Materials and Properties
WANG Chunqi, ZHANG Lei, HUANG Yanpei, FU Zhongyu
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256 )
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This article reported an investigation on the structure and performance of the polyacrylonitrile （PAN） ultrafiltration membranes prepared by a phase⁃transformation method using four types of PAN with different viscosity average⁃molecular weights （Mη≈2.2×105 g/mol， 6×105 g/mol， 7×105 g/mol， 8×105 g/mol）. PEG⁃4000 or SiO2 as a common additive was added to the solution to adjust the microstructure and performance of the ultrafiltration membranes. The results indicated that the water flux and retention flux of the ultrafiltration membranes decreased with an increase in the molecular weight of PAN. However， there is a reduction in the finger shaped⁃hole and hydrophilicity with an increase in the molecular weight of PAN. In contrast， the finger shaped⁃hole and hydrophilicity were improved with the addition of the additives. Meanwhile， the water flux of the PAN ultrafiltration membrane with a high molecular weight increased from 100 to 3 000 L/（h·bar） after the addition of the additives， and the average concentration of the filtered oil⁃water mixture was 5 mg/L.
LI Hang, DU Lingzhi, WU Xiaolin, FENG Qiao, LI Guili
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208 )
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In this study， the bipolar plate composites were prepared by using a compression⁃molding technology using natural flake graphite （NG） as conductive aggregate， phenolic resin （PF） and unsaturated polyester resin （UPR） as binders. The effects of the mass ratio of PF to UPR， resin content， and molding conditions on the electrical conductivity and bending strength of the composites were studied by differential scanning calorimetry. The results indicated that the bipolar plate composites obtained an electrical conductivity of 336.1 S/cm and bending strength of 46.5 MPa at a resin content of 20 wt% with a NG/PF/UPR mass ratio of 6∶1， a pressing temperature of 100 ºC， a molding pressure of 30 MPa， a molding temperature of 180 ºC， and a molding time of 2 h. Compared to the NG/PF bipolar plate composite under the same processing conditions， the NG/PF/UPR bipolar plate composites exhibited an increase in electrical conductivity by 134.9 % and in bending strength by 21.2 %.
LYU Dongxuan, XU Pengwu, YANG Weijun, NIU Deyu, SUN Yujie, MA Piming
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200 )
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The toughened poly（3⁃hydroxybutyrate⁃co⁃3⁃hydroxyvalerate） （PHBV）/polypropylene carbonate （PPC） blending films were prepared through solid⁃phase stretching and then characterized by using universal tensile testing machine， small⁃angle/wide⁃angle X⁃ray scattering instrument， SEM， and DSC. The PHBV/PPC blending films exhibited an increase in elongation at break by about 66 % and in tensile strength by 642.9 % at a stretching temperature of 55 ºC， a stretching rate of 300 mm/min， and a stretching ratio 3. The degree of orientation of the blending films was increased from 0.88 % to 38.96 % at a stretching ratio of 3. This effectively promotes the crystallization of PHBV and generates a positive effect on its durability of PHBV， resulting in more stable performance. The toughness of the unstretched blending film decreased by 94.8 %， whereas there was only a reduction by 46 % in the toughness of the blending film at a stretching ratio of 3.
WEI Afei, LI Qiuyi, FENG Xuemeng, HUANG Yuying, PAN Yuanfeng
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173 )
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A type of smart composite packaging film consisting of chitosan （CS）， purple yam anthocyanin extract （PYE）， ZnO nanoparticles （NPs） was prepared， and the effects of addition amounts of ZnO NPs on the mechanical properties， thermal stability， water vapor barrier performance， and antioxidant properties of the composite films were investigated. The results indicated that the synergistic effect of ZnO NPs and PYE resulted in a significant improvement in the tensile strength， thermal stability， antioxidant properties， and vapor barrier performance of the composite films. When 2 wt% ZnO NPs were added， the resultant composite film exhibited an increase in the tensile strength from 26.58 to 41.79 MPa along with a slight decrease in the elongation at break. Its initial decomposition temperature also increased from 256.12 to 271.41 ℃， but its water vapor transmission rate decreased by about 17%. In addition， the addition of ZnO NPs enhanced the antioxidant and antimicrobial properties of the composite film. In practical application， this composite film exhibited pH sensitivity， and it could visually detect a change in the quality of shrimp during storage through a change in color， providing a facile method for food safety monitoring.
