Materials and Properties
Chao LI, Chuangchuang TONG, Xin MENG, Zhong XIN
Abstract (
902 )
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Isotactic polypropylene (iPP)/zeolite and iPP/phosphate sodium nucleating agent (NA11)/zeolite compounds were prepared by a direct mixing method, and the effects of the type and content of zeolite on their crystallization temperature and mechanical properties were investigated. Furthermore, the synergistic effect from zeolite and organophosphates on the nucleation performance of the compounds was studied, and a kinetic analysis was performed for the crystalline improvement of iPP. The results indicated that the addition of zeolite improved the crystallization and mechanical properties of iPP significantly, and the type of zeolite was found to influence the performance of iPP. The ZSM?5?type zeolite could promote the formation of β?form crystal of iPP at the concentration over 5 wt%. The combination of zeolite and NA11 could further improve the mechanical properties of the compounds, and good rigidity and toughness were achieved for the compounds containing 0.1 wt% NA11 and 0.1 wt% 4A?type zeolite. The compounds gained an increase in flexural modulus by 35.2 % and in impact strength by 14.4 % compared to pure iPP, indicating a good balance between rigidity and toughness.
Ya ZHANG, Chao DING, Wenbo CHEN, Mingbo YANG
Abstract (
647 )
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431
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The mechanisms of phase separation and control method of multiphase system in the flow field were studied by capillary rheometer, and then a series of isotactic polyethylene (iPP)/polyethylene (PE?HD)/iPP trilayer blend membranes were prepared by a casting method according to a viscous encapsulation principle. The blend membranes with different phase structures were obtained by premixing iPP with PE?HD. The results indicated that the actual area of PE?HD in the blend membranes was 94 % and the porosity of blend membranes was as high as 51.82 %. The blend membrane containing 25 wt% iPP exhibited a more uniform distribution in pore size, and its macropore content was 84 % when the draw ratio reached 50 times. The study of formation mechanism for complex pores indicated that there was a complexity in the formation of intermediate layer in the blend membranes. Moreover, this work also confirmed the importance of crystalline structure and microporous morphology of the interfacial layer upon the properties of the blend membranes.
Cheng GUO, Zongli MA, Fengbo ZHANG, Xingbo SHI, Yanfang WANG, Shangtao CHEN, Xiaoyu MENG, Gongchen YAN
Abstract (
1121 )
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1155
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724 )
The rheological behaviors of fiber?grade polypropylene (PP)/propylene?ethylene copolymer (PEC) blends were studied by a capillary rheometer and rotational rheometer, and the effects of shear rate, temperature and blend composition on the rheological behaviors were analyzed. The results indicated that PP, PEC and their blends exhibited a shear?thinning behavior with an increase of shear rate. However, with the increase of temperature, the apparent viscosity of the blends gradually decreased especially at low shear rates. On the other hand, the non?Newton index of the blends tended to increase with an increase of PEC content, but their viscous flow activation energy decreased. This indicated that the sensitivity of viscosity to temperature decreased, and the melt shear modulus and melt elasticity increased.
Rui YANG, Zhengtao SU, Hongbo LI, Wenbo ZHAO
Abstract (
830 )
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518
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Polyimide (PI)/natural flake graphite (NG) composites were prepared by a hot?pressing technology, and their tribological properties as well as the morphologies of fracture and worn surfaces were investigated. The results indicated that NG was oriented in the direction perpendicular to the molding pressure in the PI matrix. When the load was constant and the sliding speed was low, the friction coefficient of the composites was reduced more significantly by the NG perpendicular to the friction surface than by that parallel to the friction surface. There was a reverse in this trend with an increase of sliding speed. Moreover, the transition point shifted to a low speed when the load increased. There was a tight relationship between the tribological properties and the morphologies of worn surfaces, and the smoother the worn surface, the lower were the friction coefficient and wear rate.
