and other process parameters on the manufacturing accuracy of PDMS/SiC composites with different SiC contents were investigated. Finally， a laser power density of 101.85 W/cm2 was selected for the printing of the functional gradient sample. The results indicated that the overall morphology of the samples prepared by the multi⁃step printing method was excellent， and their side angle increased from 40° to 80°. This greatly improved the precision of the printed shapes and dimensions.
SUN Ying, BAI Lin, REN Runhan, SHANG Wei, WENG Yunxuan
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139 )
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In this work， a high⁃performance liquid chromatography⁃mass spectrometry （HPLC⁃QQQ） method to establish to determine the migration of bisphenol⁃A in food⁃contact materials and validate the feasibility of the detection method of bisphenol⁃A by using coffee cups as a detection object. The determination of bisphenol⁃A migration in food contact materials could be realized through such a method with good repeatability， stability， within⁃day precision， and day⁃to⁃day precision. The quantitative limit was 0.10 mg/kg， the detection limit was 0.01 mg/kg， and the spiked recovery rate was 99.35 %. In the concentration range of 0~1.0 mg/L， the concentration of bisphenol⁃A is positively correlated with the peak area， exhibiting a good linear relationship. This method is simple， fast， and accurate in the quantitative and qualitative analyses and can meet the requirements of determination for the bisphenol⁃A migration in food⁃contact materials.
Additive
YANG Yang, HAN Yu, WENG Yunxuan, SONG Xinyu, HUANG Zhigang, ZHANG Caili
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134 )
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The epoxide functional groups of epoxidized soybean oil （ESO） were cross⁃linked with succinic acid （SA） through a ring opening reaction， and three types of epoxidized soybean oil⁃succinic acid copolymers （ESO⁃SA5， ESO⁃SA9 and ESO⁃SA13） with different molecular weights were obtained through regulating the reaction time， and their chemical structures were characterized. The thermal and mechanical properties of poly（vinyl chloride） （PVC） modified by using ESO⁃SA n as a plasticizer were studied， and the effects of the molecular weight and addition amount of ESO⁃SA n on the plasticizing effect were investigated. In addition， the effect of molding method （solvent casting film and melt pressing film） on the properties of plasticized PVC film was compared. Finally， the effect of thermal stabilizer on the properties of melt⁃pressing film was investigated. The results indicated that among the plasticized films prepared by different molding methods， the plasticized film containing 30 phr ESO⁃SA9 exhibited the best performance， including plasticizing effect， mechanical properties （elongation at break of 269.6 % and tensile strength of 28.7 MPa）， and thermal properties （initial thermal degradation temperature of 284.3 °C）. A better mixing effect between the PVC and plasticizer at a molecular level could be achieved. Owing to the poor compatibility between calcium⁃zinc stabilizer and matrix as well as the destruction of the plasticizing network structure formed by ESO⁃SAn in PVC， the addition of thermal stabilizer resulted in a decrease to some extent in the mechanical and thermal properties of the plasticized films.
Standard and Test
LI Tianhua, BAI Lin, SUN Ying
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154 )
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Taking polyethylene （PE） pellets， pipes， fittings， and carbon black masterbatch （PE， polypropylene） as research objects， the carbon black contents in different samples were determined by using traditional muffle furnace， tubular electric furnace， thermogravimetric， and microwave muffle furnace methods. The measurement results were analyzed， and the accuracy of these four methods for measuring carbon black content in polyethylene was investigated. The results indicated that thermogravimetric method had a high accuracy and good repeatability.
