Materials and Properties
DUAN Jingting, ZHANG Xiaolin, WANG Zhe, LI Shaoge, DI Jingjing, LYU Jinyan, ZHU Xiaofeng, WANG Yi
Abstract (
920 )
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PE-HD/WSF/Filler composites were prepared by melt mixing and injection molding using high-density polyethylene （PE-HD） as a matrix polymer， wheat straw fibers （WSF） as a reinforcement fiber， and dolomite powders， wollastonite powders， and talcum powders as fillers. The effects of filler type and content on the performance of the composites were investigated. The results indicated that with the addition of 40 wt% WSF， the tensile and flexural strength of the composite material increased at first and then tended to decrease with an increase in filler content. The composites achieved optimial mechanical properties at a filler content of 5 wt%. At this filler content， wollastonite exhibited a better reinforcing effect than dolomite and talc， leading to the highest crystallization rate. The partial replacement of PE-HD with fillers resulted in a decrease in the water resistance of the composite， and a minimum water absorption rate was also obtained at a filler content of 5 wt%. SEM observation indicated that the tiny filler particles were embedded between WSF and PE-HD， resulting in a reduction in the gap between WSF and PE-HD and an improvement in interfacial adhesion.
LI Shaojing, YANG Fuxin, YANG Jinghui, CHEN Zuguo, WANG Guanglin
Abstract (
886 )
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A series of anti-algal polypropylene films were prepared by melt blending and granulation flow using potassium sorbate （PS）， fluoride acid （FA） and salt as bacteriostatic agents， and polyester glycerin as a dispersant. The mechanical and optical performance， permeability， moisture permeability， and hydrophobic and water-resistant properties of the films were evaluated， and their algal microbial inhibition effect was investigated through the determination of the total number of microbial colonies. The results indicated that the film containing 4 wt% PS achieved optimal transverse and longitudinal tensile strength of （21.44±1.63） and （32.03±1.26） MPa， respectively. The optical properties， air permeability and moisture permeability of the films decreased with an increase in the concentration of bacteriostatic agent， but their hydrophobic properties increased. Both PS and FA can inhibit the growth of algae microorganisms. Such an antibacterial effect becomes more significant with an increase in the concentration of antibacterial agent. The films exhibit good antifouling and antibacterial properties.
YE Jinlun, YANG Liting, LI Yantao, ZENG Cong, LI Zhen, HUANG Wenjie, GUAN Jiawei
Abstract (
902 )
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Boehmite was activated and modified with a phthalate coupling agent （TC-114）， and polypropylene （PP）/BM composites were then prepared by melting extrusion. The effect of modified boehmite on the performance of the composites was investigated. The results indicated that the composites with the modified boehmite achieved an increase in flexural strength by 14.4 % and in impact strength by 30.6 % in comparison to pure PP. However， in the case of the composites with the unmodified boehmite， their flexural strength and impact strength only increased by 6.9 % and 5.7 %， respectively. However， the elongation at break of the composites with the modified boehmite was 4 times as much as those with the unmodified boehmite. In addition， the melt flow rate， thermal stability， and limiting oxygen index of the composites were also improved due to the use of the modified boehmite. The higher content of the modified boehmite can lead to better thermal stability and flame retardant properties.
ZHANG Jing, LI Xiaoqing, ZHOU Haiying, JIANG Wenzheng, ZHONG Jinhuan, LI Wenzhu, ZHANG Wenbiao
Abstract (
1514 )
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1135
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PP/EVA foamed composite materials were prepared by a chemical-mold foaming method using high-melt strength polypropylene （PP） and ethylene-vinyl acetate （EVA） as raw materials， and their structure and performance were characterized by using differential scanning calorimeter， scanning electron microscope， rotational rheometer， and other equipment. The effect of EVA content on their foaming performance and mechanical properties were also investigated. The results indicated that there was no significant change in the crystallinity of PP with the addition of EVA. The formed composite materials at an EVA content of 5 wt% achieved a significant improvement in flexural strength from 10.8 to 15.5 MPa compared to pure PP forming material. However， there is little effect on tensile strength. The formed composite materials also presented a decrease in cell pore size from 68.36 to 33.58 μm in the presence of EVA， and their pore size distribution became more uniform. In addition， the formed composite materials containing 5 wt% EVA achieved a maximum cell density and a minimum average cell diameter with the most concentrated size distribution.
