Materials and Properties
LIANG Jifeng, QU Jinping
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227 )
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In this study， high⁃density polyethylene （PE⁃HD） and polyethylene terephthalate （PET） as two common components of plastic wastes were employed as experimental materials. The mass ratios of PE⁃HD to PET were set to be 9/1， 8/2 and 7/3. A screw extruder was used to repeat the melt regeneration， and the volume⁃pulsatile injection molding method was used to prepare the reinforced/toughened hybrid recycled materials. The mechanical properties of the multi⁃recycled materials were significantly improved. The influence of injection molding method on the microstructure of the injection⁃molded samples was analyzed. The results indicated that the pulsatile stress field introduced by volume⁃pulsatile injection molding could improve the compatibility of the incompatible two phases effectively and induce the formation of in⁃situ submicron⁃fibril of the minor phase and the change of crystal morphology. This contributes to the formation of interlinked hybrid shish⁃kebab structure. Mechanical test results indicated that when the PE⁃HD/PET mass ratio was set to be 9/1， the hybrid recycled material prepared by volume⁃pulsatile injection molding exhibited yield strength and impact toughness of 38.7 MPa and 165 kJ/m2， which were 54.8 % and 3 675.7 % higher than those of conventional injection molded material. When the PE⁃HD/PET mass ratio was 7/3， the yield strength and impact toughness of the hybrid recycled material were 31.0 MPa and 11.6 kJ/m2， respectively， increased by 14.8 % and 216.1 % compared to those of conventional injection⁃molded material.
ZHANG Xinpeng, XU Jun, DU Xiyan, GUO Baohua
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130 )
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The presence of a large number of hydroxyl groups on the molecular backbone of starch endows the strong intermolecular hydrogen bonding interaction that limiting the free movement of the molecular chain，thus making it difficult for starch to achieve thermoplastic processing. That limits large⁃scale application of starch in plastic products. In this work， the esterification reaction of tert⁃butyl acetoacetate （t⁃BAA） with starch at different ratios was carried out in dimethyl sulfoxide （DMSO） solvent environment， so that the weak polar groups of acetoacetyl were introduced to modify the hydroxyl groups of starch to break the strong hydrogen bonds between starch molecules. And with the addition of modified montmorillonite （MMT）， the thermal stability of esterified starch was further promoted. The results indicated that the esterified starch with a degree of substitution of 0~1.57 was obtained， and the interlayer spacing of montmorillonite was successfully expanded from 1.53 nm to 2.02 nm， even showing a partial peeling state. Moreover， the thermoplastic processing was realized without adding plasticizer and its hydrophilicity was reduced， realizing the starch to achieve the thermoplastic processing without adding any other plasticizer， and then getting hydrophobic surface.
WANG Xingguo, LV Mingfu, HUANG Yilun, GUO Peng, GAO Dali, ZHANG Shijun
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280 )
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This work evaluated the degradation property of poly （glycolic acid） （PGA） at different temperature as well as different pH environment. The change of crystallization and thermal stability properties during degradation was studied， and the degradation product of PGA was analyzed by liquid chromatograph⁃mass spectrometer. Thereafter， PGA was separately modified using anti⁃hydrolysis agent HyMax@210 and chain extender ADR⁃6488， and the effects of the two additives on melt fluidity， thermal stability， mechanical properties and degradation performance of PGA were studied. The results indicated that the degradation performance of PGA in high temperature aqueous solution was much better than that of traditional degradable materials. PGA degraded completely at 130 ℃ for 10 h in aqueous solution， and the degradation product was mainly glycolic acid trimers. Increasing pH value promoted the degradation of PGA. The thermal stability and mechanical properties of PGA was improved at the present of anti⁃hydrolysis and chain extender， and the degradation rate of that was delayed.
