Materials and Properties
LI Kaize, XIN Yong
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493 )
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In this work， the surface of carbon nanotubes （CNTs） was treated with a mixed solution of sulfuric acid （H2SO4）/nitric acid （HNO3）， and then thermoplastic polyurethane （TPU） composites were prepared through melt blending using the modified CNTs as a raw material. The effects of CNTs content on the rheological， mechanical， wear?resistant， and thermal properties of the composites were investigated. The experimental results indicated the modified CNTs exhibited a good dispersibility in the TPU matrix due to the good compatibility between the filler and matrix. The TPU/CNTs composite retained a good processing fluidity under high?frequency shearing， and their tensile strength and wear resistance are significantly enhanced compared to pure TPU. This modification effect was especially significant for the composites with a low content of modified CNTs. The mechanical properties of the composites were improved significantly. Differential scanning calorimetry analysis results indicated that the addition of modified CNTs improved the melting temperature and crystalline level of the TPU matrix. Thermogravimetric analysis results indicated that the addition of modified CNTs improved the thermal degradation temperature and thermal stability of the composites.
NI Junjie, GUO Rui, ZHANG Bing
Abstract (
446 )
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This work attempts to conduct the resourceful disposal and recycling utilization of aramid weftless fabric ballistic layer in police equipment such as bullet?proof vests or helmets through high?temperature anaerobic pyrolysis with the passage of inert gas. The decomposition of the aramid fibre and adhesive at different pyrolysis temperatures not only destroys the original equipment form and prevents the end?of?life equipment from being recirculated for use， but also makes it decompose to produce flammable gas or extract the fibre yarn that could be used twice. This leads to the achievement of the purpose for the resourceful disposal of police ballistic protection equipment. Combined to the simulation and experimental analysis， an optimal temperature range of 410 ℃ and an optimal location of pyrolysis were obtained.
WU Xiongjie, ZHU Dongbo, SUN Jiangbo, GAO Longmei, CHU Yu, CHENG Jinsong, XIE Aidi
Abstract (
524 )
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193
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A new type of green， low?carbon and degradable eco?friendly composite film was prepared by melt co?extrusion based on the composition of 49 wt % polyethylene （PE） and 51 wt % CaSO4 nanoparticles， and its application performance as flexible packaging was investigated by comparing with the PE/CaCO3 composite film at the same loading. The application performance， hygienic performance， degradation performance， carbon content of the PE/CaSO4 composite film were measured using tensile testing machine， high temperature gel chromatograph， xenon lamp sun aging test chamber， and total organic carbon analyzer. The results indicated that the composite film obtained better tensile strength and elongation at break of the PE/CaSO4 composite film than the PE/CaCO3 one at the same loading of filler. Its total migration， including water， 4 % acetic acid， 20 % ethanol， 95 % ethanol， isooctane， the consumption of potassium permanganate， and heavy metals did not exceed the limit requirements of national standards. Under accelerated aging conditions， the tensile properties and weight?average molecular weight of the composite film could meet the requirements of photodegradable plastics， and its carbon content was much lower than other plastic films. The promotion and applications of the PE/CaSO4 composite flexible packaging can offer an important guiding significance for the promotion of national carbon reduction and emission reduction policies.
LIU Wei, WU Xian, CHEN Xiaocheng, CHENG Xiaoqiong, ZHANG Chun
Abstract (
455 )
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In this work， carboxylate carbon nanotubes （CNTs） and cellulose nanocrystals （CNC） were used to induce a dense crosslinking structure and act as reinforcement agents in poly（vinyl alcohol） （PVA）/cellulose nanofibers composite hydrogels. The results indicated that the tensile strength of the composite hydrogels increased from 50 kPa to 120 kPa with the addition of 3 wt % CNTs， whereas， their tensile strength and elongation at break both increased with the addition of 3 wt % CNC. Meanwhile， the electrical resistance of the composite hydrogels decreased significantly in the presence of CNT due to the formation of a conductive percolation threshold and ionic conductive paths. Therefore， the composite hydrogel with 3 wt % CNT can be selected as a sensing material. The hydrogels designed in this study exhibit a rapid and accurate sensing response to various stresses in tension， compression and bending.
