Materials and Properties
JIA Mingyin, DONG Xianwen, WANG Jiaming, CHEN Ke
Abstract (
270 )
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In this paper， glass fiber reinforced polyamide 6 （PA6/GF） composites were prepared through anionic polymeri⁃zation of caprolactam and vacuum⁃bag press molding （VBPM）. The effects of parameters such as curing temperature and impregnation method on the monomer conversion， crystallinity， and mechanical properties of the composites were investigated using continuous fiber⁃reinforced polyamide 6 reactive injection as a self⁃built VBPM experimental platform. The results indicated that the composites fabricated by isothermal impregnation had a high degree crystallinity and good internal homogeneity. Compared to the isothermal impregnation， the non⁃isothermal impregnation promoted higher overall reaction conversion and better mechanical performance for the fabricated composites. Through the non⁃isothermal impregnation， the composites obtained at the outlet achieved an increase in bending and shear strength by 10 %~13 % and 11 %~16 % than that at the inlet， respectively. The bending strength of the composites obtained at the outlet reached a maximum value of 273.65 MPa at 150 ºC， and their maximum shear strength reached 47.32 MPa at 170 ºC.
ZHANG Lin, XIA Zhangchuan, HE Yadong, XIN Chunling, WANG Ruixue, REN Feng
Abstract (
275 )
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In this study， a cold atmospheric pressure plasma jet was conducted to modify glass fiber. To improve the interfacial bonding properties of glass⁃fiber⁃reinforced polypropylene composites， SiOx nanoparticles were polymerized on the fiber surfaces. The properties of the modified fibers and composites， including surface morphology， chemical composition， wettability and interfacial bonding properties， were studied systematically to understand the influence of gas flow rate of the carrier on the modification effect of glass fiber. The optimal parameter was determined to be a gas flow rate of 40 mL/min. The results indicated that after plasma treatment， the fibers achieved an improvement in the surface energy by 43.18 % compared to that of the control samples. The interlaminar shear strength of glass⁃fiber⁃reinforced polypropylene composites was improved by 30.79 % when compared to the control. The high surface roughness and the content of oxygen⁃containing polarity functional groups in the glass fiber after the plasma treatment promoted an enhancement in interlaminar shear strength.
GAO Yonghong, PENG Mengmi, JIN Qingping
Abstract (
306 )
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The purpose of this study is to investigate the influence of temperature and heating/cooling modes （monotonous heating， cycle heating， monotonous heating⁃natural cooling， and monotonous heating⁃rapid cooling） on the bond performance between glass fiber reinforcement polymer （GFRP） bars and concrete. Totally 90 GFRP bars with a diameter of 10 mm and the concrete pull⁃out specimens with two bonded lengths were subjected to the tests at a temperature ranging from 20 to 220 ºC. Totally 54 concrete cubic specimens were used to measure their ultimate compressive and tensile strength under the same conditions. The results indicated that the bond performance between the GFRP bars and concrete tended to deteriorate seriously with an increase in temperature under the two heating modes. The influence of monotonous heating on the degradation of bond strength was more significant compared to cyclic heating at a temperature below 120 ºC. When the temperature exceeded 120 ºC， the effect of heating mode on the attenuation of bond performance decreased. Under the two cooling modes， the bond performance between the GFRP bars and concrete seemed not to degrade significantly with an increase in temperature during the monotone heating⁃natural cooling process， whereas there was an evident degradation under the monotonic heating⁃rapid cooling process.
HUANG Jiawei, HAN Xiaolong, WU You, JIN Yujuan, WANG Zhao
Abstract (
276 )
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In this paper， the properties of poly（3⁃hydroxybutyrate⁃co⁃3⁃hydroxyvalerate） PHBV/bio⁃based engineering polyester elastomer （BEPE） compounds were studied through analyzing their rheological properties， crystallization properties， mechanical properties， thermal properties， and microstructure. The results indicated that the number of PHBV spherulites increased along with a decrease in their size due to the hydrogen bonding， chain entanglement， and similar main chain structures between PHBV and BEPE， resulting in better compatibility and dispersion. When 30 wt% BEPE was added， the compounds achieved maximum elongation at break and impact strength， increasing by 589.2 % and 149.4 %， respectively， compared to pure PHBV. The crystallinity of the compounds decreased with the addition of BEPE， and their impact fracture surface tended to be rough along with a “brittle⁃ductile” transition according to the morphological observation.
