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2009, Volume 23 Issue 03 Publication date: 26 March 2009 Previous Issue Next Issue

Research Progress of High-density Polyethylene/Clay Nanocomposites

Zhang Yuxia

2009, 23 (03): 1-7 ; DOI: 10.19491/j.issn.1001-9278.2009.03.001

Abstract ( 2912 )

This article discussed the research development on the relationship between structure/morphology and properties of PE-HD/clay nanocomposites. It was found that organic treatment of clay and the addition of compatibilizer improved the “intercalation” and “exfoliation” structures of the nanocomposites. The influence of the molecular weight of PE-HD on the nanocomposite’s structure was in two aspects: (i) the larger the size of molecular chain, the more difficult for it to intercalate into the interlayer of clays; (ii) the higher the viscosity resulted from the high molecular weight, the larger the shearing force could be imposed to promote the intercalation or exfoliation. High content of clay was not favorable for the exfoliation. For the processing conditions, the masterbatch method was better than the single pass method, and a higher exfoliation fraction could, the toughness reduced with increasing content of clay. The clay layer constituted a two-dimensional nucleation surface, which increased the crystallization temperature and rate, however, the presence of clay may reduce the degree of crystallinity. An exfoliation structure was necessary for good barrier properties, which was positive for enhancing the thermal stability, however, the organic modifier and the catalysis action of clay may increase the degradation of polyethylene. In addition, due to the formation of a clay-enriched protective char during combustion, the flame retarding property of the nanocomposite was improved.

Recent Advance in Phenolic Resin Modified by Nanomaterials

2009, 23 (03): 8-12 ; DOI: 10.19491/j.issn.1001-9278.2009.03.002

Abstract ( 3302 )

In this paper, the current published work on nano-particle modified phenolic resin was summarized, focused on montmorillonite and nano-carbon materials based systems. The dispersion of montmorillonite in the phenolic matrix was considered a main issue. Other inorganic nano-particles such SiO2, TiO2 may impart the phenolic resin additive functions like ablative and tribological properties.

Progress in Applications of Long Fiber Reinforced Thermoplastics in Automotive Parts

2009, 23 (03): 13-18 ; DOI: 10.19491/j.issn.1001-9278.2009.03.003

Abstract ( 1045 )

In this paper, the theory, property, application, and manufacture of long fiber reinforced thermoplastics (LFT) in the field of automobile parts were reviewed. LFT satisfied the requirement of high mechanical properties and dimensional stability for the half structure parts and components in the automotive. The development of domestic LFT composite materials was at the stage of preliminary research and application, national standards and mature design and application were absent. The domestic market was basically monopolized by foreign products. Therefore, LFT constituted potential products in our country.

Study of Crystallization Behavior of PP/EPR High-impact Alloys

2009, 23 (03): 19-23; DOI: 10.19491/j.issn.1001-9278.2009.03.004

Abstract ( 2817 )

In this paper, polypropylene/EPR in-situ alloys were prepared with ethylene contents of 0.94 mol%, 1.67 mol% and 3.00 mol%. Isothermal and non-isothermal crystallization behaviors of the samples were investigated using differential scanning calorimetry (DSC). The isothermal crystallization data was well fitted with Avrami equation. The higher the crystallization temperature, the lower the crystallization rate. For the non-isothermal crystallization, the range of crystallization temperature became wider and moved to lower temperature with increasing cooling rate. It was also found that the higher the content of ethylene, the lower the crystallization rate of isothermal crystallization, except the content of ethylene was 3.00 mol %, and the crystallization temperature of non-isothermal crystallization had the same regularity.

Preparation and Properties of In-situ Polymerized PA6/nano-SiO₂ Composites with Wear Resistance

Fanxue Meng WU Wei Olaf Jacobs M Karczewski

2009, 23 (03): 24-27 ; DOI: 10.19491/j.issn.1001-9278.2009.03.005

Abstract ( 3016 )

Nano-SiO2 was introduced into PA6 via in-situ polymerization in order to improve its tribological behavior. The wear performance, heat resistance, mechanical properties, and crystallinity of the composites were studied. The optimum wear performance was obtained when content of nano-SiO2 was 1 wt%. At a content of nano-SiO2 of 3 wt%, the heat distortion temperature, tensile strength, Young's modulus, and elongation at break of the composites were obviously better than neat PA6. the heat distortion temperature was increased from 64.6 ℃ of PA6 to 130 ℃ of the composites. Using masterbatch method, the obtained PA6/nano-SiO2 composites also possessed good tribological and mechanical properties, as well as low costs.

