Materials and Properties
WANG Yu, SUN Wenjie, MA Yulu, XIE Linsheng, JI Huajian
Abstract (
845 )
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Polypropylene （PP）/Polyamide 6 （PA6） microfibrillar composites were prepared by melt extrusion-hot stretching with maleic anhydride-grafted PP （PP-g-MAH） as a compatibilizer， and their phase morphology and crystallization， rheological and tensile properties were investigated. The results indicated that the addition of 0.5 % PP-g-MAH （mass fraction） was beneficial to the formation of PA6 microfibrils with a high aspect ratio. A further increase in the content of PP-g-MAH improved the interfacial compatibility but hindered the formation of the microfibrils. The PP/PA6 microfibrillar composites containing 0.5 % PP?g?MAH presented a strong elastic response in terms of the dynamic rheological properties， leading to an obvious improvement in the crystallization and tensile properties of microfibrillar composites.
HE Yintong, LIANG Jiaqi, LIU Lubin, XU Yue, WANG Kezhu, YU Hang, WANG Shuhui, XU Miaojun
Abstract (
718 )
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457
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A flame retardant， piperazine-1，4-dialkyl bis（diphenylphosphine oxide） （PPDO）， was successfully synthesized with diphenylphosphinyl chloride and piperazine as raw materials and then was incorporated into epoxy resin （EP） to prepare flame-retardant EP compounds. The flame retardant performance， thermal decomposition behaviors， combustion behaviors and mechanical properties of the resultant EP compounds were investigated extensively by vertical burning test， oxygen index test， thermogravimetric analysis， cone calorimeter and mechanical performance tests. The results indicated that the EP compounds achieved the UL 94 V-0 classification as well as a limiting oxygen index of 28.9 vol% with the addition of 17 wt% PPDO. After the water resistance tests， the EP compounds still kept high flame-retardant efficiency due to the good hydrophobic properties of PPDO. Meanwhile， the EP matrix exhibited excellent compatibility with PPDO， leading to the good transparency and mechanical properties of the EP compounds. In addition， the introduction of PPDO significantly promoted the premature degradation and char formation of the EP matrix， resulting in the formation of a dense and stiff expansion protective char layer during the combustion process. This effectively reduced the total heat release of the EP compounds and endowed them with satisfactory flame retardant properties.
ZHONG Luohao, KUANG Tangqing, LAI Jiamei, LIU Hesheng, LAI Dewei
Abstract (
868 )
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593
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A series of short-glass-fiber-reinforced polypropylene bending pipes were prepared via gas-assisted injection molding （GAIM）， water-assisted injection molding （WAIM）， gas-projectile-assisted injection molding （G?PAIM） and water-projectile-assisted injection molding （W?PAIM）. The effect of different molding processes on the residual wall thickness （RWT） and orientation distribution of glass fibers was investigated comparatively. The results indicated that the overall RWT of the pipes decreased by an order of GAIM > WAIM > W-PAIM > G-PAIM， and the difference of RWT between G-PAIM and W-PAIM pipes was small. The RWT variance of the pipe fittings obtained from the four forming processes was small， and the uniformity of the RWT was good. The glass fiber orientation of the WAIM pipes was generally higher than that of the GAIM. The introduction of projectile made the pipe fittings a higher orientation along the flow direction.
