Materials and Properties
HE Xuetao, ZHANG Yi, MO Zhenyu, LI Changjin, WANG Shuo, YANG Weimin, LI Haoyi
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300 )
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The melt⁃electrospinning performance of poly （butyleneadipate⁃co⁃terephthalate） （PBAT） was investigated， and the relationship between the melt differential electrospinning process parameters and properties of the resultant PBAT fibers were studied. The results indicated that the fiber diameter decreased and its diameter distribution decreased at first and then tended to increase with an increase in spinning temperature. With an increase in spinning voltage， the fiber diameter decreased and the distribution was uniform. Meanwhile， the mechanical properties of the fiber membranes were improve gradually. The optimal fiber fineness and uniformity were obtained at a spinning distance of 9 cm， a spinning temperature of 260 ºC， and a spinning voltage of 45 kV. The obtained fibers exhibited a diameter of 4.31 μm， a standard diameter distribution deviation of 0.76. The fiber membranes obtained tensile strength of 9.9 MPa and elongation at break of 111.2 %.
ZHANG RUI, YAO Jiabin, LI Xuan, HE Xuelian
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281 )
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A type of cross⁃linked ethylene⁃vinyl acetate copolymer （EVA）⁃based bidirectional shape memory polymer （SMP） was prepared using EVA as a raw material and tert⁃butyl peroxy⁃2⁃ethylhexanoate （TBPE） as a cross⁃linking agent， and the effect of TBPE content on the performance of the resultant products was investigated. The results indicated that the Tm and Tc of the EVA⁃based SMPs decreased with an increase in the content of TBPE， and their driving temperature could be adjusted by the content of the cross⁃linking agent. The EVA⁃based SMPs obtained both one⁃way and two⁃way shape memory functions. The shape fixation rate presented a downward trend with an increase in the content of TBPE， reaching the lowest value of 88.83 % and a shape recovery rate of over 99 %. The EVA⁃based SMPs also exhibited two⁃way memory performance， and their Ra，2W decreases with an increase in the content of TBPE content， but their Rr，2W presented an opposite trend. The content of cross⁃linking agent showed a great influence on the performance of the EVA⁃based SMPs.
HUANG Jiawei, HAN Xiaolong, WU You, JIN Yujuan, GUO Maolin
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228 )
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A series of poly（3⁃hydroxybutyrate co⁃3⁃hydroxyvalerate） （PHBV）/ ethylene vinyl acetate elastomer （EVA） blends were prepared by melt blending using EVA as an impact modifier， and their structure and properties were characterized using Fourier⁃transform infrared spectrometer， torque rheometer， differential scanning calorimeter， thermogravimetric analyzer， mechanical property test， and hot table polarizing microscope. The results indicated that the compatibility and dispersion of PHBV and EVA were enhanced through the hydrogen bonding， entanglement， and similar backbone structure between two polymers. With a gradual increase in the content of EVA， the crystallinity of PHBV/EVA blends increased at first and then tended to decrease at the EVA content less than 10 wt%. Meanwhile， the number of PHBV spherules increased but their size decreased gradually. Compared to pure PHBV， the PHBV/EVA blends with a EVA content of 30 wt % obtained an increase in elongation at break and impact strength by 87.8 % and 338.4 % respectively.
ZHU Jingyun, GU Fenglai, YAN Wei, YI Huijun
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395 )
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The microstructures of the domestic PE⁃HD product （8100M） and some imported PE⁃HD products were comparatively analyzed using infrared spectrum， differential scanning calorimeter， gel permeation chromatography， and nuclear magnetic resonance. The performance of cross⁃linked PE⁃HD samples was further investigated. The results indicated the cross⁃linking degree of PE⁃HD could be improved by reducing MFR， enlarging molecular weight distribution， and adding co⁃monomer. The design for the MFR of PE⁃HD 8100M was considered to be reasonable， together with a high average molecular weight and narrow molecular weight distribution. The PE⁃HD 8100M powders exhibited a concentrated particle size distribution and a larger average particle size. This facilitates the uniform dispersion of additives in the matrix. The cross⁃linking reaction of PE⁃HD first occurs between macromolecules， resulting in a decrease in the tensile properties of PE⁃HD decreased after cross⁃linking. The extruded pipe based on PE⁃HD 8100M passed the classification certification and was assessed to be the PE80 grade pipe material.
