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2009, Volume 23 Issue 07 Publication date: 26 July 2009 Previous Issue Next Issue

China Plastics Recycling Industry in 2008

MA Zhan-feng ZHANG Bing

2009, 23 (07): 1-7 ; DOI: 10.19491/j.issn.1001-9278.2009.07.001

Abstract ( 2685 )

The Chinese plastics recycling industry in 2008 was reviewed in general, including the native and imported quantity, price, and consumption of waste plastics. Some problems in current plastics recycling industry were pointed out, suggestions were made for future development.

Research Progress of PLA/Montmorillonite Nanocomposites Prepared by Melting Intercalation

MA Peng-cheng WANG Xiang-dong XU Guo-zhi

2009, 23 (07): 6-11 ; DOI: 10.19491/j.issn.1001-9278.2009.07.002

Abstract ( 1473 )

This article discussed the research progress of the characterization and properties of polylactide(PLA)/montmorillonite(MMT) nanocomposites prepared by melt intercalation. It was found that organically modification of MMT expanded the distance between the layers of MMT in the nanocomposites. Because of the exfoliation/intercalation structures of MMT formed in the PLA matrix, toughness, thermal stability, gas barrier properties, and so on were improved. However, when the MMT content was high, the MMT particles tended to form clusters. The MMT particles constituted a two-dimensional nucleation agent which increased the crystallinity and the crystallization rate. Dispersed MMT particles formed a "space-linked" structure and effectively enhanced the melt strength and thus broadened the processing window. The hydroxyl groups on MMT imparted a higher biodegradation rate of the material.

Research progress of polymer/graphite nanosheets composites

HE Jie QI Shu-hua DUAN Guo-chen WU Xin-ming

2009, 23 (07): 12-17 ; DOI: 10.19491/j.issn.1001-9278.2009.07.003

Abstract ( 2319 )

In this article, the preparation and structure characterization of the graphite nanosheets were introduced. The compounding of graphite nanosheets with different polymers such as PMMA, PANI, PS, and PPy, the performance and application of these nanocomposites were reviewed. The dispersion of graphite nanosheets in the polymer matrix and the enhancement of the conductivity of polymeric materials were also discussed.

Preparation and Characterization of PLA/Esterified Cellulose Composites

DENG Chang-yong ZHANG Xiu-cheng

2009, 23 (07): 18-22 ; DOI: 10.19491/j.issn.1001-9278.2009.07.004

Abstract ( 2441 )

Cellulose was esterified by MA in a gas-solid reaction system with the esterification confirmed via FTIR. PLA/esterified cellulose composites were prepared by melt blending technology. Properties of composites were investigated by means of mechanical properties testing, TG, DSC, and SEM. The tensile and bending moduli of the composites increased, the tensile, bending strengths and thermal stability of the composites decreased with increasing fiber content. Tc of the composites was high than neat PLA, indicating the esterified cellulose acted as a nucleating agent in PLA. Though esterified cellulose could be well dispersed in PLA, the interfacial adhesion with PLA was poor.

Fire Retardancy of EVA/Multi-walled Carbon Nanotubes Nanocomposites

ZHOU Liang

2009, 23 (07): 23-29 ; DOI: 10.19491/j.issn.1001-9278.2009.07.006

Abstract ( 2289 )

Recent studies on ethylene vinyl acetate copolymer (EVA)/multi-walled carbon nanotubes (MWNTs) nanocomposites have been reviewed. A detailed introduction was given on its preparation, thermal degradation behavior, and flame retardant properties such as heat release rate, time to ignition, and char formation performance. The fire resistant mechanisms have been discussed in depth. The flame retardant effects of different nanofillers like MWNTs, organoclay, and layered double hydroxides have been compared. And the influence of various treatments of MWNTs, such as purification, surface coating with high density polyethylene, and ball milling, on the thermal stability and flammability of the corresponding EVA nanocomposites have been analyzed.

Study on Nano-P(MMA-St) Modified Polypropylene by ISBS Method

TIAN Li-fang WU Da-ming GUO An-ru ZHANG Yong-jie MENG Qing-Yun

2009, 23 (07): 30-33 ; DOI: 10.19491/j.issn.1001-9278.2009.07.007

Abstract ( 1576 )

P(MMA-St) nano-powder was introduced into polypropylene (PP) and dispersed via ISBS method. When the loading of P(MMA-St) was below 4wt%, the tensile and impact strengths increased by 7.5% and 104%, respectively, based on neat PP. XRD revealed that P(MMA-St) nano-powder induced the formation of β-crystals, which constituted a reason for the toughening.