SHAO Haofeng, JIAO Longjie, GONG Weiguang, MENG Xin
Abstract (
199 )
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Hydrogen peroxide clearance experiments and thermogravimetric analysis were conducted to compare the antioxidant activity and thermal stability of tetrakis（2，4⁃di⁃tert⁃butylphenyl） 4，4'⁃biphenylene diphosphonate （Hostanox P⁃EPQ） and tris（2，4⁃di⁃tert⁃butylphenyl） phosphite （Irgafos 168）. The results demonstrated that due to its higher phosphorus content and unique P—C bond in the structure， P⁃EPQ exhibited superior antioxidant performance and thermal stability. Furthermore， hindered phenolic antioxidants Irganox 1010 and Irganox 1076 were selected to be compounded with P⁃EPQ to investigate their synergistic antioxidant effects in isotactic polypropylene （iPP）.The comparison of changes in melt volume flow rate （MVR） and yellowing index （YI） during multiple extrusion， as well as the oxidation induction period （OIT） in oxygen atmosphere of iPP stabilized by compound antioxidants indicated that the combination of antioxidant 1010 and P⁃EPQ exhibits a significant synergistic effect. When the mass ratio of 1010 to P⁃EPQ was 6/4， the stabilized iPP had the optimal overall stability performance. At this stage， the MVR and YI of antioxidant⁃modified sample after the fifth extrusion were only 19.8 % and 79.9 % of pure iPP， while the OIT at 180 ℃ significantly increased from 0.8 min to 74.8 min.
CHEN Tianhuan, YAN Cheng, JIANG Ganbing, GUO Shuai, YAN Tiantian, QIAN Kun, YU Kejing
Abstract (
203 )
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In this paper， tannic acid （TA） was used to modify the surface of ultra⁃high molecular weight polyethylene （PE⁃UHMW） fiber. The effects of metal ion type and reaction time on the properties of PE⁃UHMW fiber modified by tannic acid and metal ion （TA⁃［M］） were studied. Polyethyleneimine （PEI） was introduced into TA⁃［M］ modified solution. The effect of PEI molecular weight on the properties of TA⁃［M］⁃PEI modified PE⁃UHMW fiber and the effect of PEI on the stability of TA coating were studied. The results indicated that the TA coating was successfully coated on the surface of PE⁃UHMW fiber， and the phenolic hydroxyl functional group was introduced on the surface of the fiber. The interfacial shear strength between fiber and epoxy resin （EP） increased by 102.03 % after TA⁃Fe modification for 12 h. The interfacial shear strength with polyurethane resin （PU） increased by 97.78 %. The interfacial bonding strength between fiber and PU increased by 44.35 % after TA⁃Fe modification for 12 h. The interfacial bonding strength with EP increased by 58.50 %. The amino compound PEI can improve the stability of TA coating. After ultrasonic cleaning experiment， the interfacial bonding strength of PE@TA⁃Fe⁃PEI600 decreased less than that of PE@TA⁃Fe.
LI Bo, MA Jun, LI Wenzhuo
Abstract (
113 )
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In this study， the sprayable garlic stem and leaf waste （GL）⁃acrylate liquid mulch film with anti⁃insect function was prepared by emulsion polymerization of GL and acrylic monomer， where GL was fully utilized. The effects of GL usage on emulsion viscosity， sprayability， wicking property and film formation were studied， and the mechanical properties， water retention and thermal insulation properties of GL⁃acrylate films were also evaluated. The structures of GL⁃acrylate films were characterized by scanning electron microscopy， infrared spectroscopy and thermogravimetric analysis. The biodegradability and pests resistance of GL⁃acrylate film were evaluated. The experimental results indicated that when the mass ratio of GL to acrylate monomer was 0.5/10， GL⁃acrylate emulsion had good film⁃forming and sprayability， and the GL⁃acrylate film had good mechanical properties， the minimum soil water evaporation rate （19.7 %） and the best soil heat preservation ability， which could increase the germination rate of pakchoi seeds by 20 %. At the same time， it reduced the area of leaf damage by 12 % and the survival rate of plutella xylostella pests by 20 %.
LIU Wei, YU Caili, CHEN Xiaocheng, ZHANG Chun, ZHAO Kewen
Abstract (
152 )
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This study prepared a series of ethylene⁃vinyl acetate （EVA） expandable tapes by using 4，4⁃oxobenzenesulfonyl hydrazine （OBSH）as foaming agent， benzoyl peroxide （BPO） as crosslinking agent， and C9 resin as a tackifier. The effect and mechanism of components on the performance of 2D foam tape were studied. The results indicated that， under the proper blending ratio of EVA/BPO/OBSH/C9 （100/3/3/40）， the expandable tape could be foamed at both 170 ℃ and 205 ℃. The expansion rate of the expandable tape exceeded 2 times. And the surfaces of foams were smooth and without irreversible flowing. The tensile strength， the elongation at break and the water absorption of the expansion tape was 5 MPa， 240 %， and less than 5 %， respectively.