ZHANG Bo, WANG Xiaofeng, GUO Meng, BAI Zhiyuan, REN Cuihong, HAN Wenjuan, UYAMA Hiroshi, LI Qian
Abstract (
949 )
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1245
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The oxygen?containing functional groups such as carboxyl groups were generated on the surface of poly（lactic acid） （PLA） by means of methyl oxidation through ultraviolet?activated sodium chlorite free radicals （ClO·）. This can enhanced the hydrophilicity and cytocompatibility of the PLA surface. The surface element composition， optimum oxidation condition， and influence of oxidation reaction on the surface hydrophilicity of PLA were investigated by X?ray photoelectron spectroscopy and contact angle analysis. The effect of oxidation process on the mechanical properties of PLA was analyzed through a tensile test. The biocompatibility of the surface?modified PLA was studied by cell proliferation and cell activity tests in vitro. The experimental results indicated that the oxygen?containing functional groups such as carboxyl group were successfully generated on the surface of PLA. The optimal oxidation time and temperature were determined to be 10 min and 90 °C， respectively. Under such a condition， the surface contact angle of the oxidized material decreased from 82 ° to 62.5 °， but its surface hydrophilicity was improved. The surface?modified PLA exhibited the unchanged tensile strength and a slight decrease in elongation at break. After oxidation， the surface of PLA showed better cell adhesion and cell proliferation， which was more beneficial to the growth of cells.
WANG Chenlei, HU Hao, QIAO Wenyu
Abstract (
750 )
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528
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The PET wire material was prepared by selecting poly（ethylene terephthalate） （PET） as a matrix using PBT as a compatibilizer along with a toughening agent and a nucleating agent. It was found that the wire material obtained at a PET/PBT weight ratio of 7/3 presented the lowest melt flow rate. The addition of too much compatibilizer resulted in bridging at the screw inlet， which was disadvantageous to screw extrusion. The results obtained from the 3D printing and mechanical measurement indicated that the wire material could be normally printed at a content of toughening agent of 15 phr. The printed specimen exhibited a smooth surface without any warps. The wire material achieved tensile strength of 25.95 MPa， bending strength of 45.99 MPa， and impact strength of 50.4 kJ/m2. The addition of 0.5 phr talc can improve the mechanical strength of the material better.
ZHANG Yijun, ZHANG Ruizhi, GUO Chengcheng, SHEN Qiang, LUO Guoqiang
Abstract (
973 )
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585
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Compared to homogeneous foams， the density-graded foams have significant advantages such as lighter weight and better energy-absorption efficiency. To investigate the influence factors of the energy-absorption characteristics of density-graded foams and optimize their design， this paper focused on a microcellular energy-absorption foam based on poly（me-thyl methacrylate） and carbon nanotubes. A graded foam model was established with an equal interlayer density difference. Through the nonlinear phenomenological constitutive model fitting of a constitutive equation under the quasi-static compre-ssion， the distribution features and corresponding advantages and disadvantages of energy absorption efficiency of the foam model were calculated under different loads. The influence rules of interlayer density difference， upper and lower density differences and thickness graded rule of foam layer on the energy absorption efficiency of the foam model were studied. The results indicated that the foams with interlayer density differences of 25 kg/m3 and 50 kg/m3 exhibited a better energy absorption capability. With reducing the upper and lower density difference， the peak of energy absorption efficiency increased， but the energy absorption efficiency at lower loads decreased. The peak of energy absorption efficiency increased with an increase in the thickness of the foam layers， whose density was closer to the apparent density. Based on the experimental results， an optimal graded foam model was established， leading to a peak value of 0.326 for energy absorption efficiency as well as a better energy absorption capability than homogeneous foam within the loading range of 15 MPa. These results can provide an important guiding significance for the design of density gradient materials for energy absorption.
YANG Li, CHEN Yuan, DING Feng, XU Zhenzhen
Abstract (
691 )
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731
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To analyze the effect of hybrid ratio on the mechanical properties of intralayer hybrid composites， an aramid/carbon fiber-hybrid-reinforced fabric was prepared by interweave， and the blending ratio of carbon fiber in the reinforcement structure was adjusted by the ratio of aramid fiber to carbon fiber in the weft yarn system. The aramid/carbon fiber?reinforced epoxy composites with a hybrid structure were prepared by vacuum assisted molding， and their tensile， flexu?ral and impact properties were investigated. The results indicated that the heterogeneity of aramid and carbon fibers in the latitudinal reinforcement system had a negative effect on the tensile strength of the composites in the warp direction. The increase of hybrid ratio could inhibit the tensile and bending damage of the composites. In the weft direction， the tensile strength and bending strength of the composites increased by 6 and 4.04 times. The synergistic effect of aramid and carbon fibers leads to an improvement in the impact resistance of the composites as well as an optimal hybrid ratio.
