Materials and Properties
SUN Wenbo, XIN Chunling, HE Yadong, ZHAI Yujiao, YAN Baorui
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496 )
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A micro?foaming injection molding experiment was performed using glass?fiber?reinforced poly（butylene terephthalate） composites as a material. The apparent density， mechanical properties， cell morphology and structure of the obtained products were investigated using a sponge density tester， a universal chemical testing machine， and a scanning electron microscope. The influence of micro?foaming process parameters on the weight loss ratio and cell structure of the products was investigated. The injection molding process parameters for an ideal cell structure was explored through a comparison of the cell structure and mechanical properties of the products obtained at different weight loss ratios. The results indicated that the gas injection rate and melt temperature were the main factors affecting the weight?loss ratio of the product. For the cell structure， the gas injection rate showed the greatest influence， following with the injection pressure and injection speed. The products obtained a good foam quality and mechanical properties at a gas injection amount of 0.2 wt%， an injection speed of 70 cm3/s， and an injection pressure of 70 MPa.
ZHAO Xinxin, JIN Xiaodong, SHI Yan, SUN Shibing, LYU Feng, TIAN Yingliang, ZHAO Zhiyong
Abstract (
428 )
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The surface of extruded polystyrene insulation board （XPSF） was modified through ultraviolet?ozone （UVO） irradiation， and then its chemical structure， wettability and surface morphology were investigated using an X?ray photoelectron spectroscope， a contact angle meter， and a scanning electron microscopy. The results indicated that more oxygen?containing groups were produced on the XPSF surface with an increase in the UVO irradiation time. Especially after UVO irradiation for 15 min， the atomic ratio of O to C elements of the XPSF surface was increased from 0.04 to 0.59. The contact angle between XPSF and deionized water droplets decreased from 101.7 ° to 37.1 ° after UVO irradiation for 30 min. The XPSF surface showed an unchanged morphology after UVO exposure. The oxygen content of XPSF decreased gradually with an increase in standing time， suggesting that the oxygen?containing groups were lost from the surface of XPSF， thus recovering the hydrophobicity. After storage for 7 days， XPSF was still oxidized， resulting in a hydrophilic surface. Nevertheless， the wettability and chemical structure of XPSF was returned to its original state after storage for 14 days. However， the XPSF surface still exhibited an unchanged morphology.
XIA Yunxia, LI Lei, LUO Zhangsheng, ZHU Qianqin, HE Lijun
Abstract (
707 )
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Two types of recycled polyethylene non?woven fabrics were prepared by a flash evaporation method using two types of recycled polyethylene with different melt flow rates as raw materials and a mixture of difluorochloromethane and tetrafluorodichloroethane as solvents. Their morphology， thermal properties， mechanical properties， air permeability， and water resistance were investigated using a scanning electron microscope， a differential scanning calorimeter， an electron intensity meter， and a digital air permeability meter. The results indicated that the recycled polyethylene non?woven fabrics were both composed of ultra?fine fibers. They exhibited maximum tensile breaking strength of 233 N/5 cm， maximum elongation break of 77 %， good air permeability， high resistance to hydrostatic pressure， good printing and dyeing properties， and satisfactory barrier performance. With such good comprehensive properties， the recycled polyethylene non?woven fabrics reach the goal for achieving addition value in the recycled polyethylene. This matches the sustainable development target and shows a broad market prospect in near future.
WANG Ke, LONG Chunguang
Abstract (
474 )
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Sepiolite fibers （Sep） were modified with a silane?coupling agent （KH550）， and the ultra?high molecular weight polyethylene （PE?UHMW）/Sep and PE?UHMW/modified Sep （O?Sep） composites were prepared on a flat vulcanizer using a hot?pressing method. The surface structure of Sep and O?Sep and the mechanical and tribological properties of the composites were investigated using an infrared spectrometer， an electronic universal testing machine， and a scanning electron microscope. The results indicated that the KH550 molecules covered the surface of O?Sep， resulting in a uniform distribution of O?Sep in the composites. When the content of O?Sep fibers reached 6 wt%， the composites exhibited the optimal performance with tensile strength of 32.1 MPa， flexural strength of 171.2 MPa， flexural modulus of 138.3 GPa， and impact strength of 17.62 kJ/mm2， which were 41.4 %， 40.0 %， 95.6 %， and 36.9 % higher than those of pure PE?UHMW， respectively. The composites also revealed a friction factor of 0.124 and a wear amount of 0.1 mg， which were 77.1 % and 80 % higher than those of pure PE?UHMW， respectively.
