Materials and Properties
Materials and Properties
SONG Jin, XU Hang, ZOU Wei, WANG Hong, ZHANG Chen
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457 )
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In this work， poly（tert?butyl methacrylate） porous beads with an open?hole structure and a uniform particle size were prepared through a W/O/W concentrated emulsion/suspension polymerization method using a concentrated emulsion as an oil phase for suspension polymerization. The effects of emulsifier content and stirring speed on the internal microporous morphology and particle size of the resultant porous beads were investigated. The results indicated that a uniform micropore distribution was obtained in the polymer beads at an emulsifier content of 4 wt%. The average particles size of the porous beads decreased with an increase in stirring speed. The beads with different particle sizes were treated through acidic hydrolyzation to obtain the surface?functionalized porous beads with carboxyl groups. The functionalized beads achieved effective adsorption to copper ions （Cu2+） thanks to their multiporous structure. The functionalized beads with an average particle size between 200~300 μm obtained a maximum removal rate of 99.3 % for the absorption of copper ions.
LI Guo, ZHU Huihao, MA Yulu, WANG Yu, JI Huajian, XIE Linsheng
Abstract (
420 )
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A thermally conductive Al2O3 filler with a spherical shape was incorporated into the conventional formula of specialized materials for breathable films to improve their thermal conductance. After melt mixing with a two rotor continuous mixer， the composites were used to prepare breathable films using casting equipment equipped with stretching units. The effects of Al2O3 content and stretch ratio on the performance of breathable films were investigated. The results indicated that compared to the original formula， the breathable films achieved an increase in thermal conductivity by over 60 % at a mass ratio of linear low?density polyethylene/CaCO3/Al2O3 of 50/35/15 and a stretch ratio between 200 % and 300 %. However， there was no influence on their mechanical properties and breathability.
TAN Liqin, LIU Weiqu, LIANG Liyan, WANG Shuo, FENG Zhiqiang, LIN Jiaming
Abstract (
829 )
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In this article， a series of polysiloxane epoxy composites were prepared through physical mixing and chemical modification methods using epoxy resin （E51） as a base material， amino?terminated polyoxypropylene （D?230） as a curing agent， and mercaptan polysiloxane （PMMS） as a modifier. The chemical structure of the cured epoxy resins were characterized using attenuated total reflection infrared spectroscope and X?ray diffractometer， and their mechanical properties， thermal stability and anti?corrosion performance were investigated through tensile and impact tests， scanning electron microscopy， contact angle measurement， dynamic thermomechanical analysis， and neutral salt spray test. The results indicated that the cured epoxy resins exhibited better comprehensive properties that the conventional epoxy resin. The cured epoxy resins containing 1 wt% PMMS obtained tensile strength of 74.63 MPa， which was 13.5 % higher than that before modification. Compared to neat pure E51， the polysiloxane epoxy resins showed an increase in elongation at break by 40.2 % and in impact strength by 43.7 %. The contact angle of the cured epoxy resins increased from 72.8 ° to 100.3 °， their surface energy decreased from 39.4 J/m2 to 17.4 J/m2， their water absorption rate decreased by 44 %， and their water resistance was enhanced greatly. In addition， their anti?corrosion performance and Tg were also improved.
SONG Yinbao, YANG Jianjun, LI Chuanmin
Abstract (
528 )
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In this paper， a type of functionally gradient flexible substrates based on polydimethylsiloxane （PDMS）/SiC composites was proposed， and the corresponding 3D printing manufacturing method and process flow were presented. The effects of SiC particle size and content on the mechanical properties and thermal conductivity of the PDMS/SiC substrates were investigated. Moreover， the effects and laws of process parameters such as backpressure， printing speed， line spacing， and temperature on the manufacturing accuracy of the PDMS/SiC substrates were studied. The results indicated that compared to the pure PDMS substrate， the performance of the PDMS/SiC substrates was improved in the presence of SiC. The PDMS/SiC substrates exhibited an increase in elastic modulus by 2.76 times and in thermal conductivity by 2.22 times when the particle size and content of SiC were 600 nm and 45 wt%， respectively.
LIU Yi, SUN Wei, QU Guoxing, WANG Ye, YUAN Ning, YANG Shaolin, XU Xia, CHANG Xiaoyi, ZHANG Yufei
Abstract (
686 )
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This paper reported an investigation on the melt crystallization properties， optical properties， molecular weight distribution， mechanical properties， capillary rheological properties， and thermal shrinkage properties of four types of transparent polypropylene （PP） specialized for injection molding. The results indicated that the K4860H?type PP presented a narrower molecular weight distribution， better toughness， and a higher transparency degree than the other three types of PP. The K4860H?type and MT45S?type PP exhibited higher crystallization temperatures and faster crystallization rates than the other two types of PP， representing a better crystallization capability. Moreover， the K4860H?type PP showed a similar molding shrinkage to the 500B?type one， indicating a good dimensional stability for thin?wall injection molding. Based on the above analysis， the main performance of the K4860H?type PP is superior to that of the other three types of PP.