CHEN Shuhua, REN Zimeng, SUN Tingting
Abstract (
393 )
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The adsorption films based on chitosan （CS）/chitosan⁃g⁃graphene oxide （CS⁃g⁃GO） composite aerogels were prepared through vacuum freeze⁃drying at different mass ratios of two raw materials， and their physical and chemical properties were investigated using SEM， FTIR， and contact angle meter. The results indicated that the filtration efficiency of the composite aerogels reached 94.1 % for PM2.5 filtration at a WCS mass of 0.155 6 g and a grafting rate of 76.04 wt% for CS⁃g⁃GO， which increased by 4.4 % compared to the aerogels without CS⁃g⁃GO.
YANG Jin, CHEN Pengran, GAO Peixin
Abstract (
392 )
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For the epoxy foams prepared using a room⁃temperature foaming method with hydrogen as an air source， the carbon layer formed on the surface of the foams is more easily damaged during the combustion process. The damaged carbon layer cannot effectively isolate heat and oxygen， leading to poor fire resistance. Flame⁃retardant In this work， a type of flame⁃retardant epoxy foams was prepared using p⁃phenethyl bridge⁃chain 9，10⁃dihydro⁃9⁃oxa⁃10⁃phosphaphenanthrene⁃10⁃oxide （DIDOPO）， polymethylsilsesquioxane （POSS）， and expandable graphite （EG） as flame retardants. When the mass ratios of DIDOPO to POSS and DIDOPO to EG were set to 3∶1 and 1∶3， respecitively， the epoxy foams obtained an optimal flame⁃retardant effect. With the addition of 20 wt% DIDOPO/POSS composite flame retardants， the epoxy foams achieved a UL 94 V⁃0 classification in the vertical burning test. The addition of 20 wt% DIDOPO/EG composite flame retardants enabled the epoxy foams to obtain a limiting oxygen index of 30.8 vol% together with a UL 94 V⁃0 classification for their flame⁃retardant level. This foaming system also exhibited a certain smoke suppression effect.
ZHANG Mengxing, LIU Rangtong, LI Liang, LI Shujing, LIU Shuping
Abstract (
360 )
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An absorbing coating fabric was fabricated by coating a micron⁃copper⁃powder⁃doped polyurethane （PU） layer on the cotton fabric. The structure and performance of the coated fabric were investigated using scanning electron microscope， infrared spectrum， and vector network analyzer. The results indicated that the real and imaginary parts of the dielectric constant increase in the band range of 8~13 GHz with an increase in the copper powder content in the coating. This suggests that the copper powder generated good dielectric properties for the coating due to the presence of polarization under the applied electric field， producing dielectric loss to the electromagnetic wave. Copper powders do not belong to a magnetic loss material， resulting in a small magnetic loss to electromagnetic wave. The absorption and electromagnetic shielding performance of the coating materials were weak at a small weight fraction of copper powder （3 wt%）. When the content of copper powder increased from 5 wt% to 11 wt%， the lowest reflection losses of the coated fabric were -20.4， -28.3， -25.6 dB at 9.0， 10.5， 12.8 GHz， respectively， and its effective absorption bandwidths were 0.2， 1.3， 1.1 GHz. The electromagnetic shielding efficiency increased from 12.24， 16.59， 21.1 to 25.92 dB.
SONG Dejian, YU Peng, PENG Jinsong, XU Miaojun
Abstract (
423 )
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In this article， a flame⁃retardant ethylene⁃vinyl acetate copolymer （EVA） hot⁃melt adhesive for quickly repairing aging cables was prepared， and the aluminum diethylphosphinate， dimelamine pyrophosphate and aluminum hydroxide were selected as flame retardant additives. EVA hot melt adhesive passed UL 94 V⁃0 rating without dripping and the limiting oxygen index was 27.1 vol% when the total loading amount of flame retardants was 50 wt% with the mass ratio of the above three flame retardants was 1：1：3. Compared with the pure hot melt adhesive， the heat release rate and total heat release of the prepared flame retardant hot melt adhesive was greatly reduced， and the flame retarded system exerted excellent synergistic flame retardant effect. The volume resistivity of the repared cable reached 3.12×1015 Ω·m. Moreover， the hot⁃melt adhesive exhibited excellent film⁃forming and adhesion on cable surface， and it will not crack or fall off during the bending process of the repared cable. The intumescent char layer is gererated on the cable surface and it can effectively protect the cable during combustion.