CHEN Sheng, LIANG Yingchao, WU Fangjuan, FANG Hui, FAN Xinfeng, CHEN Hui, WANG Yonggang
Abstract (
310 )
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The bidirectional warp?knitted glass fibers （BWKGF） were modified with 3?aminopropyltriethoxysilane and to?luene diisocyanate to prepare k?BWKGF and t?BWKGF， respectively. Polyamide 6 （PA6）/BWKGF， PA6/k?BWKGF， and PA6/t?BWKGF composites were then prepared through a thermoplastic resin transfer molding process. The structures of modified BWKGF and the microstructure and mechanical properties of the composites were characteri?zed using an infrared spectroscope， a field emission scanning electron microscope， and a universal testing machine. The results indicated that the surfaces of k?BWKGF and t?BWKGF were grafted with active groups. The surface roughness of BWKGF increased and the interfacial bonding between BWKGF and PA6 was improved after modification. In addition， the mechanical properties of the composites were improved due to the surface modification of BWKGF. The tensile strength of PA6/k?BWKGF and PA6/t?BWKGF reached 130 MPa and 140 MPa， respectively， which were 44.5 % and 55.5 % higher than that of PA6/BWKGF， respectively.
LEI Jingfa, SHEN Qiang, LIU Tao, SUN Hong, YIN Zhiqiang
Abstract (
409 )
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249
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To explore the static and dynamic mechanical properties of thermoplastic polyurethane elastomer prepared through the fused deposition modeling process as well as the influence of process parameters on the mechanical properties， the mechanical properties of thermoplastic polyurethane elastomer under a quasi?static loading of 0.01 s-1 and a dynamic loading of 1 000 s-1 were evaluated at three printing speeds of 10， 40 and 70 mm/s and three nozzle temperatures of 200， 220， and 240 °C using a universal material testing machine and a split Hopkinson pressure bar （SHPB） experimental apparatus. The process parameters were also optimized. Furthermore， the stress?strain sample space data were further obtained in a wide strain?rate range of 0.001~2 500 s-1. The results indicated that a nozzle temperature of 220 °C and a printing speed of 40 mm/s were the optimal process parameters under the quasi?static and dynamic loadings. The specimens had a strain?rate effect under both the quasi?static and the dynamic conditions， exhibiting significant hyper?elastic characteristics under the quasi?static condition. Using a viscoelastic constitutive model of the material combined with the ZWT （Zhu?Wang?Tang） equation under the dynamic condition， the fitted curves of the model were in good agreement with the experimental curves. The specimens showed an obvious "micro?phase separation" under the optimal process parameters.
YANG Musen, QIAN Lijun, WANG Jingyu, ZHAO Zhen, WANG Guangyu, XIN Xiaohua
Abstract (
456 )
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310
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To obtain a high?efficient flame?retardant polystyrene （PS） composite system based on methyloctabromoether （MOBE）， the flame?retardant properties and corresponding mechanisms of the flame?retardant PS compounds with MOBE and triphenyl phosphate （TPP） were investigated using a limiting oxygen index instrument， a cone calorimeter， a thermogravimetric analyzer， and a differential scanning calorimeter. The results indicated that the introduction of TPP and MOBE increased the limited oxygen index （LOI） of PS significantly compared to their use alone. The PS compound containing 3 wt% TPP and 4 wt% MOBE obtained an LOI of 27.7 vol%， which was 26.1 % higher than the compound only containing 4 wt% MOBE. The burning intensity of this PS compound was further depressed， and its effective heat of combustion， peak heat release rate， and total heat release was reduced when compared to those of the compound only containing 4 wt% MOBE. TPP and MOBE could release the flame?retardant elements intensively during the thermal degradation process of PS compounds， exhibiting an efficient gas phase quenching effect. Moreover， the addition of TPP also improved the melt flow rate of PS compounds and reduced their glass transition temperatures. In this case， the generated droplets could take heat away faster from the PS thermal decomposition and finally make TPP and MOBE a better flame?retardant effect.