XU Jie, ZHONG Jinfu, TONG Xiaoqian, LI Guangfu, FU Dongliang, LI Chengcheng
Abstract (
282 )
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A bio?based hyperbranched polymer （CTMTA） and a gallic acid?based epoxy resin （GAER） were prepared through an A2+B3 one?step method and a polycondensation reaction， respectively. The GAER/MTHPA/2?MI/CTMTA composites were prepared using a melt blending method. The effects of CTMTA content on the properties of the GAER/MTHPA/2?MI composites were investigated using by FTIR， 1H?NMR， DSC， SEM， mechanical measurement， and water absorption. The results indicated that the addition of CTMTA improved the mechanical properties and water absorption rate of the composites but reduced their curing temperature. The composites exhibited maximum mechanical properties and water absorption rate at a CTMTA content of 1.5 wt%. Compared to the GAER/MTHPA/2?MI composite system， the GAER/MTHPA/2?MI/CTMTA composites presented an increase in tensile strength， elongation at break， impact strength， and water absorption rate by 33 %， 37 %， 47.6 %， and 45.5 %， respectively. The optimum curing parameter of the GAER/MTHPA/2?MI/CTMTA composite system was determined to be 110 oC/20 min.
GUO Yuwen, ZENG Bei, GAO Xing, WANG Pan, REN Lianhai
Abstract (
466 )
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This study focused on the effects of polyethylene terephthalate （PET） microplastics with a particle size ranging from 30 to 250 μm on the co?digestion performance of sewage sludges and food wastes under the mesophilic conditions. The total solid levels were set to be 0， 0.45， 1.44 and 2.88 mg/g TS， and the daily methane production， cumulative methane production， soluable chemical oxigen demand， ammonia nitrogen， volatile fatty acids， and microbial communities in the anaerobic co?digestion system were investigated. The results indicated that the PET microplastics inhibited the production of methane， and a higher microplastic concentration generated a more significant inhibition effect. The presence of the PET microplastics increased the risk of ammonia and acid inhibition. The cumulative methane yields decreased by 54.49 % and 49.58 % for the microplastics with particle sizes of 30 and 250 μm， respectively， at a total solid level of 2.88 mg/g TS. The microplastics increased the bacterial diversity but decreased the archaeal diversity. During the co?digestion process， the microplastics not only inhibited the abundances of the Prevotella， Proteiniphilum， and Methanosaeta but also weakened the pathway of acetic acid methanogenesis. A correlation analysis proved that the particle size of microplastics was positively correlated with Euryarchaetota （r=0.945，p<0.01）. When the particle size of microplastics was smaller， the inhibition on the abundance of methanogens was more remarkable. Methanogens were more sensitive to the microplastics than other bacteria.
SHEN Xuemei, ZHU Xiaolong, HU Yanchao, SONG Renyuan, ZHANG Xianfeng, LI Xi
Abstract (
678 )
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The ibuprofen （IBU）?loaded poly（lactic acid）（PLA） microspheres were prepared through electrostatic spray using PLA as a skeleton carrier material and IBU as a model drug， and their morphology， microstructure， and properties were investigated using scanning electron microscope， X ray diffractometer， differential scanning calorimeter， infrared spectrophotometer， thermogravimetric analyzer， and UV?Vis spectrophotometer. The obtained PLA/IBU microspheres showed a porous and amorphous structure with good dispersibility. IBU was loaded in PLA in a molecular or random state and without any changes in chemical structure. Their stability was higher than that of pure IBU. Based on the in vitro controlled release test， The PLA/IBU microspheres exhibited a better effect for controlled release than pure IBU. The release rate and cumulative release amount of IBU from the microspheres increased with an increase in the dosage of IBU. The cumulative release amount of IBU reached 52 % at 48 h when the IBU content was 16 wt%. With the bioavailability and dissolution rate of IBU， the PLA/IBU microspheres developed by this work exhibit great application potential in the biomedicine field.