DING Ding, XU Wenzong, YAN Hongyi
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321 )
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To improve the flame retardancy and smoke suppression performance of epoxy resins （EP）， ZIF⁃67 was loaded on the surface of chitosan （CS） using a co⁃precipitation method. The structure and morphology of the resultant hybrid were analyzed by Fourier⁃transform infrared spectroscopy， X⁃ray diffraction， and scanning electron microscopy. The results indicated that the CS/ZIF⁃67 hybrid was successfully prepared. The effect of different proportions of CS/ZIF⁃67 hybrid on the flame retardant and smoke suppression properties of EP was studied. The results indicated that the addition of CS/ZIF⁃67 hybrid improved the UL 94 grade and LOI value of EP composites and reduced the heat release rate and smoke release rate of EP⁃based composites， The addition of CS/ZIF⁃67 hybrid effectively improved the flame retardant and smoke suppression performance of EP. The SEM and Raman spectroscopy analysis for the residual char after the combustion of EP⁃based composites indicated that the addition of CS/ZIF⁃67 hybrid improved the graphitization degree of the residual char， and a denser carbon layer was formed during the combustion of EP， thus generating flame retardant and smoke suppression effects.
LI Juan, WANG Yaqiao
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567 )
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The TPEE/PTFE nanofiber composites were prepared by means of a melt blending method， and the effect of different processing technologies on PTFE fibrosis was investigated. Furthermore， the effect of PTFE content on the crystallization behavior， rheological behavior and foaming behavior of TPEE were studied. The results indicated that PTFE fiber promoted the crystallization of TPEE and improved the rheological properties of TPEE. The high specific surface area of nanofibers can provide a large number of nucleation sites for cell nucleation， effectively improving the cell density and reducing the cell size. The TPEE/PTFE composite foam obtained an average cell size of 3.2 μm and a cell density of 3.11×1010 cells/cm3 at a PTFE content of 2 phr.
JIANG Siyu, LOU Chunhua, ZHOU Yongli
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277 )
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To reduce environmental pollution and improve the utilization rate of corn straw， the modified corn straw/epoxy resin biomass composites were prepared by using palm acyl chloride⁃modified corn straw as a filler and epoxy resin （EP） as a matrix resin. FTIR and XPS were used to characterize the structure of the straw before and after modification， the electronic universal testing machine was used to analyze the mechanical properties of the composites， and the SEM was used to analyze the micro morphology of the composites. The results show that there is a new C=O characteristic stretching vibration peak at 1 754 cm-1 in the FTIR spectrum； In XPS energy spectrum， the contents of C1 （C=C， C—C） and C2 （C—O） decreased from 47.85 % and 40.24 % to 41.30 % and 30.64 %， respectively， and the contents of C3 （C=O） and C4 （C—O—C） increased from 9.12 % and 2.79 % to 20.56 % and 7.20 %， respectively. This indicates that the hydrophobicity of modified corn straw was enhanced and its compatibility with epoxy resin was improved. According to the analysis of mechanical properties， the tensile properties of epoxy resin composites increased by 100.3 % and 157.77 % compared with pure epoxy resin. Their bending strength increased at first and then tended to decrease. Compared to pure epoxy resin， the composites presented a maximum increase in impact strength by 16.8 % and 70.53 % when 10 wt % unmodified straw and 15 wt % modified straw were incorporated， respectively.
CHEN Haiying, ZHANG Chenqing, ZHANG Hao, CHEN Cheng, JIN Guangyuan, WEI Lingjun
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274 )
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To evaluate the effect of poly（methyl）siloxane （PMSQ） on the mechanical and physicochemical properties of PHB/PCL films， 2 wt % PMSQ was added to the polyhydroxybutyrate （PHB）/polycaprolactone （PCL） blending systems with mass ratios of 25∶75， 50∶50， 75∶25 to prepare films by solution casting method. The results indicated that PMSQ exhibited an optimal enhancing effect on the tensile performance of the PHB25/PCL75 blends， resulting in an increase in elongation at break from 22.45 % to 70.83 %. FTIR spectra demonstrated the disappearance of the methyl （—CH3） absorption peak of PMSQ along with an enhancement in the absorption peak intensity of the C=O bond in the PHB/PCL blending system. These results indicated that PHB and PCL were grafted onto PMSQ microspheres. SEM observation showed that the addition of PMSQ reduced the particle size of the PHB and PCL domains. The phase separation between the PHB and PCL phases was depressed due to an enhancement in their compatibility. DSC analysis suggested that the addition of PMSQ restricted the motion of PHB and PCL molecular chains and disrupted their spatial regularity， thus resulting in a decrease in crystallinity. In addition， TGA analysis indicated the addition of PMSQ increased the onset degradation temperature of the PHB/PCL blending systems and enhanced their thermal stability in accordance with the mass ratio of the two components.