Processing and Application
MIAO Dan, SONG Yuping, WANG Wenqian
Abstract (
726 )
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This article introduced the status of China’s blow molding and upstream industries from the aspects of raw materials and blow molding machines. The article also analyzed the prospects of ultra⁃purity drums for electronic chemicals， type⁃IV hydrogen storage vessel， all⁃electric blow molding machine， foaming solution for blow molding， and extrusion⁃blow⁃molded PET containers during the period of “14th Five⁃Year Plan”.
YANG Bo, YANG Zhen, ZENG Chen, WANG Zhigang, ZHAI Wei, CAO Fuxiang
Abstract (
312 )
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In this paper， a cyclic loading circular bar （CRB） test was conducted to measure the corresponding relationship between the crack growth rate da/dt and stress factor KI of three types of PE materials A， B and C at loading ratios of R=0.1， 0.3 and 0.5， respectively. Through using the theory of linear elastic fracture mechanics of polymer materials in the condition by extrapolating to R=1 （static load）， the failure time tf of PE pipes with defects was obtained. The results were compared with those obtained form full notch creep test （FNCT）. When there was an initial crack defect at aini=0.4 mm on the inner wall of the three PE pipes， the failure lifetimes of extrapolated tubes obtained from the CRB test were 44， 53 and 65 years for the PE pipe A， B and C， respectively. The extrapolating results of FNCT were 53， 59 and 79 years for the PE pipe A， B and C， respectively. The test results indicated that the lifetime prediction results of CRB and FNCT had a good positive correlation， and their deviation was small. The experimental results confirmed the availability of the method.
HU Xuechuan, FANG Jiahao, LI Youbing, ZHOU Jianjun, LI Li, ZHANG Jixiang, DENG Yajun, LIU Yuan
Abstract (
497 )
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Aiming at the possible lack of material， air trapping and bleached appearance defects such as gradient in the free spray specular injection⁃molded grid with a complex curved surface， an optimization was conducted for the design methods based on the Moldflow software. These methods included the optimization of the local wall thickness and the placement sequence valve hot runner system as well as the change of the local melt flow direction. As a result， the production of appearance defects was eliminated， and the optimal surface quality of the product appearance was achieved. This greatly reduced the scrap rate of products and saved the manufacturing costs.
MA Chao, MA Lanrong, WEI Liao, YIN Huibo, LIN Xiang
Abstract (
480 )
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This paper introduced the basic principles of modification methods and principles for the processing process of poly（glycolic acid） （PGA） from the aspects of its physical properties， processing techniques， and practical applications. The paper mainly reviewed the current research progress in modification methodologies through plasticization， toughening， and copolymerization， including the usage of different additives such as compatibilizer EMA⁃GMA， chain extender ADR and plasticizer. The effects of these additives were concluded and compared. The compatibility of varied toughening agents with PGA material and the strengthening technology of interface mutual diffusion were discussed. Finally， the modification rules for PGA processing as well as its application performance were summarized.
DONG Yue, DONG Xiao, ZHU Dezhao, YANG Yanxiang, LUO Chen, LI Yang, LI Jinshan
Abstract (
2290 )
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This article reviewed the development and research progress in polyimide （PI） all over the world. The key preparation technologies and application fields of PI are introduced according to the main products such as film， slurry， resin， fiber and foam. Through analyzing the gaps of R&D and production status between the domestic and foreign countries， the future development trends and research focus of PIs were proposed.
Additive
MENG Xin, WANG Xiaolong, GONG Weiguang, JIN Yi
Abstract (
403 )
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Two types of three⁃sources⁃in⁃one shell⁃core structural flame retardants， ammonium polyphosphate （APP）@chitosan （CS）@halloysite （HNT） （ACH） and APP@CS⁃Fe@HNT （ACFH）， were prepared through a self⁃assembly method using water as the solvent， APP as a core， and CS/ferric chloride/HNT composite as a shell. ACFH was employed to improve the flame retardancy of PLA. The composition and structure of ACFH were analyzed using scanning electron microscope and thermogravimetry （TG）. The flame retardancy of PLA composites was characterized using limi⁃ting oxygen index （LOI）， vertical combustion （UL 94）， cone calorimeter （CCT）， and TG⁃FTIR. The results indicated that the flame retardancy of the PLA/15 %ACFH composite was better than that of pure PLA and the PLA/15 %ACH composite. The PLA/15 %ACFH composite exhibited the highest LOI value of 29.5 vol% with a UL 94 classification of V⁃0. Compared to pure PLA， the PLA/1 5%ACFH composite presented a decrease in peak heat release rate and total heat release by 33.5 % and 22.0 %， respectively， and its residual char yield increased by 12.5 wt%. ACFH mainly generated a flame⁃retardant effect in the condensed phase， promoting the formation of a large number of continuous and dense carbon layers in the PLA matrix. The resulting carbon layers acted as a barrier to inhibit the diffusion of oxygen and heat.
