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2010, Volume 24 Issue 04 Publication date: 26 April 2010 Previous Issue Next Issue

Chinaplastics(2009)

LIAO Zhengpin

2010, 24 (04): 1-11 ; DOI: 10.19491/j.issn.1001-9278.2010.04.001

Abstract ( 2308 )

The comprehensive situation of plastics industry in China 2009 was reviewed, including output/sales and export/import of various plastics products, synthetic resins, plastics processing machinery, and additive. Some problems occurring during the development of the industry were pointed out and a few suggestions for its future were made.

Developing Situation and Trend of China XPS Foam Sector

WANG Yong

2010, 24 (04): 12-16 ; DOI: 10.19491/j.issn.1001-9278.2010.04.002

Abstract ( 2704 )

The general situation of China extruded polystyrene foam (XPS) sector was reviewed. Substitute necessity of the blowing agent HCFCs in China XPS foam sector was discussed. The alternative technologies of HCFCs in Europe, North America, Japan and other regions were introduced. Developing trend of China XPS foam sector was put forward.

Development Scenario of China Polyolefin Industry in 2009 and Its Prospect During Twelfth Five-year-plan Period

LIU Jian

2010, 24 (04): 17-20 ; DOI: 10.19491/j.issn.1001-9278.2010.04.003

Abstract ( 1980 )

The development of the polyolefins industry at the period of Eleventh Five-year-plan was reviewed. Domestic supply and demand of polyolefin at the period of Twelfth Five-year-plan were analyzed and predicted. It was pointed out that production capacity of polyolefins in China will be increased significantly and market demand will keep a steady growth. Large-scale industrial device of polyolefins will be developed to meet the increasing demands.

Study on Indoor and Outdoor Aging Behavior of PP and PP/EPDM Blends

FANG Pengpeng GAO Liyan LIU Xiaoling YANG Qi LIU Yuxin

2010, 24 (04): 21-26 ; DOI: 10.19491/j.issn.1001-9278.2010.04.004

Abstract ( 2034 )

Outdoor and indoor accelerated aging (thermal-oxidation and ultraviolet aging) of polypropylene (PP) and polypropylene/ethylene-propylene-diene monomer (PP/EPDM) blends were studied to monitor the change in mechanical properties and surface microstructure. The outdoor aging was carried out in three western regions of China: Yuli Xingjiang, Lasa Tibet, and Chengdu Sichuan. During the outdoor aging, the tensile strength of increased at the initial stage and decreased in middle and late stages due to degradation. The addition of EPDM greatly enhanced the anti-aging properties of PP, and the retention of tensile strength was up to 115% after 24 months aging in Chengdu. The tensile strengths of both PP and PP/EPDM were little affected during thermal-oxidation aging, but gradually decreased during UV aging. The accelerated indoor and outdoor aging could be correlated by a time equivalence considering both thermal-oxidation and UV.

Effect of Structure of α-MSAN copolymer on Compatibility of PMMA/α-MSAN Blends

MENG Ting REN Liang ZHANG Lixin MA Xiaolin ZHANG Mingyao

2010, 24 (04): 27-29 ; DOI: 10.19491/j.issn.1001-9278.2010.04.005

Abstract ( 1526 )

α-methylstyrene-acrylonitrile (α-MSAN) copolymers were synthesized by emulsion polymerization and was blended with polymethyl methacrylate (PMMA) via melt blending. The compatibility of PMMA/α-MSAN blends was investigated using transmission electron microscopy (TEM) and dynamic mechanical analysis (DMA). It was found that when the acrylonitrile contents in α-MSAN was between 15 % and 25 %, PMMA/α-MSAN blends were compatible, and the compatibility became better with increasing acrylonitrile content. When acrylonitrile content was more than 30 %, PMMA/α-MSAN blends became incompatible.

Effects of Glass Bead and Carbon Black on Curing Characteristics of EPDM Rubbers

YANG Libao LU Xiaozhong LU Qingzhang SUN Xiaomin

2010, 24 (04): 30-33 ; DOI: 10.19491/j.issn.1001-9278.2010.04.006

Abstract ( 1899 )

The curing characteristics of EPDM rubber with different ratio of glass beads over carbon black (GB/CB) were studied. With increasing GB/CB ratio, the scorch time of EPDM increased slightly, and torque decreased, the mechanical properties of 180℃ vulcanized rubber were better than those of 200℃. When micro glass bead was added, the 180℃ optimum cure time of the EPDM rubber was cut down about 1/2 while that for 200℃ was not affected. The temperature coefficient of vulcanization, i.e., the effect of temperature on the vulcanization rate was decreased obviously.

