Materials and Properties
CHEN Quangui, ZHANG Meilin, WANG Xiaojun, YANG Jie
Abstract (
1031 )
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The friction and wear properties of three types of polyhexamethylene terephthalamide （PA6T） with different copolymerization structures， including polyhexamethylene terephthalamide-co-caprolactam （1132）， polyhexameth-ylene terephthalamide-co-hexamethylene adipamide （M21） and polyhexamethylene terephthalamide-co-hexameth-ylene adi-pamide （1252） were investigated under the dry sliding condition， and their worn surfaces were observed with scanning electron microscopy. The results indicated that the 1252 had the best friction and wear performance， but those of the 1132 was the worst. The addition of PTFE improved the friction and wear properties of these three resins. Among them， the friction and wear properties of 1252 were improved most effectively. When the 30 phr of PTFE was incorporated， the friction coefficient and wear rate of the 1252 decreased down to 0.16 and 1.00×10-6， respectively. As for the wear mechanism， the wear mode of the 1132 mainly belongs to adhesive wear and fatigue wear， whereas the main wear mode of the M21 and 1252 was attributed to abrasive wear. The main wear mode of the PA6T composites was transformed into adhesive wear with an increase in PTFE content.
LIU Yao, DING Jianfeng, XIA Zhean, LI Xinxin
Abstract (
1183 )
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861
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Polyamide 6 （PA6）/short-cut carbon fiber （SCF）/copper salt/potassium（KI） composites were prepared using a melt blending method. The heat-resistant oxidative aging mechanisms of copper salt/KI system for the PA6 composi-tes were studied using electronic universal testing machine， differential scanning calorimetry （DSC）， X?ray polycrystalline diffractometer （XRD） and X-ray photoelectron spectrometer （XPS）. The results indicated that there is little effect from a single copper salt or KI on the thermal-oxidative aging resistance of PA6. The copper salt/KI compounding system can effectively improve the retention rate of tensile strength for the PA6/SCF composites after heat aging. The carbon fiber has a certain capability to capture free radicals. The addition of copper salt， KI and SCF significantly prolonged the oxidation induction time of PA6. The anti-thermal oxidative aging mechanism of the copper salt/KI system is proposed as follows： firstly， KI converts the divalent copper in the polyamide matrix into monovalent copper， then excessive KI can react with monovalent copper to form Cupric diiodide ion ［CuI2］-. ［CuI2］- ions have strong reducibility， which consumes free radicals generated during the aging process of PA6， delaying the thermal degradation process of PA6 accordingly.
LI Yasen, SHANG Yudong, HE Jiangping, ZHANG Xiang, DONG Jiankun, SONG Ran
Abstract (
1163 )
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670
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Multi?walled carbon nanotubes （MWCNTs） were treated with mixed acid to obtain functionalized MWCNTs （O?MWCNTs） with reactive groups. Polyethylene glycol （PEG1000） and isophorone diisocyanate （IPDI） were used as main raw materials to produce polyurethane （PU） prepolymer， and then the MWCNTs/ PU and PU/O?MWCNTs composite materials were prepared through an in?situ composite method. The microstructure， surface morphology and dispersion performance of MWCNTs and O?MWCNTs were investigated using TEM， SEM， XPS and FTIR. The structure characteristics of PU/MWCNTs and PU/O?MWCNTs composites as well as pure PU were characterized by use of FTIR. The results indicated that the treatment with mixed acid introduced 10.2 % of oxygen?containing functional groups into the sidewalls of MWCNTs. This greatly improves the dispersibility of MWCNTs in the polyurethane matrix. When O?MWCNTs was added with the formation of prepolymers， O?MWCNTs could be grafted into the PU chains. This may facilitate the dispersion more effectively. The PU/O?MWCNTs composite emulsion exhibited a fine and dark aspect， and the O?MWCNTs still presented good dispersibility after standing for 36 h.