Properties of PLA/OMMT Nanocomposites Prepared by Melting Intercalation

YUAN Long-fei ZHEN Wei-jun LIU Yue-e PANG Gui-lin SONG Xiao-ling HUANG Dong HE Sheng-xi

2009, 23 (07): 34-38 ; DOI: 10.19491/j.issn.1001-9278.2009.07.008

Abstract ( 2252 )

Polylactic acid /organomontmorillonite (PLA/OMMT) nanocomposites were prepared via melt blending/intercalation. The microstructure, morphology, and thermal properties of PLA/OMMT nanocomposites were characterized by XRD, SEM, TEM, and TGA-DTG.. The layer spacing of OMMT was found obviously increased as a result of intercalation. The TGA-DTG curves of PLA/OMMT nanocomposites were shifted to higher temperature, which illustrated that the enhanced thermal stability. Thermal and mechanical property tests showed that the melting point, Vicat softening point, impact strength, and tensile strength of PLA/OMMT nanocomposites were evidently enhanced compared with neat PLA. The PLA/OMMT nanocomposites also showed an excellent biodegradable behavior.

Synthesis and Characterization of Non-isocyanate Polyurethane

WANG Xiao-Mei XUN Hong-di WANG Jia-xi ZHANG Liu-cheng

2009, 23 (07): 39-43 ; DOI: 10.19491/j.issn.1001-9278.2009.07.009

Abstract ( 2730 )

A preparation method of isocyanate-free polyurethane was proposed using dimethylhexane-1,6-dicarbamate (HDU) as a curing agent. The structure of the obtained polyurethane was confirmed by means of IR, NMR, and GPC. When the molar ratio of HDU to polyether glycol 3000 was 1:1, the reaction temperature was 180 ℃, a weight-average molecular weight of 8.5×104 was obtained after 1 hour.

Research on the isothermal crystallization kinetics of propylene/1-butene random copolymer resins

LIU Li-xin ZHAO Xiao-fei TAN Xiao-hong WANG Gang AN Yan-jie

2009, 23 (07): 44-48 ; DOI: 10.19491/j.issn.1001-9278.2009.07.010

Abstract ( 1475 )

In this paper, propylene/1-butene random copolymer was prepared via bulk polymerization. The isothermal crystallization kinetics of the copolymers was studied using DSC. According to Avrami equation, crystallization kinetic parameters K(T), n, t1/2, and crystallization activation energy of the samples under various crystallization temperature were obtained. The crystallization rate decreased with increasing crystallization temperature. Avrami index was between 3 and 4, indicating that the crystal growth was three-dimensional spherical growth. At the same crystallization temperature, the crystal nucleation and crystallization rate decreased and the crystallization activation energy increased with increasing 1-butene unit content.

Preparation of Polyethylene/Expanded Graphite Intercalated Composites by In-situ Expanding Method

LU Ya-yun XIE Lin-sheng MA Yu-lu SHA Jin ZHANG Xia

2009, 23 (07): 49-54 ; DOI: 10.19491/j.issn.1001-9278.2009.07.011

Abstract ( 2192 )

Using twin-rotor continuous mixer, an intercalated composite was prepared via direct blending of linear low density polyethylene (PE-LLD) melt and low temperature expandable graphite (LTEG). The structure and properties of the composites were studied uisng SEM, XRD, etc. The graphite expanded during the blending with polyethylene resulting in the intercalated into the graphite flakes. Compared with neat polyethylene, the barrier property of the composites was 40 % higher.

Optimization of Molding Processing Parameters for Automobile Bumpers Based on Minimization of Sink Index

SUN Ling ZHANG Dong LIU Xiao-ming XIN Yong

2009, 23 (07): 55-60 ; DOI: 10.19491/j.issn.1001-9278.2009.07.012

Abstract ( 2161 )

Aimed at minimizing the sink marks on the automobile bumpers, the main involved processing parameters were determined using analysis of variance method based on an orthogonal experiment and CAE analysis. A predictive response surface model was formulated for the relationship between the index of sink marks and the important processing parameters using RSM. Based on the response surface model, the processing parameters were optimized for the minimization of sink marks through genetic algorithm. The results of simulation experiment confirmed the feasibility of the technology.