LI Peiqi, LI Xingong, SI Shuang, ZHANG Shusen, LIU Chunhua, CHEN Miaowen, HUANG Qinqin
Abstract (
567 )
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627
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Aiming at improving the additional value of traditional wood plastic materials， a novel type of luminescent wood plastic composites （WPC） was prepared by a combination of alkaline earth aluminate and conventional WPC. Such a combination not only endowed the material with special properties， but also solved the problems such as poor weather resistance and the easy hydrolysis of alkaline earth aluminate. The mechanical and luminescent properties of the luminescent WPC were investigated. The relationship between the internal bonding and the luminescent properties was analyzed by scanning electron microscopy and steady?state fluorescence spectroscopy. The results indicated that the optimum technological parameters of the luminescent WPC were determined to be a PP content of 70 wt%， a residual material ratio of 1∶1.5， a coupling agent content of 1.5 %， and a hot pressing time of 10 min. The WPC achieved the maximum tensile strength of 22.2 MPa and impact strength of 12.55 kJ/m2. The luminescent WPC presented an optimal excitation region of 380~450 nm， which completely coverd the optimal excitation band of 400~440 nm from the luminescent salts. This indicates that the luminescent WPC had a wide excitation band and a wide application range. Luminescent salts can effectively emit light in the interior of the luminescent WPC， and there is no chemical effect on alkaline earth aluminate in the processing procedure.
CHEN Yanfei, LI Shupeng, WEI Wanchu, LI Bo, YU Yan
Abstract (
997 )
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The tensile and impact properties of polypropylene （PP）/recycled PP（RPP） blends were investigated in terms for the application requirement for automobiles， and their aging properties were also evaluated under the aging condition in a 100 °C hot air for 1 000 h. There was little effect on the tensile strength and impact strength of the blends at weight fractions of RPP less than 20 wt%. The tensile strength and impact strength of the blends decreased with an increase in the content of RPP， when the properties of pristine PP were superior to those of RPP. The blends exhibited a decrease in tensile strength and impact strength at first and then presented an increase trend when their properties were superior to those of RPP. However， the blends presented minimal tensile strength and impact strength at a PP/recycled PP weight ratio of 50∶50. The tensile strength and impact strength presented an upward trend after aging at 100 °C for 1 000 h，especially for the impact strength.
XU Jiayi
Abstract (
713 )
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411
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Hypromellose （HMC） was used as an impact modifier to prepare Poly（lactic acid）（PLA）/HMC composites by melt blending. The rheological， mechanical and crystallization properties of the composites were analyzed systematically. The results indicated that the composites exhibited a decrease in apparent viscosity with increasing shear rate， temperature and HMC content. HMC were uniformly dispersed in the PLA matrix due to good compatibility between PLA and HMC. The composites achieved the maximum elongation at break and impact strength at an HMC content of 10 wt%， indicating a good toughening effect on PLA. However， their tensile strength decreased gradually with an increase in the content of HMC. HMC could reduce the crystalline properties of the composites， resulting in a gradually decrease in their melting points and crystallinity with an increase in the content of HMC.
ZHANG Yihui, CHEN Shihong, WANG Conglong, WANG Xiangdong
Abstract (
673 )
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341
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Polyetherimide （PEI） foams were prepared by a batch foaming method using supercritical CO2 as a foaming agent. The effects of foaming temperature， foaming pressure， and foaming time on the foaming behavior of PEI were explored under the homogeneous nucleation condition. The PEI microcellular foam materials with a composite foaming structure were preparing by a two?step depressurization batch foaming technology. The results indicated that the foaming rate of PEI microcellular foams was improved by the composite foaming structure. The first pressure drop and the second holding time were consi?dered as two key factors that influenced the cell structure.