SUN He, HE Xin, LUO Tongyu, JI Xin, LIAO Qiling, ZHANG Yuxia, ZHOU Hongfu
Abstract (
154 )
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In this study， acrylonitrile⁃butadiene⁃styrene （ABS）/carbon nanotubes （CNTs）/ferriferous oxide （Fe3O4） composite and its bimodal foams with excellent conductivity and electromagnetic interference shielding （EMI SE） were prepared by melt blending and supercritical carbon dioxide foaming technique， respectively. The effects of the mixture ratio and content of the two fillers on the foaming properties， electrical conductivity， dielectric properties and EMI SE of ABS composites and bimodal foams were studied. The experimental results indicated that the average cell size of ABS bimodal foams decreased with the gradual increase of CNTs and Fe3O4 contents， the average large cell size descended from 283.54 μm to 70.79 μm， and the average small cell size declined from 11.89 μm to 7.19 μm. While the cell density of large cells in ABS bimodal foams went from 2.88×104 cell/cm3 to 2.51×106 cell/cm3 and the cell density of small cells increased from 2.18×108 cell/cm3 to 1.12×109 cell/cm3. The electrical conductivity of ABS composites boosted from 0.304 1 S/cm to 1.360 8 S/cm， and the total EMI SE increased from 28.65 dB to 43.05 dB with the gradual increase of CNTs and Fe3O4 contents. After foaming， the electrical conductivity of ABS bimodal foams augmented from 0.002 7 S/cm to 0.065 4 S/cm， and the total EMI SE increased from 10.89 dB to 21.08 dB. The maximum specific electromagnetic shielding effectiveness of ABS composite and its bimodal foams was 41.33 dB/（g·cm-3）.
ZHU Guangze, XIA Zhidong, ZHOU Wei, WANG Xiaolu, WU Yufeng, GUO Fu
Abstract (
159 )
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The pyrolysis products of the polyester enameled wire paint （coke） were separately co⁃pyrolyzed with the polyester enameled wire and the paint of the polyester enameled wire. And the co⁃pyrolysis behaviors were investigated by X⁃ray diffraction， morphology analysis， thermogravimetric analysis， Coats⁃Redfern integral method， infrared analysis and other methods. The results indicated that the obtained coke displayed a high degree of graphitization with folded micro⁃nano structure on its surface. Although the coke continued pyrolyzed， it increased the weight loss of the polyester enamel paint and reduced 16.9 % of pyrolysis activation energy when the coke co⁃pyrolyzed with the paint. In addition， the coke could lead to more oxygen⁃containing functional groups such as O—H and C=O and CO2 to escape during the pyrolysis of polyester paint film. This work demonstrated that the co⁃pyrolysis of coke and polyester enameled wire can further promote the pyrolysis of polyester enameled wire. It can not only contribute to reduce energy consumption， but also further promote the development of copper recovery from waste enameled wires by pyrolysis method.
Processing and Application
ZHANG Xuemin, ZHAI Lizhen, LI Houbu, QI Guoquan, HUANG Shangbin, ZHANG Dongna, YANG Zhifeng, ZHANG Xiaoyu
Abstract (
182 )
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In this work， the permeability of hydrogen in the polymer polyamide 6 （PA6） was studied by molecular simulation methods at different temperatures （30， 40， 60 and 80℃） and pressures （82， 87.5， 98 and 103 MPa）. Meanwhile， the permeability mechanism of hydrogen was analyzed. The results indicated that as the temperature increases， the adsorption heat and free volume fraction gradually increases， the thermal motion intensifies and the molecular motion space increases. And the solubility， diffusion and permeability coefficient of hydrogen in PA6 all increase. At a pressure of 103 MPa， increasing the temperature has the greatest impact on the permeability coefficient， which increases by 88.3 %. With the increase of pressure， the interaction between hydrogen and PA6 molecular chains decreases and the free volume fraction decreases， so the solubility， diffusion and permeability coefficient of hydrogen in PA6 all show a downward trend. When the temperature was 60℃， the pressure had the most significant influence on the permeability coefficient， which decreased by 38.6 %. The permeation mechanism of hydrogen in PA6 includes the aggregation adsorption process in the low potential energy region and the diffusion process of intra⁃cavity vibration⁃inter⁃cavity transition formed in the free volume. With the increase of temperature， the movement of hydrogen molecules becomes active and there are more inter⁃cavity jumps. When the pressure increases， the change is opposite.
