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2008, Volume 22 Issue 09 Publication date: 26 September 2008 Previous Issue Next Issue

A Review on the Flame Retardant Polypropylene Nanocomposites

CHEN Xiao-sui, YAO Hong, ZHANG Sheng

2008, 22 (09): 1-7 ; DOI: 10.19491/j.issn.1001-9278.2008.09.001

Abstract ( 5307 )

The structure and preparation of several nano-scale flame ratardants including layered silicate，metal hydroxides or oxides，and carbon nanotubes were reviewed. Their application in polypropylene and related flame-retarding mechanism were introduced. The present problems and developing trends were also discussed.

Progress in Polymer Conductive Composites Containing Carbon Nanotubes

LIU Wen-liang, JI Tie-zheng, DING Yang, LI Tie-hu

2008, 22 (09): 8-12 ; DOI: 10.19491/j.issn.1001-9278.2008.09.002

Abstract ( 1998 )

The fabrication methods for conductive polymer/carbon nanotube composites were introduced, including solution blending, melt blending and in situ polymerization. Particular attention was paid on the dispersion of the nanotubes in polymer matrix. Two main electrical properties, conductive percolation and positive temperature coefficient effect were discussed, using polyethylene and epoxy resin based composites as modal systems. The problems existing in processing and the related mechanism were pointed. The development trend of conductive polymer/carbon nanotube composites forecasted.

Research advances in tribological modification of polyoxymethylene

FENG Yun-cheng, WEI Gang, DUAN Hong-ji, YANG Ya-qi, ZHANG Jian-qun

2008, 22 (09): 13-17 ; DOI: 10.19491/j.issn.1001-9278.2008.09.003

Abstract ( 5077 )

A few tribological modification methods and friction-wear properties & mechanism of polyoxymethylene composites are reviewed. In the fields of blending with other polymers，filling with inorganic particles，lubricant agents and metal powders， reinforcing with fibers，compounding with multi-components and modifying by chemical way are mostly discussed for tribological modification of polyoxymethylene.

Study on Modified PVA with Copolymer of Isobutyl Vinyl Ether and Maleic Anhydride

TIAN Jun, WANG Jian-feng, YAN Qing

2008, 22 (09): 18-21 ; DOI: 10.19491/j.issn.1001-9278.2008.09.004

Abstract ( 3542 )

Polyvinyl alcohol (PVA) was blended with isobutyl vinyl ether-co-maleic anhydride [P(IBVE-MA)] and the water resistance and mechanical properties of the composite film were studied. When the amount of P(IBVE-MA) was 2wt%, the elongation at break of the composite film reached to 300% and water resistance was obviously improved.The blend modification mechanism was analyzed from the point views of plasticization and crystallization behavior.

Research on the Preparation and Flammability of PE-HD/IFR/OVMT Flame Retarded Composite

WEI Zhong-yu, LU Zhong-yuan, WANG Liang, YANG Kai, LIU Hui

2008, 22 (09): 22-27 ; DOI: 10.19491/j.issn.1001-9278.2008.09.005

Abstract ( 6784 )

flame retarding composites of high density polyethylene (PE-HD)/ intumescent (IFR)/ organic vermiculite (OVMT) were prepared via direct melt intercalation. The effect of the ratio of melamine polyphosphate (MPP) to pentaerythritol (PER) in the intumescent on composite’s flammability and the effect of the loading of OVMT on the melt intercalation were investigated. It was found that shows that the best wt ratio of MPP/PER was 3:1 at a loading of flame retardant of 30 wt%. The best intercalation result was achieved with 2 wt% OVMT. The limited oxygen index of the PE-HD/IFR/OVMT with a composition of 70/28/2 reached 28.6 %, while the UL94 was V-1 rating. Furthermore, a proper addition of PE-HD-g-MAH to the system could promote the intercalation effect.


Non-isothermal Crystallization Kinetics of Silane Crosslinked Ethylene-octene Copolymer

JIAO Chuan-mei

2008, 22 (09): 28-33; DOI: 10.19491/j.issn.1001-9278.2008.09.006

Abstract ( 6461 )

The non-isothermal crystallization kinetics of virgin ethylene-octene copolymer (POE), dicumyl peroxide (DCP) crosslinked POE, and silane crosslinked POE and were studied using differential scanning calorimetry at different cooling rates. Avrami and the Mo methods were applied to describe the crystallization data. The values of half-time of crystallization t1/2, and the parameter Zc estimated by Avrami method showed that the crystallization rates of virgin POE and DCP crosslinkeded POE were higher than that of silane crosslinked POE at the same cooling rate. For all the samples, the crystallization rate increased with increasing cooling rate. With Mo method, it found that the F(T) values of virgin POE and DCP crosslinked POE were lower than that of silane crosslinked POE, indicating the latter possessed the lowest crystallization rate.