TENG Fangrui, WANG Xiaofeng, JIANG Jing, CUI Xinnan, HAN Wenjuan, UYAMA Hiroshi, LI Qian
Abstract (
913 )
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754
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A surface modification was performed to improve the dispersibility of multi?walled carbon nanotubes （MWCNT） using an ultrasonic method. Citrated cellulose （CNFCA） as a natural filler was also surface modified by means of a noncovalent functionalization method. MWCNT/CNFCA?reinforced unsaturated polyester resin （UPR） nanocomposites were prepared and their structure and performance were investigated by using polarizing optical microscope， rotation rheometer， SEM， TEM and universal test machine. The results indicated that the tensile properties of the nanocomposites were improved with the addition of MWCNT. The dispersibility of MWCNTs could be improved with the aid of solvent ultrasound， resulting in a further improvement in the mechanical properties of the nanocomposites. The addition of CNFCA greatly improved the mechanical properties of UPR/MWCNT composites. A combination of ultrasonic dispersion and grinding method can make CNFCA and MWCNT bind together， improving their dispersibility in UPR resin.
LI Xianming, ZHANG Ning, LIU Zhengyuan, LIU Luiyuan
Abstract (
826 )
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350
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A series of butylstannate-intercalated Ca/Zn-rare-earth hydrotalcite-like compounds （CA/ZnAlLa-BS-LDHs） were synthesized with butyltinic acid， lanthanum nitrate， calcium nitrate and zinc nitrate as raw materials. Their molecular structures were characterized by using Fourier-transform infrared spectroscopy， X-ray powder diffraction， and scanning electron microscope. Furthermore， the thermal stability of the poly（vinyl-chloride） （PVC） containing the hydrotalcite-like compounds were evaluated by means of Congo red testing method， thermal aging oven method and torque rheometer. Their flame retardancy and stretching property were investigated by limiting oxygen index， vertical combustion method and mechanical spectrometer. The results indicated that there is a “Zinc burning” phenomenon appearing in the ZnAlLa-BS-LDHs appeared， but the CaAlLa-BS-LDHs exhibited a good thermal stability with initial whiteness of 30 min and a low torque value. The optimum synergistic effect was obtained at a mass ratio of ZnAlLa-BS-LDHs to CaAlLa-BS-LDHs of 0.75/2.25. Their stabilized PVC compounds presented static and dynamic thermal time of 110 and 43.6 min， respectively， and their initial whiteness was extended to 40 min together with a moderate torque. The ZnAlLa-BS-LDHs showed better flame retardancy with a limiting oxygen index （LOI） of 27.6 vol%. The LOI was increased to 29.7 % along with a UL 94 classification of V-0 grade at a ZnAlLa-BS-LDHs/CaAlLa-BS-LDHs mass ratio of 2/1. There is no obvious influence on the tensile properties of the PVC compounds from these two additives.
LI Yin, ZHOU Song, LU Chaofei, LUO Yumei, BAI Xiaodong
Abstract (
748 )
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571
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Maleic anhydride-grafted polyethylene （PE-g-MAH） was used to simultaneously improve the antistatic properties and toughness of polyamide 6 （PA6）/carbon black （CB） composite. A series of PA6/CB， PA6/PE?g?MAH and PA6/PE-g-MAH/CB composites were prepared by melting extrusion and injection molding. Their morphologies and crystallization properties were investigated by using scanning electron microscopy and differential scanning calorimetry， and their mechanical and electrical properties were examined. The results indicated that the toughness of PA6 decreased significantly with the addition of 7.5 wt% CB. CB can generate heterogeneous nucleation on the crystallization of PA6. There is good miscibility between PE-g-MAH and PA6， resulting in a fine dispersion of PE-g-MAH in the PA6/CB matrix or PA6. The addition of PE-g-MAH improved the dispersion of CB particles and changed the selective location of CB in the PA6 matrix， leading to an increase in the electric conductivity of PA6/PE-g-MAH/CB ternary composites. PE-g-MAH can effectively improve the impact strength and elongation at break of pure PA6 and PA6/CB composite. A low content of PE-g-MAH can enhance the crystal formation of PA6 in the composites.