WU Chaoting, CHEN Huayan, ZHANG Wenxin, LYU Xiaolong
Abstract (
1007 )
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500
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Carbon nanotubes （CNTs） were modified with dopamine （DA） and 3?aminopropyl?trimethoxysilane （APTMS），and then a solvent casting method was used to prepare poly（vinylidene fluoride） （PVDF） composite films with excellent thermomechanical properties. The microscopic morphology， crystallinity， thermal properties and mechanical properties were characterized by means of scanning electron microscope， transmission electron microscope， differential scanning calorimeter， X?ray photoelectron spectrometer， thermal constant analyzer， and electronic single yarn strength meter. The results indicated that the DA?APTMS?co?decorated CNTs （PDA?CNTs?NH2） exhibited good dispersion properties. The addition of PDA?CNTs?NH2 was benefical to improve the thermal stability of PVDF composite films. The thermal conductivity and mechanical properties of the PVDF/PDA?CNTs?NH2 composite films were significantly enhanced compared to the pure PVDF and PVDF/CNTs composite films. Under a loading of 8 wt.% PDA?CNTs?NH2 filler， the composite films achieved a thermal conductivity of 0.337 9 W/（m·K） and tensile strength of 52.67 MPa， increasing by 78 % and 36 % compared to pure PVDF film， respectively.
NI Jia, DUAN Kaige, ZHU Hui, HU Mingyuan, CHENG Zhi, YU Dongming
Abstract (
783 )
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Aiming at the problem that the common oxygen barrier pipes on the current market cannot be easily hot melted and recycled， a new type of ethylene?vinyl alcohol copolymer （EVOH）/heat?resistant polyethylene （PE?RT） alloy coated with a PE?RT double?layer oxygen barrier was prepared. The inner working tube was made using PE?RT as a raw material， and the outer layer was fabricated with an EVOH/PE?RT alloy barrier material. The effect of EVOH and compatibilizer contents on the oxygen barrier performance of EVOH/PE?RT alloy barrier film was studied. The oxygen permeability and hot melt recovery of the new double?layer oxygen barrier tube and the mechanical properties of the recovered material obtained from this oxygen barrier tube were evaluated. The results indicated that the oxygen permeability of the EVOH/PE?RT alloy barrier film decreases with an increase in EVOH content and tends to increase with an increase in the compatibilizer content. The new double?layer oxygen barrier tube containing 30 wt% EVOH， 64 wt% PE?RT and 6 wt% compatibilizer exhibited oxygen permeability similar to the commercially available 3?layer and 5?layer oxygen barrier tube， and hot?melt recovery could be realized in this tube. Meanwhile， the recovered material presented good mechanical properties.
PENG Jianwen, LIU Xinliang, XIAO Chong, SONG Qiang, PENG Zhongchao, HUANG Ruosen, TANG Gang
Abstract (
977 )
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863
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The microencapsulated ammonium polyphosphate （MAPP） with a silicone gel was prepared through a sol?gel method and then characterized with fourier transform infrared spectrometer and thermogravimetric analyzer （TG）. MAPP and aluminum hydroxide （ATH） were used as flame retardant to prepare a series of flame?retardant thermoplastic polyurethane composites （TPU/FR） by means of a melt?bending technology. TG， and microscale combustion calorimeter were used to analyze the thermal stability and combustion behaviors of the TPU/FR composites. The results indicated that with the fixed total loading of ATH and MAPP at 20 wt%， the composites achieved char yields of 29.7 wt%， 25.1 wt% and 20.9 wt% at mass ratios of ATH to MAPP of 5/15， 10/10 and 15/5 at 700 ℃， respectively， compared to the composites containing only 20 wt% ATH with a char yield of 16.7 wt%. Their heat release capacity decreased to 154.2， 164.2 and 170.1 J/（g·K） from 327.1 J/（g·K） of the composite only containing ATH. Moreover， compared to composites containing only 20 wt% of MAPP， there is a significant improvement in the compactness and graphitization degree of the carbon slag for TPU/FR4（15 wt% ATH，5 wt% MAPP）， indicating that a combination of ATH and MAPP generated a significant flame?retardant synergistic effect.