Xin PENG, Chunguang LONG, Ying PENG
Abstract (
991 )
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555
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The zinc aluminum alloy (ZA8)?filled PEEK composites were prepared by a compression molding method, and the effects of ZA8 content and the solid additives of graphite and polytetrafluoroethylene (PTFE) on their mechanical and tribological properties were investigated. The results indicated that the mechanical properties of the composites increased at first and then tended to decrease with an increase of ZA8 content. The composites achieved the maximum impact strength of 16.21 kJ/m2 and the tensile strength of 111.59 MPa at the ZA8 content of 10 wt%, which increased by 10.3 % and 3.9 %, respectively, compared to pure PEEK. Their friction coefficients exhibited a continuous decrease with an increase of ZA8 content and presented the minimum value of 0.275 at the ZA8 content of 40 wt%, which decreased by 38.6 % compared to pure PEEK. Moreover, the friction coefficient decreased by 38.6 % when 10 wt% of ZA8 content was incorporated into PEEK. At this content, the composites obtained the lowest abrasion loss of 7.2 mg, which was 43.3 % lower than that of pure PEEK. The addition of graphite and PTFE effectively reduced the abrasion loss of the composite. The optimum tribological properties were achieved by the addition of 10 wt% PTFE alone, and the composites gained a friction coefficient of 0.22 and an abrasion loss of 4.3 mg, which were 50.9 % and 66.1 % lower than those of pure PEEK, respectively.
Xiuqin YANG, Yaru YAN, Xiaolin ZHANG, Yanfei AN, Xiang YU
Abstract (
795 )
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530
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In this work, PET/TiO2@Ag blends were prepared by melt blending, followed by Ag loading, and their thermal, mechanical and photocatalytic properties were investigated by DSC, electronic universal testing machine and UV?visible spectrophotometer. The results indicated that the blends achieved optimum thermal and mechanical properties at the nano?TiO2 content of 3 wt%. The loading of Ag could significantly broaden the light response range of the blends. With an increase of Ag loading, the photocatalytic properties of the blends increased at first and then tended to decrease. The blends exhibited an optimum photocatalytic effect at the illumination time of 4 min. The content of VOCs in the blends decreased at first and then tended to increase with the illumination time and achieved a minimum value at 4 min.
Xiuling CHEN, Shanjun GAO, Chunhui SHEN, Hongsheng QI, Sawen LIU
Abstract (
1085 )
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556
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22 )
Konjac glucomman (KGM) nanocrystals were prepared by a hydrolysis reaction of KGM with sulfuric acid and then was modified by surface grafting with 3?(trimethoxysilylpropyl) octadecylammonium chloride and then by ion?exchanging with nonylphenol polyoxyethylene ether sodium sulfate to obtain a KGM nanocrystal fluid. The poly(vinyl alcohol)?based composite films containing different concentrations of KGM nanocrystals and their fluid were prepared by a solution?casting method, and their structures and properties were investigated by Fourier?transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis, and tensile test. The results indicated that the structure of KGM nanocrystals was not destroyed after surface modification, and their fluid was uniformly dispersed in the PVA matrix. The composite films achieved an improvement in initial decomposition temperature by 23 °C and in tensile strength 34.7 % when 3 wt% of KGM nanocrystal fluid was incoporated.
Jiaheng LIU, Dongqin WANG, Sheng HU, Weibing HU
Abstract (
905 )
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659
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Graphene oxide (GO)/attapulgite (AT) composites were prepared by a solution blending method. The effect of the mass ratio of GO/AT on the adsorption capacity of the composites was investigated, and the phase composition and microstructure of the composites were analyzed. The results indicated that the composites gained a maximum adsorption capacity when the mass ratio of GO/AT was 3/4, and their adsorption rate reached 93.06 %. The effects of adsorption time, the initial concentration of tetracycline hydrochloride, and the pH values on the removal of tetracycline hydrochloride from aqueous solution were further investigated, and the mechanism and process of tetracycline hydrochloride adsorption were explored. The adsorption behavior of the composites for tetracycline hydrochloride was found to comply with the Langmuir isothermal equation and quasi second?order kinetic model with apparent adsorption activation energy of 37.19 kJ/mol. This indicated that the adsorption behavior was dominated by electrostatic adsorption. Moreover, the adsorption process was determined as an endothermic, spontaneous and entropy increasing process in the temperature range of this study according to the important parameters of ΔHO=7.77 kJ/mol, ΔGO＜0 and ΔSO=57.62 J/(mol·K).