ZHU Ruixia, GAN Lu, WU Zhixuan
Abstract (
1009 )
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861
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This paper reported a comparative analysis on four types of engineering PVC pipes， including unplasticized PVC （PVC-U） water supply pipe， high performance unplasticized PVC （PVC-UH） water supply pipe， modified impact resistance PVC （PVC-M） water supply pipe， and oriented unplasticized PVC （PVC-O） water supply pipe. This analysis covered five aspects， including the technical requirements for compound， the allowable internal pressure and external pressure resistance capacity， the requirement for equipments， the requirement for performance， and the bell type. The advantages and application cases of PVC-UH pipeline were also summarized， and some practical suggestions for PVC-UH pipeline construction were proposed.
JI Cao, ZHOU Guofa
Abstract (
805 )
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802
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Aiming at the common problem that the metal-matrix polymeric composites are easy to induce interface peeling damage and failure， this paper focused on the composite interface strengthening through a short fiber bridge formed at the interface between the polymeric composite layer and adhesive layer by means of the multi-layer composite assembly injection molding. On the basis of a cohesive peeling damage model， a simulation technology was constructed for the failure process of interfacial peeling crack propagation and the fracture failure of the composites with short fiber bridging. A synergetic relevance theory based on the failure critical load-bridging fiber properties-interface peeling fracture toughness （damage crack initiation stress T0 and critical strain energy release rate Gc） was constructed for the interfacial peeling unstable crack rapid propagation fracture damage failure. The interface strengthening mechanism of short fiber bridging was explored， with the design criterion proposed for preventing the peeling unstable crack rapid propagation fracture damage failure induced by the short fiber bridge strengthening interface. The results indicated that the critical load was increased by 55.9 % with a density of bridging fiber at 20/mm2. The critical load was controlled by the density of bridging fiber， initial pre-crack area， damage crack initiation stress and critical strain energy release rate. The critical load was positively correlated with the density of bridging fiber， damage crack initiation stress and critical strain energy release rate， but negatively correlated with the initial pre-crack area.
Processing and Application
HAN Bohong, HE Yandong
Abstract (
769 )
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359
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A transient calculation method and a slip grid technique were employed to compare and analyze the full filling condition of flow field and the gas-liquid two-phase condition of 4WS mixer. The maximum velocity and shear rate of the flow field were found to be located at the top of the rotor edge in the full filling condition. Meanwhile， the maximum positive and negative pressures were located at the rotor propulsion area and the back pressure area， respectively. There was almost no diffusion flow in the gas-liquid two-phase condition when rubber flowed out of the mixing chamber on both sides. The position at maximum velocity and shear rate was not only located at the top of the rotor edge but also at the intersection interface between the rubber phase and air in the mixing chamber on both sides. The mixing index of the rubber group in the left and right mixing Chambers was relatively high. However， there was no obvious distribution law observed.
XU Meng, GAO Dali, ZHANG Shijun
Abstract (
1195 )
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This paper introduced the performance characteristics of polymer materials commonly used in food packaging as well as the new processing methods and packaging materials. The biaxially oriented polyethylene， casting polyethylene， polypropylene films， biaxially oriented polyamide films obtained prepared by the LISIM method， and polyester films were discussed. The research status of multilayer composite packaging materials was reviewed. The development trend of food packaging technologies in future was prospected. It can be speculated that packaging materials will be developed to a high-barrier， lightweight， and environment-friendly direction. The preparation of high-performance packaging materials can be realized by using composite and advanced processing technologies.