Surface Modification of Super-fine Brucite Powder and Its Application in Polyolefin

CHEN Xiao-Ping LIU Jun-kang NI Zhong-bin JIN Shan

2009, 23 (07): 61-64 ; DOI: 10.19491/j.issn.1001-9278.2009.07.013

Abstract ( 1595 )

Super-fine brucite powder was surface modified using several surfactants as modifier, with the effect of modification characterized through water adsorption and contact angle measurements. After washed with 2,2,4-trimethylpentyl, the surface of brucite powder changed from hydrophilic to hydrophobic. Surface modified super-fine brucite powder was used in polyolefin flame retardant formulations. It was found sodium stearate was the best modifier in this study with an optimal dosage about 2 %, resulting in a limited oxygen index of 32.9 % and an elongation at break about 30 % higher than devoid sample.

Study on Infrared Barrier of Optical Interference Films

TIAN Xin-ping WANG Lan LAI Jin-ya HE Ying

2009, 23 (07): 65-68 ; DOI: 10.19491/j.issn.1001-9278.2009.07.014

Abstract ( 2029 )

Gradient interference film formed by overlaying films with different thickness was investigated using self-made equipment. It showed that the reflected wavelength range by the films was mainly determined by its thickness. With increasing optical thickness, the maximum reflecting wavelength shifted from shorter to longer wave. As the layer of the gradient film increased, the reflection band became wider. The gradient interference film exhibited a temperature difference of 8 ℃ compared with ordinary glass under infrared lamp radiation.

Study on Flexural Behavior of Concrete Beams Reinforced with BFRP Bars

LI Bing-hong JIANG Shi-yong FEI Wei ZHOU Hai-liang

2009, 23 (07): 69-72 ; DOI: 10.19491/j.issn.1001-9278.2009.07.015

Abstract ( 2130 )

Concrete beams reinforced with plastic/basalt fiber composite (BFRP bars) were prepared, whose cracking load, failure load, and deflection bending were tested. The experimental study showed that, due to the low modulus of BFRP bars, the flexural behavior of the beams were featured as following: (1) the beams exhibited a brittle failure; (2) the cracking load and the pre-cracking deflection were little influenced by the fraction of reinforcer; (3) the failure load increased with increasing fraction of reinforcer; (4) the load-deflection curve exhibited a turning point corresponding to cracking.

Fresh-keeping Effect of PE/EVA/ Molecular Sieve Composite Films for Spinach

GUO Yu-hua HUANG Zhen TENG Li-jun JI Lin

2009, 23 (07): 73-76 ; DOI: 10.19491/j.issn.1001-9278.2009.07.016

Abstract ( 2098 )

Molecular sieve was introduced into blends of polyethylene/ethylene-co-vinyl acetate (PE/EVA), based on which composite blown film was prepared as packaging film for fresh spinach. The tensile strength, elongation at break, and tearing strength of the film were examined. The sensory evaluation for the fresh-keeping effect of the film was also made. The effect of content of molecular sieve on the weight loss, fraction of soluble solids, and respiration rate of spinach were examined. At ambient conditions, with increasing content of molecular sieve the air permeation of the film increased, and the respiration rate of spinach was increasingly restrained. When, the content of molecular sieve was 7.5 %, an equilibrium concentration of O2 8.7 %~9.3 % and CO2 7.2 %~7.7 % in the package was obtained.

Effect of Butt Fusion Welding Beads on Tensile Properties of Polyethylene Pipes

ZHENG Jin-yang QIN Yong-quan SHI Jian-feng LI Xiang XU Ping GUO Wei-can WANG Fei

2009, 23 (07): 77-80 ; DOI: 10.19491/j.issn.1001-9278.2009.07.017

Abstract ( 1986 )

Tensile tests were carried out to investigate the failure mode, tensile strength, and tensile process of polyethylene (PE) pipe samples with different weld bead situations. It was found that, the failure mode of samples with weld beads was crack propagation because of the stress concentration around the notch tip between weld beads and pipe, and a phenomenon of brittle fracture was observed after large deformation in tensile process of samples without beads. The tensile strength and break elongation of samples without weld beads were much higher than that with weld beads, and the difference would be no less than 27 % and 100 % respectively with a tensile rate of 10 mm/min. It demonstrated that the removal of both butt fusion weld beads could improve its tensile properties notably, but it would be improved slightly when just one of them was removed.

