Materials and Properties
HE Hezhi, HUANG Zonghai, LAI Wen, XIONG Huawei
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243 )
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PLA/PBAT and PLA/PBAT/ carbon black （CB） blends with different CB contents were prepared through melt blending. The effects of CB on the morphology， rheological behavior， crystallization properties， thermal stability， electrical conductance， and mechanical properties of the blends were investigated. Scanning electron microscopy observation indicated that CB was selectively dispersed in the PBAT phase as a result of a thermodynamics theory. Furthermore， a change in phase morphology could be clearly observed in the presence of 2 wt% CB. The rheological test results indicated that the viscosity of the PLA/PBAT/CB blends increased with an increase in the CB content. Differential scanning calorimetry analysis demonstrated that the crystallinity of PLA decreased with the addition of 1 wt% CB but increased with an increase in the CB content. Thermogravimetric analysis （TG） showed that the addition of CB improved the thermal stability of the blends slightly. The tensile and conductance test results indicated that adding appropriate amounts of CB could improve the electrical conductivity of the blends and maintain their mechanical properties. However， the addition of excessive amounts of CB reduced the toughness of the blends greatly. The blends exhibited tensile strength of 40.7 MPa， a Young's modulus of 830 MPa， and elongation at break of 365 % at a CB content of 2 wt%， and they obtained an electrical conductivity of 8.69×10-7 S/m， which is about 8 time higher than that of the blends without CB. This new type of compounding material exhibited suitable electrical conductance and good mechanical performance. This study provides a method for preparing biobased polymeric blends with good conductive properties， and the developed blends exhibits application potential for antistatic packaging as a degradable material.
LIU Ying, SUN Hao, YANG Yong, JIANG Kaiyu, YU Tongmin, MA Sai, ZHU Tieli
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196 )
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To improve the mechanical properties of fiber⁃reinforced thermoplastic composites， ultrasonic assisted injection molding experiments were carried out for rectangular flat parts based on polyamide 6 （PA6） reinforced by glass fiber （GF）. Ultrasonic vibration was applied in the following two situations： （1） filling stage， （2） filling and packing stages. X⁃ray diffraction， scanning electron microscopy， Fourier⁃transform infrared spectroscopy， and tensile experiments were performed to investigate the effects of ultrasonic application time and ultrasonic power on the crystallinity and mechanical performance of the parts， the orientation degree of glass fibers， and the bonding strength between glass fibers and the matrix. The changes in the internal crystallinity and mechanical properties of the parts subjected to ultrasonic vibration after water absorption were also studied. The results indicated that crystallinity of the parts was significantly improved by applying ultrasonic vibration with a power of 400 W. When 560 W ultrasound was applied， both the orientation morphology of glass fiber and the bonding strength between the matrix and fibers were improved. Moreover， the tensile strength and bending strength of the parts molded by applying ultrasound during the filling stage were increased by 11.9 % and 10.1 %， respectively. However， the mechanical properties of the parts tended to drop with continuously increasing the ultrasonic power. After absorbing water， the parts showed a decrease in the crystallinity and mechanical properties. Such a reduction could be depressed by introducing ultrasonic vibration into the molding process of the parts.
WU Li, XU Pengwu, YANG Weijun, MA Piming
Abstract (
150 )
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To improve the compatibility between enzymatic lignin and bio⁃based poly（propylene carbonate） （PPC） and to endow PPC with UV resistance， acetylated lignin （ACEL） was prepared through an acetylation reaction and then was melt blended with PPC to obtain PPC⁃based composites. When 15 wt%（mass fraction， same below） ACEL was incorporated， the composites showed an increase in the yield tensile properties from 10 to 23 MPa， and their elongation at break reached 725 %. Meanwhile， the addition of ACEL also endows PPC with excellent UV resistance. After 96 h UV irradiation， the PPC⁃ACEL⁃15 composites showed retention rates of all above 80 % in the yield strength and elongation at break. These results are significantly better than those of pure PPC and PPC⁃EL⁃15 composites.
