QIN Aiwen, ZHANG Linbin, SUN Jinxi, ZHANG Panpeng, WU Wenjing, XIN Changzheng
Abstract (
642 )
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229
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A series of poly(lactic acid) (PLA)/poly(ether sulfone) (PES) composite nanofiber membranes were prepared by coaxial electrospinning with different extrusion rates of skin solution and different types of nano?sized additives including graphene、carbon nanotubes and halloysite in the core solution. The morphology, mechanical properties, hydrophobicity and oil absorption ratio of the obtained membranes were analyzed by means of scanning electron microscopy, universal testing machine, and contact angle and oil absorption measurements. The results indicated that all of the nanofiber membranes had a contact angle greater than 130 ° and exhibited the oleophilic and hydrophobic characteristics. The nanofiber membranes gained the optimum oil absorption and tensile properties when graphene oxide was introduced as a core additive. The nanofiber membranes achieved an oil absorption rate of 67.61 g/g in glycerin and 8.02 g/g in edible oil, the longitudinal breaking strength of 62.68 MPa, the transverse breaking strength of 43.98 MPa, and the transverse elongation at break of 697.66 %.
ZHANG Yanzhao, MA Qiaoyu, HOU Lei, LIU Zheng, LI Yuqi, DI Mohan, LIU Caiyun, LIU Yanfang, RUN Mingtao
Abstract (
578 )
PDF (3240 KB)(
190
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A series of poly(acrylic acid) copolyester/graphene latices were prepared by in?situ polymerization using graphene, acrylic acid (AA), methyl acrylate (MA) and ethyl acrylate (EA) as raw materials, and a composite electrode sheet was prepared by a fabric impregnation method. The effects of graphene and monomer contents on the electrical conductivity, flexibility, mechanical properties and electroencephalography (EEG) monitoring performance of the composite electrode sheet were investigated by using Ohm meter, differential scanning calorimetry, universal material testing machine and EEG tester, and its morphology was observed by scanning electron microscopy. The results indicated that the prepared composite electrode sheet exhibited good flexibility at a graphene content of 46.5 wt%, a reaction temperature of 80 °C, a reaction time of 3 h, and an AA/MA/EA volume ratio of 0.2/1/1.8. In this composite electrode sheet, and the fabric was made from the non?woven fabric impregnated by copolyester emulsion. This composite electrode sheet exhibits good electrical conductivity and mechanical strength at room temperature and is suitable for the use in EEG monitoring, and its signal intensity and stability for EEG is similar to the commercial Ag/AgCl electrode. There is no conductive paste needed for this composite electrode, so it is more convenient for use without any skin contact.
FANG Jiyong, LI Bo, YU Yan, LI Shupeng, WANG Weijian
Abstract (
601 )
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238
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The coolant resistance of glass?fiber?reinforced polyamide 66 (PA 66) was investigated, and the effect of coolant on their mechanical properties was studied. The bending strength and impact strength was evaluated at different aging stage for the PA 66?matrix composite containing 30 wt% glass fiber during 1008?hour thermal aging test in coolant. Moreover, the microstructure was investigated and the corresponding aging mechanism was discussed. The results indicated the materials PA66/30%GF?1 and PA66/30%GF?2 achieved the bending strength higher than 70 MPa along with the retention higher than 25 %. It was concluded that the PA 66 composites with 30 wt% glass fiber supplied by DuPont and Solvay were suitable for long?term use under the coolant condition.
LI Xia, GAO Zhao, LIU Benxue, ZHANG Sanchuan
Abstract (
462 )
PDF (3432 KB)(
146
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In order to study the influence of structural parameters of longitudinal vibration ultrasonic transducer on the viscoelastic heat generation of polymers during the ultrasonic plasticization process, the composition of ultrasonic viscoelastic heat generation system was determined, and then the structure of longitudinal vibration ultrasonic transducer was designed. The ultrasonic viscoelastic heat generation process and the corresponding mechanisms were analyzed. A single variable method was adopted to investigate the influence of structural parameters of the transducer on the longitudinal vibration frequency and maximum amplitude of the particle at the front end of tool head. Finally, the longitudinal vibration excitation of the transducer was loaded on the molten polymers to study the effect of structural parameters on the ultrasonic viscoelastic heating process of the polymer and the time required for reaching its glass transition temperature. The results indicated that the polymer temperature increases nonlinearly with an increase of longitudinal vibration excitation time. The amplification ratio generated the much greater influence on the variation of polymer temperature than on the front cover thickness and tool head length, but there was the least influence on the horn length.
