Materials and Properties
SHI Xingbo, CHEN Shangtao, ZHENG Lijun, GUAN Jian, WANG Junqi, DU Bin, LI Rongbo, WANG Yanfang
Abstract (
956 )
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In this paper， three commercial polypropylene （PP） products with the medium?flowing and impact-resistant characteristics were selected to analyze the content of ethylene and the content， molecular weight and morphology of rubber phase. The thermal and mechanical properties of these three products were also investigated. The results indicated that the ethylene content determined the rubber phase content， and the rubber phase content and molecular weight of the rubber phase played an important role in the stiffness-toughness balance performance of the PP products. A good toughening effect could be achieved only when the ethylene content was higher than 50 wt% in the rubber phase. According to this conclusion， the structure and copolymer content of impact-resistant PP can be optimized to achieve an optimal balance between rigidity and toughness.
WU You, WANG Bohua, SUN Jianjian, JIN Yujuan
Abstract (
941 )
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404
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Poly（propylene carbonate） （PPC）/poly（butylene succinate） （PBS） blends were prepared by melting blending using epoxy?terminated hyperbranched polymer （EHBP） as a modifier and then were characterized by dynamic mechanical analysis，thermogravimetric analysis，tensile and impact measurements，rotational rheometer and scanning electron microscopy. The results indicated that the PPC/PBS/EHBP blends presented a decrease in the difference of glass transition temperature with the addition of EHBP， indicating an improvement in compatibility between PPC and PBS. The blends also exhibited an increase in tensile strength by 68.7 % and in impact strength by 81.2 % at the EHBP content of 0.5 wt%. Their elongation at break also increased by 74.9 % at the content of EHBP of 1.0 wt%. Their complex viscosity was found to decrease with an increase in the EHBP content.
WU Shouang, TU Zheng, LIU Beijun, GONG Xinghou
Abstract (
1022 )
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413
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The citric acid-coated zinc-doped nano?ferroferric oxide（Zn0.2Fe2.8O4，ZFO）nanoparticles with good dispersibility in water were prepared by a chemical coprecipitation method and then characterized by X-ray diffractometer， transmission electron microscope and comprehensive physical property tester. The results indicated that the nanoparticles presented a relatively uniform distribution with a particle size of 3~8 nm as well as saturation magnetization up to 60 emu/g. A new type of PVA/PAAS/ZFO interpenetrating network hydrogels were prepared through the initiates polymerization of sodium acrylate by crosslinking in the aqueous phase， followed by freezing and thawing cross-linking. It was found that the introduction of nano-ZFO particles increased the tensile strength of the hydrogels by about 1.5 times and also improved their thermal stability. Moreover， the addition of nano-ZFO particles accelerated the electrical response rate and strength of hydrogels.
SHENG Leihui, MA Yuji, HUANG Ming, LU Bo, LIU Chuntai, ZHANG Na
Abstract (
872 )
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244
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The three car front class brackets， including a failure bracket from Chongqing， Southwest China， a failure bracket from Guangzhou， South China and a normal man-made damaged bracket， were observed and comparatively analyzed using Fourier transform infrared spectrometer， depth-of-field microscope and scanning electron microscope. The effect of isopropanol on the brackets was also investigated. The results indicated that isopropanol had little effect on the brackets. There were different degrees of defects and cracks in the bottom coating part and the degumming part of the two failed brackets， indicating a decrease in the interface binding force of the bonding parts. This directly resulted in the falling off of scaffold. The thickness of the base coat had a great influence on the interface adhesion of the bracket.
WANG Wei, WANG Dong, DONG Weifu
Abstract (
774 )
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376
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In this study， a novel type of hydrophobic polyurethane rigid foams was prepared through a semi-prepolymerization foaming process using perfluoropolyether as a foam stabilizer and water as a green chemical foaming agent. The results indicated that the contact angle of the rigid foams increased up to 139.7 ° with an increase in the content of perfluoropolyether. The foams exhibited a higher closed cell ratio with the addition perfluoropolyether. As the content of perfluoropolyether increased， the cell became more uniform， the cell size gradually decreased， the cell density increased， and the thermal conductivity decreased significantly. The compressive strength reached up to 0.822 MPa.