HU Yongxiang, XIE Jiling, LI Weiming, ZHANG Lu, TANG Xianggang, LYU Yitong, SHEN Hongwang, JU Guannan
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155 )
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Maleic anhydride （MAH） was grafted onto the surface of waste rubber powder （GTR） to obtain GTR⁃g⁃MAH （MGTR） using benzoyl peroxide as an initiator. Poly（lactic acid） （PLA）/MGTR blends were prepared through melt blending， and their micromorphology， crystallization behavior， and mechanical properties were thoroughly investigated. As a result of successful grafting of MAH onto GTR， the MGTR particles were uniformly distributed in the PLA matrix due to good phase compatibility. Additionally， MGTR could facilitate the crystallization of PLA and the formation of more perfect crystals. The tensile strength of the PLA/MGTR blends decreased with an increase in the MGTR content， while their elongation at break and impact strength exhibited an increasing trend at first and then a decrease. The blends containing 10 wt% MGTR exhibited the highest crystallinity of 16.4 %， which is 7 times that of pure PLA. With 15 wt% MGTR was incorporated， the blends showed the highest elongation at break and impact strength， which were 30 % and 60 % greater than those of pure PLA， respectively. This allowed the blends to maintain good tensile strength and also resulted in effective toughening for PLA.
LIU Chaofan, LIAO Shenglong, ZHONG Shuying, LIN Ying
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199 )
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Hyaluronic acid （HA） is a natural polysaccharide with cancer cell targeting properties， and it can be used to construct polymeric nanocarriers sensitive to lesion environments based on special functional groups. Herein， the reversible addition⁃fragmentation chain transfer （RAFT） polymerization was used to synthesize a block copolymer of 3⁃acrylamide phenylboronic acid and vinyl pyrrolidone controllably. This block copolymer was self⁃assembled with hyaluronic acid through the borate ester bond to form nano⁃micelles. Adjusting the feeding concentration of two types of polymers and optimizing the chain length ratio of copolymers can obtain the regulation of micellar hydrodynamic diameter. When the concentration of copolymer was 7.5 mg/mL， the degree of polymerization was 40 and the molecular weight ratio of block was 2. The obtained particle size could be tunable from 73.3 to 163.9 nm， which is advantageous to long circulation in vivo and lesion penetration. The findings indicated that the nanoparticles had suitable pH， sugar， and salt responsiveness. In summary， a multi⁃responsive cancer cell targeting polymer nano⁃micelle has been synthesized in this study， and it exhibits great potential for applications as an antitumor drug and probe carrier.
WEI Jia, LIU Kai, PENG Lijuan, TIAN Yangyang, ZHAO Lin, LI Yanhong, YANG Peipei, LI Songwei, LU Bo
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215 )
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Chitosan （CS）/polyaniline （PANI）⁃graphene oxide （GO） nicotine⁃imprinted composites with anti⁃swelling properties were prepared through cross⁃linking CS and PANI with GO. The swelling rate of the CS/PANI⁃GO nicotine⁃imprinted composite was 2.7 % after soaking in water for 10 h. Nicotine as an adsorbent exhibited an adsorption capacity of 198 mg/g. Meanwhile， the selective adsorption capacity of the adsorbent was studied， and nornicotinine and cotinine were found to obtain adsorption selectivities of 2.97 and 2.4， respectively， indicating good nicotine specific adsorption performance.
FAN Shuting, ZHANG Zhiyu, GUO Rui, ZHANG Lijun
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208 )
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Chitosan （CS）/corn starch （St）/citric acid （CA） crosslinked films were prepared by a tape casting method using CS and St as raw materials and CA as a crosslinking agent. The effects of CS and ST contents on the thermal stability， water solubility， moisture resistance， and mechanical properties of the crosslinked films were investigated. The results indicated that the addition of CA generated a significant impact on the performance of the crosslinked films， and the as⁃prepared films exhibited the best comprehensive performance when the mass ratio of CS/St was 2∶1 and the mass fraction of CA in the solution was 2. In this case， the films presented a maximum thermal decomposition temperature of 366.3 ℃， a mass residue rate of 28.3 %， a water content of 8.16 wt%， a water solubility of 28.48 %， a swelling degree of 18.72 %， a water contact angle of 101.5 ° on the film surface. Their water vapor permeability was determined to be 8 g/（m2·24 h）， which was reduced by 12.25 times. The films also exhibited a water vapor permeability coefficient of 0.488×10-13 g·cm/（cm2·s·Pa）. Their tensile strength was increased from 3.7 to 12.5 MPa， and their elongation at break was increased from 85.3 % to 113.2 %.