Friction and Wear Properties of PTFE Composites Filled with Nano-SiC，Nano-SiC/Graphite and Nano-SiC/MoS2

2009, 23 (03): 28-31 ; DOI: 10.19491/j.issn.1001-9278.2009.03.006

Abstract ( 3325 )

The friction and wear properties of PTFE composites filled with nano-SiC, nano-SiC-graphite or nano-SiC- MoS2 against 45# steel under dry conditions were studied using MM-200 wear tester. The hardness of the materials was examined using HR-150A, the frictional surface was observed using scanning electron microscope (SEM). It showed that the addition of nano-SiC increased the wear resistance and hardness of PTFE. When a mixture of nano-SiC and MoS2 was used, the wear resistance of PTFE was remarkably enhanced, especially at high loads. The friction coefficient of nano-SiC filled PTFE decreased with increasing load, which could further reduced by introducing MoS2 and graphite.

Study on the Nonisothermal Crystallization Behavior of PET/PTT Alloys

2009, 23 (03): 32-36 ; DOI: 10.19491/j.issn.1001-9278.2009.03.008

Abstract ( 2809 )

The nonisothermal crystallization of melt blended PET/PTT alloys was studied USING differential Scanning Calorimetry. At same cooling rates, the crystalline peak temperature of PET/PTT alloys shifted toward lower temperature with increasing PTT contents. When the content of PET and PTT in PET/PTT alloys was comparable, double crystallization peaks were given. With increasing cooling rate, the crystallization temperature decreased and the peak became wider. The nonisothermal crystallization data was analyzed using Jeziorny method, the results showed that the nonisothermal crystallization rate constant increased with increasing cooling rate. The Avrami index was between 1 and 5.

Effect of Grafting Ratio on the Structure and Properties of PVC/PA6-g-SMA Blend

Cai-hong WANG Bing-Zheng ZHOU Min HE LU Sheng-Jun Jie YU

2009, 23 (03): 37-40 ; DOI: 10.19491/j.issn.1001-9278.2009.03.009

Abstract ( 3113 )

PA6 was grafted with styrene/maleic anhydride copolymer (PA6-g-SMA）and was subsequently blended with poly vinyl chloride (PVC) via melt blending. The effect of grafting ratio of PA6-g-SMA on morphology and mechanical properties of PVC/PA6-g-SMA blends were discussed. A good compatibility between PA6-g-SMA and PVC was identified. With increasing grafting ratio of PA6, the decreasing domain size of PA6-g-SMA and enhanced toughening and reinforcing on PVC was observed. When the graft ratio was 5.12 %, the addition was 15 %, the impact strength of the blend was 64.7 kJ/m2 , the tensile strength of the blend was 55 MPa.

Effect of Thermoplastic Polyamide Elastomer on Morphology and Properties of PLLA/Ternary Polyamide Blends

2009, 23 (03): 41-45 ; DOI: 10.19491/j.issn.1001-9278.2009.03.010

Abstract ( 3021 )

In this study, the effect of TPAE contents on the morphology, mechanical properties, and thermal properties of PLLA/ ternary polyamide blends was investigated using SEM, DSC, and XRD. The tensile strength, elongation at break and impact strength of PLLA/ ternary polyamide blends significantly increased after the addition of TPAE. When the mass ratios of PLLA/ ternary polyamide /TPAE were 70/30/5, the blend gave the highest elongation at the break of 370 % and Izod impact strength of 90 J/m. SEM analysis showed that the domain size of ternary polyamide significantly decreased after the addition of TPAE. DSC and XRD analysis showed that the crystallinity of the blends significantly increased after tensile testing.

Thermal Conductivity of PE-LLD/CF Composite

SHAO Shi-yu Qun-li AN

2009, 23 (03): 46-49 ; DOI: 10.19491/j.issn.1001-9278.2009.03.011

Abstract ( 3312 )

Carbon fiber (CF) reinforced linear low-density polyethylene (PE-LLD) composites were prepared via hot-molding. The effects of content, dispersion method, and surface treatment of CF on thermal conductivity of PE-LLD/CF composites were investigated. The thermal conductivity of PE-LLD increased when filled with coupling agent treated carbon fiber. Thermal conductivity of the sample made by ultrasonic dispersion method was higher than those made by mill- or melt-mixing. Thermal conductivity of PE-LLD/CF increased with increasing CF content, without reduction in the mechanical properties. When the content of carbon fiber was 10 mass% and using ultrasonic dispersion, the thermal conductivity of PE-LLD/CF reached 1.4 W/(m·K), six times that of neat PE-LLD.

Preparation and Properties of PBT Based Conductive Multiphase Composites

Zuo Cheng

2009, 23 (03): 50-53 ; DOI: 10.19491/j.issn.1001-9278.2009.03.012

Abstract ( 2948 )

Carbon black and carbon nanotubes were introduced into polybutylene terephthalate resulting in binary composites of PBT/CB and PBT/MWNTs and ternary composite of PBT/CB/MWNTs via melt-blending. The synergistic effect of MWNTs and CB on the properties of the composites was investigated. When adding MWNTs to PBT/CB composites, the percolation threshold for the occurring of conducting network shifted to lower filler contents, resulting in a enhanced conductivity.