Preparation and Application of New β-Nucleating Agent of Polypropylene

LV Zhi-ping WANG Wei-xing ZHANG You-qiang WAN Zhao-rong XUE Jian-wei

2009, 23 (07): 81-84 ; DOI: 10.19491/j.issn.1001-9278.2009.07.018

Abstract ( 2026 )

Nucleators SLG1 and SLG2 were prepared from TEOS, stearic acid, and calcium phthalate. The thermal stability of SLG1 and SLG2 was studied with thermogravimetry(TG). Their nucleation behavior in polypropylene was studied with X-ray diffraction, polarized optical microscopy, and differential scanning caloimetry. The showed both SLG1 and SLG2 induced polypropylene to crystallize into β form. The crystallization temperature and crystallization rate were increased, but degree of crystallinity was decreased. Upon adding the nucleators, the spherulites became smaller with interface blurred. While the addition of SLG1 and SLG2 were 0.15 % and 0.3 %, the impact strength of PP was increased from 9.43 kJ/m2 to 21.82 kJ/m2 and 37.79 kJ/m2, respectively, while the tensile strength decreased slightly.

Flame Retardancy of Nano-SiO₂ and RDP Flame Retarded PC/ABS and Their Synergism

ZHONG Liu CHU Hong-ying LIU Zhi-guo

2009, 23 (07): 85-89 ; DOI: 10.19491/j.issn.1001-9278.2009.07.019

Abstract ( 1543 )

Blends of bisphenol-A polycarbonate/acrylonitrile-butadiene-styrene(PC/ABS) were flame-retarded by resorcinol bis(diphenyl phosphate) (RDP) and nano-SiO2. The limiting oxygen index, UL94V flame retardancy, and thermal stability of the flame-retarded PC/ABS were measured. The morphology of the pyrolysis residue was investigated by SEM. Cone calorimeter (CONE) was employed to determine peak heat release rate (p-HRR), average heat release rate (av-HRR), total heat rate (THR), average effective combustion heat (av-EHC), and average mass lose rate (av-MLR). When the loadings of nano-SiO2 and RDP were 5 %and 9 %, respectively, a limiting oxygen index of 29 % and V-0 grade were obtained. The values of p-HRR, av-HRR, THR, av-EHC, and av-MLR were decreased by 16.12 %, 58.82 %, 40.83 %, 17.91 %, and 36.90%, respectively.

Synthesis and Properties of Biodegradable Poly（butylene succinate-co-butylene 2,2-dimethyl succinate）

Gao Bing SUN Yuan-Bi Wang Guo-Li XU Jun XU Yong-Xiang GUO Bao-Hua

2009, 23 (07): 90-95 ; DOI: 10.19491/j.issn.1001-9278.2009.07.020

Abstract ( 2155 )

A series of polyesters, poly(butylene succinate-co-butylene 2,2-dimethyl succinate) (PBS-2M), were obtained from the polycondensation of succinate and/or 2,2-dimethyl succinate with 1,4-butanediol. The compositions and physical properties of the resulted homo- and co-polyesters were investigated by 1H-NMR, differential scanning calorimetry, and X-ray diffraction. The results suggested that the introduction of comonomer containing 2,2-dimethyl side-group led to a change in thermal properties and crystallization behavior. The equilibrium melting temperature obtained by the Hoffman-Weeks plot significantly decreased with increasing concentration of comonomers containing two symmetrical methyl side-groups. Furthermore, Avrami method was used to analyze the kinetics of isothermal crystallization of PBS and PBS-2M-20. The Avrami exponents estimated using Avrami plots, ranging from 2.8 to 3.0 for PBS and 2.6 to 2.8 for PBS-2M-20, indicating that the mechanism of crystallization for both homo- and co-polyester was a tri-dimensional growth with heterogeneous nucleation. Meanwhile, X-ray diffraction showed that there was almost no effect of the 2,2-dimethyl succinate unit on the crystal structure.

Mixing Effect of Twin-rotor Continuous Mixer with Different Rotors

ZHANG Hai-yan HE Xue-tao YANG Wei-min DING Yu-mei

2009, 23 (07): 96-100 ; DOI: 10.19491/j.issn.1001-9278.2009.07.021

Abstract ( 1923 )

In this study, the rotor structure of twin-rotor continuous mixer was designed with the PRO/Engineer software. The meshing and the setting of boundary conditions were made by the GAMBIT. The mixing processes with different rotors were simulated by POLYFOW, and the shear rate, the average velocity, the viscosity and the pressure in the axial direction were compared when the rotors rotate to different angle. Finally, it is found that the rotor whose meeting point of the screw flight at its 1/3 length position has obvious back pressure, which was beneficial to the counter flow of the mixing. This study is helpful to optimize the structure of the rotor and improve the mixing effect.