WANG Jie, XIN Dehua, LI Hui, JIANG Hongshi, ZHOU Hongfu, ZHAO Jianguo
Abstract (
152 )
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PLA was adopted as a polymeric matrix to prepare PLA/nanoclay composites. The effect of the amount of nanoclay together with 2 phr SiO2 as a hybrid reinforcement on the structures and properties of the composites were investigated. The results indicated that the crystallization behaviors， melt processability， mechanical toughness， and gas barrier property of the PLA composites were significantly improved. The PLA composite with 2 phr SiO2 and 4 phr clay exhibited good filler dispersion， ductile fracture， and good gas barrier property. Compared to pure PLA， the PLA composites presented an increase in elongation at break by 151 % and in impact strength by 74.1 %. Their oxygen and water vapor permeability coefficients were reduced by 67.4 % and 65.0 %， respectively. The excessive amount of clay was disadvantageous to the toughness and also generated a slightly influence on gas barrier.
SUN Fangfang, SONG Yunyun
Abstract (
201 )
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A poly（N⁃phenylmaleimide⁃styrene⁃acrylonitrile） copolymer （PNSA） latex with a uniform molecular structure and good compatibility with PVC was successfully prepared through seed emulsion polymerization combined with a semi⁃continuous feeding method. PNSA/PVC blends were prepared through directly compounding PNSA with PVC resin， and its heat⁃resistant modification effect was evaluated. The results indicated that the PNSA latex exhibited a random structure and a uniform particle⁃size distribution ranging from 155.6 to 249.3 nm. The molecular structure of PNSA is uniform. The differential scanning calorimetry curve shows a single glass transition temperature （Tg） for PNSA， suggesting its excellent compatibility with PVC resin. When the addition amount of PNSA was increased from 0 to 50 wt%， the blends presented an increase in Tg from 84.8 to 107.2 ℃， and their Vicat softening temperature increased from 71.2 to 91.9 ℃. In addition to heat⁃resistant modification， the mechanical properties of the blends were also improved to a certain extent. This study is conducive to further expanding the application field of PVC.
Processing and Application
SHEN Qiangfeng, LYU Mingfu, XU Yaohui
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179 )
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The melting and crystallization behavior of two types of polypropylene， named as mPP and ZNPP， were studied by using differential scanning calorimeter （DSC） and polarized microscope （POM）， and their rheological characteristics were analyzed through frequency scanning and melt stretching. Autoclave foaming experiments were conducted to investigate the melting crystallization behavior， foaming ratio， and cell structure of the expanded polypropylene （EPP） beads. The results indicated that ZNPP had a higher complex viscosity and more obvious shear thinning， leading to higher molecular weight size and distribution. ZNPP exhibits higher melting strength than mPP at higher temperatures due to more intense molecular chain entanglement. However， its melt strength is similar to that of mPP at lower temperatures. The quality of the cell structure needs to be improved， when mPP is used to produce EPP beads with similar ratios to ZNPP.
REN Qinghai, SUN Zudong, GENG Tie
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159 )
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Based on the dual⁃carbon goal， the gas⁃assisted molding technology can provide an effective way for plastic molding to reduce carbon emissions. To design the gas⁃assisted molding parameters accurately， improve the gas⁃assisted molding quality and efficiency， and reduce carbon emissions effectively， the orthogonal optimization with a parameter interaction was studied through 3D numerical simulation and experiments. The results indicated that the parameter interaction had little effect on the gas penetration length but a significant effect on the gas finger defect. Based on the range analysis， the optimized parameter group was obtained at a polymer temperature of 240 ℃， a gas injection pressure of 3 MPa， a delay time of 4 s， and a mold temperature of 40 ℃. The numerical simulation and experiments indicated that the gas penetration length and gas finger under the optimized parameter group were excellent， which could be used in the actual gas⁃assisted molding production.