ZHANG Wencai, HAO Xiaogang, LI Ping, LIN Hao, PEI Qiang, FENG Gongji, FU Zhaohua, YU Xiaofang
Abstract (
547 )
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155
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A type of complex modifier （CM） comprising recycled polyethylene and maleic?anhydride?grafted polyethylene （PE?g?MAH） with concentrations of 0， 1， 3， 5， 7， and 9 wt % was prepared using a twin?screw extruder. The asphalt modified with 4 wt % CM was prepared， and its softening point， needle penetration， ductility， rotational viscosity， high?temperature storage stability， and rheological properties were investigated. The results indicated that the esters compounds were produced through the chemical reaction between the OH groups in asphalt and the MAH groups in CM. The softening point， ductility， viscosity， high?temperature storage stability， and high and low temperature performance were improved significantly with an increase in PE?g?MAH content. However， its needle penetration and phase angle decreased. Therefore， the CM?modified asphalt with a reasonable PE?g?MAH content can be considered as a good candidate for the asphalt pavement construction in regions， especially suitable for use in the zones with a significant change in temperature. In addition， the improvement of high?temperature storage stability was also analyzed.
ZHANG Yunfeng, ZHONG Wei, ZHANG Lu, LAN Zhixing, DONG Zhibo
Abstract (
453 )
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139
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A novel type of microencapsulated phase change material （PCM） with a liquid paraffin wax core， a polysulfone shell， and a nano?SiO2 inlay was synthesized through a solvent evaporation method， and its structure and properties were characterized using SEM， FTIR， DSC， and TGA. The results indicated that the resultant microcapsules obtained the smallest particle size of 164.8 μm at a nano?SiO2 addition amount of 5 wt %. There is an optimal enthalpy and encapsulation efficiency for the microcapsules， resulting in a melting enthalpy of 88.03 J/g， a crystallization enthalpy of 86.48 J/g， and a packaging efficiency of 57.37 %. The FTIR analysis indicated that the chemical structure of the phase?change microcapsules was not affected by the addition of nano?SiO2. The particle size of the microcapsules increased by the modification of nano?SiO2， and their surface structure showed small voids. Meanwhile， their phase?change performance and thermal stability were improved.
WANG Shuai, ZHANG Yudi, YANG Fukai, XU Xinyu
Abstract (
432 )
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153
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Polyimide/multi?walled carbon nanotubes （MWCNT） composite foams were prepared through in?situ polymerization of polyimide with different mass fractions of MWCNT， and their morphology and properties were investigated using scanning electron microscopy and thermogravimetry. The results indicated that the cell diameter of the composite foams increased with an increase in the mass fraction of MWCNT， but their foam density decreased. There was an agglomeration occurring when the MWCNT content exceeded 0.4 wt%. This limited the formation of the foam structure and led to foaming an irregular shape. The composite foams obtained an optimal enhancement effect on compressive strength， compressive modulus， and hardness when 0.2 wt% MWCNT was incorporated. The enhancement effect was found to increase at first and then tended to decrease with an increase in the mass fraction of MWCNT. The composite foams achieved a maximum thermal stability when 0.05 wt% MWCNT was added.
CHEN Liang, ZHANG Pingbo, JIANG Pingping, BAO Yanmin, GAO Xuewen, XIA Jialiang
Abstract (
779 )
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286
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A series of self?healing waterborne polyurethane materials （WPUs） was prepared using a aromatic disulfide compound， 2，2'?diaminodiphenyldisulfide （AD）， as a raw material. The resulting WPUs were characterized using FTIR spectrometer， Raman spectrometer， thermogravimetric analyzer， particle size analyzer， hot?stage polarized light microscope， and contact angle meter. Their thermal stability， surface hydrophobicity and self?healing properties were investigated together with its tensile properties and self?healing efficiency evaluated quantitatively though a tensile experiment. The results showed that AD was successfully introduced into the molecular chain of WPUs. The thermal stability of WPUs decreased gradually with an increase in AD content， and its surface hydrophobicity increased as well. The sample WPU?3 presented a static contact angle of 81.2 ° and tensile strength of 5.6 MPa. However， WPU?0 only has tensile strength of 1.1 MPa. On the other hand， WPU?1 has a tensile strain healing efficiency of 81 % after heating for 3 h under a moderate healing temperature of 80 ℃.