In-situ Preparation of PA6/SiO₂ Masterbatch and Its Composites

TIAN Li-wei, TANG Song-chao, SHAO Jia-min, FAN Xiao-ye

2008, 22 (09): 34-37 ; DOI: 10.19491/j.issn.1001-9278.2008.09.007

Abstract ( 2099 )

Nano silica was surface modified through solvent transfer method. In presence of the modified silica, ε-caprolactam was in situ polymerized leading to a master batches, which was subsequently blended with neat polyamide 6 resulting in nano-composites. TEM showed that a uniform dispersion of SiO₂ in the matrix was achieved, which may react as nucleating agent. The tensile stress and elongation of the nanocomposites were improved by 12.17% and 37.30% compared with those prepared by melting methods. The izod impact was increased by 37.25%.

Effects of Expandable Graphite and Phosphates on the Fire Retardance of Unsaturated Polyester

YOU Chang-jiang, XIE Qing, FENG Jian-zhong, ZENG Yi-zheng, JIA De-min

2008, 22 (09): 38-42; DOI: 10.19491/j.issn.1001-9278.2008.09.008

Abstract ( 5748 )

The effects of the combination of expandable graphite (EG) and phosphates on the structure and fire retardancy of unsaturated polyester (UPR) were investigated through limiting oxygen index, cone calorimetry test, thermogravimetric analysis, infra-red spectroscopy, and scanning electron microscope (SEM). It showed that the limiting oxygen index was increased markedly, heat release rate and mass loss rate of UPR were decreased significantly by adding both EG and phosphate. The fracture surface of impact samples showed a ductile feature.

Study of the Nonisothermal Crystallization Kinetics of PBT / Nano-SiO₂ Composites

ZHANG Tian-shui, NIU Jian-hua, ZHANG Ling, HONG Yue-rong, LI Chun-zhong

2008, 22 (09): 43-48; DOI: 10.19491/j.issn.1001-9278.2008.09.009

Abstract ( 6411 )

Poly(butylenes terephthalate)/Nano-SiO₂ nanocomposites were prepared by melt blending using a twin screw extruder. The nonisothermal crystallization kinetics of the nanocomposites was studied with differential scanning calorimetry (DSC) and the effect of SiO₂ was explored. It showed that crystallization peak temperature for the nanocomposites was much higher than that of neat PBT. Nano-SiO₂ accelerated the crystallization rate, indicating an obvious heterogeneous nucleation. Crystallization kinetics data was analyzed by Ozawa, Mo, and Kissinger methods. The results confirmed the applicability of Mo, and Kissinger models, and the inadequacy of the Ozawa approach. In addition, a lower activation energy was observed at a low content of nano-SiO₂ (0.3wt%) than that at a high content (3.0wt%).

Preparation and Interface Characterization of PA6/nano-SiO2 Nanocomposites

WU Lin-lin, LIU Wen-tao, HE Su-qin, ZHU Cheng-shen, LU Xao-wen

2008, 22 (09): 49-52; DOI: 10.19491/j.issn.1001-9278.2008.09.010

Abstract ( 4671 )

PA6/SiO2 nanocomposites were prepared by in-situ polymerization. The interfacial compatibility between nano-SiO2 and PA6 matrix was characterized by mechanical experiment, SEM, and DSC. It showed that The interfacial parameters B for PA6/modified SiO2 was larger than that for PA6/unmodified SiO2. SEM observation showed that the introduction of SiO2 changed the microstructure of the materials. Better interfacial binding was observed between PA6 matrix and modified SiO2, which resulted in a flexible interface layer favorable to the crystallization of the PA6.

Synthesis and Study on Mechanical Properties of Cross-linked Polystyrene

ZHU Quan-yao, WU Fei, WANG Jun, SUN Hua-jun, CHEN Wen

2008, 22 (09): 53-56; DOI: 10.19491/j.issn.1001-9278.2008.09.011

Abstract ( 3208 )

Cross-linked polystyrene (CLPS) with compact structure was prepared by free radical crosslinking copolymerization (FCC), with styrene as the monomer, and divinylbenzene as crosslinker. Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) were employed as a characterization role. The influence of crosslinker and thermal treatment on the mechanical properties of CLPS was researched. The results indicated that the mechanical properties of CLPS was increased and then decreased with the increasing of DVB, and the curves showed optimal mechanical properties at 1.6～1.8 wt%, what’s more, the tensile strength and rupture ratio were increased nearly by 12 % and 20 % respectively after being suitable anaphase thermal treatment.