YI Huijun, TANG Ming, ZHANG Qingyi, BAI Yinna
Abstract (
506 )
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228
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According to the current market demands for light curing （SLA） resins， bisphenol?A epoxy acrylate， diacrylate， and triacrylate resins together with a photo?initiator were used to prepare hard UV SLA resin products. The mechanical properties， viscosity， and volume shrinkage of the resultant resins was investigated using an electronic universal material testing machine， a plate rheometer， and an electronic hydrometer， and their product formulas were determined. SLA 3D printing was carried out using these formulas. The results indicated that 2.0 mol of oligomer bisphenol?A epoxy acrylate， 20.0 mol of active diluent， and an appropriate amount of photo?initiator were determined as a proper formula for the SLA resins. The SLA resins obtained a viscosity of 240.8 mPa?s， tensile strength of 47.1 MPa， elongation at break of 5.62 %， and a volume shrinkage rate of 4.44 %. The printed products exhibited a smooth surface and excellent performance.
LUO Jun, HUANG Hongsheng, YE Xiaolan, REN Jun, NIE Shengqiang, WANG Yi, ZHANG Chunmei, LIU Yuan
Abstract (
450 )
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367
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To explore the effect of hydrogen bonds on the properties of polyurethane， two types of polyurethanes were synthesized using polytetrahydrofuran， isophorone diisocyanate， 4，4’?dihydroxybiphenyl， and N3，N5?bis（4?hydroxyphenyl）pyridine?3，5?diformamide as raw materials. Their chemical structure， thermal stability， mechanical properties， and self?healing properties were investigated by Fourier?transform infrared spectroscopy， thermogravimetry analysis， and a universal material testing machine. The results indicated that the two polyurethanes presented excellent self?healing performance， and both of them could completely self?heal the damages after healing at 60 ℃ for 30 min. As a chain extender， the polyurethane synthesized with N3，N5?bis（4?hydroxyphenyl）pyridine?3，5?dicarboxamide exhibited a better mechanical property than that with 4，4’?dihydroxybipheny， exhibiting higher tensile strength of 1.2 MPa， superior thermal stability with thermal degradation activation energy of 230.3 kJ/mol， and a higher carbon residual yield of 5 wt% at 800 oC.
LI Fujie, QI Bin, XU Huating, WANG Limei
Abstract (
484 )
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Chitosan （CS）/poly（vinyl alcohol） （PVA）/snail mucus （SM） composite films were prepared through crosslin?king with vanillin using a casting method. The effect of CS/SM mass ratio on the optical properties， water vapor permeability， water vapor， oxygen barrier capability， and mechanical and biodegradable properties of the composite films were investigated using a thermogravimetric analyzer， a scanning electron microscope， and a universal material testing machine. The results indicated that the composite films were biodegradable and hydrophilic， and their properties were optimal when the volume ratio of CS solution to SM solution was set to 5/3， presenting an antioxidant activity of 87.51%. Comparing to pure CS film， the composite films showed a decrease not only in water vapor transmission rate by 75.16 % but also in opacity by 87.74 %. However， they showed an increase in tensile strength by16.03 % and in elongation at break by a factor of 28.26. The thermal stability of the composite films decreased with an increase in the proportion of SM. In addition， the composite films exhibited good compatibility at CS/SM volume ratios of 5/1， 5/2， and 5/3. The addition of SM endowed the composite films with good ductility and flexibility， whereas the addition of vanillin improved their tensile strength and antioxidant activity. The CS/PVA/SM composite films exhibit potential prospects in the application for food packaging.
