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2009, Volume 23 Issue 10 Publication date: 26 October 2009 Previous Issue Next Issue

Pregress in Reasearch on Aging of Polyurethane Foam

LI Sha-sha QI Shu-hua LIU Nai-liang QIU Hua WU Bo SHANG Lei

2009, 23 (10): 1-5 ; DOI: 10.19491/j.issn.1001-9278.2009.10.001

Abstract ( 2396 )

This article summarized the thermal, hydrothermal, and radiation aging of polyurethane foam and the resulted changes in external form, internal structure, and mechanical properties. The recent research progress in anti-aging measures for polyurethane foam including the use of anti-aging additive was reviewed.

Properties and Application of High-temperature Resistant Polyamides

YUAN Shao-yan LIU Qi-xiang YE Nan-biao HUANG Rui

2009, 23 (10): 6-9 ; DOI: 10.19491/j.issn.1001-9278.2009.10.002

Abstract ( 2767 )

The application of high-temperature resistant polyamides, such as PA46, PA6T, PA9T, and PA10T in the automobile, electric, and electronic fields was reviewed. Their structure related performance and some important properties including thermal, chemical, molding, reflow soldering, crystallinity, and water absorption were discussed.

Research Progress of Thermosetting Resins/Carbon Nanotubes Composites

ZHANG Yi YAN Hong-xia LI Peng-bo SONG Chang-wen

2009, 23 (10): 10-14 ; DOI: 10.19491/j.issn.1001-9278.2009.10.003

Abstract ( 2279 )

In this paper, the application of the composites of carbon nanotubes (CNTs) reinforced thermosetting resins including epoxy resin (EP), phenolic resin (PF), bismaleimide resin (BMI), and cyanate resin (CE) was introduced, The recent development in research of these composites was reviewed. The inclusion of CNTs improved the mechanical, thermal, and frictional properties of the thermoset matrix. The measures to improve the dispersion of CNTs in epoxy resin and bismaleimide resin were presented. The present problems and development prospect of thermosetting resin/CNTs composites were also discussed.

Investigation and Application of In-situ Synthesized Polylactic Acid Grafting Starch Copolymer

SHAO Jun ZHAO Yao-ming

2009, 23 (10): 15-20 ; DOI: 10.19491/j.issn.1001-9278.2009.10.004

Abstract ( 2184 )

Polylactic acid was in-situ grafted onto starch via anionic ring opening polymerization. Starch was first dissolved in dimethyl sulfoxide, in which ring opening grafting of lactide was initiated by potassium text-butoxide. The product was characterized using FT-IR, NMR, and XRD. It was found that the optimal copolymerization temperature and time were 75 ℃ and 4 h. When the weight ratios of starch/lactide/potassium text-butoxide were 10/75/3, a graft efficiency of 83 % was obtained. Introducing the prepared graft copolymer into blends of starch/PLA, better dispersion of starch in PLA was observed.

Study on Heat-resistant ABS Resin Prepared by Continuous Bulk Polymerization

TIAN Ye XIA Bao-lin LIANG Cheng-feng XIN Min-qi LI Rong-qun

2009, 23 (10): 21-26 ; DOI: 10.19491/j.issn.1001-9278.2009.10.005

Abstract ( 2138 )

N-phenyleimide-arcylonitrile-styrene-butadiene (NPMI-AN-St-BR) tetrapolymer was prepared via continuous bulk polymerization. The effects of NPMI content, polymerization temperature, and feed patterns, etc. on the properties of the products were investigated. Thermal analysis indicated that both Vicat softening point and heat distortion temperatures of the tetrapolymer elevated rapidly with the increasing content of NPMI, whereas the melt flow rate decreased. The comprehensive properties of the tetrapolymer were comparable or superior to two important heat-resistant ABS resins (BH-102H and BH-202). Rheological measurement with torque rheometer showed that the tetrapolymer possessed good processibility.

