YUAN Jiaoliang, YANG Bin
Abstract (
2314 )
This review focused on the recent research progress in the modification of poly(lactic acid). The modification methods included direct polycondensation method, ring-opening polymerization, and chain-extending method. The molecular weight of poly(lactic acid) copolymers obtained by ring-opening polymerization was higher than that by direct polycondensation method. The chain-extending method could be used together with others. The application of modified poly(lactic acid) was reviewed, particularly in medical and packaging area.
ZENG Weili
Abstract (
2421 )
The action mechanisms of flame retardants for polypropylene were reviewed, including gas phase flame retardancy, condensed phase flame retardancy, and interrupting heat exchange flame retardancy. The research and development status of some flame retardants of polypropylene such as hydrated metal compounds flame retardants, phosphated flame retardants, intumescent flame retardants, silicone flame retardants, and nanometer flame retardants were introduced. It was pointed out that the development directions of flame retardants of polypropylene were nanometer inorganic flame retardants, intumescent flame retardants, and compound flame retardants with high-efficiency, low-smoke and non-toxicity.
HOU Pan, ZHOU Keyong, WANG Ming
Abstract (
2363 )
An overview of current development on antistatic agents for polymers was presented. The antistatic agents can be divided into cationic, anionic, nonionic, amphiphilic and polymer-type according to chemical structure，and can be divided into coating-type, addition-type, and permanent polymer-type according to using methods. The main influencing factors on the antistatic agents for polymers were also reviewed such as ambient humidity, ambient temperature, compatibilization, surface concentration, and molding processing. The application of antistatic agents included plastics, rubbers, fibers and coatings.
LIU Liang, ZHANG Liye
Abstract (
2076 )
Polymer blends were prepared via thermo-pressing mixtures of soy protein isolate(SPI) and poly (vinyl alcohol) (PVA) using glycerol as a plasticizer. The structure, morphology, and properties of the blends were investigated using X-ray diffraction, dynamic mechanical analyzer, differential scanning calorimetry analyzer, universal electronic tensile testing machine, and scanning electron microscopy. Phase separation was observed between glycerol and SPI forming glycerol-rich and protein-rich domains. The addition of PVA significantly damaged the crystalline structure of SPI in glycerol-rich domain, and increased its glass transition temperature. When the content of PVA was 1 phr, the tensile strength of SPI/PVA increased by 41.5 %, and the 24 h water absorption of SPI/PVA decreased from 134.86 % to 77.38 %, based on neat SPI.
KONG Qing, CUI Ning, ZHANG Zhiying, DONG Zhizhi
Abstract (
2124 )
The rheological behavior of two imported poly (phenylene sulfide) (PPS) was determined using a capillary rheometer, and the influences of shear rate and temperature on the rheological properties of PPS were studied. It was found that the non-Newtonian index was less than 1, and the dependence of the apparent melt viscosity on the temperature was reduced while the shearing rate was higher. The viscous flow activation energy of PPS melt was decreased with increasing shearing rate, and the structural viscosity index was decreased with the increasing temperature.
LI Junwei
Abstract (
1948 )
Polypropylene/maleic anhydride grafted polypropylene/hollow glass bead (PP/PP-g-MAH/HGB) composites were prepared via extrusion molding. The nonisothermal crystallization behavior of the composites was investigated using differential scanning calorimetry. The nonisothermal crystallization kinetics of the composites was analyzed by Jeziorny and Mo equation. It was found that crystallization temperature, initial crystallization temperature, and crystallinity of PP, PP/HGB, and PP/PP-g-MAH/HGB were decreased, and the crystallization rate was increased with increasing cooling rate. The crystallization rate of PP was decreased by adding HGB. The mechanisms of nucleation and growth of crystallization were changed by mixing HGB and PP-g-MAH.
YANG Biao, TIAN Hua, GAO Fei, XU Guozhi
Abstract (
2255 )
Thermogravimetric analysis was used to characterize the modification effect of silicane coupling agent on nano-silica. It showed that the optimized dosage of silicane coupling agent for chemical-bonded coating was 5 phr. The modified nano-silica was introduced into poly (butylene succinate) (PBS) and the crystallization kinetics of the system was studied using differential scanning calorimeter and polarizing optical microscope. It showed that the surface modified nano-silica had a heterogeneous nucleation effect and led to an increase in crystallization rate and a decrease in crystallinity. However, the crystallization temperature raised only 4 ℃ even at high nano-silica content of 10 %. With the increase of silica content, the tensile strength and elongation at break firstly increased and then declined, nevertheless the change of tensile strength was moderate. When the content of modified nano-silica was 1.5 %, the elongation at break reached 10.79 %, which contrasted to 7.53 % of neat PBS.
