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2013, Volume 27 Issue 12 Publication date: 26 December 2013 Previous Issue Next Issue

Research Progress in Modification of Poly(lactic acid)

WEI Bing Lu Qi

2013, 27 (12): 1-5 ; DOI: 10.19491/j.issn.1001-9278.2013.12.001

Abstract ( 1343 )

The synthesis methods of poly(lactic acid)(PLA) were briefly introduced in this paper, and some common materials used for modification of PLA were reviewed, including polymer, fiber and inorganic powder. Finally the problem currently faced and the research trend in PLA modification was prospected.

Research Progress on Modification of Glass Fiber Reinforced Polyamide 66 Composites

2013, 27 (12): 6-11 ; DOI: 10.19491/j.issn.1001-9278.2013.12.002

Abstract ( 1213 )

In this paper, the research progress on the modification of PA66/GF composites in recent years was reviewed, the topics such as flame retardancy, wear resistance, interfacial performance, water absorption, mechanical strength, and processing technology were discussed. At the same time, the development trend was also prospected.

Research Progress in Polymer/Carbon Nanotubes Composites

2013, 27 (12): 12-16 ; DOI: 10.19491/j.issn.1001-9278.2013.12.003

Abstract ( 1262 )

The advance in the study of polymer modification with carbon nanotubes （CNTs）was reviewed. Both thermosetting resin such as polyether-ether-ketone, epoxy resin, bismaleimide, cyanate ester resin, and phenolic resisn and thermoplastics resins such as polyamide 6, propylene resin, polyethylene resin and polyacrylonitrile were involved. The development trend of polymer modification with CNTs in the future was forecast.

Epoxy Resin Modified with Hyperbranched Polyesters as LED Packaging Materials

Qing-peng ZENG Rong Min-Zhi

2013, 27 (12): 17-22 ; DOI: 10.19491/j.issn.1001-9278.2013.12.004

Abstract ( 926 )

Hydroxyl-terminated hyperbranched polyester H20 and H30 with different molecular weights, as well as carboxyl-terminated hyperbranched polyester H20-COOH were used for the toughening of o-cresol formaldehyde epoxy resin. It was found that all the hyperbranched polyesters could improve impact toughness and flexural strengths, and remain flexural modulus of the epoxy resin. The addition of 2.5phr H30 could bring about 90 % increase of impact strength, while flexural strength of epoxy resin could be raised by 60 % with 2.5phr incorporation of H20-COOH. In addition, various hyperbranched polyesters could increase the initial decomposition temperature of the material. There were no evident influences of hyperbranched polyesters on the light transmission of the epoxy resin. With increasing H20-COOH content the water absorption of the epoxy resin decreased.

Study on the Effect of Multi-functional Epoxy Chain Extender on the Foaming Behavior of Poly (lactic acid) / Clay Nanocomposites

LIU Wei Hangquan LI Zhongjie DU

2013, 27 (12): 23-29 ; DOI: 10.19491/j.issn.1001-9278.2013.12.005

Abstract ( 1038 )

Poly(lactic acid)(PLA)/clay nanocomposites were prepared using multi-functional epoxy compound as a chain extender. The chain extender obviously affected the rheological properties and crystallization behaviors and thus the foam-ability of the nanocomposites. The melt elasticity was increased with increasing content of chain extender. The crystallization nucleation sites were increased with the addition of clay and chain extender. Subsequently, chain extended PLA/clay nanocomposites were foamed with supercritical CO2. The cell structure, cellular size, and cellular density was investigated.

The Preparation of mPE-g-MAH and Properties Investigation of Polyolefin/mPE-g-MAH Composites

2013, 27 (12): 30-33 ; DOI: 10.19491/j.issn.1001-9278.2013.12.006

Abstract ( 936 )

The grafting technology of maleic anhidride (MAH) onto mPE was studied inthis paper. When the loading of DCP was 0.2 wt %, maleic anhydride was 2 wt % and inhibitor was 0.2 wt %, all based on PE, the graft rate was 1.37 wt % and the gel fraction was 0.22 %. Compared with neat mPE, the tensile strength and elongation at break of mPE-g-MAH (graft rate 0.80 wt %) increased by 20.8 % and 17.1 %, respectively, the oxygen index increased from 27.0 % to 28.6 %. When the grafting rate reached 1.37 wt %, the tensile strength and elongation at break were further increased by 9.2 % and 15.0 %, respectively, the oxygen index increased to 29.8 %.

Effect of POE-g-MAH on Morphology and Rheological Behavior of r-PET/PP Blends

2013, 27 (12): 34-40 ; DOI: 10.19491/j.issn.1001-9278.2013.12.007

Abstract ( 1025 )

Maleic anhydride grafted polyethylene-octene copolymer (POE-g-MAH) was used as a compatibilizer in the blends of recycled poly(ethylene terephthalate) (r-PET) and polypropylene (PP). The effect of POE-g-MAH on the morphology and rheological behavior of the r-PET/PP blends was investigated using SEM and dynamic rheometer, etc. It was found that the average size diameter of PP domains in the blends decreased with increasing POE-g-MAH content. When POE-g-MAH content was 5 wt %, the average size of PP decreased from 2.71±2.65 for uncompatibiliezd blends to 1.18±0.62 μm. In addition, the interface between the two phases became vague, and the Tg of r-PET shifted to lower temperatures, indicating a remarkable improvement of compatibility between r-PET and PP. The addition of POE-MAH increased the entanglement between r-PET and PP leading to a remarkable increase in complex viscosity, storage modulus, loss modulus, as well as the notched impact strength, however, the ?exural strength decreased slightly.