GAO Zhenqiang, WANG Fei, BAI Yanjun
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197 )
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A flexible surface myoelectric electrode based on a polydimethylsiloxane （PDMS）/silver paste/PDMS@fiber skeleton@flexible silver paste three⁃layer structure was proposed. The resistance changes under different external stimuli such as bending and twisting were analyzed， and the stability of the electrodes was evaluated through adhesion and ultrasonic experiments. The results indicated that such a three⁃layered flexible surface EMG electrode had a high conductivity of below 0.5 Ω/sq， excellent resistance stability with a resistance change rate lower 3 % after 1 000 bending）， good mechanical strength with an electrode⁃substrate adhesion higher than 1 000 N/m， and good skin consistency. When used for an electrical muscle sensor， the developed electrode could effectively recognize various movement intensities with a signal⁃to⁃noise ratio， which was 36 % and 49 % higher than those of the conventional Ag/AgCl gel electrode and copper electrode， respectively.
YANG Rui, GUO Yang, ZHOU Jinyou
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171 )
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To study the mechanism of thermal damage of concrete caused by steam when mixed with waste plastics， the compressive strength tests of concrete with different contents of polystyrene foam （EPS） particles were carried out， and the effect of EPS⁃particle incorporation on the porous structure characteristics and microscopic evolution of steam⁃cured specimens was revealed through mercury intrusion test and SEM observation. The results indicated that the strength of steam⁃cured specimens increased slightly with an increase in the EPS content. The introduction of EPS particles is beneficial for the development of the later strength of the steam⁃cured concrete. The thermal stress caused by steam curing was significantly alleviated， and the number of micro cracks and through cracks decreased， effectively suppressing the thermal damage caused by steam curing. The presence of EPS particles refined the pore structure of the steam⁃cured concrete and reduced the crack width on the interface of the EPS particle and cement matrix.
Additive
XU Chen, LUO Bofei, LIU Tengteng, XING Jingkai
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315 )
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Polypropylene （PP） produced through current industrial processes has typical drawbacks such as poor thermal properties， electrical properties， and optical properties， especially under extreme conditions like low temperatures or high strain rates. These issues can often be addressed by adding nucleating agents. Nucleating agents can induce heterogeneous nucleation in PP， leading to a further refinement of the crystalline structure. In this case， there is an increase in the crystallinity of PP and a reduction in the diameter of spherulites， thus improving the various properties of PP. Starting from the types of nucleating agents for PP， this paper introduced different categories of alpha⁃crystalline nucleating agents （inorganic and organic types） and beta⁃crystalline nucleating agents （inorganic， polycyclic aromatic hydrocarbons， rare earth compounds， etc.） as well as their respective characteristics. Based on this foundation， the paper also reviewed the recent development in the nucleating agents for PP and summarized their nucleating effects on the performance modification of PP. Finally， an outlook was provided for the research direction of nucleating agents of PP in combination with their practical applications.
Plastic and Environment
WANG Shen, LIU Xuanbo, ZHANG Yanfang, JIA Xuefei, ZHU Guixiang, ZHANG Longgui
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281 )
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With a growth of concern about the concept of sustainable development and environment protection， biodegradable nonwoven materials have not only become an important topic in academic research， but also been expected to exhibit great development potential in future because of their advantages such as excellent performance， environmental friendliness， and wide application range. This paper reviewed the research progress in biodegradable polymeric nonwovens in terms of three different sources of biodegradable polymers， including natural polymers， microbial polymers， and synthetic polymers， and their future development perspective was also analyzed.
ZHAO Yongfei, ZHANG Wencai, WANG Ke, HAO Xiaogang, SHEN Jun, YANG Xiying, ZHAO Lirong, LI Jianhong, ZHAO Zhixin, QIAO Jie
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171 )
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This paper reviewed the research progress and application in waste polyethylene （WPE）⁃modified asphalt in recent years. WPE is a solid waste material with the largest proportion of waste plastics in the world， and its research and application in asphalt is of great significance. Most of relevant studies focused on the performance of WPE⁃modified asphalt and its microscopic characterization， analysis， and verification of performance changes. These research results indicated that there were some controversies about the poor storage stability of WPE⁃modified asphalt in high⁃temperature and low⁃temperature performance. Therefore， researchers have actively performed the compounding modification of WPE with other polymers or the high temperature pyrolysis of WPE to prepare modifiers in recent years. They analyzed and evaluated the performance of modified asphalt and achieved certain results； however， there are still technical or cost limitations restricting its popularization and applications. Finally， the application technology of WPE⁃modified asphalt in China was analyzed， and its future research and application perspectives were discussed and predicted.