QIAO Zongwen, DENG Jiaqi, JI Wei
Abstract (
332 )
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Chloroprene polysulfone and chloroprene polysulfone were prepared through an acylation reaction， and then pyrene sulfonic acid polysulfones with different side chain lengths （4PS?SA and 5PS?SA） were prepared through a nucleophilic substitution reaction with 8?hydroxy?1，3，6?pyrene trisodium as a reagent. A series of 4PS?SA and 5PS?SA cation exchange membranes were prepared using a solution?casting method. The chemical structures， bonding amount of sulfo?nic acid groups， and effect of flexible side chains on the performance of pyrene sulfonic acid polysulfone cation exchange membranes were investigated using an infrared spectrometer， a UV?visible spectrophotometer， a nuclear magnetic resonance instrument， and an atomic force microscope. The result indicated that 4PS?SA and 5PS?SA cation exchange membranes exhibited an excellent dimensional stability and methanol resistance， and their water absorption rate， water swe?lling rate， and proton conductivity increased with an increase in temperature. The 5PS?SA with a longer side chain exhibi?ted a better dimensional stability and proton conductivity at the same ion exchange capacity. The 5PS?SA?3 showed water sorption rates of only 23.7 % and 39.1 % at room temperature and 85 oC， respectively. Its proton conductivities were 0.093 S/cm at room temperature and 0.142 S/cm at 85 oC， and its methanol permeability was only 7.09×10-7 cm2/s. These results indicated that the polysulfone cation exchange membranes had good comprehensive performance and were expected to be used for cation exchange membrane fuel cells.
Processing and Application
WANG Yang, CHENG Lisheng, TAN Jing, YANG Weimin, WANG Ruixue, ZHANG Zhenghe
Abstract (
362 )
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Moldflow software was adopted to design and analyze the injection molding of joints in polyether ether ketone （PEEK） profiles. The effects of filler type and its content in PEEK matrix on the injection pressure， clamping force， fiber orientation tensor distribution and warpage of molding parts were analyzed in terms of the perspective of injection flow process and molding part quality. The results indicated that the introduction of fillers improved the flow characteristics of PEEK， and the incorporation of glass fiber as a filler could optimize its mechanical threshold. A high?modulus carbon fiber could significantly enhance the stiffness and reduce the warpage degree. The increase of filler content could optimize the stiffness of the molded parts. Based on the results obtained from this study， the type and content of filler for PEEK profile can be targeted to ensure a high quality of injection molding.
TIAN Chifeng, ZHANG Hongshen
Abstract (
348 )
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The charge of polymer particles for vehicles in a friction barrel?type tribicharger was explored preliminarily， and the friction charge sequences of six types of vehicle polymer particles including polypropylene （PP）， polyurethane （PU）， polyamide （PA）， polyethylene （PE）， polyvinyl chloride （PVC）， and acrylonitrile?butadiene?styrene （ABS） were investigated using a friction barrel?type tribicharger based on the Faraday cage. The charge laws were verified by taking ABS and PA as examples under different rotational speeds （n） and charge time （t） with the friction barrel?type tribicharger， and the optimal electrostatic separation parameters of ABS and PA were determined. The results indicated that the charge of polymer particles was proportional to n and t. The friction charge sequence of polymer particles for vehicles was as follows： （-） PE→ABS→PVC→PU→polymethyl methacrylate→PP→PA （+）. The optimal separation parameters of ABS and PA were determined to be n=20 r/min and t=1 min. Under this condition， the separation purity of ABS and PA reached 94.18 % and 99.86 %， respectively. The recovery rates of ABS and PA were 88.4 % and 75.3 %， respectively. This resulted in a total recovery rate of 90.15 %.