ZHEN Jian, GAO Zhiwu
Abstract (
365 )
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The properties and existing problems of random copolymerization polypropylene pipe materials were briefly introduced， and the development of new technologies and products at home and abroad were discussed. Taking two representative PP⁃RCT tube materials as a research object， the structures and properties of the specific tube materials were analyzed and characterized by means of nuclear magnetic resonance carbon spectroscopy， gel permeation chromatography， differential scanning calorimetry， wide angle X⁃ray diffractometer， and rheometer. The results indicated that the two special materials presented different molecular structures， aggregation characteristics， rheological behaviors， and physical properties. This study offers a significant reference for the domestic development of PP⁃RCT tube materials with a high pressure⁃resistance grade.
GONG Shaofeng, TENG Xia, TANG Wufei
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241 )
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AlPO⁃based zeolites （AlPO⁃n， n=5， 11， 17， and 34） were prepared through hydrothermal synthesis. The obtained products were incorporated into polypropylene （PP） to prepare the intumescent flame⁃retardant composites for enhancing its flame retardancy and thermal stability. The flammability and mechanical properties of the composites were evaluated through limiting oxygen index， vertical burning test， cone calorimetry， and tensile test. The results indicated that the PP composite containing 1 wt % AlPO⁃17 achieved a significantly enhancement in LOI and char residue， which increased by 34.8 % and 14.3 %， respectively， compared to pure PP.
Processing and Application
WEN Jinsong
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325 )
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This paper introduced the role， performance requirements， common structures of photovoltaic backsheets as well as the product types， properties and production scales of major domestic backsheet manufacturers. The current situation of raw materials for backsheets such as PET⁃supported membranes， fluorine films， and adhesive was analyzed. Finally， the backsheet market was forecasted， and the new generation backsheet， transparent backsheet， was introduced on the basis of the development trend of photovoltaic backsheets.
LI Ningli, WANG Meng, WANG Rui, ZHU Zhuangzhuang
Abstract (
224 )
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To utilize waste rubber powders and waste plastics reasonably and effectively and also improve their compatibility with asphalt， two type of waste materials were melt blended in advance using a precision mixer to prepare three types of rubber/plastic alloy modifiers with mass ratios of rubber to plastic of 5∶5 （Type I）， 6∶4 （Type II） and 7∶3 （Type III）. According to the orthogonal test scheme for the Trent 70 # asphalt matrix modification， the rubber/plastic alloy⁃modified asphalt was prepared. The optimal formulation was determined through the 48⁃h segregation softening point of the rubber/plastic alloy⁃modified asphalt， penetration at 20 ℃， softening point， and ductility index at 5 ℃. The optimal key preparation technology and processing parameters were determined by means of the grey correlation analysis and extreme⁃difference analysis methods. The results indicated that the optimal blending scheme was determined to use the rubber/plastic alloy with a mass ratio of rubber to plastic of 7∶3 （Type III）， 2 wt % solvent increasing （furfural extraction oil）， and 9 wt % stabilizer （sulfur）. The rubber/plastic alloy⁃modified asphalt exhibited good storage and high temperature stabilities. The optimal key processing parameters were determined to be a shear temperature of 180 ℃， a shear rate of 3 500 r/min， a shear time of 1.5 h， and a development time of 0.5 h. Finally， the structural morphology， rheological properties， low temperature crack resistance， and fatigue resistance of rubber/plastic alloy⁃modified asphalt were analyzed by means of scanning electron microscope， Brookfield rotate viscosity tester， BBR tester， and DSR tester. The results indicated that the rubber/plastic alloy modifiers exhibited good compatibility with asphalt， and the prepared rubber/plastic alloy⁃modified asphalt exhibited lower temperature sensitivity， better low⁃temperature crack resistance， and higher fatigue resistance.