Processing and Application
JIANG Hong, ZHANG Lanze, LIU Jintong, YUAN Zhihao
Abstract (
538 )
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344
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A fast clustering method was established for plastic steel window samples with unknown product information under the three indicators including product source， brand， and use purpose. The element contents of 40 plastic steel window samples with different brands， different use purposes and different sources were analyzed by X?ray fluorescence spectrometry and a handheld fluorescence spectrometer under the experimental conditions of Ag as anode target， voltage of 50 kV， current of 200 μA and acquisition time of 70 s. According to the experimental results， the index elements of Pb， Ti， Cl with species difference were selected. Through calculating the sum of standard deviation of the samples and considering the relative significant relationship among the brand， source and use purpose， the clustering results of 40 samples of plastic steel windows were obtained. This method can provide a new model for the clustering of samples collected in field investigation， indicating a certain practical significance.
LU Jing, WANG Wei
Abstract (
619 )
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320
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With the help of two differential viscoelasticity constitutive models， i.e. DCPP model and S?MDCPP model， the complex rheological behavior of branched polymer melts was described， and the problems of convection dominance and the lack of elliptic operators in the process of viscoelastic flow were solved by means of the discrete viscoelastic stress splitting method and upwind streamline method. A pressure-stabilized iterative fractional step scheme based on the finite incremental calculus method was used to solve the mass and momentum conservation equations. The flow behaviors of PE-LD melt in the capillary and extrusion swell were simulated， and the simulation and experimental results were compared. The results indicated the extrusion-swelling ratio and wall shear stress predicted by the model at low shear rate were close to the experimental results. The velocity， stress and backbone stretch predicted by the two models were also in good agreement with the experimental results. This indicates that the two models can well predict the complex rheological behavior of PE-LD melt in capillary and the algorithm is reliable to be used to resolve the S-MDCPP model.
JIANG Ruitao, WU Zhifeng, WANG Zhiwei
Abstract (
687 )
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577
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6 )
A leak tightness experiment was performed for the steel-plastic-transition joint parts with different structures after tensile tests. The results indicated that that wall thickness of the joint parts had an influence on the leak tightness between the steel and high-density polyethylene （PE-HD） after tensile loading. When the wall thickness in the PE-HD part became smaller， the joint was more easily subject to yielding， pulling-out， rupture， or leakage. Meanwhile， the low?height anti-pulling-out gear structure of the steel part was more easily subject to pulling-out and leakage on the transitions with larger sizes. The transitions made from injection?molded PE-HD parts or PE?HD pipe segments with higher standard dimension ratios were found to exhibit better performance than those made from common PE?HD pipe segments. The first two types had higher safety margins and better stability at a low temperature and under the creeping process of PE?HD with extreme circumstances.
ZHUANG Wei
Abstract (
901 )
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706
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This paper introduced the production technology for the extrusion molding of polyamide corrugated tubes and analyzed the factors affecting the quality of polyamide corrugated tubes. These factors include the raw material moisture content， drying time， molding temperature and speed， and mold design. The method for determination of the diameter of tube tools， and the calculation formula of pin diameter was emphasized. The start?up procedure of the extrusion molding， the precautions during production， and the correspondence between the length of support rod and the number of modules were described. To control the module， it was emphasized that the optimal mold cavity clearance and maximum temperature were determined to be 1.3 mm 40 °C. The technique for centering the molding cavity and die and the technique for adjusting the wall thickness of products were described. The common quality problems arising in the production were discussed and their solutions were analyzed.