YAO Junlong, WANG Xinrui, HU Li, JIANG Xueliang, YOU Feng, ZHOU Min
Abstract (
668 )
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339
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The three?phase composite materials based on polypropylene （PP）， nano-alumina （Al2O3） and the bernary barium titanate （BT） modified with tartaric acid were prepared and their structure and performance were characterized by Fourier transform infrared spectrometer， scanning electron microscope， dielectric spectrometer and thermal conductivity analyzer. The results indicated that the surface modification for BT particles effectively improved the compatibility of PP with BT， Al2O3 and other inorganic fillers， promoting the uniformity of BT， Al2O3 and other particles dispersed in the PP matrix. As a result， the thermal conductivity and dielectric properties of the composites was improved simultaneously. The three-phase composites presented an increase in thermal conductivity from 0.90 to 1.24 at a PP\BT\Al2O3 volume ratio of 5\4\1. Their relative dielectric constant at 100 Hz also increased from 18 to 21.2， but their dielectric loss decreased from 0.055 to 0.035. The dielectric properties of composites exhibited a good temperature stability with a dielectric constant?temperature coefficient of -124×10?6 °C?1 in the temperature range of 25~130 °C， and their dielectric constant-temperature coefficient decreased by 62.8 % in comparison with the unmodified composites.
CHENG Long, HAO Yanling, SONG Xiaoshuang
Abstract (
1247 )
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397
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Chitosan/corn starch composite edible films were prepared by a solution-casting method using corn starch as a raw material in the presence of plasticizer glycerin. Their membrane structure and microscopic morphology were characterized using Fourier-transform infrared spectroscopy and scanning electron microscopy. The effects of chitosan content on the mechanical properties， water vapor permeability， oil resistance and antibacterial properties of the resultant films were investigated. The results indicated that chitosan not only improved the mechanical properties of the films but also enhanced their water-proof and oil-proof properties. The membrane obtained at a chitosan/starch mass ratio of 1/3 exhibited a uniform structure， and it tensile strength and water vapor transmission rate reached 21.54 MPa and 4.52×10-5 g·mm-1·d-1， respectively. The membranes could inhibit the growth of Escherichia coli and Staphylococcus aureus， with antibacterial rates of 43.55 % and 32.89 %， respectively.
MA Zhongyun, DING Lili, FU Wei
Abstract (
956 )
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597
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PP/GF composite films were prepared with the acidcorroded glass fiber （GF） net introduced into polypropy-lene （PP） matrix by a hot-pressing molding technique. Their crystalline structure， thermal behavior， interfacial morpho-logy and mechanical properties were characterized using scanning electron microscope， wide-angle X-ray diffraction， differential scanning calorimeter and universal material testing machine. The effect of GF content on the microstructure and mechanical properties was emphatically discussed. The results indicated that there were many grooves developed on the surface of GF after being etched with acid， leading to an increase in surface roughness. This is helpful to improve the interfacial adhesion between GF and PP. The nucleation points were increased with the addition of acid-treated GF， resul-ting in an increase in crystallinity. The mechanical properties of the PP/GF films at a low content of GF were improved significantly compared to pure PP samples， and their tensile strength and toughness increased by 33.75 % and 41.15 % at a GF content of 0.2 wt%， respectively. In addition， the tensile strength and toughness tended to decrease with an increase in the GF content.
Processing and Application
MA Xiuqing, SUN Kaixin, LI Rui, ZHANG Yajun, FAN Yiqiang
Abstract (
804 )
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636
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The microfluidic chip was manufactured by injection molding with poly（methyl methacrylate） （PMMA） as a raw material. Through a series of injection?molding experiments， it was found that the mold temperature， holding pressure， melt temperature and injection speed were considered as the main factors affecting the molding quality of the PMMA microfluidic chip. Through the orthogonal experiment and range analysis， the optimal injection?molding process parameters for the PMMA microfluidic chip was determined to be a melt temperature of 260 °C， a mold temperature of 50 ℃， a holding pressure of 60 MPa and an injection speed of 400 mm/s without changing other parameters. The single?channel test device B achieved a top width of 591.90 μm， a bottom width of 381.26 μm and a depth of 408.47 μm under this processing condition with the design value of 400 μm for these three parameters. The confocal microscope observation indicated that the chip surface was relatively clean and its microstructure was relatively complete. In addition， the liquid?mixing and droplet?generating experimental results indicated the microfluidic chip manufactured by the optimal injection?molding process parameters could meet the normal requirement for use. This is of great significance for the mass production of the microfluidic chip in future.