Textural Properties of Mesostructured Silicas and Reinfocement for Epoxy Resin Mesocomposites

JIAO Jian, ZHANG Jia-yun

2008, 22 (09): 57-62; DOI: 10.19491/j.issn.1001-9278.2008.09.012

Abstract ( 3081 )

Mesostructured silica MSU-J-SS and MSU-J-SS with worm-hole framework are assembled from tetraethylorthosilicate (TEOS) and sodium silicate (SS) as precursors, respectively. The textural property details of these two mesostructured silicas are characterized. The rubbery and glassy epoxy resin mesocomposites are prepared with the 2wt %--10wt % mesostructured silicas, MSU-J-SS and MSU-J-TEOS, as the filler and their tensile properties, microstructure and morphology are investigated. The results demonstrate that the textural property details of mesostructured silicas are greatly affected by the silica resource and synthesizing conditions. The mesostructrue silica MSU-J-SS exhibits more uniform structure, larger average pore size, smaller surface area, pore volume and wall thickness in comparison to the mesostructured silica MSU-J-TEOS. The mesocomposites containing mesostructured silica exhibit improved tensile properties in comparison to the pristine polymer. Moreover, the improved tensile strength and tensile modulus without compromising the strain-at-break provided by MSU-J-SS with larger pore size in comparison to MSU-J-TEOS are attributed to better dispersion in epoxy resin and more efficient polymer impregnation of the particle mesopores.

Effect of Vibration Injection Molding on Crystal Morphology and Physics Properties of Polyamide6

LEI Yan-wei, YANG Liang-bo, WEN Yao-feng, SHEN Kai-zhi, ZHANG Jie

2008, 22 (09): 63-65 ; DOI: 10.19491/j.issn.1001-9278.2008.09.013

Abstract ( 3274 )

The physics properties of polyamide 6 samples by regular and vibration injection moldings were compared in this paper. Effects of vibration frequency and vibration pressure on the physics properties and crystal morphology of polyamide 6 were studied. The tensile strength of samples obtained by vibration injection molding was higher than that by regular one. The crystal structure was characterized using WAXD. The γ form of polyamide 6 was decreased by vibration injection molding.

3-D Viscoelastic Simulation of The Interface in Polymer Coextrusion Process HUANG Yi-bin，LIU He-sheng*，HUANG Xing-yuan，LAI Jia-mei

HUANG Yi-bin, LIU He-sheng, HUANG Xing-yuan, LAI Jia-mei

2008, 22 (09): 66-69; DOI: 10.19491/j.issn.1001-9278.2008.09.014

Abstract ( 3621 )

The numerical model with Giesekus constitutive equation was established for the 3-D isothermal coextrusion flow within a die with the square shaped cross section. The simulation of the moving interface between two polymer melts was performed using Polyflow. The numerical results were compared with the experimental data of Karagiannis et al. and the numerical error was discussed. The analysis shows that the interface position in coextrusion could be predicted at a relatively high order of accuracy for the numerical model with viscoelastic constitutive equation and slight-slip wall boundary condition, The interface obtained from simulation is a little higher than the real interface obtained from experiment. The simulation error at the center part of the die is less than that beside the wall. Surface tension on interface and wall boundary condition is the main factor which affects the accuracy of the simulation on moving interface in coextrusion process.

A Study on Dynamic Rheological Behaviour of PE-HD/nano-SiO2

WANG Shu-ping, YU Jia-hua, GONG Fang-hong

2008, 22 (09): 70-73 ; DOI: 10.19491/j.issn.1001-9278.2008.09.015

Abstract ( 1822 )

dynamic rheological behaviour of high density polyethylene/nano-silica composites were investigated in this paper. And discuss the surface-modification of nano-SiO₂ affect the rheological behaviour of composites. Experimental results show that PE-HD/SiO₂ composites belong to pseudoplastic fluid. The complex viscosity (η*) of the composites increased with increasing of SiO₂ content.When the content of SiO₂ is greater than 6%,η* appear increasing suddenly, and appear shear thinning behaviors. In the relation curve of the storage moduli (G′), loss moduli (G″) and frequency(ω), it is appear second flat which indicate that it is form local order percolation network because the particle is correlation and glomeration. And the surface-modification SiO₂ is not change the pseudoplastic fluid.The η* of surface-modification SiO₂ by the coupling agent system is lower. In the relation curve of the storage moduli (G′), loss moduli (G″) and frequency(ω), it is not appear second flat. The system of composites is disperse more homogeneously.