Study on PA6/PS Blends with Compatibilized Functionalized Graft Copolymer

TAN Zhiyong WANG Dandan MU Xingwen CHEN Min ZHANG Huixuan

2010, 24 (04): 34-38 ; DOI: 10.19491/j.issn.1001-9278.2010.04.007

Abstract ( 2239 )

During the emulsion polymerization, polybutadiene (PB) was grafted with Styrene (PS) and glycidyl methacrylate (GMA) forming copolymer PB-g-(St-GMA), which was used as a compatibilizer in blends of blends of polyamide 6 (PA6) and polystyrene (PS). The system of PA6/PS/ PB-g-(St-GMA) was studied with rheological and dynamic mechanical testing and scanning electron microscope. When GMA content in PB-g-(St-GMA) was 1%, the torque of the blends increased, the glass transition temperatures of PA6 phase and PS closed each other, the size of dispersed phase decreased evidently. These showed that the compatibility between PA6 and PS was improved. However, when the GMA content was above 1%, the compatibility between PA6 and PS decreased.

Effects of Antistatic Agents on Antistatic and Mechanical Properties of Polypropylene

LIU Wei WANG Xiangdong XU Guozhi

2010, 24 (04): 39-43 ; DOI: 10.19491/j.issn.1001-9278.2010.04.008

Abstract ( 2002 )

Polyol aliphatic and sulfoacid antistatic agents were introduced into polypropylene (PP) and their effects on antistatic and mechanical property of PP were studied. It showed that both antistatics could reduce the surface resistivity of PP but not the volume resistivity. The tensile strength and surface hardness of PP were decreased by either antistatic, however, the impact strength was little affected. Generally, polyol aliphatic antistatic agent was better than sulfoacid. When the content of the former was 6 wt%, surface resistivity of 4.7×1011Ω, tensile strength of 27.28MPa, impact strength of 4.9kJ/m2, hardness HD of 64.8, were observed.

Study on Synthesis and Properties of Maleic Anhydride Modified Lactic Acid Prepolymer

CHEN Youning ZHANG Juncai ZHAO Wei

2010, 24 (04): 44-48 ; DOI: 10.19491/j.issn.1001-9278.2010.04.009

Abstract ( 2193 )

Hydroxyl terminated lactic acid prepolymer （PLEG） was synthesized from poly ethylene glycol (PEG) and lactic acid, which was further condensed with maletic anhydride (MA) forming MPLA. The effect of reaction conditions (composition, temperature, reaction time, etc.) on the molecular weight (MW) of the product was studied via orthogonal design experiments. The maximum MW about 60000 was obtained at a weight ratio of MA/PLEG of 1/15, reacted at 130 C for 15 h. The mechanical properties, hydrophilicity, and in vitro degradation behavior of MPLA were studied. Modified with MA, MPLA exhibited better tensile strength, modulus, elongation at break, and hydrophilicity than PLEG. In addition, MPLA showed good in vitro degradation behavior, with the degradation rate related to the content of maletic anhydride.

Chain Extension of Polyamide 6 with 2,2'-(1,3-phenylene)bis(2-oxazoline)

ZHANG Qian WAN Chaoying DANG Xiaorong WU Kemian

2010, 24 (04): 49-53 ; DOI: 10.19491/j.issn.1001-9278.2010.04.010

Abstract ( 1969 )

Chain-extension of polyamide6 (PA6) was carried out by reacting with 2,2'-(1,3-phenylene)bis(2-oxazoline) (MPBO) in melt. The optical chain-extension was found when the loading of MPBO was 2.0 % at 240 ℃. After chain-extension, the number-average molecular weight of PA6 increased from 1.4×104 to 2.5×104, the tensile strength, elongation at break, and intrinsic viscosity increased, the melt flow index dropped. However, crystallinity and crystallization temperature were decreased.

Synthesis and Characterization of Thermally Induced Shape Memory PCL/PU Copolymers

CHEN Yadong PENG Zhenbo ZHANG Huibo ZHANG Yongchun

2010, 24 (04): 54-57 ; DOI: 10.19491/j.issn.1001-9278.2010.04.011

Abstract ( 1939 )

Shape memory polyurethane (SMPU) was prepared using polycaprolactone (PCL) as the crystallizable soft segment and toluene diisocyanate (TDI) as the hard segment. The microstructure of SMPU was characterized using differential scanning calorimetry, Fourier transform infrared spectroscopy, and X-ray diffraction. It was found that with increasing content of hard segment, the melting temperature of SMPU increased, the crystallinity and shape recovery ratio decreased, the shape fixed ratio remained 98 %. Increasing the molecular weight of PCL, the crystalline melting temperature and shape recovery temperature of SMPU decreased, the crystallinity increased.