Processing and Application
Ranran JIAN, Zhonghe SHI, Yumei DING, Weimin YANG
Abstract (
843 )
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583
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In terms of the conservation equations of momentum and energy, the synergy effect from the velocity and temperature fields was proposed as an important influence factor on the flow and heat transfer of polymer. A novel torsion screw configuration and field synergy screw were designed, and the heat and mass transfer properties of conventional screw and field synergy screw were studied through extrusion experiments for the polypropylene/polystyrene compo?sites. The results indicated that the field synergy screws with a torsion screw configuration had a smaller average particle size, a larger particle size distribution density and a longer average residence time compared to the conventional screw. This can improve the mixing capability of the extruder. The field synergy screws had a larger convection heat transfer coefficient and a smaller radial temperature difference, which improved the heat transfer ability of the extruder.
Gang LIU, Nanhong FU, Xiaolong JIAO, Xiyu DOU, Yuxuan XU, Pengcheng XIE
Abstract (
699 )
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433
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The phenomenon of mold separation caused by a cavity pressure greater than the clamping force during the injection molding process has a significant impact on the quality of injection?molded products. Based on an all?electric three?plate elbow?bar injection?molding machine, the characteristics of mold separation during the injection molding process and the change in clamping force caused by the mold separation were systematically investigated. The results indicated that the change in clamping force could reflect the degree of mold separation during the injection cycle of the toggle injection?molding machine. Both the increment of maximum clamping force and the change of clamping force could be used as an indicator to measure the weight of injection?molded product.
Guo SONG, Yulu MA, Linsheng XIE, Huihao ZHU
Abstract (
829 )
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476
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30 )
Based on the FLUENT software, the VOF model was adopted to study the changes of the melt delamination in the flow channel when the four?layer melt was multiplied to the eight?layer one by a laminator under different wall slip degrees and flow channel structure parameters. The analysis results indicated that the reduction of the degree of wall slip led to the accumulation of the melt on the upper and lower wall surfaces. This led to an increase in thickness of the melt layer at the upper and lower wall surfaces. The three structural parameters of fillet radius between the confluence section and the exit section, expansion angle of the confluence section and length of the equilibrium section only affected the accumulation of the melt on the left and right wall surfaces and therefore inflenced the dimensional accuracy of the melt in each layer. The influence of the angle was most signficant, followed by the length of equilibrium section. However, the influence was least from the radius of the fillet.
Zhu LIU, Ziqian LIN, Hongping XIANG, Minzhi RONG, Mingqiu ZHANG
Abstract (
1193 )
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A type of thiol?functionalized MDT silicone resin (MDT?SH) with different molecular structures was synthesized by hydrolysis?polycondensation, and then the MDT?SH was mixed with vinyl?functionalized silicone resin and photo?initiator to prepare a UV?curable silicone resin. The UV?curing kinetics of this UV?curable silicone resin was studied, and its thermal stability, transmittance and package performance were analyzed in detail. The results indicated that the MDT?SH exhibited a more uniform molecular weight distribution and a higher yield when synthesized at the R/Si molar ratio of 1.88/1 and the thiol content of 0.34 mol/100 g. The UV?curable silicone resin with a TPO?L dosage of 1.0 % and an SH/Vi molar ratio of 1.5/1 could be instantly cured when exposed to UV irradiation at 80 mW/cm2. The UV?cured resin exhibited an excellent thermal stability and transmittance. The LED packaged by this UV?cured silicone resin also showed much better performance than those packaged by the Dow Corning OE?6550 commercial counterpart. The UV?curable silicone resin developed by this work shows a great potential in LED package in future.
Additive
Zhongying YAO, Yong QIU, Xisheng YANG, Zhen ZHAO, Lijun QIAN
Abstract (
1123 )
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1167
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This paper reviewed the recent research progress in the addition?type flame retardants based on 9,10?dihydro?9?oxa?10?phosphenanthrene?10?oxide (DOPO) for epoxy resins as well as the reactive flame?retardant curing agents involved in the reaction between the P—H bond and the C＝N, C＝O and C＝C bonds. The performance characteristics and relevant mechanisms of each flame?retardant system are summarized. Moreover, the future trend in development of DOPO?based flame?retardant epoxy resins was prospected.