WU Jianguo, HONG Yan, GU Zhengbiao, CHENG Li, LI Zhaofeng, LI Caiming, BAN Xiaofeng
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149 )
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In this study， high amylose corn starch （HACS） was esterified with octenyl succinic anhydride （OSA） to obtain three types of OSA starchs with different degree of modification （OS⁃3， OS⁃6， and OS⁃9）. Three types of OSA⁃modified high amylose corn starch composite films （OS⁃3/GEL， OS⁃6/GEL， and OS⁃9/GEL） were prepared using the as⁃prepared OSA starchs as raw materials and gelatin as a compound material. The light permeability， water solubility， moisture absorption， and surface hydrophobicity of the composite films were investigated. The results indicated that the properties of OSA⁃modified starch composite films were greatly improved compared to the unmodified starch composite film. OS⁃6/GEL exhibited the best performance with high light transmittivity of 87.72 %. However， its water solubility， moisture absorption， and water vapor transmittance decreased by 24.5 %， 29.6 %， and 30.35 %， respectively. In addition， its maximum static contact angle and dynamic contact angle reached 124.6 °and more than 100 °， respectively， after contact with water for 3 min. X⁃ray diffraction results indicated that the crystallinity of the original starch was reduced by the OSA modification， and the compatibility between the film⁃forming components was improved. Infrared spectroscopy analysis demonstrated that the introduction of OSA group weakened the interaction between the starch and the hydroxyl groups in gelatin molecules， causing the stronger hydrogen bonding between the two groups. Based on the properties and structure of the composite films， it could be concluded that the OSA modification enhanced the hydrophobic properties of the high amylose corn starch composite films. Through introducing an appropriate number of OSA groups， the resultant OS⁃6/GEL presented the best properties and excellent hydrophobic performance.
YANG Xiying, ZHANG Wencai, QU Lijie, SHI Wenxiu
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135 )
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In order to better utilize the excellent UV shielding function of nano⁃TiO2， improve the anti⁃aging performance of SBS⁃modified asphalt， and address a difficulty in the dispersion of nano⁃TiO2 in the SBS⁃modified asphalt system， the Si⁃Al coated nano⁃TiO2 was prepared using a Si⁃Al coprecipitation method to form the coating film on the surface of nano⁃TiO2. This approach can effectively prevent the oxidation of SBS⁃modified asphalt caused by nano⁃TiO2 due to its photocatalytic activity and thus enhance the anti⁃aging performance of nano⁃TiO2⁃functionalized SBS⁃modified asphalt. The coating effect and morphological microstructure of the coated nano⁃TiO2 were investigated by TEM and XRD， the ultraviolet （UV） absorption capacity of the modified asphalt was analyzed by UV spectrophotometry， the influence of Si⁃Al coating on the dispersion and stability of nano⁃TiO2 and SBS was evaluated by SEM and fluorescence microscopy， and the anti⁃aging mechanism of the Si⁃Al coated nano⁃TiO2 functionalized SBS⁃modified asphalt was analyzed by FTIR spectroscopy. Finally， the performance of the functionalized SBS⁃modified asphalt was studied. The results indicated that the dispersion and stability of nano⁃TiO2 and SBS in asphalt were effectively improved when 6 wt% Si⁃Al coated nano⁃TiO2 was incorporated. In this case， the oxidation effect of nano⁃TiO2 on the modified asphalt could be suppressed， and the anti⁃aging performance of the SBS⁃modified asphalt could be improved.