YANG Xiaochun, YU Jing, ZHANG Qing
Abstract (
469 )
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A series of polyhydroxyl compounds with a low price were selected， and their static thermal stability was comparatively investigated using a Congo red method. The results indicated that the presence of chitosan could generate an optimal static thermal stabilizing effect on PVC. The static thermal stabilizing effects of chitosan and conventional primary heat stabilizers， including calcium stearate， zinc stearate and lanthanum stearate， were further evaluated using the Congo red method， and their anti?discoloration ability was compared using a thermal aging oven method. The dynamic thermal stabilizing effect on PVC was compared between chitosan and conventional stabilizers using a torque rheometer. The effect of chitosan on the thermal degradation process of PVC was studied through thermogravimetric analysis. Chitosan exhibited an optimal thermal stabilizing effect on PVC with static and dynamic thermal stabilization time of 4 020 and 1 355 s， respectively.
ZHOU Shuyi, ZHU Min, LIU Yiying, CAO Shuhui, CAI Qixuan, NIE Hui, ZHANG Yuxia, ZHOU Hongfu
Abstract (
943 )
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This paper introduced the natural polymers （such as chitosan and collagen） and synthetic polymers such as poly（lactic acid） and poly（vinyl alcohol） used as hemostatic materials for medical application. These hemostatic materials could be formed as sponges， hydrogel， aerogel， particles， nanometer fiber membranes， and films. The research progress of the hemostatic materials in the trauma hemostatic application was reviewed， and their relevant properties such as bleeding， blood coagulation， antibacterial， bioactivity， and compatibility were discussed emphatically. Finally， the application prospect of hemostatic materials was elaborated.
Processing and Application
YANG Yifei, WANG Minghuan, LI Jie, HE Yadong, XIN Chunlin, REN Feng
Abstract (
419 )
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Permeability is a very important index in the impregnation model of continuous long?fiber?reinforced thermoplastic composites. An accurate measurement for the permeability of fiber bundles impregnated with a high?viscosity resin melt in the melt?impregnation process can help the impregnation model to better guide the design of melt?impregnation molds and the optimization of process parameters for the preparation of thermoplastic resin?based composites with excellent performance. The effects of fiber bundle tension and impregnation pressure variation on the permeation rate during the melt impregnation process with high?viscosity resin impregnating unidirectional fiber bundles were investigated using a homemade experimental setup. A formula for the relationship between the process parameters and permeation rate was fitted according to the experimental results. The results indicated that a greater tension of fiber bundle resulted in lower permeability， but a greater impregnation pressure led to greater permeability of the fiber bundle. Moreover， the increment rate decreased with an increase in tension.
HUANG Xuemei, LIU Hesheng, HUANG Xingyuan, YU Zhong, JIANG Shiyu
Abstract (
459 )
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A die–gas–melt three?phase heat transfer model was established by introducing gas?assisted extrusion into the extrusion process of U?shaped parts. The simulation results indicated that the melt flow velocity was uniform in the same section of the die. The melt temperature field was seldom affected by the outside environment. The melt temperature range varied with the die wall temperature during the conventional extrusion process. The U?shaped parts were prepared through both conventional extrusion and gas?assisted extrusion. In the conventional extrusion， the PP melt could be stretched smoothly under certain technological conditions. However， the melt was affected by gravity in the gas?assisted extrusion molding process. After the extrusion process was balanced， the sample surface was transparent and smooth， and the droop from the die was reduced significantly. The PP composite with 10 wt% glass fiber showed significant extrusion swell in the traditional extrusion process. The fibers were not homogenously distributed on the side wall and bottom of the U?shaped part. The delamination was serious at the corner of the U?shaped part. In the gas?assisted extrusion process， the extrusion swell and the inhomogeneous distribution of fibers on the side wall and the bottom surface were improved， and the fiber delamination at the corner of the U?shaped part were also partially alleviated. The thickness of the U?shaped part became thinner the PP composites with 20 wt% glass fiber. The fiber distribution in the sample was more homogenous， and there was no significant fiber delamination at the corner. However， there was a remarkable fiber emergence on the sample surface， with serious opening deformation on U?shaped parts.
LI Zhengdian, SONG Le, LI Minghao, HE Xuetao, XIE Pengcheng, YANG Weimin
Abstract (
289 )
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To meet the specific requirement of spectacle lens manufacturing， a flexible zoom?molding device was proposed to realize the production of spectacles with different diopters on a molding system. This might further reduce the mold cost and the time for mold change. The UG static simulation module was used to simulate the metal diaphragm， and the equivalent stress diagrams were obtained at different set pressures. According to the simulation parameters of the metal diaphragm， the hydraulic pressure of the hydraulic station in the subsequent experiment was set reasonably. To perform the follow?up experimental verification with an injection?molding machine， pressures were input to the hydraulic cavity through the hydraulic station. The lens thickness was measured using a laser measurement instrument. The variance value of the lens thickness was calculated and compared under the same scheme and average value of the lens thickness with different schemes data. The results indicated that the hydraulic pressure of the hydraulic station was affected by the dimensional stability of the injection?molded spectacles. The influence of hydraulic pressure of the hydraulic station on the power of the spectacle lens could be characterized by the thickness of the spectacle lens.