XU Jingyi, LUO Baoshu, WANG Shengwang, CHEN Jianbo, GE Fujiong, YANG Yafeng, HE Yadong
Abstract (
134 )
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In this study， in⁃line measurement of pressure⁃volume⁃temperature in injection molding was achieved by using a modified conventional microcellular injection molding machine that generates high pressure on the recovered entrained gas polymer melt. The studies on the pressure⁃volume behavior of entrained gas melts of polystyrene and polypropylene at a certain temperature indicated that the compressibility of entrained gas polymer melts was much greater than that of gas free polymer melts at specific temperature. In practical applications， the larger compressibility of entrained gas polymer melts can be used to assist in injection and speed up the gas integration process into the melt， thereby improving foaming quality. On the other hand， the pressure release test based on the potential safety hazards of entrained gas polymer melt due to its large compressibility of the melt has put forward a new safety operation guide for injection molding of entrained gas materials for the first time in China.
GE Jiarong, GUAN Guoying, YAO Zijia, TONG Fangqiang, WANG Boqun
Abstract (
134 )
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According to the difficulty on forming composite rudder of large⁃sized unmanned aerial vehicle integrally， a metal combined female mold and a detachable core mold that made of “silicone rubber + aluminum blocks” were designed. Hand laying⁃up and oven curing processes were used to manufacture the rudder with good internal and external appearance， stable forming process， easy manufacturing， and low cost. The results indicated the proposed method is effective and efficient.
Additive
LUO Bofei, XU Chen, XING Jingkai, WANG Bo, ZHANG Yanni
Abstract (
215 )
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In this paper， the working principle of polypropylene （PP） nucleating agent was reviewed， and the molecular structure of common carboxylic acids and their salt nucleating agents was classified.Meanwhile， the modification effect of each nucleating agent was introduced. In addition， the methods for improving the performance of such nucleating agents were also proposed， which provides some ideas for the subsequent research and development of carboxylate nucleating agents.
WU Weihong, ZHANG Jing, ZHANG Ge, GENG Rongrong, QU Hongqiang
Abstract (
160 )
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A covalent organic framework （COF） was prepared by solution synthesis， and then the COF was coated on piperazine pyrophosphate （PAPP） to form PAPP@COF hybrid flame retardant， which was applied to epoxy resin （EP）. The effects of PAPP@COF hybrid flame retardants on the flame retardancy and smoke suppression of EP were analyzed by oxygen index meter， vertical combustion meter and cone calorimeter. The results indicated that the oxygen index of EP composite can reach 30.0 %， the peak heat release rate was 911.35 kW/m2， and the peak smoke release rate was 0.394 m2/s， which were 37.36 % and 34.27 % lower than that of pure EP by adding 2 phr PAPP@COF. PAPP@COF hybrid flame retardants have excellent flame retardancy and smoke suppression effects on EP， which provides a certain basis for the research of COF flame retardants.
Plastic and Environment
XU Chuanhao, SHI Zhenwu, CHI Bo
Abstract (
94 )
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In this paper， the fatigue resistance of waste plastic/butadiene styrene block polymer（SBS） composite modified asphalt was analyzed by temperature scanning test， time scan test， linear amplitude scanning test and infrared test using a dynamic shear rheometer. The results indicated that BMH warm mixture could reduce the fatigue factor， reduce the dissipation energy， and improve the fatigue resistance of waste plastic/SBS modified asphalt， and the best performance was at a content of 1.2 wt%. Both normalized dynamic modulus decays to an index value of 50 % of the initial modulus and stiffness ratio （）×times of cyclic loading （） can be used to characterize the fatigue life of warm⁃mix waste plastic/SBS composite modified asphalt， and the fatigue life characterized by × index was generally lower than that of ， the fatigue resistance improved by 1.2 wt% content was the best， and the improvement effect of 1.4 wt% content did not increase but decreased. BMH warm mix had a more obvious effect on the fatigue performance of aging asphalt samples. Regardless of whether it is an aged asphalt sample or an unaged asphalt sample， the improvement effect of warm mix was more prominent in the environment with high strain level. The fatigue resistance of 1.2 wt% BMH mixture sample was the best. BMH warm mix could improve the fatigue resistance of asphalt by reducing the content of carbonyl and sulfoxide groups， and the effect on the aging asphalt was more obvious， which was consistent with the test results of linear amplitude scanning.