ZHOU Wenxian
Abstract (
2346 )
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The discoloration of the polarizer of liquid crystal displays after solar irradiation was analyzed， and its optical properties， weather resistance， surface elements and of discoloration mechanism were investigated using an intelligent xenon lamp aging tester， a wide?angle/small?angle X?ray scattering applause， an X?ray energy dispersive spectrometer， and a spectrophotometer. The results indicated that the peak intensity of UV absorption for I3- was doubled after exposed to 105 oC for 1 h， and its peak intensity increased by a factor of 3 after exposed to 120 oC for 120 h. However， and the peak intensity of UV absorption for PVA?I5- decreased， whereas the peak intensity for PVA?I3- increased. The discoloration mechanism of the iodine?based polarizer was attributed to the molecular structure conversion from PVA?I5- to PVA?I3-. With an increase in test time at a high temperature， the color of the polarizer gradually changed to brown as the ratio of I3- increased. Meanwhile， the color of the discolored polarizer could recover after a high?temperature and high?humidity treatment. A conversion between the PVA?I5- and PVA?I3- could be operated mutually in the polarizer. The solar radiation discoloration of the polarizer was mainly affected by the anti?ultraviolet performance and high?temperature resistance of the polarizer. The anti?purple performance of the polarizer could be improved by increasing the content of UV absorber through optimizing the raw materials and manufacturing process， and its high temperature resistance could be improved by increasing the content of PVA?I5-. This can solve the problem of discoloration of the iodine?based polari?zers under sunlight.
TANG Yuanjun, LI Xuan, DONG Jun, LI Guoneng, LUO Guanqun, WANG Weimin, XU Yousheng
Abstract (
587 )
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238
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Waste poly（vinyl chloride） （PVC） plastic was pyrolyzed to investigate its multi?steps thermal degradation reaction kinetic properties. The kinetic parameters were characterized in three different?scale methods， including the integrated method， weight?loss stage method， and overlapping complex reaction?deconvolution method. The overlapped reactions were separated by peak?fitting of the differential thermogravimetric curves using Fraser?Suzuki deconvolution function. Three model?free methods， including the Friedman’s differential method， Kissinger?Akahira?Sunose’s integral method， and Ozawa?Flynn?Wall’s integral method， were adopted to simplify the kinetics model and estimate the kinetic triplets. The master plots theory was used to obtain the most suitable mechanism model. The results indicated that the integrated method or weight?loss stage method was not appropriate to the determination of the kinetic characteristics of PVC pyrolysis due to the complex overlapping multi?step reactions. The results from the deconvolution method showed that the apparent activation energy of the separated three pseudo reactions based on the KAS method were 128.01， 182.34， and 246.49 kJ/mol， associated with the corresponding pre?exponential factors of 19.84， 26.99， and 33.26 s-1， respectively. The pseudo reactions 1 and 3 accorded with Avrami?Erofeevmechanism model， whereas the pseudo reaction 2 complied with the Prout?Trompkins mechanism model. The results obtained from this work could be used as a theoretical basis for the development and application of clean and efficient waste plastics pyrolysis technology.
OUYANG Yu, LIU Hongbin
Abstract (
332 )
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This paper reported an intensive study on the injection molding of polyphenylene ether/polyamide fender. Based on the results from numerical simulation， a research method of principal component analysis combined with grey relational analysis was proposed to obtain the first principal component equation. Then， the contribution degree of each index， the influence degree of each process parameter on the comprehensive quality， and the combination of better process parameters were achieved to optimize the defects such as wing warpage deformation， uneven volume shrinkage and shrinkage mark. The results indicated that the influence degree of each process parameter on the comprehensive quality increased by an order of： cooling time > die temperature > melt temperature > holding time > holding pressure. After optimization， the maximum warpage deformation decreased by 9.6 % from 11.29 to 10.21 mm， volume shrinkage decreased by 11.33 % from 16.24 % to 14.4 %， and shrinkage mark length decreased by 7 % from 0.060 6 to 0.056 4 mm.