SUN Wei, LIU Yi, LIAO Yunlong, CHEN Junjia
Abstract (
570 )
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A working curve was established for the determination of ethylene content of random and impact copolymerized polypropylene using an analysis methods provided by foreign investors and a series of standard samples. Owing to the instability and heterogeneity in structure and properties of polypropylene powder samples， the ethylene content of actual powder samples is often not completely consistent with the establishment of marking treatment. By selecting different grades of ethylene?propylene copolymer?type polypropylene powder samples， the effects of cooling mode， antioxidant， and particle size of samples on the determination result of ethylene content in hot?pressing sampling were analyzed. The results indicated that the cooling mode generate an obvious effect on the determination of ethylene content in powders during the hot?pressing process. Similarly， there was a significant influence on the determination results resulting from the powder samples with or without antioxidant as well as the antioxidant types. In addition， the particle size of powder samples generated a great effect on the determination results of ethylene content.
HUANG Suyuan, CAO Lin, LI Wei, LIN Zhidan, ZHANG Peng
Abstract (
359 )
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119
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PEEK/TaB2 composite coatings were deposited on the surface of pure titanium substrates using a cathodic electrodeposition technique. Transmission electron microscopy， scanning electron microscopy， X?ray diffractometer， and friction and wear tester were used to characterize the suspension dispersion， surface morphology， microstructure， crystallinity， and tribological and biological properties of the composite coatings. The results indicated that there were a uniform morphology and a certain thickness for the composite coatings through adjusting the electrodeposition parameters. After thermal sintering at 390 ℃， the resulting coating became uniform and dense. Thermal sintering improved the crystalline properties of the PEEK/TaB2 composite coatings， and the addition of TaB2 particles led to a higher crystalline degree for the composite coatings. When a lower content of TaB2 particles was added， the composite coatings showed good tribological properties in a medium of fetal bovine serum. Their wear rates decreased by 48.1 %and 69.1 %compared to the pure PEEK coating. However， there was an evident aggregation of TaB2 particles at an excessive loading in the PEEK matrix， resulting in an increase in friction coefficient and wear rate. Cell experimental results indicated that TaB2 had a good bioactivity to promote cell proliferation on the sample surface.
LI Jie, XU Ran, REN Feng, YANG Yifei, XIN Chunling, HE Yadong
Abstract (
434 )
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125
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To improve the performance of prepreg tapes， a continuous?glass?fiber?reinforced polypropylene （PP/GF） prepreg tape was prepared using a melt impregnation method， and the impregnation process of continuous fiber bundle in the PP melt was investigated. A mathematical model of fiber fracture was established by means of the Weibull distribution function to predict the fiber fracture rate during the producing process of the prepreg tape and to describe the experimental results. The results indicated that the prediction results obtained from the model was in good agreement with the experimental data. This provides guidance for the industrial production. The fiber fracture was mainly influenced by the effect of resin melt on the fiber bundle in the mold as well as the friction between the fiber and the equipment. Through improving the mold temperature appropriately， reducing the fiber traction speed， and increasing the mold gap， the fiber breakage was reduced effectively and the process stability was improved.
ZHU Jingyun, YI Huijun, YAN Wei, LI Dawei
Abstract (
317 )
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The article focused on the structure and performance analysis of polyethylene special materials， confirmed the specification of the PE?HD special resin with a commercial grade of 6903B. Through adjusting the addition amounts of comonomers and the processing conditions of polymerization， a PE?HD special resin was successfully produced for the use of compound films. Application experiments confirmed the PE?HD 6903B could meet the requirement of production for compound films with different thicknesses.