Study on Flame Retardancy of Polypropylene/Nano SiO2 Composites

YU Bao-gang LU Lin-gang GAO Wei-ying YANG Shou-sheng

2009, 23 (10): 27-30 ; DOI: 10.19491/j.issn.1001-9278.2009.10.007

Abstract ( 2170 )

An intumescent flame-retardant was prepared by compounding 1,3,5-tri(5,5-dimethyl-1,3-dioxacyclophosphorinane phosphonate) benzene (FR), ammonium polyphosphate (APP), and nano-silica, and used in polypropylene(PP). Testing through limiting oxygen index, horizontal burning test, thermo gravimetric analysis (TG), and cone calorimeter showed that the compound flame-retardant increased the limiting oxygen index, horizontal burning rate, thermal stability, and residual char, and decreased the heat release rate. When the weight ratios of FR/APP/SiO2 were 15/7/3 and its content was 25 %, limiting oxygen index of 29.4 % and horizontal burning rate of FH-1 were obtained.

Properties of PTFE Modified with Nano-Si3N4 and Its Hybrid Fillers

GU Hong-yan SHI Li-ping HE Chun-xia

2009, 23 (10): 31-35 ; DOI: 10.19491/j.issn.1001-9278.2009.10.008

Abstract ( 2115 )

The composites of polytetrafluoroethylene (PTFE) filled with nano-Si3N4, MoS2, GF, and nano-Al2O3 were prepared by compression molding. The mechanical, friction, and wear properties of the composites were studied. The tensile fracture surface was observed by a scanning electron microscope (SEM) and the reinforcement mechanism was explored. The inclusion of the inorganic fillers increased the surface hardness, tensile strength, and wear resistance, with the optimal loadings of 5 % Si3N4 and 10% Al2O3. However, the fillers had little effect on the friction coefficient. The SEM showed that Si3N4 and Al2O3 have a better combination with the PTFE matrix.

Study on Non-isothermal Crystallization Kinetics of Propylene/1-Butene Random Copolymers

LIU Li-xin Jia Xiang-chen LIU Yong-wei HU Zhen-feng ZHAO Xiao-fei

2009, 23 (10): 36-39 ; DOI: 10.19491/j.issn.1001-9278.2009.10.009

Abstract ( 2435 )

The non-isothermal crystallization kinetics of bulk polymerized propylene/1-butene random copolymers was studied using DSC. It was found that Jeziorny method had some limitations to interpret the non-isothermal crystallization behavior of this system, and that of Mo Zhishen method could do this well. The F(T) values increased with increasing degree of crystallinity. At the same crystallinity, crystallization rate of the copolymers decreased with increasing 1-butene content. For a given sample, the αvalue did not vary with crystallinity.

Toughening Effect of PEB-g-MAN on SAN Resin and Its Toughening Mechanism

ZHU Yong-ping WANG Lian-shi CAI Tong-min WANG Xia ZENG Xiang-bin LIN Cheng

2009, 23 (10): 40-44 ; DOI: 10.19491/j.issn.1001-9278.2009.10.010

Abstract ( 2115 )

PEB-g-MAN, synthesized by suspension grafting copolymerization of methyl methacrylate and acrylonitrile onto PEB, was blended with styrene-acrylonitrile copolymer (SAN). The mechanical properties, phase structure, and toughening mechanism of the SAN/PEB-g-MAN blends were studied using SEM and TEM. The notched impact strength of the blends (25 % PEB) reached 63.3 kJ/m2, which was nearly 60 times that of neat SAN. When the content of PEB was between 15 %-20 %, a brittle ductile transition was observed. TEM and SEM showed that SAN/PEB-g-MAN were partially compatible. When the PEB content was low, the toughening mechanism of the blends was crack branching and termination with slight cavitation. As the PEB content increasing, the toughening mechanism shifted to extensive cavitation, and further to shear yielding accompanied by cavitation.