LIU Xuejun
Abstract (
419 )
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The temperatures at the surface of a rotational mold and inside the mold heated directly by electricity along with the consumed electric energy were measured in the heating stage. Based on the experimental data， a thermal analysis was conducted for the heating phase of the rotational molding process， and effective heat energy and ineffective heat energy were calculated. The rotational molding process was evaluated by three indexes， including the utilization rate of heat energy， the electricity consumed for heating powder per unit mass， and the time needed for heating powder per unit mass. The results indicated that the temperature distribution at the rotational mold surface is inhomogeneous， resulting in a maximum temperature difference of 8 ℃ at different locations. The highest utilization rate of heat energy was determined to be 37.5 % in three experimental cases. The utilization rate of heat energy decreased with an increase in the mass of powders inside the mold at the same heating temperature inside the mold.
WANG Xiaodong, WANG Quan, CHEN Tuo, ZHENG Yue
Abstract (
393 )
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Taking a double color plastic bowl as an example， a multi?objective optimization analysis was carried out in this paper. The mold temperature， melt temperature， and holding time of the first injection and the second injection were selected as factor variables. The average volume?shrinkage and total warpage rates of the second injection were selected as optimization indexes. The orthogonal experiments with six factors and five levels were designed and simulated by means of the Moldflow software. The signal/noise ratio was processed using the index parameters obtained from the experiment， and the weight of two optimization indexes was calculated using an entropy weight method. Finally， the grey relational degree was obtained， and the transformation from the multi?objective optimization to the single?objective optimization was realized. The optimized process parameters were simulated and analyzed. The maximum average volume?shrinkage rate of the second injection and the maximum total warpage rates were determined to be 15.67 % and 1.964 mm， respectively， which decreased by 7.8 % and 18.4 %， respectively， compared to the analysis results of the original process parameters. This resulted in an improvement in product quality. The experimental results indicated that a combination of orthogonal experiment， grey relational analysis and entropy weight method could effectively optimize the injection?molding process parameters.
Additive
YU Changyong, XIN Zhong
Abstract (
468 )
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An α/β complex nucleating agent was prepared using the calcium salt of hexahydrophthalic acid as an α nucleating agent and the zinc salt of hexahydrophthalic acid as a β nucleating agent， and its effect on the mechanical properties and crystalline performance of isotactic polypropylene （iPP） was investigation. The Avrami theory was used to describe the isothermal crystallization kinetics of nucleated iPP. The results indicated that the α/β complex nucleating agent improved the rigidity and toughness of iPP synchronously. When the mixing ratio was set to 7∶3， the nucleated iPP obtained an increase in tensile strength by 6.7 %， in flexural modulus by 21.8 %， and in impact strength by 108.2 %. The effect of concentration of the α/β complex nucleating agent in iPP was further studied. The crystallization temperature of iPP increased gradually with an increase in the total addition amount of the complex nucleating agent. The mechanical properties of the nucleated iPP tended to be stable when the addition amount of the complex nucleating agent reached 0.4 wt%. Its impact strength increased by 175.3 %， flexural modulus increased by 15.0 %， and tensile strength increased by 6.5 %. The isothermal crystallization kinetic results indicated that the presence of the α/β complex nucleating agent system reduced the surface energy required for crystallization， shortening the crystallization time of iPP significantly.
WEI Simiao, SHAO Lushan, XU Zhun, LIU Yanting, ZHAO Siheng, XU Bo
Abstract (
524 )
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A hypophosphite/siloxane bi?functional compound （MVC?AlPi） and a diethyl aluminum hypophosphite compound （AlPi） were combined as a complex flame retardant to enhance the flame retardancy of polyamide 6 （PA6）. The effect of the aluminum hypophosphite/ siloxane weight ratio in the aluminum phosphate?rich compound on the flame?retardant efficiency of PA6 was investigated. The results indicated that there was a synergistic barrier and protective effect on the PA6 composite at a MVC?AlPi/AlPi weight ratio of 2.2/8.8. This made the PA6 composite obtain an improved limiting oxygen index of 31.5 vol% and reach a flammability rating of UL 94 V?0 in the vertical burning experiment. The composite exhibited a decrease in peak heat release rate by approximately 50 % compared to pure PA6， and meanwhile the total heat release decreased by 15 %. The PA6 composite with 2.2 wt% MVC?AlPi and 8.8 wt% AlPi showed a lower char yield than that the composite with 11 wt% MVC?AlPi. A two?layer carbon structure with a hard inner layer and a ceramic?like outer layer was observed from the residual char of the composite after combustion. The interaction of MVC?AlPi， AlPi， and PA6 could lock more P and C fragments， promoting the formation of a barrier protective carbon layer based on the silicon?containing phosphorus?rich residue. A better synergistic flame retardant effect could be achieved through adjusting the ratio of each component at the fixed total amount of flame retardants.