Plastic and Environment
ZHU Guangze, ZHOU Wei, XIA Zhidong, WANG Xiaolu, LI Bingyi, GUO Fu, WU Yufeng
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191 )
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In the paper， the main analytical methods used in the pyrolysis process of organic waste were reviewed. The types and influencing factors of thermal analysis were introduced， and the application of thermogravimetric analysis was focused. It was concluded that temperature rise rate， pyrolysis atmosphere， residence temperature， and residence time were the major factors for controlling the pyrolysis process. The pyrolysis kinetics and thermodynamics were summarized， and the model⁃free methods （FWO’s， KAS’， and Starink’s methods） and model⁃free methods （C⁃R method） was compared. The analysis methods for pyrolysis gas including thermogravimetric Fourier⁃infrared spectroscopic analysis， thermogravimetric mass spectrometric analysis， and pyrolytic⁃mass spectrometry chromatographic analysis were compared and summarized. Finally， the current problems of organic waste pyrolysis analysis technology and the prospect of future pyrolysis technology development were put forward from the perspectives of industrial production， pyrolysis mechanism， and pyrolysis product control.
SUN Wenxiao, YANG Fan, HOU Mengzong, HE Dandan, WU Hui, LIU Qiang, ZHANG Hong
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223 )
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The excessive use of plastic products and the recycling difficulty have led to most plastics entering the environment. The combination of biotic and abiotic factors changes their physical and chemical properties， causing serious microplastic pollution of the atmosphere， water bodies and soil. It even generates a certain degree of negative impact on humans. With an increase in the awareness of environmental protection， it is essential to find an efficient and eco⁃friendly method for plastic degradation. A lot of attention has been attracted by biodegradation because of its advantages of being green and free of secondary pollution. This paper summarized the sources and hazards of microplastics pollution in the atmosphere， water， and soil. The biodegradation and non⁃biodegradation of plastics and the enzymatic degradation mechanism of different types of plastics were further discussed. Finally， the future research direction of microplastics biodegradation was prospected.
Machinery and Mould
MA Xiuqing, LAO Zhichao, LI Mingqian, HAN Shuntao, HU Nan
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140 )
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Four types of screw configurations in the mixing section were designed for a co⁃rotating twin screw extruder using shear elements （KB⁃elements）， tensile elements （S⁃elements）， conventional threaded elements （SE⁃elements）， and mixed elements （SME elements）. The influence of screw configuration on the mixing effect of poly（lactic acid） PLA/ethylene⁃butyl acrylate⁃glycidyl methacrylate copolymer （PTW） blends was simulated and studied. The forward conveying ability， dispersion mixing ability， and distribution mixing ability of the screw configuration were investigated through employing the pressure difference between the inlet and outlet， weight⁃average shear stress， cumulative maximum shear stress， backflow rate， and cumulative residence time， respectively. The mechanical properties of as⁃prepared composite materials were studied using an experimental method. The results indicated that KB elements and SME elements had strong dispersion and distribution mixing abilities， and the PLA/PTW blends obtained a better mixing effect. Such a screw configuration could further improve the impact strength of the composite materials， whereas their tensile strength almost kept stable. At the same time， the simulation results were consistent with the experimental ones， indicating that the simulation can provide guidance for optimizing the screw configuration in the mixing section.
GAO Kun, YAN Wei, LIU Zhigang, ZHU Xiangzhe
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127 )
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Twin⁃screw extruders often have problems such as screw wear in the production process， which seriously affects the service life of the screw and the quality of polymer processing. The screw wear of twin⁃screw extruder was simulated numerically by using a discrete element method and Archard wear model， and the effect of screw speed and filling rate on the wear characteristics of twin⁃screw extruder was analyzed. The results indicated that the screw wear mainly occurred in the top area of the screw edge and the inlet of the feed， and serious extrusion wear occurred at the entrance of the material entering the barrel. The wear degree of screw increased continuously with an increase in the screw speed and filling rate. The screw in the rear conveyor section of the feed trough mainly produces transverse cutting wear， and the tangential accumulated energy is the key factor which leads to wear.