Optimization Design of Weld Line of Automobile Decoration Parts Based on Numerical Simulation

SHAN Zhi MEI Yi GUO Jianbing LI Yangjun QIN Shuhao

2010, 24 (04): 58-60 ; DOI: 10.19491/j.issn.1001-9278.2010.04.012

Abstract ( 1986 )

In this paper, the weld line on auto outer decoration was analyzed and simulated using Moldflow software. The best processing parameters and its effect on the weld line were obtained via orthogonal design methods. Finally, the optimal processing parameters were verified by Moldflow software. The results showed that this method can optimize the properties of weld lines.

Parameter Optimization of High-gloss & Non-Weld Line Injection Molding for Cases of Automotives Bluetooth Based on CAE

HU Wenwen XIN Yong

2010, 24 (04): 61-64 ; DOI: 10.19491/j.issn.1001-9278.2010.04.013

Abstract ( 1916 )

Using automotive bluetooth as a model system, differences between the injection moldings for high-gloss and local dense hole plastic parts were studied. The high-gloss injection molding was studied using Moldflow combined with Taguchi method, numerical simulation, and data processing. The influence of mold and melt temperatures on warpage, volumetric shrinkage, and weld line was studied. Based on the research, molding process parameters were optimized.

Visualization Study on Effect of Melt Temperature on Water Penetration Behavior During Water-assisted Injection Molding

LIU Xuhui HUANG Hanxiong

2010, 24 (04): 65-69 ; DOI: 10.19491/j.issn.1001-9278.2010.04.014

Abstract ( 1989 )

This report investigated the effect of melt temperature on the water penetration behavior in water-assisted injection molding process by using visualization technology. Experiments were carried out with the help of a newly home-developed water injection system and visual mold. The material used was polystyrene. The water-assisted melt filling processes with different melt temperatures were observed. It was found that low melt temperatures increased the melt inertia in the front of water flow, which leaded to the appearance of a water channel in broken lines. The rate of water front was closer to that of water-front melt. The time for water jet penetration and water penetration in the front half mold, increased with increasing melt temperature.

Finite Element Analysis of Flexural Failure Mode of Concrete Beams Reinforced with BFRP Bars

LI Binghong JIANG Shiyong FEI Wei

2010, 24 (04): 70-75 ; DOI: 10.19491/j.issn.1001-9278.2010.04.015

Abstract ( 2206 )

Concrete beams reinforced with plastic/basalt fiber composite (BFRP bars) were prepared and analyzed by three-point testing and finite element analysis. The flexural failure mode of the beam was different from traditional reinforced concrete beam in that the failure sections were all located near the load point. Finite elements analysis was carried out on the failure mode and the follows was considered as the main reasons: the mechanical behavior of BFRP bars was much adversely influenced by the dowel effect in the beam; the width of cracks affected the flexural failure mode; the failure mode was closely associated with the apparent surface deformation, the lower transverse shear carrying capacity, and the lower elastic modulus of BFRP bars; local bonding failure between BFRP bars and concrete, dowel effect, and stress concentration. The fourth constituted the main reasons of the failure mode.

Effect of Injection Molding Process on Environmental Stress Cracking Behavior of Polycarbonate Parts

HAN Jian HAN Dongxue LIU Chuntai CHEN Jingbo SHEN Changyu

2010, 24 (04): 76-79 ; DOI: 10.19491/j.issn.1001-9278.2010.04.016

Abstract ( 2544 )

This work investigates the environment stress cracking behavior of polycarbonate (PC) injection molded plates with different process conditions. When exposed to carbon tetrachloride, crack appeared at the edge surface of the molded parts. Higher injection temperature increases resistance to the environmental stress crack, while higher packing pressure makes the cracking more serious. Additional study was concentrated on the effect of molecular orientation and residual stresses on crack formation of the parts.

Study on Fresh-keeping Poly(vinyl alcohol) Composite Film for Fruits

LI Yangbo WU Wenqian LIU Zhewei XIANG Aimin

2010, 24 (04): 80-85 ; DOI: 10.19491/j.issn.1001-9278.2010.04.017

Abstract ( 2013 )

Compared with the PE film，the fresh-keeping effect of poly(vinyl alcohol) (PVA) composite film on strawberries and bananas was studied, and the fresh keeping mechanism of PVA film was analyzed. The PVA composite film could decrease weight loss of fruits, delay aging, prolong the storage life, maintain the flavor and appearance. In the environment of "low oxygen, high carbon dioxide" maintained by PVA film, the fresh-keeping period of strawberry could be extended by 5 days. Although it was not satisfactory for banana, the weight loss of banana was anyway decreased.