Processing and Application
WANG Jinye, TANG Bohu, YANG Lining, XIE Meng, GUO Zechao, YANG Guang
Abstract (
412 )
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110
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PA12 parts were prepared using a multi?jet?fusion （MJF） 3D printing technology， and the effect of construction orientation on the forming accuracy and mechanical properties of PA12 parts were investigated. The results indicated that the size accuracy was always positive deviation when the position size was the width direction. There is no obvious change law at different forming angles. Compared to the width direction， the size accuracy in thickness direction and the length direction increased with the forming angle， indicating a more obvious change law. The mechanical properties of parts presented a similar influence of forming angle with the elongation rate. When the forming angle increased from 0 ° to 45 °， the tensile strength and elongation rate of parts gradually decreased. The tensile strength and elongation rate increased significantly after the forming angle was greater than 45 °. The trend in the induced density change was consistent with the mechanical properties. According to comprehensive analysis， the size accuracy of the parts reaches an optimal level when the molding angle was 45 °. The forming direction for optimal mechanical performance was parallel to the x?y plane direction. Under this condition， the PA12 parts obtain average tensile strength of 50.95 N/mm2， average elongation of 37.02 %， a forming angle of 0 ° for the highest density， and an average density of 99.311 %. The MJF technology was more efficient compared to the traditional 3D printing technology. This study offers a theoretical and experimental foundation for the mass production of high?performance and high?precision nylon parts.
ZHANG Qingtao, BI Chao
Abstract (
458 )
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168
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Based on the CFD?DEM coupling method， the flow state of particles in the water chamber in an underwater?pelletizing device was studied， and the effects of the cutter shaft speed， inflow rate of the particle water， and chamber outlet angle on the palletizing process were analyzed. The results indicated that the discharge of particles in the water chamber could be enhanced by increasing the cutter shaft speed， inflow rate of the particle water， and chamber outlet angle. Furthermore， there was a separation angle between the pellets and polymer crumbs at the chamber outlet. The research results obtained in this paper can provide theoretical guidance for in?depth analysis of the working principle of underwater pelletizing device.
WEI Maoqiang
Abstract (
534 )
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465
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Based on the extensive collection of literature and materials， this paper introduced the degradable agricultural film and sustainable development from the aspects of covering technology agricultural plastic film， including the production process， application status， and the requirements of equipment and staff. The paper also proposed some suggests for the development of agricultural films through combining with the research technology of agricultural film at home and abroad.
LIU Zheng, LIU Zhenfeng, ZHOU Guofa
Abstract (
396 )
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116
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Aiming at the common industrial problem in a difficulty to control the key qualities， including the uniformity of particle size distribution， the apparent quality of particle， and granulation yield for the granulation process in China， a simulation method of the continuous counter?rotating twin?screw high?shear wet granulation process was constructed on the basis of the Edinburgh Elastic?Plastic Adhesion contact model. The cooperative coupling evolution mechanism of process parameters. i.e.， ? particle size distribution uniformity and yield， was simulated， and the regulation mechanism of key qualities for twin?screw wet granulation was analyzed. The simulation results indicated that the continuous counter?rotating twin?screw high?shear wet granulator could prepare spheroidized particles with a smooth surface. The particle size was positively correlated with the feed speed of powder but negatively correlated with the screw speed. The granulation yield， powder feeding speed， and screw speed presented an evolution law that the yield increased at first and then decreased with an increase in powder feeding speed and screw speed. When the powder feeding speed was 360 kg/h or the screw speed was 1 400 r/min， the granulation yield exhibited an optimal status along with optimal granulation yields of 87.9 % and 83.91 %. The particle size was mainly controlled by the average residence time and holding up mass of particles， showing a positive correlation. A technical method for on?line real?time regulation was proposed. In this method， the size and yield of qualified particles were controlled by the frequency conversion speed control of the screw for the powder weight loss feeding device and continuous counter?rotating twin?screw high?shear wet granulator.