SUN Qiwei, CHEN Yuhong, DONG Shuyuan, LANG Jianlin, ZHOU Xiaowei, ZHANG Yun
Abstract (
822 )
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589
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A joint simulation method was established on the basis of the Moldflow and ABAQUS softwares to analyze the warpage of overmolding injection-compression molded PMMA/PC composite panels. The numerical simulation of the warpage was carried out through a two-step method. The filling， packing and cooling stages during the overmolding injection compression molding process were first analyzed by the Moldflow software. The temperature field of the demol-ded part and the grid file obtained from the Moldflow analysis were then imported into the ABAQUS software to calculate the warpage when the composite panels were completely cooled to room temperature after demolding. The warpage resulting from the stress release and complete cooling were linearly added to obtain the final value. Meanwhile， the war-page of the part was measured through an injection-molding experiment. The results indicated that the joint simulation was in good agreement with the experimental results.
DONG Zhijia, WANG Xiaoxin, GUAN Hang, LI Shao
Abstract (
624 )
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357
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Taking a medical hemostatic clamp as a research object， a mechanical model was established. The deformation and stress-strain situation in the process of closure were simulated by the ABAQUS software，and the product structure was optimized according to the analysis results. The resultant products could meet the requirement for practical use.
ZHAO Xingmin, ZHAO Jianping, YAN Jizhong
Abstract (
632 )
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397
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8 )
This paper reported an investigation on the material performance difference between the butt fusion welded joint and pipe body of high-density polyethylene （PE-HD） through an experimental method. With the formation of the butt fusion welded joint according to the ISO 21307 standard method， the inner and outer crimps were removed， and the joint sampling method was design to improve the tensile specimen. A new constitutive analysis and a Suleiman method were used to study the difference of constitutive models through the tensile testing of pipes and welded joints at different strain rates. The nonlinear relationship between model parameters and strain rate was obtained. Through comparing the model prediction and test results， the effectiveness and rationality of the nonlinear fitting constitutive model were verified. The model can predict the stress-strain curve under a low strain rate， providing a basis for engineering practice and finite element analysis. The results indicated that the elastic modulus and yield stress of the PE-HD welding area were better than the pipe， but the difference was not obvious.
SONG Congyu, ZHENG Kai
Abstract (
534 )
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528
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This article statistically analyzed the situation of Chinese patents in the 3D-printing technology for continuous fiber-reinforced composites on the basis of the trends and technical distributions of patent applications and the status of principal applicants.
Additive
XING Jian, ZHANG Shucheng, YU Qin, LI Changlong, XU Zhenzhen
Abstract (
614 )
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320
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Aiming at the oxidation characteristics of polyphenylene sulfide （PPS）， a high temperature antioxidant GA?80 was used to compound with PPS by melt blending with a micro twin?screw extruder. The effect of GA?80 on the morphology， crystallization behavior， thermo?oxygen stability， dynamic oxidation induced temperature and surface element changes of PPS was investigated by field emission scanning electron microscopy， differential scanning calorimeter and X?ray photoelectron spectrometer. The results indicated that GA?80 had good compatibility with the PPS matrix and could be homogeneously dispersed in the matrix without obvious agglomeration. The effect of GA?80 on crystallization changed from inhibition to promotion with an increase in the content of GA?80. The crystallization temperature and crystallinity decreased at first and then tended to increase， whereas the degree of supercooling presented an opposite variation trend. The addition of GA?80 improved the thermal?oxygen stability of PPS， and the dynamic oxidation induced temperature of PPS increased with an increase in the content of GA?80. When the content of GA?80 was 5.0 wt%， the dynamic oxidation induced temperature increased by 19.4 ℃ compared to pure PPS. Moreover， GA?80 could inhibit the combination of S and O elements from the PPS macromolecular chains and environment， respectively， and it could also eliminate the free radicals to improve oxidation resistance.
Plastic and Environment
CAO Ying, XU Pengwu, WU Baogou, YANG Weijun, MA Piming
Abstract (
540 )
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346
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The recycled poly（butylene terephthalate） （r-PBT）/epoxidized elastomer （EVMG） blends were prepared by a reactive melt blending method using r-PBT as a raw materials. The effect of EVMG on the mechanical properties of r-PBT blends was studied systematically. The results indicated that EVMG was uniformly dispersed in the r-PBT matrix and its particle diameter was determined to be 500 nm. The notched impact strength and the elongation at break of the （r-PBT）/ EVMG） blends increased by 14 times and 7 times at an EVMG content of 20 wt%， respectively. Furthermore， glass fibers （GF） were incorporated to improve the mechanical strength and heat resistance of the blends. After adding 30 wt% GF， the tensile strength and flexural strength of r-PBT/EVMG/GF composites increased by 70 % with good toughness maintained. In addition， the thermal deformation temperature of the blends increased up to 176 ℃. This work provides a new idea for the reuse of r-PBT.