LIN Bingrong
Abstract (
230 )
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Polyhydroxyalkanoates （PHAs） are a type of high molecular⁃weight bio⁃polyesters synthesized within microbial cells and have attracted widespread attention due to their potential to replace traditional petroleum⁃based raw materials for the preparation of biodegradable thermoplastics. However， the high cost of PHAs currently limits their large⁃scale production and applications. Developing a technology to synthesize PHAs using low⁃cost carbon sources is one of the most effective ways to reduce their costs. The anaerobic fermentation liquor obtained from organic waste is rich in volatile fatty acids and can serve as an excellent substrate for the synthesis of PHAs. Utilizing anaerobic fermentation liquor for the synthesis of PHAs not only can obtain the resourceful utilization of waste but also can produce PHAs to replace traditional petroleum⁃based thermoplastic materials. Meanwhile， the production cost of PHAs can be reduced. Taking the synthesis of PHAs derived from low⁃cost carbon sources as an important direction for reducing production costs， this paper mainly discussed the mechanism of organic waste anaerobic fermentation and focused on the research progress and influencing factors related to the synthesis of PHAs from the anaerobic fermentation liquor of sludge and kitchen waste. Finally， the paper gave an outlook on future research directions for synthesizing PHAs using anaerobic fermentation liquor as a substrate.
WU Junfeng, YANG Shenyu
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136 )
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In this study， poly（hydroxyalkanoate） （PHA）/graphene oxide （GO） composites were prepared through melt blending， and the effect of GO on the mechanical properties， thermal properties， crystallization behavior， and microstructure of the composites was systematically investigated by tensile testing， differential scanning calorimetry， X⁃ray diffraction， and scanning electron microscopy. The results indicated that introducing an appropriate amount of GO （0.04 wt%） could improve the tensile strength and elongation at break of PHA significantly. The crystallinity of the PHA/GO composites increased with an increase in the GO content， indicating that GO could promote the crystallization of PHA. SEM observation demonstrated that GO was well dispersed in the PHA matrix and exhibited good compatibility with PHA. In summary， GO can act as an ideal modifier to reinforce and toughen PHA.
DING Tianyu, YANG Yang, YAN Yong, ZHANG Shibo ZHAO Yanfang
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135 )
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At present the increasing traffic axle load brings a greater pressure to asphalt pavement. In this study， the waste rubber powders with different activation degrees and the surface⁃modified nano⁃CaCO3 were employed as modifiers to prepare activated rubber powder/nano⁃CaCO3 composite⁃modified asphalts， and three optimal modification systems were proposed through comparing the penetration and softening point ductility of the modified asphalts. The high⁃temperature performance of the modified asphalts was investigated by DSR， their anti⁃aging performance was evaluated by a thin film oven test， their storage stability was assessed by a segregation test， and their morphology and functional groups were analyzed by fluorescence microscopy and Fourier⁃transform infrared spectroscopy. The results indicated that an activation treatment improved the compatibility between rubber powders and asphalt， thus enhancing the storage stability of the modified asphalts. The modified asphalts obtained from the three optimal modification systems exhibited good high⁃ and low⁃temperature performance， anti⁃aging performance， workability， and storage stability. Both physical reaction and chemical reaction occurred in the modification of activated rubber powders and activated rubber powder/nano⁃CaCO3 composite⁃modified asphalts. Among the three optimal modification systems， the sample 5# exhibited the best comprehensive performance.
LI Xi, WANG Xin, QI Wen, QI Dingwen
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146 )
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The severe pollution of marine organisms has greatly restricted the development and utilization of marine resources. At present the surface coating with marine anti⁃fouling coatings is one of the most widely used， effective， and economical methods to avoid marine organism pollution. The marine anti⁃fouling coatings based on fluorosilicone polymers are a class of non⁃stick coatings with great development prospects. This article introduced four common methods for synthesizing fluorosilicone polymers， including anionic ring⁃opening polymerization， atom transfer radical polymerization， hydrosilylation reaction， and thiol⁃ene click reaction. The research progress in the modification of fluorosilicone polymers was reviewed from the perspectives of organic chain segment modification and nanomaterial modification. Furthermore， the challenges and future development directions for the marine anti⁃fouling coatings based on fluorosilicone polymers were proposed.