CAO Weina, ZHAO Yahao, YAN Yaru, ZHOU Mengjie, WANG Pengfei, YU Xiang∗
Abstract (
654 )
PDF (2300 KB)(
229
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PVDF/TiO2 hybrid fiber membranes were prepared by an electrospinning method, and their morphology, crystalline structure and photocatalytic performance were investigated by using SEM, XRD and visible spectrophotometer. The results indicated that there were more TiO2 particles exposed onto the surface of the hybrid fiber membranes with an increase of TiO2 content. The hybrid fiber membranes presented an increase trend in tensile strength with an increase of TiO2 content at first, and then the tensile strength tended to decrease. Their photocatalytic degradation ability was also gradually enhanced with the increase of TiO2 content. Moreover, the hybrid fiber membranes exhibited a good recyclability.
SHU Mengying, WENG Yunxuan, ZHANG Caili
Abstract (
1814 )
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315
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Poly (ethylene terephthalate?butylene adipate) (PBAT) was modified by chain?extension reaction extrusion in a twin?screw extruder using a multi?component epoxy chain extender (ADR), and the effects of the addition amount of ADR on the content of terminal carboxyl groups, relative molecular weight, mechanical properties, crystallinity and color of PBAT were investigated. The results indicated that the terminal carboxyl group content of PBAT was reduced after the chain extension, and its mechanical properties and relative molecular weight were improved. The terminal carboxyl group content of PBAT decreased significantly from 23.3 mol/t to 13.8 mol/t when 1 wt% of ADR was added, and its relative molecular weight, crystallization temperature, and mechanical properties were also improved. Moreover, the maximum mechanical properties were achieved for PBAT when 1 wt% of ADR was added, and its elongation at break was higher than those of the other samples during the aging process. In addition, the PBAT after chain extension exhibited better aging resistance in view of its chemical structure as well as the relative molecular weight higher than the other samples during the aging process.
Abstract (
521 )
PDF (3639 KB)(
262
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Vulcanization plays a key step in rubber forming and processing. In this work, a low?field nuclear magnetic resonance instrument was used to analyze the crosslinking density of rubber materials at different curing times, and the obtained results were compared with the torque measured by the disc?type curometer at the same time. The results indicated that the relationship between the torque and crosslinking density is approximately linear. The degree of cure distribution was calculated by means of the finite element heat transfer analysis and self?written algorithm, and the simulation results for temperature?rising curves and degrees of cure on the surface and in the heart of cylindrical rubber specimens were highly consistent with the experimental data. This work provides a design reference for the vulcanization process of rubber articles.
XIAO Qingwu, LIU Hesheng, HUANG Yibin
Abstract (
668 )
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242
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Based on the viscoelastic theory of polymers and the characteristics of external gas?assisted injection molding (EGAIM), a mechanical model for the stress?strain in both gas?packing stage and natural cooling stage of EGAIM was established. According to this mechanical model, the warpage of flat parts molded by EGAIM was simulated by a coupled finite element method. The simulation results were basically consistent with the experimental results, indicating that the model was effective and feasible.
YANG Bo, HE Jiaping, ZHAI Wei, XIANG Jianping, WANG Zhigang, ZUO Xiaofeng
Abstract (
390 )
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201
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To investigate the performance reliability of polyethylene (PE) pipe under the slow crack growth (SCG) condition, five different graded PE pipes were selected for the evaluation of SCG resistance by a cyclic load gap (CRB) test and a full?notch tensile creep test (FNCT), and the correlation of experimental results was analyzed. Moreover, the macromolecular structural parameters of PE pipes including molecular weight and distribution, crystallinity and wafer thickness were investigated to further verify the performance reliability of selected PE tubes under the SCG condition, and meanwhile the reliability of CRB test method was also confirmed. The results indicated that the CRB test method not only could be used to reliably and effectively evaluate the SCG resistance of PE pipes, but also revealed a shorter test time and closer test conditions than the FNCT.
DONG Aiqing
Abstract (
467 )
PDF (2298 KB)(
283
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The hot melt adhesive with a high temperature resistance for steel?plastic composite pipe were prepared by reactive extrusion of PP melt?grafted with maleic anhydride. The effects of initiator, grafted monomer and elastomer concentration on the hot melt adhesive were investigated. The result indicated that the comprehensive performance of the resultant hot melt adhesive was excellent, and its peel strength and tensile elastic recovery rate reached 131.4 N/25 mm and 65.5 % respectively. According to the results obtained from the T?cycling resistance test in the temperature range of -40~130 °C, the peel strength of 122.2 N/25 mm could still maintained after 800 times of circulation, and the loss ratio of peel strength rate was kept at just 7.0 %, which was evidently lower than the other two commercial hot melt adhesive.
HU Anqi, YU Fa, YANG Ruobing, SHI Jianfeng, CUI Ying, ZHENG Jinyang
Abstract (
545 )
PDF (914 KB)(
953
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With a successful field application of polyethylene (PE) pipes in the Sanmen and Daya Bay nuclear power plants, PE pipes have been taken as the first choice for the cooling water systems in a large number of construction or renovation projects for new nuclear power plant. There is extremely urgent requirement for the development of technical standards for PE pipes in nuclear power plants. This paper introduced the history and application status of PE pipes in nuclear power plants. The design method and scope of ASME Class 3 PE pipes standards were compared with those of the relevant PE pipes without a nuclear safety standard including the gaseous fuels PE pipes and water supply PE pipes. The differences and gaps between Chinese current PE pipe technology standards and ASME Class 3 PE pipe technology standards were discussed. This paper provides a reference for the design, manufacture and standard development of PE pipes in nuclear power plants.