ZHU Chenxi, CHEN Chenhui, HU Guoming, ZHANG Lei, JIANG Wei
Abstract (
218 )
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This study simulated the photo⁃thermal aging of discarded polystyrene （PS） in a landfill environment. Firstly， the molecular structure of the aged samples was characterized. The aging process of PS was then studied through X⁃ray diffraction， differential scanning calorimeter tests， and the tool⁃narayanaswamy⁃moynihan （TNM） model， along with molecular dynamics calculations of enthalpy relaxation processes.The results indicated that PS undergoes chain scission after photoaging， with the molecular weight decreasing from 112 200 to around 13 000. This process generates PS oligomers， benzoic anhydride， acetophenone， and methyl benzoate. Furthermore， aging leads to a reduction in PS crystallinity and the glass transition temperature. The enthalpy relaxation changes rapidly in the early stages of aging， gradually slowing down as aging progresses， with a corresponding enthalpy value of 4.2 J/g at equilibrium.
Machinery and Mould
HU An, MAO Yuanrui, ZHOU Guofa
Abstract (
136 )
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Based on the digital virtual prototype simulation method of collaborative integration of twin screw high shear wet granulation process and equipment， influence of the structural characteristics and screw scale on the granulation performance and key quality attributes were simulated and evaluated for D11 small twin screw high shear wet granulator， and the synergistic coupling evolution law was constructed among the key quality attributes of endpoint granulation， structural features， screw scale. The research results indicated that the D11 small twin screw high shear wet granulator in this article can achieve the manufacturing of particle with diameter size of 750~936 μm，which can achieve the maximum granulation yield with 88.84 %. Moreover， the relation between the diameter sizes d10， d50， d90， granulation yield and screw pitch pre compression ratio， screw scale exhibit synergistic evolution law of a positive correlation，while the relation between the consistency of granulation particle size and screw pitch pre compression ratio and screw scale exhibits the synergistic evolution law of a negative correlation. Increasing the pre compression ratio of the screw pitch to 3.67 can increase the maximum particle size to 936 μm， Particle size span reduced to 0.49. Increasing the pre compression ratio of screw pitch can improve the granulation performance and consistency of endpoint granulation for D11 small twin screw high shear wet granulator， which can compensate for the deterioration of granulation characteristics caused by the reduction of screw scale.
Review
ZHENG Tianyi, ZHANG Ben, GUO Min, WANG Ying
Abstract (
247 )
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Natural bone tissue has piezoelectric properties， and reconstruction of the local electrical microenvironment at the defect site is an effective strategy to stimulate bone regeneration. Using electroactive polymer materials to prepare bone tissue engineering scaffolds can imitate the piezoelectric properties of bone tissue， repair the physiological electrical microenvironment at the defect， and then promote bone tissue regeneration and repair. This article categorized and introduced several types of electroactive polymer materials， including conductive polymers， piezoelectric polymers， and electret polymer materials. It summarized their research progress in the field of bone tissue repair and analyzed the advantages and challenges of different materials.
LEI Xiaoping, LI Song, DENG Cuicui, WANG Pidong
Abstract (
191 )
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As the main raw material of vehicle tires， the friction performance of rubber determines the braking efficiency and safety performance of vehicles. Therefore， how to accurately characterize and improve the friction properties of rubber materials is a major focus of current research. In this paper，the friction mechanism of rubber material was briefly introduced， the characterization methods of rubber material friction properties were discussed， and the commonly used methods to enhance rubber material friction properties were summarized. Finally， the future research direction was prospected.
TANG Bo, XIANG Lixue, DAI Xumin, WANG Erke, JIANG Tao, WANG Ying, WU Xinfeng
Abstract (
233 )
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This paper summarized the mainstream ways of preparing diamond thermally conductive composites， and introduced the preparation process， thermal conductivity mechanism， etc. of each preparation method， including blending method， constructive template method， electrodeposition technology， sintering technology， magnetron sputtering technology， and chemical vapor deposition technology， etc. It outlined the molding process of the different preparation methods and summarized and generalized their thermal conductivity properties. Finally， the studies about diamond thermally conductive composites were summarized and prospected.
DONG Guang, HOU Yangzhe, YUAN Hongyue, LIU Xianhu, PAN Yamin
Abstract (
191 )
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This paper reviewed the research progress of porous poly（lactic acid） （PLA） materials in terms of molding process， pore structure modulation and performance optimization. Typical molding processes for porous PLA materials were introduced， including template method， non⁃solvent induced phase separation method， freeze⁃drying method and supercritical CO2 foaming method. The effects of different pore structures and variations in pore size and density on the properties were presented. In addition， the effect of stereo⁃complex crystal on the pore structure and macroscopic properties of porous PLA materials was emphasized.