Plastic and Environment
LI Menglu, SU Tingting, WANG Zhanyong
Abstract (
663 )
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Poly（ethylene terephthalate⁃co⁃butylene adipate） （PBAT） was prepared through transesterification using waste poly（ethylene terephthalate） （PET） as a raw material. The structure and compositions of the PBAT products were determined by nuclear magnetic resonance and infrared spectroscopy， and their thermal properties were investigated using TGA and DSC. The contact angle of PBAT was measured by a five⁃point method， and their tensile properties were measured using a universal test machine. The results indicated that there was no thermal decomposition occurring below 300 ºC for the PBAT products. This is an indication of good heat resistance. The PBAT developed in this work exhibited a contact angle of 78.54º， indicating a good hydrophilic nature. Moreover， the PBAT presented elongation at break of over 900 %， indicating a good application potential.
MA Guocheng, HE Zhen, CHEN Shaojun
Abstract (
1061 )
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This paper introduced the degradation mechanism and research status of cellulose acetate biodegradation， hydrolysis， and photolysis. The factors that affect the degradation rate of cellulose acetate were explored. Based on the current studies， the molecular structure of cellulose acetate was the main factor that affects the degradation rate of cellulose acetate. The physical modification， chemical modification， and plasticizing modification affected the degradation performance of cellulose acetate through changing the molecular structure of cellulose acetate. Finally， the application fields of acetate fiber were summarized and its prospect was analyzed.
QUAN Shumiao, ZHANG Yanjun, SONG Xiaofei, DU Runping, YU Dan
Abstract (
526 )
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The chemical recycling of waste plastics has become a research hotspot. However， in the chemical recycling process of the waste plastics containing chlorine， the chlorides are highly corrosive to the production equipment. This leads to the environmental pollution as well as a reduction in product quality. Through the analysis of the current relevant emission standards for chlorine content in our country， the development of dechlorination technology is recognized to be an important way to improve the chemical recycling process of waste plastics. At present， the domestic and foreign dechlorination technologies mainly include sorting， machinery， solvent dechlorination， step⁃by⁃step thermal decomposition， adsorption， and catalysis technologies. The characteristics， reaction mechanisms， and industrial applications of various dechlorination technologies were introduced in detail. Moreover， the advantages and disadvantages of each technology were analyzed and compared. A combined dechlorination technology was proposed to accelerate the development of chemical recovery process of chlorine⁃containing waste plastics.
Standard and Test
HE Anqi, HUANG Jian, ZHANG Ying, SUN Huali, XIANG Aimin, XU Haiyun
Abstract (
400 )
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This paper analyzed the differences between the standard systems and grading requirements of plastic pressure pipes in China （GB）， America （ASTM） and Europe （ISO）. The GB standard system of China has the same requirements with ISO （Europe） standard system， but there are some differences with the ASTM standard system of America. However， the principle of long⁃term performance evaluation of polymer pipes is the same for three parts. This paper introduced the pressure design basis of PVC⁃pipe and grading curve of mixed materials of the pipes according to the ASTM D2837， ISO 9080， and GB 182525 standards. According to the GB/T 39380.1—2021 standard， the determination of qualification for the grading curve of PVC⁃C pipe mixture for fire sprinkling was clarified. The standards of PVC⁃C fire pipe at home and abroad were compared. The specifications， dimensions， pipe wall thickness， and other performance requirements were almost same for the Chinese national and American standards. The piping system in accordance with the national standard GB/T 39380 can guarantee the safe use at 20 ºC for 50 years under the fire pressure design conditions in China.