Study on Thermal Kinetics for Chemical Crosslinking of SEBS

WANG Xiao-li WU Si-zhu WANG Ke-jian LI Jia SUN Chong-xaio

2009, 23 (10): 45-49 ; DOI: 10.19491/j.issn.1001-9278.2009.10.011

Abstract ( 2639 )

The non-isothermal crosslinking of hydrogenated styrene-butadiene-styrene block copolymer (SEBS) in present of benzoyl peroxide (BPO) was studied by differential scanning calorimetry (DSC) analysis. The thermal kinetics of the reaction was analyzed using model-free methods including Friedman, Ozawa-Flynn-Wall, and Kissinger methods and the initial kinetic parameters were calculated. The precise parameters were also obtained by using model-fitting method via multivariate nonlinear regression analysis. Three steps in the crosslinking reaction of SEBS were identified with the activation energies becoming smaller. It showed that the crosslinking degree of SEBS could be controlled by varying the reaction temperature and time.

Study on Combustion Performance and Available Safe Evacuation Time in Fire for Flame Retarded ABS

XU Xiao-nan LIU Yan-fei

2009, 23 (10): 50-54 ; DOI: 10.19491/j.issn.1001-9278.2009.10.012

Abstract ( 2086 )

ABS/DBDPO/Sb2O3 and ABS/DBDPE/Sb2O3 composites have been prepared, and their flame retarding performance was studied using cone calorimeter and simulated with field simulation software (FDS). Compared with ABS/Sb2O3, the average value of heat release rate, peak heat release rate, effect heat combustion, and total heat release of ABS/DBDPO/Sb2O3 system decreased by 42.29 %, 48.87 %, 24.11 %, and 63.24 %, those of ABS/DBDPE/Sb2O3 system decreased by 41.49 %, 44.99 %, 21.37 %, and 62.31 %. The specific extinction area, total smoke release, and average CO production of ABS/DBDPO/Sb2O3 and ABS/DBDPE/Sb2O3 were higher. The FDS results indicated that the available evacuation time of ABS/Sb2O3 was 67.7 s, while that of ABS/DBDPO/Sb2O3 and ABS/DBDPE/Sb2O3 were larger than 150 s, higher than the required evacuation time 139.5 s.

Static Analysis of the Steel Reinforced Plastic Pipe

MA Wen-qi SUN Hong-yi

2009, 23 (10): 55-59 ; DOI: 10.19491/j.issn.1001-9278.2009.10.013

Abstract ( 2039 )

Based on elasticity assumption and section conversion method, stress analytic formula for internal pressure condition was derived. Using 3D discrete finite element model, stress and displacement distributions were analyzed and the tubular reticular stress distribution in plastic pipe was obtained. The reliability resulted from the calculation and finite element simulation was confirmed by hydrostatical burst experiment.

Application of Valve-gate Technology in the Control of Weld Lines of Large Injection Molded Products

XIA Wei ZHANG Sheng-hua LIAO Xiao-ping LUO Bin

2009, 23 (10): 60-63 ; DOI: 10.19491/j.issn.1001-9278.2009.10.014

Abstract ( 2025 )

The problem of weld line on large injection molded products caused by multiple gates was explored using hot runner and automatic control technologies. The injection mechanism in hot runner/valve-gate and the silting pattern were analyzed, aiming to improve the operation and design of valve-gate system. Through a simulation of the valve-gate process of a car front bumper, a general design process of the valve-gate system using Moldflow was obtained.

Application of Moldflow in Optimized Design of Injection Molding Gates

JIANG Yi XIAO Ren-xian YU Dong-ling ZHANG Pei-dong

2009, 23 (10): 64-67 ; DOI: 10.19491/j.issn.1001-9278.2009.10.015

Abstract ( 2125 )

Moldflow was applied to the design of plastics injection mold to optimize the position and quantity of gates．Exemplified by a camera cover，through analysis of melting-joint imprint and bubble chamber, an optimization of the gate design was carried out. Such designing process would improve the products quality, reduce the cost of production, and shorten the product development cycle.

Study on Synergistic Retarding Effect of Rectorite and Intumescent Flame Retardant on Polypropylene

LIU Hui LU Zhong-yuan KANG Ming SONG Li-xian YANG Kai

2009, 23 (10): 68-72 ; DOI: 10.19491/j.issn.1001-9278.2009.10.016

Abstract ( 2066 )

Acid treated with HNO3, ion-exchanged with NaCl, and intercalated with hexadecyltrimethylammonium bromide (HDTMA·Br), organic rectorite (OREC) was prepared and used in polypropylene (PP)/intumescent flame retardant (IFR) composites. The synergistic flame-retarding effect of OREC and IFR was investigated. The composite was characterized using XRD, LOI, TG, and SEM. It was found that the layers of organic rectorite were delaminated by PP chains. There was a clear synergistic effect between OREC and IFR. When 2 % of OREC was introduced, the LOI increased by 4.8 %, the carbon residue increased to 22 %.