Processing and Application
ZHANG Zheng, LI Changjin, ZHENG Cui, WANG Ying, GUO Min, GUO Zifang
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210 )
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A higher standard for medical packaging materials can meet a requirement for packaging safety， sterility， and multiple sterilization compatibility in various application scenarios. Therefore， high⁃density polyethylene non⁃woven packaging materials with robust properties fabricated by the flash⁃spinning process have attracted tremendous attention from academic and industrial fields. This review introduced the selection of solvent systems， specific process flow， basic principles of phase separation， and solvent supersonic steam flow in the flash⁃spinning process. Meanwhile， the domestic flash⁃spinning⁃related techniques and corresponding non⁃woven materials were discussed in detail. Moreover， the parameters and evaluation criteria of Du Pont Tyvek® serial products were summarized， and the application performance of the materials was analyzed. This may provide theoretical and technical references for the development of the flash⁃spinning process and medical non⁃woven packaging materials.
SU Yingxia, QIAO Meng, OU Xianglin
Abstract (
111 )
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The design of thin⁃walled automotive parts is an important way to reduce their weights. This article analyzes the reinforcing rib structure of thin⁃walled door panels. Simulation analysis was conducted on the parts from the dimensions of reinforcement rib shape， width， height， and spacing. The results indicated that compared to a rectangular structure， the use of hexagonal reinforcement ribs was more stable， and it generated a better resistance to warping deformation. Increasing the width， height of the reinforcement ribs and reducing their spacing can all enhance the stiffness of the part； when the mass of the reinforcement ribs is the same， compared with increasing the width and reducing the spacing of the reinforcement ribs， increasing the height of the reinforcement ribs is more effective in improving the stiffness of the part.
ZHENG Chenxiao, LIU Jiaqi, CUI Yangang, LIU Zeqin, TIAN Shen, CAO Yibao
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140 )
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Phase change materials （PCMs） is a type of thermal energy⁃storage materials with high latent heat⁃storage capacity. In the field of construction， PCMs can be used in the radiant floor heating system. Through the use of phase⁃change energy⁃storage floor， a large amount of latent heat can be stored and released to reach the purpose of cutting down the peak load of the heating system， thus achieving a building energy⁃saving effect. This paper reviewed the current thermal storage technology and phase⁃change floor radiant heating technology and briefly discussed the influence of physical and chemical properties of PCMs， floor structure， and encapsulation and shape⁃stabilization technologies on its thermal performance. Finally， its future research direction was outlooked.
WEI Jia, LIU Kai, PENG Lijuan, TIAN Yangyang, ZHAO Lin, LI Yanhong, YANG Peipei, LI Songwei
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200 )
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In recent years， molecularly imprinted polymers （MIPs） have attracted more and more attention due to their remarkable properties such as low cost and simple preparation and processing. In addition， MIPs exhibit great potential for highly selective recognition in chemical sensor design. Advanced molecular imprinting technologies from polymers to electrochemical sensors become a pathway to achieve this goal. Therefore， a great number of studies have been done on molecularly imprinted polymer sensors. This paper reviews the research status and progress of MIP sensors in the detection of nicotine. This paper introduced the classification， preparation method， and detection principle of MIP sensors and discussed the application of MIP sensors in the rapid detection of nicotine. Finally， the prospects of the MIP sensing technology were proposed.