LIN Jianhui, LU Jiahui, WU Xinying, FAN Xueying, DENG Guirong, GAO Liang, MEI Chengfang, YANG Yonggang
Abstract (
347 )
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There is no relevant literature report about the evaluation of uncertainty in degradation performance test of degradable plastic. A measurement uncertainty of the ultimate aerobic biodegradability of materials was evaluated under controlled composting conditions of Dt. After the normalization and visualization of uncertainty components according to the combination， the main uncertainty components of frepeatability of test group， frepeatability of blank group， MC round， frepeatability of TC， and mTC were confirmed. The main uncertainty components of the three A⁃class uncertainties of frepeatability of test group， frepeatability of blank group andfrepeatability of TC were concentrated after the optimization， and the other uncertainty components could be ignored. The standard uncertainty of Dt could be calculated quickly by three A⁃class uncertainties after simplification. This concluded more than 90 % of the uc （Dt） by holistic computation and provided the example for the evaluation of the uncertainty in degradation performance test of degradable plastic.
LI Yan, TANG Xiaoxu, ZHANG Weijie, HUANG Ruipeng, ZHANG Shan
Abstract (
511 )
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In this paper， the three failure modes of pipes were summarized and the molecular mechanism and fracture mechanics mechanism of slow crack growth were briefly described. The principle and test process of the strain hardening modulus （SH） method were introduced in detail. The paper also reviewed the research progress in the correlation of material microstructures， the domestic and foreign reliability research of SH method for the evaluation of the slow crack growth resistance of pipes， and the application of SH method for the evaluation of the environmental stress cracking resistance of materials. Finally， the applications of SH method for the control of outlook on product quality was discussed.
Review
LI Juan, LI Ying, GUO Xiaolin, ZHANG Chen
Abstract (
478 )
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The production process of extruded polystyrene foam （XPS） prepared by carbon dioxide（CO2） foaming technology was briefly introduced. Through the analysis of safety production， the hidden dangers of the foaming agent storage area and the high⁃pressure pump room were described in detail， and the possible release position and release probability of the flammable foaming agent in the process were indicated. The safety measures for the foaming agent storage area， the high⁃pressure pump room and the production workshop were given， mainly involving the detection and alarm system of flammable gas， the ventilation system， the fire protection system and anti⁃static system.
YANG Chaoyong, GUO Jinqiang, WANG Fuyu, ZHNAG Yuxia
Abstract (
628 )
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This paper introduced the properties of six high⁃performance resins， including poly（ether ether ketone）（PEEK）， poly（phenylene sulfide）（PPS）， liquid crystal polymer（LCP）， poly（etherimide）（PEI）， polysulfone（PSF）， and polyimide （PI）. The preparation processes and modification methods of the films based on these six respective resins were discussed in detail， and their applications were prospected.
XU Yuxuan, DANG Kaifang, FU Nanhong, JIAO Xiaolong, XIE Pengcheng, YANG Weimin
Abstract (
445 )
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This paper introduced the research progress in the self⁃adaptive optimization technology of plastic injection molding process. The research progress in the self⁃adaptive optimization of injection molding by domestic and foreign scholars was summarized， which included the analysis and quantitative characterization of changes in the physical and quality parameters of polymer melts as well as the adaptive optimization of plastic injection molding process. The exis⁃ting problems were discussed and the future research directions were prospected.
SONG Danyang, ZHENG Hongjuan, LI Yilong
Abstract (
442 )
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261
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A new type of poly（lactic acid） （PLA） oil⁃water separation material with super hydrophobic， super lipophilic and biodegradable characteristics was introduced. The research and application status of pure PLA and PLA⁃based oil⁃water separation materials were compared and analyzed. The preparation of oil⁃water separation films using PLA as a main raw material or matrix material not only can achieve an ideal oil⁃water separation effect， but also can be recycled for many times after post⁃treatment. The PLA⁃based oil⁃water separation material can be considered as one of the ideal oil⁃water separation materials at present. Finally， the future development direction of PLA in the field of oil⁃water separation was proposed.
LI Zhuolin, MU Wenying, DING Yumei
Abstract (
549 )
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This paper reviewed the application status and existing problems of medical radiation protective clothing based on the relevant standards and requirements of different application scenarios. The preparation methods of radiation protective clothing were highlighted， which included spinning， coating， and hot pressing methods. The research status of lead⁃free radiation shielding composite materials was also prospected according to the different lead⁃free shielding materials such as rare earth elements， tungsten， bismuth， carbon nanotubes， polyimide， and polyether ether ketone.