Research on thermal oxidative aging and stability of Polyvinyl Alcohol

WANG Jian-chao, XIANG Ai-min, LIU xiao-jian

2008, 22 (09): 74-77 ; DOI: 10.19491/j.issn.1001-9278.2008.09.016

Abstract ( 4619 )

The aging of PVA on heating in the presence of oxygen were investigated. The conjugated double bounds were observed by FTIR&XPS, which confirmed the elimination reaction of hydroxyl groups from poly (vinyl alcohol) at high temperature. By introduction of composite stabilizers of phosphates and phenols into PVA, the elimination of hydroxyl groups was effectively inhibited, which was evidenced by the decrease torque of PVA melt and yellow index.

Effect of Injection Rate on the Breakthrough of Core-melt Front

WANG Tao, FU Jian, ZHOU Sheng

2008, 22 (09): 78-80; DOI: 10.19491/j.issn.1001-9278.2008.09.017

Abstract ( 4642 )

The core-melt breakthrough was one of common flaw of sandwich injection molding. By means of the software of Moldflow Plastics Insight, the effect of injection rate of core-melt and skin-melt on the tendency of core-melt breakthrough were simulated, and the relation of pseudoplasticity, injection rate and core-melt breakthrough were discussed. It was found that for materials association this paper, the effect of injection rate of core-melt on core-melt breakthrough was different as the materials association was different, while increasing of injection rate of skin-melt even reduced the tendency of core-melt breakthrough.

Compound Experiment of Environmental Heat Stabilizers Applied to PVC

ZHANG Shu-hua, CAO Jian, LIU Bo

2008, 22 (09): 81-84 ; DOI: 10.19491/j.issn.1001-9278.2008.09.018

Abstract ( 2985 )

The static and dynamic stabilities for PVC was compared for combination of ester-tin with various assistant stabilizers including stearate, epoxide, and alkyl tin by means of congo red rheometer. By compounding ester-tin with Ba/Zn and alkyl tin, the heat stability time increased from 32 min to 49 min and 32 min to 57 min, respectively. A good synergistic effect was observed when epoxide was used as an assistant stabilizer. The combination of ester-tin with alkyl tin not only resulted in a better transparency, but also a better dynamic thermal stability at high temperature than with Ca/Zn. After UV irradiation of 72h, the remaining tensile strength was 98.14 % and elongation at break was 91.71 %.

Structural Characteristic of Domestic Random Ethylene-propylene Copolymer Special Resins

YUAN Chun-hai, ZHANG Chuan-zhi

2008, 22 (09): 85-88; DOI: 10.19491/j.issn.1001-9278.2008.09.019

Abstract ( 1881 )

Structure of three kinds of industrial polypropylene random copolymer（PPR） with different impact property was characterised in this paper. Morphology of fracture shown by SEM indicates that
the PPR2 has brittleness fracture, PPR1 has toughness fracture and PPR3 has both brittleness fracture and toughness fracture. Results of Polarizing microscope observation show that PPR1 has more and bigger spherulite than PPR2 has, and PPR3 has a large number of small spherulite. From the results of SEM and Polarizing microscope observation, we can safely draw the conclusion that existing of a small sum of insufficiently modified PP in samples leads to the different impact property of three kinds of industrial PPR. Insufficiently modified PP can also be observed by 13C-NMR and DSC characterisation.


Applying new technology of porous material in precision injection mold

JIANG Bing-yan, SHEN Rui-xia, ZHAI Zhan-yu, Gerhard Ziegmann

2008, 22 (09): 89-95; DOI: 10.19491/j.issn.1001-9278.2008.09.020

Abstract ( 6059 )

The rapid development of plastic parts brought new challenges to precision injection mold design. The advantages and working principle of porous material in precision injection mold were reviewed in this paper. Currently, porous materials were employ in injection mold as vent system, cooling system, demolding system, vacuum system, and In Mold Labeling (IML) technology. The strength, porosity, pore size and distribution, surface topography control, and machinability constituted the hot topics. Low cost and mass production will be the development trend in the near future.