DONG Shaoce, LI Chenggao, ZHANG Xufeng, XIAN Guijun
Abstract (
420 )
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The environmental impact of plant fiber honeycomb core was assessed using a life?cycle assessment method using eleven environmental impact categories for the characterization of environmental performance of two manufactured honeycomb cores. The results indicated that after using plant fiber and polyester fiber to replace partial aramid fiber， the environmental impact of plant fiber honeycomb core decreases with a reduction rates ranging from 0.68 % to 49.41 % in terms of the eleven categories. The weighting results indicated that the overall environmental impact of plant fiber honeycomb core was 18.77 %， which was lower than that of aramid paper honeycomb core. The environmental impact of aramid paper honeycomb cores was mainly influenced by the aramid paper production and electricity consumption. Partially replacing aramid fiber with plant fiber and polyester fiber is the reason accounting for the environmental impact reduction.
Additive
LI Jinfeng, LIANG Zhuoen, PENG Xinlong
Abstract (
731 )
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132
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Unsaturated polyester （UP） resin composites were modified with an intumescent flame?retardant （IFR） system based on the mela mine?coated a mmonium polyphosphate （APP）， pentaerythritol （PER）， and mela mine （MEL）， and the effect of APP/PER/MEL mass ratio and total amount on the flame retardant and mechanical properties of the UP/IFR composites were investigated. According to the optimal mass ratio of IFR， alu minum diethyl phosphate （ADP） was then added into the UP/IFR composites as a flame?retardant synergistic agent， and the flame retardant properties， mechanical properties， and thermal stability of UP/IFR?ADP composites with different content of ADP were evaluated. The results indicated that the composites achieved a UL 94 V?0 classification in the vertical burning test at a APP/PER/MEL mass ratio of 4∶1∶1， a IFR content of 15 wt%， and a limiting oxygen index （LOI） of 27.4 vol%， and their flexural strength and impact toughness were 100.3 MPa and 6.3 kJ/m2，respectively. The introduction of ADP further improved the flame retardancy of IFR/UP composites， and the flame?retarding effect was enhanced with an increase in the mass fraction of ADP. When the mass fraction of ADP was 2 wt%， the UP/IFR?ADP composites obtained an LOI of 28.5 vol%， a UL?94 V?0 classification， flexural strength of 110 MPa， and impact toughness of 7.8 kJ/m2. Compared to the UP/IFR composite containing 15 wt% of IFR， the UP/IFR?ADP composites achieved an increase in flexural strength by 9.7 % and in impact toughness increased by 23.8 %. TG analysis results indicated that ADP could promote the formation of amorphous char layer and slow down the thermal degradation of the matrix.
Plastic and Environment
LEI Yujie, CHEN Minghuan, WANG Jieyao, CHEN Wangzhi, LI Lei
Abstract (
584 )
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164
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A cross?linked foamed polyethylene board was prepared through compression molding using three types of recycled linear low?density polyethylene as raw materials and expandable microspheres as a foaming agent. The thermal properties， morphology， impact resistance and tensile properties of cross?linked foamed polyethylene were characterized using differential scanning calorimeter， scanning electron microscope， film impact tester， and electronic universal testing machine. The experimental results indicated that the melting point and molecular weight of recycled polyethylene materials increased after processing owing to the crosslinking effect of dicumyl peroxide. The network structure formed after crosslinking favored the stability of cells. There were independent cells in the recycled polyethylene after crosslinking and foaming. The foamed materials obtained maximum tensile strength of 9.7 N/mm 2， impact strength of 21.5 kJ/m2， and oxidation induction time of 7.3 min， and therefore they could meet the requirement for producing various types of plastic products such as floats and buoyancy balls.