CAI Hengfang, SUN Ling
Abstract (
675 )
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This paper focused on the effects of temperature and shear rate on CO2 diffusion behavior in the foaming process of critical CO2-assisted injection molding. Taking poly（lactic acid） （PLA） and CO2 as research objects， a PLA/CO2 diffusion model was constructed by molecular dynamics simulation along with the CAMPASS force field on the basis of periodic boundary conditions and SA algorithm， minimizing the energy of the model. From two aspects of temperature and shear rate， the effects of PLA main chain activity， system energy response and radius of gyration on the diffusion behavior of CO2 molecules in PLA during the foaming process of injection molding were investigated. Mean square displacement （MDS） analysis indicated that the CO2 diffusion coefficient increased with an increase in temperature， but there was no influence from shear force. The CO2 diffusion coefficient reached 0.219 8×10-5 cm2/s a temperature of 388 K， and it also increased with an increase in shear rate. Moreover， a diffusion coefficient 17.743 6×10-5 cm2/s was achieved at a temperature of 378 K and a shear rate of 1 ps-1. According to the calculated results， the activity and system energy of the PLA molecular chain increased due to a rise in environmental temperature， resulting in a increase in the diffusion paths of CO2 molecules together with an increase in the CO2 diffusion rate. The energy and activity of the molecular chain increased with a continuous increase in the shearing force on the molecular chain. A single molecular chain was separated from the entangled network to form a flow orientation along the direction of the shear force， increasing the CO2 diffusion rate accordingly.
ZENG Wenguang, DU Dongdong, GE Pengli, GAO Duolong, XIAO Wenwen, XU Yanyan
Abstract (
642 )
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475
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There is an urgent requirement for treating the harsh corrosive environment and special topography of the Shunbei Oilfield. The construction of ground gathering and transportation pipeline has to face a series of unfavorable factors such as the large dunes （drop > 10 m） and strong mobility （the period of sand storm > 1 month）. A study on the force analysis and structural design of metal pipe bodies and joints was carried out in this work. A finite element analysis software was employed to analyze the pipes with different inner diameters under different external pressure loads. The effect of pipe materials on the deflection and stress of the pipes under different loads was calculated. The designed structures were compared to find an optimal result to meet the requirement of use. The results indicated that the reinforcement layer acted as a main pressure-bearing layer under an internal pressure load. The damage of reinforcement layer represented the failure of the pipeline. The wind load under an external pressure load exhibited little influence on the pipeline， and however the inertial load and sand dune movement generated a greater impact on the suspended pipeline. The feasibility of the pipeline connection can be judged by stress analysis.
ZHANG Xuemin, WANG Pin, LI Houbu, ZHOU Teng, XIAO Chunhong, FENG Jinmao, ZHONG Mingqiang
Abstract (
740 )
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558
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The adsorption and diffusion behavior of CH4 in poly（vinylidene fluoride） （PVDF） was studied by a combination of molecular dynamics （MD） and Grand Canonical Monte Carlo （GCMC） simulations. The effects of temperature and pressure on the adsorption and diffusion capabilities of CH4 were discussed， and the adsorption sites and diffusion paths of CH4 in PVDF were analyzed. It was found that the solubility coefficient and permeability coefficient of CH4 in PVDF increased at first and then tended to decrease with an increase in temperature. However， these two parameters always increased with an increase in pressure. As the temperature and pressure increased， the diffusion coefficient and fractional free volume increased. The simulated results indicated that the CH4 molecules exhibited a selectively aggregated adsorption in PVDF， and they were mostly absorbed in the low potential region of the simulated cell. The CH4 molecules in PVDF diffused within the free volumes in the form of cavities. The higher temperature and greater pressure can result in a better diffusion capability.
Additive
LIU Runqing, XING Mingming, HUANG Jiming
Abstract (
612 )
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In this paper， a new type of carbon-based solid acid catalyst （C-SO3H） was successfully prepared after a series of carbonization and sulfonation using waste biomass camellia husk as raw material. The catalytic ability was performance by catalyzing waste polyethylene terephthalate. The product of the alcoholysis reaction were also characterized by infrared spectroscopy and nuclear magnetic spectroscopy. In additin， the alcoholysis reaction kinetics and mechanism of were also analyzed in this paper.By investigating the influence of factors such as temperature and concentration during the catalyst preparation process， the result manifest that the best preparation conditions are：impregnation ratio 1∶1， impregnation concentration 2 mol/L， carbonization temperature 700 ℃， sulfonation temperature 160 ℃. The maximum PET conversion rate and BHET recovery rate were 95 % and 68 %， respectively. In addition， powder diffraction shows that the catalyst has an amorphous carbon structure， infrared spectroscopy shows that the catalyst contains a large number of hydroxyl groups， scanning electron microscopy shows that the catalyst has pores， exhibting a large specific surface area. The product of alcoholysis reaction was monomer BHET.