CHENG Ming, WANG Yongkang, HE Jie, WANG Ruyi, XIANG Guanghui
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153 )
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Cellulose diacetate plastic （DACP） was injection molded under different process conditions with a change in the injection temperature， injection speed， pressure， and other conditions one by one. The mechanical properties of the injection⁃molded products were investigated. The results indicated that with a change in the injection conditions， the molded products presented a regular change in their performance. The injection temperature exhibited a greater influence on the toughness and elongation at break of the molded products. Their toughness was further enhanced with an increase in the injection temperature， followed by a significant improvement in the elongation at break. However， the molded products started yellowing at a temperature of above 230 ℃. An over high or over low injection speed might lead to deterioration in the impact resistance of the molded products. The products molded at a medium speed of 55 % exhibited the highest impact strength. The change of injection pressure generated little effect on the performance of the molded products； however， an excessive pressure led to some defects such as flashing. The molded products exhibited the optimal overall performance at an injection temperature of 225 ℃， an injection speed of 55 %， and an injection pressure of 9 MPa In this sense， selecting an appropriate injection molding process condition can improve the performance of the injection⁃molded DACP products.
Additive
XIE Aihua, CHEN Daijin, ZHAGN Chan, WANG Qing, MENG Fanjin, DONG Xuewei, WANG Yiming, WANG Aili
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159 )
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Nano⁃ZnO is a type of inorganic antibacterial material with low cost， high safety， and long⁃term stability and has received wide attention in polymer composites. The dispersion state of nano⁃ZnO in the polymer matrix is an important factor affecting its antibacterial performance. In this study， Zn（NO3）2 and KOH were directly precipitated in the presence of dodecyl trimethyl ammonium bromide to obtain petal⁃shaped ZnO nanosheets （PS⁃ZnO）. The antibacterial performance of PS⁃ZnO and conventional nano⁃ZnO in polypropylene （PP） foams were compared. The results indicated that PS⁃ZnO exhibited a specific surface area of 59.6 %， which is larger than that of conventional nano⁃ZnO due to the staggered three⁃dimensional microstructure， and its packing density also reached 0.23 g/cm3. PS⁃ZnO presented higher antibacterial efficiency than conventional nano⁃ZnO in the PP foams. The PP foam containing 3 wt.% PS⁃ZnO obtained an antibacterial rate of 99.9 % against Staphylococcus aureus and Escherichia coli. This might be due to the fact that the petal⁃shaped structure made PS⁃ZnO more easily dispersed in the PP matrix， thus generating an excellent antibacterial effect.
Plastic and Environment
ZHANG Hongyu
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119 )
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Waste tire ground （wTG）， recycled polyethylene （rPE）， and recycled polypropylene （rPP） are typical waste polymeric materials with large output. The applications of these waste materials in traffic construction not only can reduce their pollution to the environment but also improve the performance of asphalt pavement to a certain extent. In this sense， a ternary blending modifier （TM） was prepared by incorporating different amounts of wTG into the matrix of rPE and rPP at a mass ratio of 3/2. The effect of TM on the properties of modified asphalts and its mixtures （AC⁃13） was investigated. The experimental results indicated that the softening point of the TM⁃modified asphalts increased with an increase in the wTG content， but their penetration degree tended to decrease. Nevertheless， their ductility reached a maximum. The modification mechanism was analyzed by FTIR and microtopography. Furthermore， the high⁃temperature stability， low⁃temperature cracking resistance， water stability， and water permeability performance of the AC⁃13 modified asphalt mixtures with different contents of wTG were investigated. The results indicated that with an increase in the wTG content， the modified asphalt mixtures presented a rapid increase in the dynamic stability at first， and then the incremental rate tended to decrease. However， their low⁃temperature cracking resistance， water stability （freeze⁃thaw splitting strength ratio）， and water permeability resistance showed an increasing trend at first and then tended to decrease. In conclusion， the addition of 20 % wTG facilitates to improve the performance of the AC⁃13 modified asphalt mixtures under current experimental conditions. This study provides an important theoretical basis for the future engineering applications of this type of modified asphalt mixtures.