Plastic and Environment
ZHANG Xin, QUAN Shumiao
Abstract (
447 )
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In this paper， the recycling technologies of waste agricultural films were introduced， and their advantages， disadvantages， applicability， and application prospects were analyzed. A combined recycling technology was proposed to accelerate the recycling of waste agricultural films and prevent the residual pollution of waste agricultural films in China.
LIN Wen, ZHAO Jingjing, SU Tingting, WANG Zhanyong
Abstract (
637 )
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This paper summarized the research progress in PS biodegradation in recent years， especially in the microbial degradation of polystyrene（PS）. The microbial degradation of PS in the environment like insect gut microbes and soil was explained in detail. The paper also prospected the development trend of PS biodegradation. There is an urgent requirement of a green biodegradation solution for the white pollution caused by PS.
Machinery and Mould
LIU Yang, ZHU Xiangzhe
Abstract (
487 )
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A new eccentric three?screw extruder was designed on the basis of the traditional tri?screw extruder. The tri?screw extruder had the characteristics of eccentric screw geometry， special gradient change of screw groove configuration， and high area utilization coefficient. The three?dimensional numerical simulation of the flow and mixing law of polypropylene （PP） melt in the new eccentric three?screw extruder was carried out using the finite element method. The distribution law of pressure and velocity in the eccentric tri?screw extruder were presented. The mixing characterization parameters such as the residence time distribution， distribution index， separation scale， and maximum shear stress of the tri?eccentric screw extrusion flow fields were calculated. The results indicated that the screw eccentricity not only determined the shape of the screw end face but also changed the variation degree of the screw groove gradient. The particle agglomeration effect in the extruder decreased but the material shear effect increased with a gradual decrease in the spiral groove gradient. Among the three new eccentric tri?screw extruders， the new eccentric screw extruder with an eccentricity of 3 mm had relatively good mixing performance.
Review
FENG Kai, LI Yongqing, MA Xiuqing, HAN Ying
Abstract (
598 )
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This paper briefly introduced the toughening modification methods of polyoxymethylene （POM）， including elastomer toughening， inorganic rigid particle toughening， alloying toughening， and composite toughening. The recent research progress in the toughening modification of POM was reviewed. The applications of POM and its modified products in various fields were introduced， and the prospect of toughening modification of POM was proposed.
FENG Bingtao, WANG Xiaoke, ZHANG Xin, SUN Guohua, WANG Dianlong, HOU Lianlong, MA Jinsong
Abstract (
967 )
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This paper reviewed the research progress in the preparation and applications of continuous carbon?fiber?reinforced thermoplastic composites at home and abroad. The interface modification methods， impregnation process， and molding process of the composites were introduced. The application status of continuous carbon?fiber?reinforced thermoplastic composites was introduced， and their development prospect was prospected.
ZHU Zixuan, LIU Haifen, FAN Jiazhao, LI Huafeng, WANG Lixin
Abstract (
643 )
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The paper introduced the reasons， methods， and research results of modification for ethylene vinyl acetate copolymer （EVA） as an adhesive material for solar cell modules in terms of tensile strength， flame retardancy， UV aging resistance， and adhesion. In view of some defects of EVA materials， the research progress and development direction in new adhesive materials such as polyurethane and polyvinylbutyral were reviewed. Finally， the production technology of co?extruded solar backplane was briefly introduced.
ZHANG Qiang, ZHANG Jian, LIN Lin, LIU Jing, WANG Tianhe
Abstract (
345 )
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This paper summarized the research progress in the enhancement of the thermal conductivity of the wall materials from three aspects： the modification of inorganic wall materials （calcium carbonate， titanium dioxide）， inorganic carbon materials （graphene oxide， carbon nanotubes， composite carbon materials）， and nanomaterials （nano alumina， nano titanium dioxide and other nano materials）. The characteristics of each method were analyzed， providing a theoretical guidance for the modification direction and measures of enhancement in the thermal conductivity of microencapsulated PCMs in future.