Additive
FENG Xiu, SHEN Ying, XU Sheng
Abstract (
451 )
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425
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Seven novel types of nontoxic organic bismuth catalysts were synthesized， and their chemical compositions were confirmed by nuclear magnetic resonance spectroscopy， mass spectroscopy， and infrared spectroscopy. Then， these catalysts were used to prepare polyurethane coating materials， and the effects of catalyst structure and dosage on the curing time， corrosion resistance and tensile properties of the polyurethane coating films were investigated. The results indicated that the pentavalent organic bismuth catalyst exhibited better catalytic performance than the bismuth trivalent one. The bismuth metal catalyst with a total mass fraction of 0.3 wt% shortened the curing time of polyurethane coating films one quarter， significantly improving their solvent resistance by 30 % and tensile strength by 33 %， but reducing their elongation at break by 35 %. The bismuth catalyst promoted not only the polymerization reaction but also the chain crosslinking and aggregation to some extent， thus improving the performance of the films. The planarity of the aryl group in the bismuth molecules had a great influence on its activity， and the catalyst containing the oxygen?bridged diphenyl ligand showed good catalytic performance due to its good planarity.
ZHANG Zongyin, LYU Mingfu, GUO Peng, XU Yaohui, ZHANG Shijun
Abstract (
380 )
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The natural aging behavior of poly（butylene succinate?butylene terephthalate） （PBST） films in Turpan and Hainan was studied， and their tensile， optical， and thermal properties before and after aging were investigated using a high?speed tensile tester， an enhanced projection haze tester， and a differential scanning calorimeter. The effect of UV absorber UVA on the weather resistance of PBST films were evaluated. The results indicated that the tensile strength and elongation at break of the PBST films gradually decreased with an increase in natural aging time， but the light transmittance seemed not to change significantly. Moreover， the haze of the films gradually increased， and their melting peak temperature shifted to a lower temperature. The UV absorber could significantly improve the weather resistance of PBST at an optimal addition amount of 0.5 wt%.
Standard and Test
SUN Ying, HUANG Yan, WANG Xingyu, WENG Yunxuan
Abstract (
646 )
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To study the characteristic odor components of express packaging bags， the volatile odor components of express packaging bags were obtained using a liquid?liquid extraction method， and then they were separated and identified by gas chromatography?mass spectrometry. The results indicated that there were 30 types of identified compounds， in which alcohols exhibited the highest relative mass fractions. The relative mass fractions of 2?（octadecyloxy）?ethanol， tributyl acetylcitrate， 1?chloro?heptacosane， 2?hexadecanol， 2?bromo?octadecanal， and tert?hexadecanethiol were also higher than other compounds. These odor components may play an important role in the special odor compositions of express packaging bags.
Plastic and Environment
JI Feng, GONG Weihua, ZHANG Yan, LUO Shuiyuan, YU Qingyu, ZHU Junqiu, GUO Jiangbin
Abstract (
1151 )
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Biodegradable poly（butylene adipate?co?butylene terephthalate） （PBAT） foaming particles were prepared using a supercritical carbon dioxide autoclave foaming technology. The chemical composition and thermal properties of the obtained PBAT were investigated using a nuclear magnetic resonance spectrometer， a gel permeation chromatographer， and a differential scanning calorimeter. Moreover， the effects of infiltration conditions on the foaming properties of PBAT were studied. The results indicated that the molar ratio of butylene adipate segment to butylene terephthalate segment in the PBAT chains was 53 and 47 mol%， respectively.The glass transition temperature， melting peak temperature， and crystallinity degree of PBAT were -33 ℃， 122 ℃， and 13.16 %， respectively. In addition， the obtained PBAT exhibited a decomposition temperature of 280 ℃. When the permeation temperature increased from 76 to 90 ℃， the density of PBAT foamed particles decreased but their expansion ratio increased. Their density tended to increase but their expansion ratio decreased after holding for one day. Their density and expansion ratio kept stable when the storage time was increased to seven days. When the permeation time increased from 0.5 to 2 h， the density of PBAT foamed particles decreased but their expansion ratio increased. With a further increase in permeation time from 2 to 3 h， their density and expansion ratio both kept stable. When the permeation pressure increased from 10 to 12 MPa， the density of PBAT foamed particles decreased but their expansion ratio increased. Their density and expansion ratio kept unchanged with a further increase in permeation pressure from 12 to 14 MPa.