ZHOU Jiwei, WANG Mingwei, WU Di, ZHANG Wenchao, LIN Lianming, YU Junwei
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178 )
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According to the structural characteristics and molding requirements of the left and right window frame trim panels of an automobile tailgate， a pair of “one mold and two cavities” hot runner gas⁃assisted injection mold with a sequence valve control was designed. After the gating system was designed， the rationality of the gating system was verified by the CAE mold flow analysis， and the possible problems in the molding process were predicted. The lateral holes， inverted buckles， stiffeners， inverted buckles on the inner surface and concave features of the tail in the lateral area of plastic parts were more difficult for demolding. In this case， the demolding mechanism of “oblique guide column+slider” was designed for 4 side holes and 1 inverted feature in the lateral area. According to the characteristics of lateral stiffeners， the release mechanism of “hydraulic cylinder+large slider” was designed. The release mechanism of “oblique guide column slider” was also designed according to the concave feature of the tail. Meanwhile， the release mechanism of "inclined top block+inclined top bar" was designed according to the four inverted features on the inner surface. The ejection system was designed to use an ejection cylinder to provide the release force， and drives the combination of "ejector pin+straight ejector rod+straight top block" to participate in ejection. After actual production verification， the result indicated that the mold structure design was reasonable， the working process was stable and reliable， and the products could meet the design requirements.
Review
WU Liwen, QIAO Liang, FAN Junming, WEN Jiongming, LI Zhaopu, ZHANG Yi
Abstract (
186 )
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This paper reviewed the failure modes and failure criteria of polyethylene （PE） pipelines and summarized four pipeline life prediction methods， including the long⁃term hydrostatic test method， Arrhenius formula method， slow crack growth method， and hyperbolic constitutive equation method. Five pipeline risk assessment methods were summarized， which included expert scoring method， fault tree analysis method， pipeline index risk scoring method， and analytic hierarchy process and fuzzy comprehensive evaluation method. In the future， a finite element analysis model under the force⁃chemical coupling action should be established through combining with the big data analysis and pipeline risk assessment methods to ensure a safe operation for the in⁃service PE pipelines.
ZHOU Ziyu, SANG Xiaoming, GENG Xu, CHEN Xinggang
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155 )
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Thermosetting resins have excellent mechanical and thermal properties. However， they cannot be reprocessed and is difficult to degrade. The introduction of Schiff base into thermosetting resins and the achievement of plasticity and degradability of thermosetting resins through a dissociation mechanism have become a research hotspot of biomass materials. This paper introduced the synthesis methods of thermosetting resins with the Schiff base structure in recent years， enumerated the commonly used synthetic materials， and expounded the degradation mechanisms of the Schiff base structure. According to the structure of the Schiff base， different application fields were listed. Finally， the summarization was presented and the prospect was put forward.
LYU Chong, ZHU Wenwen, SHI Zhengxue, JIA Yingzi, JIANG Xueliang, YOU Feng, HUANG Ligang, YAO Chu, LIU Fangjun
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143 )
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In this paper， the action mechanisms of porous sound absorbing materials， multi⁃layered sound absorbing materials， composite porous sound absorbing materials， single⁃layered sound insulating materials and multi⁃layered sound insulating materials were briefly introduced from the aspects of polymeric sound absorbing materials and sound insulating materials. Based on the limitations of the performance of existing materials， the preparation methods of polymeric composite soundproofing materials and the ways to improve their soundproofing performance were reviewed in detail. Moreover， through combining with the literature， the preparation methods and acoustic properties of layered composite noise⁃reducing materials， environmentally friendly composite noise⁃reducing materials， and acoustic metamaterials were introduced to provide a direction for the future improvement of noise⁃reducing polymeric materials. Finally， a brief outlook on the development prospects of high⁃noise composite materials was presented.
MA Juncheng, XU Shuangping, WANG Xintian, JIA Hongge, ZHANG Mingyu, QU Yanqing
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160 )
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This paper reviewed the research progress in biomass⁃based materials used for iodine adsorption in recent years and introduced their classification in terms of their composition. Their synthesis methods， adsorption mechanisms， and adsorption effects were introduced， and their influence factors of iodine adsorption performance were summarized and evaluated， which included peak pyrolysis temperature， residence time， and activation methods. Moremover， the activation mechanisms of different activation methods for biomass⁃based materials in chemical activation methods were discussed. Finally， the future research directions of biomass⁃based materials in the field of iodine adsorption were presented based on a sustainable development concept.