Machinery and Mould
YE Weiwen, CHEN Zhensen, JIANG Bingchun, FENG Jing
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153 )
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This paper reported a plastic mold structure design for a certain model of car seat headrest. A design scheme was proposed for a composite mold structure through analyzing the forming process， demolding mechanism， mold flow， etc. Meanwhile， the Haff position， dovetail large inclined top， inclined inner top， and straight top core pulling was combined to solve the technical challenges in product iterative manufacturing. Through the verification by flow analysis， this design scheme can successfully prevent against the defects occurring in molds and products. The verification results of actual production demonstrated that this design scheme effectively shortened the product development cycle and improved the efficiency and quality of mold manufacturing.
Review
XIAO Yang, YUE Nan, GUO Xuezhong, LU Bo, FENG Yuezhan, HUANG Ming, LIU Chuntai
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221 )
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This paper reviewed the recent research progress in the vitrimer⁃based carbon⁃fiber⁃reinforced composites and particularly introduced the vitrimer systems with different types of dynamic covalent bonds and their applications in the composites， including the catalytic methods， recycling capabilities， the introduction of bio⁃based raw materials， multifunctionality， and interface enhancement. The main molding methods used for the vitrimer⁃based carbon⁃fiber⁃reinforced composites were also summarized， and the features of each method were analyzed in detail. Moreover， the current limitations of these composites were analyzed， and their direction in future development was proposed.
ZHAO Yunpu, WAN Zhouyuanye, QI Yungeng, LI Haiming
Abstract (
155 )
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3D printing is an additive manufacturing technology that has been used in many fields to manufacture complex and high⁃precision products. As the most abundant renewable biomass resource， lignocellulose has great potential in the manufacture of green 3D⁃printing materials. This paper reviewed the application progress in lignocellulosic and its derivatives for ink⁃direct writing 3D printing. The challenges and industrialization prospects of lignocellulosic 3D⁃printing materials were discussed.
LI Juan, LI Ying
Abstract (
147 )
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This paper introduced the industrial background and application fields of XPS foams and discussed the environmental issues stemming from the use of HFCs as blowing agents in the XPS foaming production. Subsequently， the global initiative to phase out HFCs was discussed， and the significance of the Kigali Amendment in controlling and reducing the use of HFCs was particularly analyzed. The current utilization of HFCs in the XPS foam sector was then analyzed， and the alternative technologies that can replace HFCs were evaluated. Finally， a prospective outlook on the gradual elimination of HFCs in the XPS foam sector was presented.
TAN Jiani, XU Zhen, OUYANG Yuge
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168 )
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With the rapid development and application of flexible electronic devices， traditional thermal management materials cannot meet a requirement of application for high thermal conductance， high toughness， and good mechanical adaptability. Thermally conductive flexible thin film materials with high a thermal conductivity exhibit great potential in thermal management applications for next⁃generation devices and therefore have attracted great attention by many researchers. At present， thermally conductive thin film materials have shown great application potential in smartphones， ultra⁃thin notebooks， flexible wearables， and smart home appliances. This paper introduced the classification of filled polymer⁃based thermal conductive composite films and their thermal conduction mechanisms from the aspects of the improvement in their thermal conductivity. The thermal conductivity of the composite films was improved by designing fillers to construct a low thermal resistance and high thermal conductivity path as well as a three⁃dimensional thermal conduction network. The research progress in the filled polymer⁃based thermal conductive composite films was also reviewed.
WANG Xuejing, XIN Fei, LAI Qiaojie
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178 )
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In recent years， carbon nitride （g⁃C3N4） has become a hotspot in the field of fluorescence due to its intrinsic covalent organic framework， high porosity， photoluminescence capabilities， tunable pore structure， and large specific surface area. This paper reviewed the research progress in the optic area of g⁃C3N4 and introduced its research status from the aspects of synthetic methods， photochromic mechanisms， and application scenarios. The development prospects of g⁃C3N4 was also analyzed.