Effect of CPE on Melt Rheological Behavior of Foamed PVC/Wood-flour Composites

2009, 23 (03): 54-57 ; DOI: 10.19491/j.issn.1001-9278.2009.03.013

Abstract ( 2977 )

The effects of chlorinated polyethylene (CPE) on the rheological properties of foamed wood-flour/PVC composites were investigated via small amplitude oscillatory rheological measurement using a rotary rheometer. The complex viscosity (η*) of the melt sample decreased with the increasing angular frequency (ω) in range of 0.1~100 rad/s, exhibiting a typical "shear thinning". Loss modulus( G〞)and storage modulus( G′ )of the melt increased with increasing ω. Gelation of PVC in composites was promoted by adding 5phr CPE to the system, in which G〞and η* of the melt increased with increasing ω, and G′ showed little change. As the contents of CPE increased to 10phr, G′, G〞and η* of the composites melt decreased. With increasing ω, elastic response of melt became stronger, therefore tanδ decreased. For the composites containing CPE 10phr, the impact strength of solid composites increased 20 %.

Visualization Analysis of Water Penetration Behavior in Water-assisted Injection Molding

LIU Xu-Hui

2009, 23 (03): 58-61 ; DOI: 10.19491/j.issn.1001-9278.2009.03.014

Abstract ( 3345 )

This research focused on water penetration behavior in water-assisted injection molding process with the help of a newly developed water injection system by the author's lab and visualization technology. A flow visualisation mold of rectangular cavities with dimensional variations and curved sections,.was specially designed and made for this study. The material used was Polystyrene. The water-assisted melt filling processes on different water pressures were also observed during water-assisted injection molding. It was found that the water penetration behavior is a turbulent jet after water penetrates the high-viscosity melt which is caused by the cooling of the water injector. Water jet penetration length increases with water pressure increasing. When water pressure is low, water is inclined to change its penetration direction. The higher water pressure is, the more smooth water channel will be. The water front gradually contracts in the inlet of the curved section and at the contractional transitons, while expanding in the outlet of the curved section and at the expansional transitons.

Preparation of Fire Retarded and Antistatic Polyamide 6 Pole Shoes

Fu Hong-Sheng huagang liu

2009, 23 (03): 62-65 ; DOI: 10.19491/j.issn.1001-9278.2009.03.015

Abstract ( 2930 )

Polyamide6 pole shoe was prepared via two methods: (1) Using a blend of polyamide6 with masterbatches of fire retardant and antistatic agent;(2) Coating fire retardant and antistatic agents on the surface polyamide6 pole shoe. Fire retardant, antistatic, and mechanical properties of the pole shoe were studied. The pole shoe prepared via blending method gave rise to outside and inside surface resistance of 2.1×106Ω and 6.4×106Ω, burning times with and without flame 1 s and 10 s, respectively. However, its compressive strength was poor. The corresponding properties by coating method were 8.3×106Ω, 3.2×107Ω, 2 s, and 12 s, with the compressive strength obviously improved.

Shape Changing Mechanisms in Micro Profile Extrusion

FU Zhi-hong

2009, 23 (03): 66-69 ; DOI: 10.19491/j.issn.1001-9278.2009.03.017

Abstract ( 3619 )

The effects of surface tension and die swell on the shape of extrudate during micro profile extrusion were studied and compared both analytically and numerically. As the size of the extrudate reduces, the surface tension increased and affected the cross-sectional shape change significantly. Strategies were proposed to reduce the influence from surface tension and produce precision micro profiles.

Research on Process Characteristic of High-gloss Surface Part Injection Technology：Wrapage, Shrinkage and Sink Index

LIU Dong-Lei Yong XIN

2009, 23 (03): 70-75 ; DOI: 10.19491/j.issn.1001-9278.2009.03.018

Abstract ( 2196 )

Using front panel of LCD television as a model system, the high-gloss surface part injection technology was studied using Taguchi method combined with finite element (FE) analysis and data processing. Wrapage, sink index, and volumetric shrinkage were selected as the main quality indexes. It was found that the pressure at v/p switch-over point was decisive for the wrapage, which decreased rapidly, quasi-linearly with increasing pressure at v/p switch-over point at the first stage, then increased slowly after reached a peak value. Injecting and packing pressure are two main factors for sink index and volumetric shrinkage, which decreased quasi-linearly with increasing injecting and packing pressure. When injecting pressure reached to a certain peak value, it became no longer importance to sink index and volumetric shrinkage.