Plastic and Environment
Yinghao XUE, Zhanxiang SUN, Xuehai JU, Bin XI, Tuo JIN, Tao JIA
Abstract (
1634 )
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2752
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This paper briefly introduced the history of degradable agricultural soil films, which could be classified into two categories: biodegradable and disintegrating soil films. The paper also summarized the composition, performance, degradation mechanisms, and agricultural applications of synthetic biodegradable, natural bio?based biodegradable, oxidation?catalytic and photosensitive soil films. Moreover, the existing problems and development direction of degradable soil films in China were discussed. These viewpoints provided a theoretical basis for the application of degradable agricultural soil films in a broader range in future.
Machinery and Mould
Zhongqi YI, Liucao HE
Abstract (
1252 )
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680
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This paper reported the structural design of a two?plate injection mold for the special?shaped plastic part of the rain deflector of automobile. This mold was designed on the basis of the difficulty in the complete demolding of the plastic part by the conventional slide core?pulling and inclined top mechanisms. Aiming at a breakthrough in the traditional design scheme, a core floating top side core?pulling mechanism was designed to realize the automatic injection production of the plastic part. In this mechanism, the plastic part and the part of the mold were ejected through an ejector plate and an ejector rod after the mold was opened, and then the plastic part was ejected from the local core through the side secondary ejection mechanism to realize the complete demolding. Such a design effectively simplified the mold structure, reduced the difficulty level in the processing and manufacturing of the mold and also reduced the manufacturing cost of the mold. The mold structure was complex and novel, but it was stable and reliable. This work provided a good reference for the innovative design of molds and mechanisms of special?shaped plastic parts.
Review
Zhanfeng MA, Wanjun JIANG, Sen YANG
Abstract (
1360 )
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913
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The paper reviewed the general situation about the plastic industry of China in 2019. The apparent consumption of plastics, the amount of plastic waste, the amount of recycled plastics and the utilization rate of recycled plastics in 2019 were analyzed on he basis of the data of plastic industry in China. Moreover, the relationship between plastics and environment was discussed.
Jingyu WANG, Jianwei HAO
Abstract (
899 )
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This paper introduced the application areas and combustion performance of plastics materials as well as the advantages of halogen?free flame retardants and furthermore focused on the demands of thermal insulation materials in the construction field for energy saving and environmental protection in China's emerging strategic industries. The paper also reviewed the recent research progress in halogen?free flame?retardant rigid polyurethane foam (RPUF) from several aspects including bio?based polyols, the combination of reactive and additive?type flame retardants, surface treatment technology, and catalyzing carbonization for inhibiting smoke and toxicity. Moreover, the paper summarized the problems in the application research and prospected the development trend in the application research of flame?retardant materials, which could provide references for further research and industrial application of flame?retardant materials.
Meilin ZHANG, Wenbin YUE, Xuzhi LANG, Xiaojun WANG, Jie YANG
Abstract (
1423 )
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2888
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This paper reported a comparative introduction and analysis on the homopolymerization?type and copolymerization?type semi?aromatic polyamides in terms of their classification, structure, and performance, and also introduced their production methods in industry by taking poly(hexamethylene terephthalamide) as a typical case. The current situation and development dynamics in the oversea industry of semi?aromatic polyamides were summarized according to the production capacity and programming of each manufacturer. Furthermore, the development status and existential problems in the industry of semi?aromatic polyamides in China were also discussed. Finally, the applications of semi?aromatic polyamides in the fields of electronic & electrical and automobile industries were introduced, and their development trend in future was prospected.
Xiaoqian DIAO, Yunxuan WENG, Xinyu SONG, Yingxin ZHOU, Ye FU, Zhigang HUANG
Abstract (
3506 )
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9211
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229 )
This paper introduced the latest development of biodegradable plastics industry in China and abroad as well as the applications of biodegradable plastics in fibers, daily expenses of membranes and bags, agricultural products and automobile industrial products. These biodegradable plastics included poly(lactic acid), polyhydroxyalknoates, poly(butylenes adipate?co?terephthalate), and poly(propylene carbonate). The present status of biodegradation detection methods and standards in China was analyzed in comparison with international standards. Moreover, the paper also reviewed the latest policies and rules in prohibition or limitation of the disposable products that are unrecyclable and easy to pollute the environments.