LI Haifeng, QIAO Pengcheng, SUN Rui
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332 )
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A lightweight parking wedge was developed from the three aspects， including structure， materials， and technology based on the requirements of laws and regulations as well as the actual demand for automobile lightweight， and the resulting product was tested and analyzed from its performance to the whole vehicle according to the technical requirements. The results indicated that the developed parking wedge met the requirement of all the tests specified through adopting a cylindrical hollow structure and using the PP⁃matrix composite containing 30 wt % glass fiber. Its weight was only 0.98 kg， indicating a significant weight reduction effect compared to the original rubber and metal parking wedge， together with good economy and good environmental protection.
JIN Qingping, ZHOU Dian, HU Yanlei
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238 )
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To investigate the bonding behavior of GFRP bars and seawater⁃sea sand concrete under seawater environment， totally 54 GFRP bars⁃seawater⁃sea sand concrete center pullout specimens were designed and tested. A temperature acceleration experiment was conducted to study the changes of bond strength of the specimens after corrosion in the clear water and seawater environments， and the rising section of the bond slip curve of specimens was analyzed. The results indicated that the increase of temperature accelerated the degradation of bond strength of GFRP reinforcement⁃seawater⁃sea sand concrete specimens. The bond strength decreased by about 15% at 60 ºC compared to that at 10 ºC. The effect of the seawater condition on the bond strength of the specimens is slightly more significant than that of the clear water condition. The rising section of the bond slip curve of the specimens was analyzed using the BPE， CMR， and Malvar models， and the results indicated that the Malvar model was suitable for the rising section of the bond slip of GFRP reinforcement⁃seawater⁃sea sand concrete under the seawater condition. According to the TSF life prediction， the bond strength of the GFRP reinforcement⁃seawater⁃sea sand concrete specimens presented a retention rate of 65.58 % after 100 years of use under the 20 ºC seawater condition.
Additive
ZHANG Zewen, ZHU Enci, ZHANG Xixiang, WEI Lijuan, ZHAO Shicheng
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256 )
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Two types of α⁃form nucleating agents with a similar chemical structure， sodium bicyclo［2.2.1］hept⁃5⁃ene⁃2，3⁃dicarboxylate （NA1） and sodium bicyclo［2.2.1］heptane⁃2，3⁃dicarboxylate （NA2）， were synthesized， and their nucleation effects on the crystallization behavior of isotactic polypropylene （iPP） was studied. The crystallization temperature and crystal morphology of iPP nucleated with the two nucleating agents were investigated using differential scanning calorimetry and polarized optical microscope （PLM）. The results indicated that the crystallization peak temperature of iPP increased by 14.5 ℃ and 16.0 ℃ at 0.3 wt % NA1 and NA2， respectively. Meanwhile， the two nucleating agents could refine the spherical crystal size of iPP significantly. The nucleated iPP was characterized using wide⁃angle X⁃ray diffraction. Both of two nucleating agents were found to induce the formation of α⁃form crystalline polypropylene， indicating good α⁃form nucleation effectiveness. The mechanical properties of the nucleated polypropylene were characterized. The nucleated polypropylene exhibited an increase in tensile strength and flexural modulus at first and then tended to be stable with increasing the contents of two nucleating agents. Compared to pure iPP， the tensile strength of the nucleated iPP increased by 4.6 % and 8.6 % at 0.05 wt % NA1 and NA2， respectively. The iPP nucleated with 0.05 wt % NA1 and NA2 also showed an increase in flexural modulus by 8.2 % and 21.7 %， respectively， and its impact strength keep stable basically.
Plastic and Environment
DENG Zixuan, GAO Ce, SHI Siyuan, SONG Xinsheng, SU Zhenghao, WANG Xiaoke, MA Jingsong, ZHANG Xin, HOU Lianlong
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296 )
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This paper analyzed the materials， structure， and functionality of existing biodegradable seedling containers from the viewpoint of the necessity of container seedling cultivation， providing a reference for relevant researches. Finally， the current problems in environmentally friendly seedling containers were summarized and their future development trends were overviewed.