Machinery and Mould
YU Jiabin, WANG Fei, SHI Wentian, JIANG Yating
Abstract (
205 )
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This article summarized three ways to achieve the intelligent manufacture of molds： Relying on 3D software can provide more accurate product parameters for production in order to quickly and efficiently complete the high⁃precision manufacture of molds； Relying on 3D printing technology to manufacture molds with complex internal structures and high personalization in small batches； Relying on the design optimization of intelligent manufacturing systems can make the manufacturing process of various types of molds more reasonable， fast， and smooth. Finally， the problems in the three development directions of intelligent mold manufacture were analyzed， and the future development directions of mold manufacture were analyzed.
ZHAO Liping, ZHANG Xiaojuan, PENG Xinhua
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212 )
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Taking the plastic shell of paper shredder as the research object， a large hot runner plastic mold with a complex structure was designed. According to the structural characteristics of the plastic parts and the requirement of use， a two⁃hot⁃nozzle⁃feeding mode was designed in the mold to ensure the balance of feeding. A sliding block core⁃pulling mechanism of female die tunnel driven by an oil cylinder， a sliding block core pulling mechanism driven by an overhead cylinder， a sliding block core⁃pulling mechanism driven by a ground side⁃inclined pin together with a time⁃delay elastic pin， and five inclined pin core⁃pulling mechanisms were designed. These designs solved the demolding problem in all of inverted plastic parts. A U⁃shaped waterway was designed for the female die. The uniform distribution way for water wells was adopted for the male die， and the water⁃cooling system on the slider was separately designed. With such designs， the mold exhibited excellent performance in the molding cycle and quality of plastic parts in the actual production process. The die ejection was mainly completed by a declined pin core⁃pulling mechanism and a straight ejecting mechanism.
Review
LIU Shunquan, ZHANG Xinyue, FENG Zhanmiao, FU Chenchao, XUE Ping, ZHANG Run
Abstract (
365 )
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Polytetrafluoroethylene （PTFE） is widely used in the electrical， aerospace， and biomedical fields due to its excellent high⁃temperature resistance， corrosion resistance， and self⁃lubricating properties. However， PTFE still has certain limitations as a result of its diverse service scenarios. This article provided an overview for the research status and advances in PTFE modification from the view of performance optimization， focusing on four aspects of filling， blending， graft copolymerization， and surface modification. These approaches have been extensively explored domestically and internationally in recent years. The article also summarized the current problems in the current development of the PTFE industry and prospected its future development directions.
REN Xiaolong, LI Yi, SU Danyi
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345 )
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This paper introduced the recent research status in the industrial production of colorless transparent polyimide film and reviewed the research progress in fluorine⁃substituent， alicyclic moieties， non⁃plane conjugate structure， sulfone moieties， ester group， amide group， and polymerizable inorganic nanoparticles into the polyimide backbone as main technologies. Finally， the development trends and potential applications of colorless and transparent polyimide film was prospected.
SONG Wenlan, SONG Wenxing, LI Bing, LIU Qian, OUYANG Yuge, TIAN Huafeng, GUO Gaiping
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244 )
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Currently， the biaxially oriented polypropylene （BOPP） is primarily employed as a core material by commercially available thin film capacitors. Although BOPP is the most commonly used polymer film for thin film capacitors， it still presents challenges in low energy density and limited operating temperature range. This paper presents a comprehensive review in the recent advancements in utilizing BOPP films for capacitors， focusing on the studies on enhancing the dielectric and energy storage properties of dielectric materials. The new insights provided by this paper can serve as a valuable reference for the future research and development of high⁃performance polymer⁃based dielectric materials. This paper also offers prospect for the potential research direction in future.