WANG Guoan, ZHAO Wenjie
Abstract (
761 )
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A cement mortar modifier， PB?g?PSG emulsion， was prepared with polybutadiene grafted styrene and glycidyl methacrylate as main raw materials and Tween?80 as a stabilizer， and cement mortar was modified by mixing cement and standard sand with PB?g?PSG emulsion and Tween?80. The micromorphology of the modified cement mortar was observed， and the effect of contents of Tween?80 and PB?g?PSG emulsion on the fluidity， mechanical properties， water retention rate and water absorption of the modified cement mortar were studied using scanning electron microscope， cement mortar fluidity tester and laser particle size analyzer. Meanwhile， the effect mechanism of Tween?80 for PB?g?PSG emulsion was analyzed. The results indicated that the modified cement mortar exhibited an excellent water retention with a maximum water retention rate of 99.3 %. The water absorption quality of modified cement mortar decreases at first and then increases with an increase in the Tween?80 content. The compressive strength of the modified cement mortar decreased gradually with an increase in the content of PB?g?PSG emulsion and was less than that of the unmodified cement mortar. The flexural strength of the modified cement mortar increased at first and then tended to decrease， which was essentially higher than that of the unmodified cement mortar. The modified cement mortar achieved the highest flexural strength of 9.52 MPa at a content of PB?g?PSG emulsion of 10 wt%. The PB?g?PSG emulsion can generate an adhesion and bridging effect on cement hydrate， and an interpenetrating network structure can be formed between them. The hydrophilic group in the Tween?80 molecules can adsorb water on the surface of PB?g?PSG emulsion particles and form a thick layer of hydration. In this case， the latex particles can be isolated from each other， avoiding the occurrence of condensation.
JIANG Ruyuan, LI Liying, LIU Juhui, WANG Lin, YUAN Wei, HUI Yingxuan, XIAO Xiong
Abstract (
752 )
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635
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Polypropylene （PP） composites were prepared based on a fire retardant ANTI?660 and an antistatic agent glyceryl monoacetate （Gm）. The effects of flame retardant and antistatic agent on the flame retardant， antistatic and mechanical properties of the composites were characterized using horizontal and vertical combustion tester， oxygen index tester， surface resistance tester， universal testing machine and pendulum impact testing machine. The result indicated that with the addition of 18.0 wt% fire retardant and 2.0 wt% antistatic agent， the limiting oxygen index of the composites reached 26.0 vol%， their vertical combustion reached a V?0 classification， and their surface resistance decreased down to 1.7×1012 Ω. There is no obvious difference in mechanical properties between the composite system with only a flame retardant and the system with both of the flame retardant and antistatic system. However， the composites with both of additives still keep high comprehensive mechanical performance.
ZHANG Yaocheng, WU Yongzhen, LI Yang, ZHAO Zhu, WANG Guosheng, DING Xuejia
Abstract (
934 )
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748
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To solve the problem that poly（vinyl chloride） （PVC） medical consumables are easily infected by bacteria during the use， a new type of antibacterial agent， C8?6?8 gimini quaternary ammonium salt （GQAS）， was synthesized. This new quaternary ammonium salt was then used as an additive to blend with PVC physically. The resultant blends were compressed to pellets as a type of modified PVC materials with good antibacterial properties. The structure and thermal stability of GQAS and the antibacterial properties， dissolution capacity and mechanical properties of modified PVC materials were characterized using nuclear magnetic resonance spectrometer， thermogravimetric analyzer， colony counter， and electronic universal material testing machine. The results indicated that GQAS did not decompose with heating when blended with PVC. The modified PVC material containing 5 wt% GQAS can effectively inhibit the growth of E.coli and S.aureus. After soaked for 7 days， the modified PVC materials containing 5 wt% GQAS still had a good antibacterial capability. The modified PVC materials showed a decrease in tensile strength（22.3 or 18.9 MPa） and elongation at break（318.8 % or 295.3 %） comparing with pure PVC（24.6 MPa，341.5 %）， which was still in an acceptable range.
LYU Qiang
Abstract (
667 )
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656
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A halogen?free flame retardant LX?15 and a permanent antistatic agent MH?2030 were added into a glass?fiber?reinforced polyamide 6（PA6/GF）matrix to prepared a series of compounds through melt blending. The flame retardant， thermal stability， antistatic and mechanical properties of the compounds were characterized using vertical combustion tester， insulation resistance tester， thermogravimetric analyzer， cantilever beam impact tester and microcomputer controlled universal tester. The results indicated that with the addition of only 15 wt% LX?15， the flame retardant level of PA6/GF achieved a UL 94 V?0 classificaton. Their surface resistance decreased down to 1.1×108 Ω with the addition of only 20 wt% MH?2030. The compounds achieved a V?0 classificaton， and their surface resistivity decreased down to 1.1×108 Ω when 25 wt% of LX?15 and 20 wt% of MH?2030 were added together. Their antistatic property could be maintained for a long time. Meanwhile， their tensile strength， notched impact strength and initial decomposition temperature were 103 MPa， 15.3 kJ/m2 and 376 ℃， respectively， which are still acceptable in comparison with the values of 143 MPa， 22.3 kJ/m2 and 382 ℃ for pure PA6/GF.