Study on Combustion Properties and Flame-retarding Mechanism of Brominated Epoxy Resin and Antimony Trioxide Synergistically Flame-retarded PET

XU Xiaonan YANG Haichao WANG Fang

2010, 24 (04): 86-90 ; DOI: 10.19491/j.issn.1001-9278.2010.04.018

Abstract ( 2071 )

The synergetic flame-retardant effect and mechanism of brominated epoxy resin (BER) and antimony trioxide（Sb2O3）for PET were studied via measuring vertical combustion performances (UL94), physical performances, and smoke release. CONE data showed that the PET system passed ULV-0 test, the smaller the particle size of Sb2O3, the better the flame-retarding effect. However, the BER/ Sb2O3 system was poor on the suppression of smoke effect and its av-SEA, SPR, and av-CO increased. With BER and Sb2O3 introduced, PET exhibited increased melt flow rate, higher Vicat softening point, smaller parallel and vertical injection mold shrinkage, higher shore D hardness, and larger flexural strength and flexural moduli, but lower notched impact strength, elongation at break, and tensile strength. FTIR and gas chromatography (Py-GC) analysis showed that the residue char of pure PET and flame-retarded PET was not complete the same; the retention time of main peak was different indicative that the BER/ Sb2O3 system had flame-retarded effects not only in gas phase but also in solid phase.

Study on Ultrafine Iron Powder Modified Polyoxymethylene

LIU Li SUN Lishui LI Shaochun LIU Guangye

2010, 24 (04): 91-95 ; DOI: 10.19491/j.issn.1001-9278.2010.04.019

Abstract ( 1609 )

Two kinds of Fe powder with the average particle size of 1μm and 140nm, respectively, were used to modify polyformaldehyde (POM). It showed that the smaller particle size was preferred. The dispersant TAS-2A and coupling agent NDZ-201 could effectively improve the dispersion of Fe powder in POM leading to higher toughness of the composite. When the content of Fe powder was 4%, Izod impact strength of POM/Fe/NDZ-201 blend reached 9.6 kJ/m2, 4.6 kJ/m2 higher than neat POM.

Research of Test of Elastic Modulus of Magnetorheological Rubber

CHEN Xianzhong XIAO Jing YOU Shihui

2010, 24 (04): 96-99 ; DOI: 10.19491/j.issn.1001-9278.2010.04.020

Abstract ( 2017 )

With the change of volume fraction of the iron particle and magnetic field strength, the characteristics of the elasticity for the isotropic and the aligned silicone rubber-based magnetorheological rubbers were investigated. Using ultrasonic testing methods, the longitudinal modulus of the isotropic and the aligned magnetorheological rubbers were measured. The magnetorheological rubber samples with the different volume fraction of the iron particle were tested using a three-point bending test. The results from experiment were compared with the relevant theoretical prediction model. The elastic modulus and shear modulus increases linearly with the increasing volume fraction of the filler. The moduli of parallel are significantly different from perpendicular if the filler volume fraction exceeds 15%. The chain structure of rubber does not have a cubical symmetry when the iron particles filler volume fraction more than 15%.

Study on Mold Separations of Injection Molding Machines with Different Clamping Units

ZHANG Panpan XIE Pengcheng HUA Wei YANG Weimin

2010, 24 (04): 100-103 ; DOI: 10.19491/j.issn.1001-9278.2010.04.021

Abstract ( 1843 )

In this paper, the characteristics of the mold separation of injection molding machine with different clamping units are systemically analyzed. The paper points out there are several typical differences between the different clamping units. Meanwhile, it shows there is a linear relation between the mold separation value and the product weight. The injection pressure and injection time affect the mold separation linearly. The greater the injection pressure, the bigger the mold separation. The longer the injection time, the bigger the mold separation.

Design of Injection Mold for Back Cover of CRT Display Based on CAE

KUANG Tangqing LI Qiuping LIU Yan

2010, 24 (04): 104-108 ; DOI: 10.19491/j.issn.1001-9278.2010.04.022

Abstract ( 2310 )

Development of injection mold for a back cover of CRT display was carried out based on CAE technology in this paper. The gates location were determined by gate location analysis and the optimum molding conditions was got by molding window analysis, then filling analysis was carried out to inspect the filling result, maximum injection pressure and clamp force, welt lines, and air trap locations. Finally, the mold was design based the result of CAE analysis and its structure and movement principle were illustrated.

Optimization Design of Gate Location for Multi-cavity Mold by CAD/CAE

LIU Guoliang

2010, 24 (04): 109-112 ; DOI: 10.19491/j.issn.1001-9278.2010.04.023

Abstract ( 2010 )

An optimization model of gate location is established for injection molding. An alternative finite element model transformation for geometry model transformation was formulated to overcome the shortcomings of geometry model transformation. As a result the finite element model was successfully transformed from CAD system to CAE system in "zero distortion". The training-data were acquired through the MOLDFLOW simulation. With the aid of optimization system, the gate locations for multi-cavity molding were determined. A simple case was illustrated.