ZHAO Zhanfeng
Abstract (
567 )
PDF (4809 KB)(
179
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Aimed at the difficulty in the formation of plastic parts with a large wall thickness, shrinkage and deformation, a gas?assisted injection molding process was determined by CAE analysis. After the optimization for this injection mold, a single?point side?gate was adopted for gating, and a two?point gas port was applied for gas?assisted forming. With the optimized injection parameters, the shrinkage deformation of plastic parts could be controlled within 0.3 %~0.42 %. Based on the analysis of CAE, a gas?assisted two?plate injection mold with two cavities and two opening was designed. A compound twice?core?pulling half slider mechanism and a universal angle pin half slider mechanism were set up to carry out side core pulling and demolding. In these compound mechanisms, the first opening between the moving plate and moving?base plate on the moving mold side was adopted to realize the core pulling of the inclined core, and then the second opening between the fixed plate of fixed mold and the moving plate of moving mold was applied to drive the two half?sliders to carry out the side?core?pulling. The CAE optimization analysis played a very important role in the structural design of gas?assisted injection mold and it was advantageous to the improvement of overall design efficiency.
HAO Yanqin
Abstract (
442 )
PDF (4750 KB)(
311
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A three?plate injection mold was designed for the two?color injection molding process of thermometer shell plastic parts. In this mold, there are two functions in the three?plate die holder. One is for meeting the requirement for multi?point pouring of the mould cavity, and the other is for driving a variety of core?pulling mechanisms through the opening of the template to complete the demolding of plastic parts. Aiming at the pouring difficulty in the first and second forming die cavity, a point gate runner along with a side gate runner was set up to meet the requirement for multi?point pouring formation of the die cavity. Aiming at the demolding difficulty in plastic parts, five types of mechanisms were set up to realize the automatic demolding of plastic parts. The first one is a composite mechanism composed of first core pulling of Harvard slider, which is used for the side core?pulling demolding of the outer wall of plastic parts. The mechanism can complete the interference core pulling of Harvard slider by driving the first and second opening of the three?plate die and then driving four Harvard sliders through the third opening of the template. The slider mechanism can complete the automatic demolding of the outer wall of plastic parts twice. The second one is a core?pulling mechanism consisting of the bending pin, which is used for core pulling and demolding in the local area of the upper and outer walls of plastic parts. The third one is a cylinder?driven side core?pulling mechanism. The fourth one is a core?pulling mechanism of double bread glue oblique slider driven by moving template. The fifth one is a reinforced core?pulling mechanism with inclined ejector. The overall structure of the die is reasonable, and the mechanism is set up properly, which can well meet the requirement for automatic production of plastic parts.
FENG Wenjing, LI Shouping, CHEN Yajun, QIAN Lijun
Abstract (
670 )
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314
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This review provided a comprehensive description for flame?retardant technologies on flexible polyurethane foams (FPUFs), including the addition of reactive/unreactive flame?retardant additives and the utilization of flame retardant coatings, and also analyzed their advantages, disadvantages, and flame?retardant mechanisms and effectiveness. Moreover, the future direction of development in this growing field was prospected.
ZHANG Na, ZHOU Yawen, BAI Yu, ZHOU Zhongkai, JIANG Yumei
Abstract (
883 )
PDF (662 KB)(
572
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Microplastics has gradually become a global environmental pollution problem and may bring some harm to the human public health and animal health. A number of studies have also shown that gut microbiota is closely related to host health and can act as a toxicity target for certain environmental pollutants like microplastics. This paper reviewed the research status in this issue in terms of the recent literature and summarized the sources, classifications and research direction of microplastics. The paper analyzed the changes in intestinal flora for the tested animals after exposure to microplastics and also discussed the potential mechanisms of microplastics against intestinal flora. This paper can provide a reference and help for the future research about the influence of microplastics on intestinal flora.
XIE Pengcheng, ZHU Jinbai
Abstract (
798 )
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401
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The successful close of the 2019 International Plastics and Rubber Exhibition (K?SHOW 2019) indicates that plastics are still the most innovative, indispensable and future?oriented fundamental materials. With the circular economy as a central topic, this K?SHOW 2019 focused on the innovative harvest in the materials and industry including the resource?saving processes, digitalization, functionality, renewable energies, circularity and sustainability, and also exhibited innovative solutions related to circular economy, intelligence, and integration that highlighted by the global injection molding industry. This paper also briefly discussed the highlights of the K?SHOW 2019 and prospected the development trends of technology in the injection molding industry.