LIU Xianggui, FANG Wei, SHU Hongbin, ZHENG Genwen, LIU Hai
Abstract (
810 )
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648
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5 )
In this work， hydrotalcite （HT） was surface modified with a liquid nitrile rubber （LNBR）. The resultant LNBR?modified HT was filled into poly（vinyl chloride） （PVC） to prepare PVC/LNBR?modified HT composites. The modification of HT by LNBR，the effect of the content of HT before and after modification on the mechanical properties， flame retardant properties， dynamic mechanical properties and micro morphology of the composites was investigated using， infrared spectrometer simply supported beam impact testing machine， universal testing machine， oxygen index tester， dynamic mechanical analyzer and scanning electron microscope. The results indicated that the surface modification of HT with LNBR belonged to a physical modification. Own to good compatibility between LNBR and the PVC matrix， the dispersibility of LNBR?modified HT in the PVC matrix was improved， and the interfacial adhesion between LNBR and the PVC matrix was enhanced. The PVC/LNBR?modified HT composites exhibited better performance than that of the PVC/unmodified HT composites. The PVC/LNBR/HT composites achieved maximum tensile strength of 29.8 MPa and maximum notched impact strength of 17.7 kJ/m2 with the addition of 5 phr and 10 phr of LNBR?modified HT， respectively. Moreover， the PVC/LNBR/HT composites presented an limiting oxygen index of 34.6 vol% with the addition of 40 phr LNBR?modified HT. LNBR plays dual roles as compatibilizer and plasticizer in the PVC/LNBR/HT composites. This leads to an increase in rigid， but a decrease in heat resistance.
Processing and Application
WANG Yanqing, KUANG Tangqing, LAI Jiamei, LIU Hesheng, LIU Tian
Abstract (
820 )
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8 )
In this paper， the method and process of gas?water?assisted injection molding（GWAIM）process were described in detail. The key technology of the specific device design for the GWAIM process and its process control as well as the advantages of GWAIM process were discussed based on our previous research and practical work. The results indicated that the inner wall of GWAIM was brighter， the wall thickness was more uniform， and the molding quality was better. The GWAIM process still has a problem of material applicability， but it has a wider range of material applicability than the water?assisted injection molding process.
SHENG Tianyang, TAN Jing, ZHANG Zhenghe, GAO Xiaodong, YU Jingchao, CHENG Lisheng, YANG Weimin
Abstract (
644 )
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562
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A 3D and finite element mesh model of flow channel was established， and then Polymat was used to fit the parameters of the material according to the rheological test results. The Polyflow software was used to analyze the numerical simulation of the 3D isothermal flow process of polyacrylonitrile gel in a channel. The results indicated that the outlet velocity of the channel was more uneven as the inlet flow increased. The pressure in the channel gradually decreased along the flow direction and decreases down to the same minimum value at the outlet. The inlet and outlet pressure difference of the channel has a positive correlation with the inlet flow rate. The shear rate was uniformly distributed on the central section of the channel under a small fluctuation range.
WANG Ruizhe, LIU Hesheng, HUANG Xingyuan, YU Zhong, JIANG Shiyu, LIU Tongke
Abstract (
701 )
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396
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8 )
In this work， a sheet polymer extrusion experiment was conducted on the basis of the vertical and parallel air intake separately though a gas?assisted extrusion technology. A three?dimensional model was established based on rheological principles， and a finite element method was applied to the numerical simulation of gas?assisted extrusion molding under the different air intake angles of 0°， 15°， 30°， 45°， 60° and 90°. The experimental results indicated that a change in air intake angle generated different effects on the gas?assisted extruded products. There was a largest degree of deformation in the melt in the die under an air intake angle of 90°. As the air intake angle decreased， the melt deformation was weakened. The air inlet angle of 15°~30° is most beneficial to the gas?assisted extrusion molding of polymer sheets.
WANG Weijian
Abstract (
1095 )
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690
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5 )
In this study， a natural exposure test of bumper was designed for solving the problem of a tiger stripe defect after natural exposure， and the causes of this defect were analyzed. The results indicated that the bumper showed some black and white tiger stripe defects after the natural exposure test. Compared to the black section of tiger stripe， the color difference in white section was significant， and there were many microcracks. The content of O element on the surface increased drastically， indicating a visible aging phenomenon. The rubber toughening phase in bumper material presented an unbalanced shear orientation. The orientation degree of the white segment is clearly greater than that of the black segment. This leads to the existence of large orientation internal stress in the white segment. It is easier for the bumper to fracture under the action of external environmental stress， resulting in a large number of microcracks accordingly.