ZHAO Yan, PAN Xiang, LIU Bengang
Abstract (
1649 )
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811
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This paper reviewed the advantages of expandable polystyrene（EPS） geofoam in civil engineering applications， including excellent thermal insulation performance， low density and easy local construction， good mechanical properties， excellent stability and strong self-support. Application examples of EPS geofoam in the field of civil engineering were introduced， including subgrade insulation， bridgehead filling， high filling section road， road widening， man-made landscape， retaining wall seismic field and prevention of uneven settlement. In addition， the problems in the actual application of EPS geofoam and its application directions were briefly discussed.
Additive
YING Jie, QIU Qihao, ZHANG Xing, GU Hainan, LUO Rui
Abstract (
1113 )
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1522
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Talc was used to modify the flame retardancy of polycarbonate （PC） filled with titanium dioxide. The effects of talc on the thermal stability， combustion and mechanical properties， flame retardancy and anti-aging performance of resultant PC compounds were investigated. The results indicated that the PC compounds presented a decrease in impact strength. With the addition of 0.5 wt%~2 wt% talc， the flame?retardancy of the compounds reached the UL 94 V?0 classification， the total heat release decreased by 4~8 MJ/m2， and the initial decomposition temperature increased by 8~10 °C. Meanwhile， the compounds exhibited an improvement in the ability to resist the heat oxygen aging and damp heat aging in the presence of adding talc.
Machinery and Mould
KONG Xiaoya, ZHANG Xiang, ZHU Jianxiao, HOU Chuanyu, GUAN Guotao, YAN Zhenhao, LI Qian
Abstract (
657 )
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752
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The plasticizing process of a rotating disc screw in the disc-screw micro injection molding machine was simula-ted by using the COMSOL Multiphysics finite element simulation software. The phase change of polymer flow and the heat transfer in the cavity were analyzed during the rotation of the screw. The analysis and simulation results indicated that the heating temperature had greater impact on the plasticizing performance under the premise of the same screw structure， and however the rotate speed had a smaller impact on the plasticizing performance. Base on these simulation results， this paper provides a reference for the structural optimization of the disc screw.
Review
MA Zhanfeng, JIANG Wanjun
Abstract (
1460 )
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1559
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This paper reviewed the general situation and the latest development status about the plastics industry of China in 2020 and also reported a prospect for the development situation in 2021. On the basis of the data of plastics industry and apparent consumption of plastics， the amounts of plastics waste and recycled plastics and the utilization rate of recycled plastics in 2020 were analyzed and calculated.
GONG Meihua, ZHANG Xiaojuan, WEN Bianying
Abstract (
1173 )
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1543
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This paper summarized the main preparation methods of polypyrrole?coated inorganic nanoparticle composites with a core?shell structure and reviewed their research progress in the field of electromagnetic shielding. Their electromagnetic shielding performance and corresponding shielding mechanism were discussed， in particular for metal， oxygen/carbon/nitride compound and carbon?based materials as core components. The results suggested that the core?shell structure not only integrated the superiority of polypyrrole and inorganic nanoparticles， but also generated a synergistic effect. This method was proved to be an effective way for the fabrication of new electromagnetic shielding materials.
LIU Tong, WEI Jianfei, WANG Rui
Abstract (
808 )
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1306
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This paper reviewed the current research status of anti?dropping flame retardant polymers and introduced the app-lications of metal catalysts for catalyzing the degradation and carbonization of polymers. These metal catalysts include iron， molybdenum， nickel， zinc compounds， and some rare earth materials. The paper also reviewed the research progress in catalyzing carbon into anti?melt droplets in polymer flame retardancy， especially for the main role of iron catalysts. Finally， the application of metal catalysts for anti?melt droplets in polyester was prospected.
GUO Jinqiang, WANG Fuyu, ZHANG Yuxia
Abstract (
1594 )
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1660
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42 )
Modification ways for polymeric materials with high barrier performance are introduced， including blending and compounding，multilayer coextrusion， orenitation， surface treation and chemical structure control，etc. Properties and modification research on barrier performance of EVOH， PVDC，PA and PVA are listed in detail.