WEI Zhenjie, LIU Weiqu, LI Hongjing
Abstract (
2276 )
Trimethylolmelamine-silicon (TMMSi) was prepared via the polycondensation reaction of tetraethoxysilane (TEOS) and trimethylolmelamine (TMM), which was synthesized by melamine and formaldehyde. The cured epoxy resins containing TMMSi were prepared via in situ curing of the bisphenol-A type epoxy resin and 4,4'-diaminodiphenylmethane with TMMSi. Thermogravimetric analysis, differential scanning calorimetry, and limited oxygen index determination were carried out to characterize the cured products. It was found that the flame ratardancy of the cured epoxy resins with TMMSi was remarkablely improved, although thermal property was not improved obviously and the glass transition temperature changed less than those of the cured epoxy resins containing TMM. When the content of TMMSi was 15 phr, limited oxygen index was 29.6 %, higher than that of neat epoxy resin by 40 %.
XU Minghan, GONG Qishan, LI Tiantian, QIU Guixue
Abstract (
2110 )
Ethylene-propylene rubber grafted maleic anhydride (EPM-g-MAH) was introduced into blends of polyamide 6 /ethylene propylene rubber (PA6/EPM) as a compatibilizer. The effects of EPM-g-MAH on the rheological behavior, mechanical properties, and morphology of the ternary blends were studied. It showed that PA6 and EPM were compatibilized by in-situ reaction between PA6 and EPM-g-MAH. EPM domains were distributed more homogeneously in PA6 matrix with the increasing EPM-g-MAH content. When the weight ratio of EPM/EPM-g-MAH was 10/10, the notched impact strength reached maximum of 47 kJ/m2, which increased 8 times that of neat PA6.
YUAN Yi, LIU Shunshu
Abstract (
1896 )
In order to meet the requirements in the oil-treating and dynamite equipment industries, electrostatic-conducting poly(vinyl chloride) (PVC) was produced via dipping molding. When the articles were coated with electrostatic-conducting PVC, they possessed a permanent electrostatic-conducting property, which could prevent the sparks caused by bumping. So the hazards of igniting and exploding were avoided effectively.
ZHAO Hong
Abstract (
2266 )
The development of welding technology, quality control and assessment of polyethylene pipes were reviewed. Principles, technology, method and quality control of butt fusion and electro fusion were described in details. Several evaluation systems of welding of pressure pipes were summarized and compared, including breaking, non destructive test, long term property analysis, etc. It was pointed out that welding technology of polyethylene pipes and quality evaluation should be paid more attention to.
LIU Shurong, CAO Sujiao, TAN Bin, FENG Yanhong, QU Jinping
Abstract (
2017 )
Composites were prepared by blending high density polyethylene (PE-HD) with steam-explosion treated cotton bast. The effects of steam explosion, cotton bast content, and moisture content on the mechanical properties and density of the composites were studied. It showed that steam-explosion improved the mechanical properties of the composites. The mechanical properties of the composites were the best when the content of cotton bast was 30 %. The tensile strength of the composites increased with increasing moisture content of cotton bast; however the flexure strength was the best when moisture content was 40 %.
LI Yuntao, LI Ran, HE Jing, WANG Zhichao, WANG Huixia
Abstract (
1929 )
Self-healing microcapsules were synthesized by encapsulating epoxy resin /butyl glycidyl ether within the poly (urea-formaldehyde) coating via in-situ polymerization. The optimum reaction conditions for the pre-polymer were to control the pH value at 9～10, the reaction temperature at 60～65 ℃, and the reaction time at 1 h. The optimum conditions of the in-situ polymerization were the pH value of 2, the reaction temperature of 50～60 ℃ and the reaction time of 2 h with sodium dodecyl beneze sulfonate as the surfactant. The as-prepared microcapsules exhibited complete encapsulation with compact and tightly united surface.