Additive
CAI Xiaofang, YUAN Hang, DIAO Xiaoqian, LI Ziyi, FENG Di
Abstract (
725 )
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In this study， a national standard method was used to measure the total migration of a food?contacted polylactic acid cup cover. The migration of talc powders in a food simulation solution was analyzed using atomic absorption spectrometry， and the talc powders in the evaporation residue of the migration was qualitatively identified using fourier transform infrared spectroscopy. The safety of talc powders in food?contacted materials was discussed. The results indicated that the method used in this work was accurate， rapid and simple， and it could be used for the rapid identification and safety evaluation of talc in food?contacted materials. Talc is not easily migrated into the food simulation solution. There is a low risk for talc to migrated to food when PLA products are contacted with foods.
Standard and Test
TIAN Luchuan, JIANG Hong, CHEN Tanzhi, WANG Yilin, DUAN Bin, LIU Feng
Abstract (
711 )
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640
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3 )
To establish an efficient and accurate differential Raman spectroscopy method for the detection of wire plastic skin， the differential Raman spectroscopy data with 35 different brands and types of wire plastic skin were measured by a portable standard differential Raman spectrometer. The samples were preliminarily classified according to their different main components and fillers. A principal component analysis was used to reduce the dimension of the Raman data after preliminary classification. The samples could be grouped by hierarchical clustering， and a K?means clustering analysis was used to test the accuracy of the grouped results. For the same group of the samples， the relative peak height ratio of Raman characteristic peaks was used to distinguish. The results indicated that the samples of group I?1（white sample containing only talc） were divided into 7 groups at a distance of 1， and they could be distinguished. This method is easy to operate without any damages in the sample. It can provide help for the detection of trace evidence and the public security organs to handle cases.
Plastic and Environment
LI Yuzhu, YAO Lihui, YE Shiqiang, LYU Guoyong, LIU Panpan, XU Longfei, QIU Dan
Abstract (
1366 )
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1198
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This article reviews the current research status of the degradation performance of typical biodegradable materials in water environments， and introduces the degradation performance of poly（lactic acid） （PLA） polymer materials （PLA， PLA copolymers， PLA composite materials， etc.）， polyhydroxyalkanoates （PHA）， polycaprolactone （PCL）， polybutylene succinate （PBS）， poly（butylene adipate?ethylene terephthalate）（PBAT） and carbon dioxide copolymer in different water environments. Finally， summarizes the issues and development directions that biodegradable materials need to pay attention to in the future.
Review
ZHANG Ting, ZHANG Caili, SONG Xinyu, WENG Yunxuan
Abstract (
2153 )
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1656
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72 )
This paper reviewed the research progress in polybutylene adipate?terephthalate （PBAT） and its composite films used as the food active packaging and mulch films. The main methods for improving the performance of PBAT films were introduced in detail， which included compounding with polymers， inorganic fillers and other renewable resources. The degradation performance of PBAT and its composite membrane was also discussed， and the future research direction of PBAT membranes was prospected.
DONG Xingtong, WANG Xiangdong, SUN Xiaohong, CHEN Shihong
Abstract (
720 )
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722
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11 )
This article introduced the reasons that the density functional theory was introduced into the field of foaming. The current research status of density functional theory at home and abroad was reviewed. The development and application of density functional theory in polymer systems were introduced， especially in the field of foaming. An innovative DFT model based on the homogeneous and heterogeneous nucleation combined with different dynamic and thermodynamic formulas was summarized. The applications of this DFT model were reviewed. Finally， a comparative analysis was presented for the DFT model and other computational models to reflect its uniqueness in the polymer foaming process.
DUAN Xuyuan, ZHENG Hongjuan
Abstract (
943 )
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1058
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This paper introduced the research progress in the modified poly（lactic acid） （PLA） foaming technology at home and abroad in recent years. In view of the insufficient melt strength and crystalline properties of PLA in foaming， the paper also discussed the methods， effects and mechanism for improving the foaming properties of PLA through the addition of various additives such as chain extenders， crosslinkers， nucleating agents， fibers and other polymers. Finally， the future development of modified PLA foaming technology was prospected.