Standard and Test
SHI Jianfeng, HU Anqi, ZHENG Jinyang
Abstract (
836 )
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The differences in the design methods of polyethylene （PE） pipes and metal pipes were compared， and the differences and connections between the two systems of PE pipe standards were reviewed. One of them is an internationally recognized standard system made by the International Organization for Standardization （ISO）， and the other belongs to the standard system compiled by the American Society of Mechanical Engineers （ASME）， the American Society for Testing and Materials （ASTM）， and the American Plastic Piping Association （PPI）. The basis and test methods for the classification of PE materials in these two standard systems are different， and the design coefficient values in the wall thickness calculation are also different. The problems in the current domestic and foreign standards were proposed and analyzed. On the basis of the application of PE pipes in the fields of natural gas， water supply， and nuclear power plant in China， some suggestions were proposed for the Chinese government to establish a set of technical standards that can meet the requirement of various applications and are also suitable for the industrial status of PE pipes.
YAN Wenjie, WEI Chenjie, FAN Linyuan, WANG Jifen
Abstract (
610 )
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To realize the data?based， visualized， non-destructive and high-efficiency identification of automobile lampshades as physical evidence frequently appearing in the judicial appraisal work， the PCA principal component analysis pre?processing method combined with a FDA-SVM （RBF） combination analysis was adopted to identify the physical evidence. An experiment and theoretical analysis was conducted for 173 sets of the Raman infrared spectroscopy data obtained from 18 brands “Aodi” and “Bieke” cars. With the help of Pearson correlation analysis and PCA principal component analysis， the characteristic Raman shift was selected， and the data classification models based on the Fisher discriminant analysis and SVM support vector machine were established. The results indicated that the FDA and SVM （RBF） models had a comprehensive discrimination accuracy of 97 % and 51.85 % for lampshade samples， respectively. The SVM model had an accuracy of 100 % for 8 brands of “Benchi” and “Bieke” cars. The FDA-SVM （RBF） model obtained from the complement of the FDA and SVM models can accurately distinguish the Raman infrared spectra of different brands of lampshades. This method is efficient and accurate， and it can provide some references for reducing the scope of investigation when using the lampshade material evidence identification in case investigations.
Review
LUO Xuanang, LIU Shumei, ZHAO Jianqing
Abstract (
1532 )
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1932
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With the rapid development of the Internet of Things （IoT） and the fifth generation mobile communication technology （5G）， the higher level of requirement has been put forward for the dielectric performance of packaging materials and component substrates. The development of epoxy composites with a low dielectric constant and low dielectric loss has become an important research direction. Some methods for the preparation of low-dielectric epoxy composites were reviewed from the aspects of raw materials， curing conditions， fillers， blends， copolymerization， and multi-layers cast. The mechanisms for low?dielectric composites were also analyzed. Finally， some problems in the preparation of low-dielectric epoxy resins were discussed， and some prospects for future research were provided.
ZHANG Ze, LIU Shuaidong, CUI Yongyan
Abstract (
2113 )
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Phytic acid has a high content of phosphorus for flame retardancy. As an important organophosphorus additive， phytic acid has been widely used in food， medicine， and other fields. However， the application of phytic acid as a flame retardant still has a large space for development. This article classifies the current research findings of phytic acid for the flame retardant application of polymer materials into three categories： fabric flame retardancy， plastic flame retardancy， and intumescent flame retardancy for green buildings. Some representative experimental protocols were introduced briefly. Moreover， the future trend in the development of phytic acid as a flame retardant was prospected.
ZHU Wenyao, SHAO Weiguang, WANG Xinhua, LI Hua, YE Haimu, CAI Lihai
Abstract (
1551 )
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This paper reviewed the research progresses and preparation technologies in industrialized battery separator materials with high-temperature resistance. Particularly， the high-temperature resistant performance of traditional and new lithium ion battery separators fabricated with different matrices with or without coating was introduced. The characteristics of high-temperature resistant separator materials were discussed， and its research direction in future was prospected.