WANG Chuanbao, WANG Yufeng, YIN Jianmei
Abstract (
2020 )
Composites of poly(vinyl alcohol) (PVA) and upper-section straw powder were prepared by hot pressing. The effects of PVA content, pressing temperature, and pressing time on the tensile properties, bending properties, and hardness of the composites were studied. Scanning electron microscopy was used to characterize the microstructure of the composites. It showed that the tensile strength of the composites obviously increased with increasing content of PVA. If hot pressing temperature and hot pressing time were appropriately increased, the tensile strength of the composites would be improved but the rate of increase was moderate. The hardness of the composites showed non-uniform characteristics and was not affected obviously by material ratio and processing conditions. The tensile strength reached the highest value of 7.54 MPa, when the content of PVA was 40 % and hot pressing was carried out at 140 ℃ for 14 min.
ZHANG Qiang, XUE Ping
Abstract (
2084 )
Ultrahigh molecular weight polyethylene (PE-UHMW) microporous materials were prepared by sintering method, and the properties of microporous materials were studied. The forming reason of micropores was gap among particles. The properties of microporous materials were affected by molecular weight, particle siz, packing density, sintering temperature and sintering time. The compressive strength of microporous materials increased with increasing molecular weight of PE-UHMW. The particle size of PE-UHMW powder decided the pore size, the bigger the particle size was, the bigger the pore size was. With increasing sintering temperature and sintering time, the pore size decreased; meanwhile the width of pore size distribution increased.
MA Lina, QI Shuhua, CHENG Bo, HE Dong
Abstract (
2415 )
Research progress in heat-resistant modifiers for poly(vinyl chloride) (PVC) resins was reviewed. The main heat-resistant modifiers were discussed, including N-substituted maleimides copolymers and its derivatives, α-methyl styrene copolymer, styrene-maleic anhydride copolymer, heat-resistant engineering plastics, etc. Finally, an outlook for the future direction of research and development was given.
ZHANG Jing, YAO Haoping, YANG Heimei
Abstract (
2140 )
The friction and wear properties of polyamide 6 (PA6) composites filled with glass fiber (GF) and one of three nano-silicon-based particles were investigated using a MM-200 wear tester. The worn surfaces of the composites were examined through a scanning electric microscopy. It showed that the friction coefficients of the composites were reduced when GF and a silicon-based particle were filled in, and nano-SiO2 was the best. The optimal filler contents for the composites were 5 % SiO2, 3 % Si3N4 and 3 % SiC, respectively. Nano-SiO2 and nano-Si3N4 improved the anti-wear properties of the composites, while nano-SiC increased the wear mass loss of PA6 composites.
WANG Zhaohui, SUN Shuguo, LIU Jinyu, HE Ying, KAN Xingchuan, XU Yinhua
Abstract (
2846 )
Commission Regulation (EU) No 10/2011 on plastic materials and articles intended to come into contact with food has been brought into force on May 1st, 2011. The new regulation extended its scope to plastic layers in multi-material, multi-layer materials and articles. New rules were laid out, such as the requirements of placing on the market of plastic materials and articles; the union list of authorized monomers, other starting substances, macromolecules obtained from microbial fermentation, additives and polymer production aids; generals restrictions of the specific migration limits on barium, cobalt, copper, iron, lithium, manganese and zinc；the requirements for the declaration of compliance and supporting documents the business operator supplied; the contents of compliance testing; the modified types and concentrations of food stimulants; the testing requirements for specific migration into dry foods stimulants, etc.
ZHANG Panpan, WANG Jian, XIE Pengcheng, WANG Xiaohua, YANG Weimin
Abstract (
2155 )
The configuration and characters of several microinjection molding plasticizing units were systematically introduced. A novel concept of microinjection molding system was presented. The system was designed as a multi microinjection module, which is matched with a vertical injection molding machine and applied on common injection molding machines. The mechanism and basic process of the multi microinjection molding was stated; via the multi microinjection molding, multiple microparts were obtained. The molding experiment indicates the efficient microinjection capability of the multi microinjection molding machines.
ZHANG Jianwei, TANG Qinghua, YAN Junhu, HUAN Suocheng
Abstract (
2110 )
A plastic injection molding and auxiliary device used for processing articles of high gloss surface without weld lines and flow marks were studied. Surface defects of product were eliminated because the mold temperature changed with the injection molding action; high gloss surface of articles was made because the special channel design of mold could quickly raise the mold cavity temperature above the softening point. The design methods for the channels, materials, and temperature measurement points of the stream heating mold were analyzed. The component parts, the control theory, and the selection calculation method for the corresponding heating auxiliary control device were discussed. The system was verified through the actual production and application. It showed that the system could manufacture plastic products with high gloss surface and without weld lines and flow marks. The system could reduce processing costs and environmental pollution for eliminating spraying process. Injection molding cycle time was reduced from 120 s to 43 s.