Standard and Test
SUN Haitao, LING Ligong, CHEN Shushan, ZHOU Meiwu, XIANG Aimin, XU Haiyun, WANG Xun
Abstract (
713 )
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640
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This paper introduces the standard specification and engineering application of high-density polyethylene （PE-HD） tubes for nuclear power plants at home and abroad. Although there are few cases of PE-HD material being used in nuclear grade 3 pipeline， the application prospect of PE-HD material is broad due to its excellent corrosion resistance. Standards and specifications play an important role in the application of nuclear power engineering. The United States has established the ASME code and France has established the RCC-M code. At present， China carries out work with reference to the ASME code and also begins to write relevant national codes.In order to ensure the reliability of cooling water for nuclear power plants and the safe and stable operation of the units， the design， manufacturing， welding， nondestructive testing， in-service supervision， aging management and other aspects should be considered in engineering application
Machinery and Mould
REN Li, BAI Haiqing, BAO Jun, JIA Shikui, QIN Wang, AN Yiwei
Abstract (
1224 )
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737
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The extrusion principle of traditional desktop FDM 3D printer and screw extrusion 3D printer was analyzed. To improve the compatibility of desktop FDM 3D printer with printing materials and to reduce the production cost of printing materials， a new structure of screw extrusion 3D printer was designed with a function of convenient disassembly and replacement of screw and barrel. A screw metering section structure suitable for the ABS printing materials was obtained through combining the design calculation. Under the requirements of low rotating speed and miniaturization of the screw， the high-precision printing with a small flow rate could be realized， and a higher flow rate could be obtained through improving the rotating speed. The characteristics of melt velocity field， pressure field and shear rate field in the metering section were analyzed by means of the simulation experiment. The regression equation regarding the screw speed and outlet flow rate was obtained through a least square method， and the rationality of the calculated results was verified. The results indicated that the screw extrusion mechanism was suitable for 3D printing. This mechanism can reduce the printing cost， widen the selection range of printable materials， and realize the more accurate adjustment of the material extrusion flow rate through controlling the screw rotation speed.
Review
ZHANG Hongyu, WAN Xian, CHEN Yan, GUO Baohua
Abstract (
920 )
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814
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This paper reviewed the research progress in phase change cold-storage materials in cold chain logistics and also introduced the development situation of cold chain logistics in China. Furthermore， the research progress in the phase change cold storage materials at home and abroad in the aspects of composition， method preparation， cold storage performance and application effect were summarized. Moreover， the performance comparison of various storage and transportation equipments before and after combining with phase change cold-storage materials in the process of cold chain logistics was summarized. The applications and development prospect of phase change cold-storage materials in cold chain logistics were prospected.
MA Chaoqun, SHI Wenzhao, CUI Shanshan, ZHANG Manyan, ZHOU Hongjuan
Abstract (
1056 )
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1083
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27 )
This paper reviewed the influences of preparation methods on the porous structure and properties of polyvinyl alcohol （PVA）?based porous composites， including the emulsion template method， supercritical carbon dioxide method， electrostatic spinning method， freeze-drying method， pore-forming method and phase separation method. The applications of this type of porous composites in the adsorption field were presented in detail. Their relevant research and recent progress in the fields of oil/water separation， inorganic salts， and dye adsorption were described. The development trend in the functionalization of the porous composites through crosslinking modification was prospected.
ZHANG Yihui, WANG Conglong, CHEN Shihong, WANG Xiangdong
Abstract (
849 )
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392
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This paper introduced the preparation technology of high-performance thermoplastic polymer foams ［polyetherimide （PEI） foams］， including batch solid-state foaming， extrusion foaming， injection molding foaming and other preparation technology. The effect of the selection of foaming agent and nucleating agent on the forming performance of PEI foams was discussed， and the research progress in the recent PEI domestic and foreign foaming technologies was summarized in detail. Finally， the development trend of PEI foams was prospected.