Study of Heat Resistance, Toughness and Frame Retardancy of Epoxy Resins Modified by Hybrid of Organosilicon and Organophosphorus

HU Chao-hui LIU Wei-qu WANG Zheng-fang MA Song-qi

2009, 23 (10): 73-77 ; DOI: 10.19491/j.issn.1001-9278.2009.10.017

Abstract ( 2098 )

A kind of modifier was prepared via the hydrolysis of phosphorus-containing silicon coupling agent and polymethyltriethoxysilane, which was used in an epoxy/novolac curing system. Determinations of differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, as well as limited oxygen index, impact and tensile testing were carried out to characterized the cured products. It showed that the modified epoxy resin possessed higher glass transition temperatures, impact strength, limited oxygen index, and better thermal stability.

Chain Extension of Recycled PET by Reactive Extrusion

GAO Kun WANG Lan WU Wen-qian

2009, 23 (10): 78-82 ; DOI: 10.19491/j.issn.1001-9278.2009.10.018

Abstract ( 2429 )

Using pyromellitic dianhydride (PMDA) and epoxy resin as chain extenders, reactive extrusion for recycled PET flakes was carried out in a co-rotating twin screw extruder. The intrinsic viscosity, carboxyl content, and crystallinity of the reaction products were analyzed. It was found that either PMDA or epoxy resin played a good role in chain extending, their combination was more effective. After the chain extending, the intrinsic viscosity of PET increased from 0.45 to 0.58 dl/g. When using epoxy resin, the carboxyl content decreased obviously and the degree of crystallinity increased.

Mixing Capacity of Screws in Injection Molding Machines Evaluated by Ultrasonic Monitoring

LIN Hong-wei LIU Ying WU Da-ming

2009, 23 (10): 83-86 ; DOI: 10.19491/j.issn.1001-9278.2009.10.019

Abstract ( 2079 )

Calcium carbonate-filled polypropylene (PP) and ABS were measured with ultrasonic systems and found that ultrasonic velocity decreased with increasing concentration of calcium carbonate. Based on the fluctuation of ultrasonic velocity at the injector nozzle and mechanical properties, the in-line ultrasonic monitoring was found able to evaluate the mixing capacity of the screw.

Application of Moldflow in Design of Injection Moulds for Right Lap Support in Display Boards

ZHAO Long-zhi LIANG Ju-xing ZHAO Ming-juan HU Guo-liang ZHANG Shang-bing

2009, 23 (10): 87-91 ; DOI: 10.19491/j.issn.1001-9278.2009.10.020

Abstract ( 2340 )

Take the right lap support in the automobile display board as an example, the plastic product was simulated and analyzed using Moldflow software. Based on the comparative analysis of single-gate and double-gate, the effects of several factors on the injection molding were determined, Through the optimization of the gate location and number, the rationality of the mold design was ensured.

Effect of Screw Configuration of Co-rotation Twin-screw Extruders on Mechanical Properties of Glass Fiber Reinforced PA66/PA6 Alloy

LIU Zhi-zhong WANG Ke-feng Tao Wei WANG Cheng-wang

2009, 23 (10): 92-96 ; DOI: 10.19491/j.issn.1001-9278.2009.10.021

Abstract ( 2788 )

In this study the effect of screw configuration on the mechanical properties of glass fiber reinforced PA66/PA6 alloy at given processing temperature, screw speed, and feed speed was investigated. By adjusting the screw configuration, the tensile, bending, and impact strengths of the glass fiber reinforced PA66/PA6 alloy were increased from 56 MPa, 100 MPa, and 64 J/m to 169 MPa, 238 MPa, and 136 J/m, respectively.