Study on the Warping Deformation of Super-long Worktable Decoration Strips

2009, 23 (03): 76-80 ; DOI: 10.19491/j.issn.1001-9278.2009.03.019

Abstract ( 2063 )

Using CAE and FEM, the effects of temperature and pressure on residual stress and warpage of super-long decoration strip were investigated. The computation was focused on mould temperature, melt temperature, rate of injection, and holding pressure. The cause of warpage and the improving measures for the injection product were proposed. Results demonstrate that the main reasons of warpage deformation were the asymmetry of plastics shrinkage. The second reason was the temperature asymmetry resulting from the cool-off asymmetry in the filling mold process. The last reason was the non-uniform of molecule orientation.

Compatibilization Effect of Silane Coupling Agent KH-550 on Polypropylene/Dibromoneopentyl Glycol Phosphate Ester Melamine Salt

2009, 23 (03): 81-85 ; DOI: 10.19491/j.issn.1001-9278.2009.03.020

Abstract ( 3013 )

The effect of silane coupling agent KH-550 on the compatibilization in the composite of polypropylene/dibromoneopentyl glycol phosphate melamine salt（PP/BPMS）(90/10) was studied. When 0.3 % KH-550 was added, the impact and tensile strength composites were 34.34 MPa and 4.48 kJ/m2, which were 7.9 % and 40.4 % higher than neat PP/BPMS blends, respectively. The composite was self-extinguish and free from burn-dripping. IR and rheological studies proved that KH-550 grafted on the BPMS through chemical linkage. The encapsulation of KH-550 weakened the heterogeneous nucleation of BPMS, as indicated by the large spherulites of PP by POM and the weakened (040) refraction by XRD. The SEM revealed that adhesion of PP and BPMS was improved.

Thermal Stabilization of Antioxidants on PMMA

2009, 23 (03): 86-89 ; DOI: 10.19491/j.issn.1001-9278.2009.03.021

Abstract ( 2987 )

Different antioxidants were blended with pure PMMA resins synthesized by continuous bulk polymerization. The thermal stability of PMMA resins was measured by thermalgravimetry (TG) analysis under the atmosphere condition. The effects of the kind, content, and ratios of antioxidant on the thermal stability of PMMA resins were investigated. It showed that the thermal stability of PMMA was apparently improved by main-antioxidant, such as antioxidants 1076, 2246, 245, and 1010. The initiation decomposition temperature was improved by an assistant-antioxidant(antioxidant 168). In the systems based on 1010 and 168, the thermal stability increased with increasing content of 1010. When the contents of the antioxidant 2.5 wt‰ (1010/168= 3:1), the best thermal stability was obtained.

Test Level and Problems of Plastics Tensile Property at Yield in China

Liu Shansheng

2009, 23 (03): 90-94 ; DOI: 10.19491/j.issn.1001-9278.2009.03.022

Abstract ( 3489 )

The CNAS T0381 proficiency testing program was summarized and was compared with the average result of 7 national plastics test centers in China. The result showed that 75 % of the laboratories were trustworthy on the test results of tensile stress at yield and tensile stress at 5 % strain tests, 68 % of the laboratories were trustworthy on the test results of tensile strain at yield test. The influencing factors on the test result, such as the pre-stress during grip, wrong operating of reset, and understanding of standards were also analyzed. It was found that the main factor was eliminating the pre-stress. The precision of equipment, understanding of standards, the working attitude should be improved.

Experimental Study on Continuous Expansion Equipment for Biaxial Self-reinforcement Pipes with A Cloth Bag

2009, 23 (03): 95-97 ; DOI: 10.19491/j.issn.1001-9278.2009.03.023

Abstract ( 2972 )

Hoop expanded PVC pipe and biaxial self-reinforcement PVC pipe were produced with a continuous expansion equipment with cloth bag. When the diameter of the pipe was expanded from Ф40 mm to Ф50 mm ，the hoop tensile strength increased 23 % ～25 %, the hoop young's modulus increased 12 %. Through biaxial self-reinforcement, the hoop tensile strength of the pipe increased 26 % ～33 %, hoop young's modulus increased 30 %～33 %. For the biaxial self-reinforcement pipe, the hoop tensile strength increased with increasing axial stretching ratio.

Computer Aided Injection Mold Design for Side Cover of Printers

ZHANG Xiao-Li

2009, 23 (03): 98-102 ; DOI: 10.19491/j.issn.1001-9278.2009.03.024

Abstract ( 3129 )

Injection mold design for side cover of printer was introduced in this paper. There are many lateral concaves and bores in the part, so the inner and outer lateral openings should be applied in this mold structure. Under the premise to meet the requirement of configuration, the design simplified as far as possible. The Moldflow analysis was introduced to designs of runner and cooling systems so as to ensure the appearance quality and surface level. The designed mold was produced in batch and worked well, and thus provided a reference to similar plastic parts mold design.