WU Xiongjie, TAO Qiang, ZHU Dongbo, CHENG Jinsong, CHU Yu, XU Lei
Abstract (
502 )
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The materials obtained from six types of commercially available biodegradable plastic shopping bags （samples 1#~6#） for food contact were identified by an infrared spectrometer， their total migration amounts were measured under different soaking conditions， and the evaporation residue components of some samples were investigated. The results showed that the qualitative results of the materials from the bag samples 2# and 4# were inconsistent with those as the materials marked. The total migration amount of the biodegradable plastic shopping bags was much greater than that of the traditional polyethylene plastic shopping bags. The total migration results of the 2#~6# samples exceeded the required limit （10 mg/dm2） when immersed in 4 vol% acetic acid simulation solution. So did the samples 1#~6# when immersed in 95 vol% ethanol simulant solution. This indicates that there was a certain food safety risk when biodegradable plastic shopping bags were directly used for food contact. The PBAT in the bag samples could be dissolved in 95 vol% ethanol. The CaCO3 in the samples presented a large migration amount in the 4 vol% acetic acid simulation solution， which was attributed to the migration mass of CaCO3 as well as the calcium acetate formed by the reaction between CaCO3 and acetic acid. Starch particles could gelatinize and fall off in the water， and acetic acid could enter the starch particles to destroy the molecular structure of starch， resulting in a significant increase in the total migration of biodegradable plastic shopping bags compounded with starch.
Review
SUN Qi, GAO Xing, CUI Xuemei, LIAN Huiqin, CUI Xiuguo, WANG Xiaodong
Abstract (
599 )
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Black phosphorene is a new type of two?dimensional nanomaterial with unique properties， and its narrow?band semiconductor properties make it a broad application prospect in field?effect transistors， optoelectronic devices， spintroni?cs， gas sensors， and solar cells. In recent years， the use of black phosphorene for the flame retardancy of polymers has become a hot research field. This paper reviewed the latest research progress in the preparation technology and flame retardant mechanism of black phosphorene. The research advances in the use of black phosphorene as a flame retardant for polymers such as epoxy resin， polyurethane and polyacrylonitrile were introduced. Then， the problems in the flame?retardant application of black phosphorus were analyzed， and the future development direction of the black phosphorene?based flame retardants was prospected.
DENG Tianxiang, XU Lina, LI Shouhai, ZHANG Yan, YAO Na, JIA Puyou, DING Haiyang, LI Mei
Abstract (
835 )
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This paper reviewed the recent research progress in the grafting and crosslinking modification methods for poly（vinyl chloride） （PVC）. The grafting modification methods included the grafting of groups containing C， N or S elements on carbon atom of PVC chains as well as other nucleophilic substitution methods. The crosslinking modification methods involved peroxide crosslinking， triazine compound crosslinking， diene compound crosslinking， silane crosslinking， and other chemical crosslinking methods. Finally， the development prospect of chemical modification for PVC was prospected.
WEI Liao
Abstract (
545 )
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374
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Based on the temporary plugging balls and temporary plugging agents used in fracturing of oil and gas fields in China， this paper systematically summarized the temporary plugging mechanism， performance characteristics， and application status of temporary plugging products synthesized through different processes and formulas. The dissolution characteristics of each product were introduced， and the existing problems in the water?soluble temporary plugging balls and temporary plugging agents were pointed out through a combination with the requirements for the development of green environmental protection of oil and gas fields. Finally， the future development direction of temporary plugging products was prospected.
WANG Rongchen, ZHANG Heng, SUN Huanwei, DUAN Shuxia, QIN Zixuan, LI Han, ZHU Feichao, ZHANG Yifeng
Abstract (
543 )
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This paper briefly introduced the preparation technologies of poly（lactic acid） （PLA） nonwovens such as electrospinning， spunbonding， and meltblown techniques. The hydrophilic modification methods of PLA nonwovens such as fiber?forming modification， web?forming modification and post?finishing were especially introduced. Then， the applications of PLA nonwovens in the medical and health field， including drug release， wound dressing and mask manufacturing， was discussed. Finally， the future development trend in the hydrophilic modification of PLA nonwovens was prospected.