DONG Jinghan, ZHAO Yiquan, ZHANG Tongzhu, WANG Yanmeng, DIAO Shuai, LI Minghe, XU Changzhu
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324 )
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To verify the utilization feasibility of the recycled polypropylene （RPP） in automobile bumper， the effects of contents of post⁃consumer recycled polypropylene （PCR⁃PP） on the impact resistance and tensile， bending， and compression properties of RPP were investigated. The thermal properties and tensile fracture morphology of RPP were also analyzed. The results indicated that the mechanical properties of the RPP exhibited a slow downward trend with an increase in the content of PCR⁃PP from 0 to 50 wt %. The elongation at break decreased significantly from 467 % to 210 %. At， the RPP only presented a slight change in impact resistance and tensile and bending properties at a PCR⁃PP content of 10 wt %， which can meet the requirements of performance for bumper materials.
Machinery and Mould
ZHANG Weihe, DENG Chenglin, ZHANG Yanhua, XU Yonglin
Abstract (
365 )
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According to the structural characteristics of the door cladding under C⁃pillar of car， a thin⁃wall injection mold with a sequential valve gating （SVG） hot runner was designed. The appearance of the molded plastic part meets the design requirement by employing the mold structure of the outer surface formed by the dynamic mold and the inner surface formed by the fixed mold. The demoulding problem with a large area， a large force and a large inclination angle of inclined top core pulling was solved by using a double guide rod and an auxiliary rod inclined top lateral core pulling mechanism. The mold adopted a temperature control system based on the straight through water pipe， inclined water pipe， and spacer well， which is close to the shaped water path. The water path was evenly arranged， the mold cooling was balanced and sufficient， the injection cycle was shortened by about 15 %， and the molded plastic parts reached a dimensional accuracy matching the standard of MT3 （GB/T 14486—2008）.
Review
HAN Shuntao, DUAN Changyu, LI Mingqian, MA Xiuqing
Abstract (
448 )
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To solve the problems in the flammability of polyamide 6 （PA6） and the toxicity of halogen flame retardant modification， the combustion and flame⁃retardant mechanisms for PA6 were introduced. The research progress in the halogen⁃free flame⁃retardant modification of PA6 in recent years was reviewed， which included organic⁃flame⁃retardant modification （phosphorus⁃flame⁃retardant modification， nitrogen⁃flame⁃retardant modification， silicon⁃flame⁃retardant modification）， inorganic⁃metals⁃flame⁃retardant modification， nano⁃flame⁃retardant modification， and halogen⁃free synergistic⁃flame⁃retardant modification. The future development prospect of halogen⁃free flame⁃retardant modification for PA6 was proposed.
CAO Ning, LI Kai, WANG Zhiyan, LI Jianhua, WANG Yatao, CHEN Xi, JIA Weiyi, LIU Yang, WANG Xiaodong, LIAN Huiqin, CUI Xiuguo
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259 )
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The present paper reviewed the latest research progress of proton exchange membrane nanocomposites used in DMFC. The influence of the morphology and structure of nanocomposites on the physical and chemical properties of materials were analyzed and commented in terms of methanol permeability and proton conductivity. Furthermore， the development prospect of the proton exchange membrane composites for methanol fuel cells is also discussed.
ZHANG Weimeng, WANG Jie, HU Jing
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431 )
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This paper reviewed the research status of the microstructure of scaffold pores from five aspects， including the pore shape， pore size， porosity， surface roughness， and connection pathways of bone tissue engineering scaffolds. The pore shape of the scaffold with a gradient structure was found to be closer to those of the natural bone. The rough surface can improve the cell adhesion and proliferation of the scaffolds， and the internal structure of the non⁃orthogonal connection pathway can provide a dynamic growth space for later bone regeneration.
SUN Yongtao, LU Daosheng, LIU Lian, ZHANG Hailong, LIU Mingtai
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380 )
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This paper briefly introduced the classical fatigue fracture mechanism of rubber composites and reviewed the latest research process in the flurorubber composites with diatomite， nano zinc oxide， attapulgite， cerium dioxide， graphene， and carbon nanotubes.