Machinery and Mould
DENG Shixin, WANG Jian, YANG Weimin
Abstract (
374 )
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139
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An L?shaped mixing head model with a version number of MK?8/12UL?2K was used to simulate and analyze the high?pressure and high?speed collision of two?phase material fluid in the mixing head cavity using a CFD numerical simulation software. The effects of flow rate and viscosity on the mixing effectiveness were investigated using a controllable variable method. To better characterize the motion of glass beads in the mixing process， particle tracer analysis was carried out on the whole flow field. By comparing the pressure and velocity cloud diagram， it is concluded that the increase of mass flow leads to an increase in velocity pressure in the mixing chamber. This means that the collision degree becomes higher and the collision location becomes more inclined to the outlet side of the material with a high viscosity. The increase of viscosity resulted in a decrease in the pressure lifting speed of the material in the mixing chamber. The collision position was more inclined to the outlet side of the material at a high viscosity， resulting in a significant increase in friction force. The particle residence time decreased with an increase in mass flow rate but increased with an increase in viscosity. The simulation results provide a certain reference value for the design and processing optimization of mixing heads.
XU Yonglin, ZHANG Weihe, FENG Guoshu, SONG Dongyang, DU Hai, WANG Jing, WEI Haitao
Abstract (
602 )
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Based on the structural characteristics and technical requirements of the smart kettle shell， an injection mold with a complex core?pulling mechanism and a conformal cooling channel was designed. The structure of this injection mold with a large wrapping force and difficult demoulding modes was improved effectively by using a sequential lateral core?pulling mechanism and a delayed lateral core?pulling mechanism in the mold. The problems in the temperature control system， including a great amount of heat from the melt， a large temperature difference in the formed parts， and a high mold temperature， were solved using the 3D?printing conformal cooling channels. The temperature difference of the mold was reduced by 50 %， the injection molding cycle was shortened by about 20 %， the deformation of the plastic part was reduced by 75 %， and the dimensional accuracy was improved by two levels， reaching the MT3 grade （GB/T 14486—2008）. A one?time success was achieved for the injection?molding test. The appearance quality and dimensional accuracy of the injection?molded parts could meet the requirement of design， confirming that the mold structure was advanced and innovative.
Review
MA Zhanfeng, NIU Guoqiang, LU Shan
Abstract (
989 )
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362
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The general situation and the latest developments about the plastics industry of China in 2021 was reviewed. And the development situation in 2022 was expected. On the basis of the data of plastics industry and apparent consumption of plastics， the amount of plastics waste， the amount of recycled plastics and the utilization rate of recycled plastics in 2021 are analyzed and calculated.
CHEN Ke, LIU Mingfei, ZHAO Biao, PAN Kai
Abstract (
611 )
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426
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This paper reviewed the research progress in the flame retardancy and ablation resistance of silicone?modified polymeric materials in three aspects， including flame retardant and ablation mechanisms， processing modification methods， and specific applications. The paper also focused on the three main processing modification methods， including direct blending， synergistic effect with other flame retardants， and synthesis of silicon?containing polymers. The existing problems in the research of the flame retardancy and ablation resistance of silicone?modified polymeric materials were pointed out， together with the development direction in future prospected.
SHAO Linying, XI Yuewei, WENG Yunxuan
Abstract (
941 )
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471
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This paper reviewed the biodegradation performance of poly（lactic acid） composites and summarized the variation trends in their mechanical properties， thermal properties， biocompatibility， antibacterial properties， and biodegradation rate under different environmental conditions after compounded with organic substances such as lignin， cellulose， etc. and inorganic substances such as calcium carbonate， nano silver particles， etc. Furthermore， the material structures of polylactic acid composites and the relationship between the compositions and degradation properties were discussed， and the application prospect of poly（lactic acid） composites with controllable degradation properties was prospected.
YANG Xiaolong, CHEN Wenjing, LI Yongqing, YAN Xiaokun, WANG Xiulei, XIE Pengcheng, MA Xiuqing
Abstract (
574 )
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This paper introduced the conductive mechanism， preparation methods， and relevant application areas of polymer/graphene of conductive composites. The existing problems and current research status of the conductive composites were analyzed， and their future development was prospected.