Influence of Methylphenyl Polyborosiloxane on Flame Retardancy of PC/ABS

2013, 27 (12): 41-46 ; DOI: 10.19491/j.issn.1001-9278.2013.12.008

Abstract ( 1030 )

Polyborosiloxane flame retardants (PB) were prepared through a two-step synthesis. The flame retardancy of the polyborosiloxane in polycarbonate/acrylonitrile- butadiene-styrene copolymer (PC/ABS) alloy was studied using thermogravimetric analysis, cone calorimeter analysis, and limited oxygen index. It was found that the PB prepared from a 1:1 ratio of silane/boric acid provided the most effective flame retardancy in PC/ABS system. Introducing 5 wt % of PB into PC/ABS alloys increased the limited oxygen index from 24.1 % to 34.1 %. The presence of PB reduced the thermal degradation rate and promote the formation of carbon residue during combustion. Moreover，adding PB increased the fire performance index of the PC/ABS alloy, significantly reduced the generation of heat and the emissions of smoke, CO, CO2 during the combustion.

Modification Research on Reinforcement and Toughness of PP/GF Composites

Youbing LI

2013, 27 (12): 47-51 ; DOI: 10.19491/j.issn.1001-9278.2013.12.009

Abstract ( 943 )

Effect of PP-g-MAH on the physical/mechanical properties of glass fiber reinforced polypropylene/polyethylene wax（PW） composites was investigated. A little loading of PP-g-MAH improved compatibility of the GFRPP/PW composites, γ-phase crystal occurred in the PP matrix. The impact strength increased by 37.9 %; the yield strength increased by 3.2 %; and the heat resistance temperature increased by 3.9 ℃。

Effect of Composite Flame Retardant on Flame Retarding and Mechanical Properties of Polyurethane Grouting Materials

Mu Bo-yuan

2013, 27 (12): 52-56 ; DOI: 10.19491/j.issn.1001-9278.2013.12.010

Abstract ( 901 )

A compound flame retardant made of solid tribromoneopentyl alcohol and liquid DMMP was studied when used in grouting polyurethane. A synergetic effect was found between tribromoneopentyl alcohol and DMMP. As the laoding of compound flame retardant (tribromoneopentyl alcohol/DMMP=1:2) increased, the mechanical property of grouting polyurethane increased first and then decreased. When the loading was 24 %, the material gave rise to the highest impact toughness, compressive strength, and tensile strength, i.e., 12.47 kJ/m2, 18.55 Mpa, and 8.11MPa, respectively. In addition the vertical burning time was 8.2 s. The addition of flame retardant did not change the skeleton structure of polyurethane materials.

Preparation and Properties of BMI/DBA/PC Modified Resin

ZHU Ya-hui Ke KE Yaqin JI

2013, 27 (12): 57-61 ; DOI: 10.19491/j.issn.1001-9278.2013.12.011

Abstract ( 763 )

A modified resin system of N, N'-4, 4' -diphenylmethanebismaleimide (BMI)/o, o'-diallylbisphenol (DBA)/polycarbonate (PC) was prepared by melting prepolymerization. The mechanical properties, thermal stability, and structure of the resin were investigated．Both toughness and strength of the resin was obviously depecdent on the content of PC. When the loading of PC was 8 wt %, the tensile and impact strengths increased by 36.3 and strength 109.1 %, respectively．In addition, the modified resin system shjowed an excellent thermal stability. The PC phases with microsphere shape were uniformly dispersed in the BMI/DBA matrix.

One-dimensional Temperature Analysis of Multi-fluid Multiple Injection Process

2013, 27 (12): 62-67 ; DOI: 10.19491/j.issn.1001-9278.2013.12.012

Abstract ( 931 )

Using numerical simulation and experiment method, one-dimensional temperature profile of high density polyethylene (PE-HD) in multiple injection molding process were calculated and analyzed by MATLAB software. With the model suitablly simplified，using different initial conditions for the skin and core materials, the simulated temperature distribution in the cooling process was compared with that obtained by experimental. It proved that the viscous dissipation in the filling process of the skin melt was negligible. The numerical and experimental values were in good agreement in the melt cooling stage. However, due to shrinkage, in the solid state of cooling section, the experimental value was higher than that of simulation.

Study on Positive Displacement Conveying Characteristics of Polymer Vane Extruder

LIN si-ke

2013, 27 (12): 68-72 ; DOI: 10.19491/j.issn.1001-9278.2013.12.013

Abstract ( 845 )

Based on an analysis of structural characteristics and the working principle of vane plasticization extruder, a theoretical model of polymer conveying of vane extruder was formulated for studying the polymer materials conveying characteristics in a vane extruder. The experiments related to the polymer materials conveying characteristics were performed using a vane extruder and a screw extruder. It showed that the theory and practical productions of vane extruder were consistent. Compared with conventional single-screw extruder, the efficiency of extrusion conveying of vane extruder was higher, and less dependent on die pressure and material properties.

Study of the Effect of Gate Size on the Injection Molding Products' Performance

Pengcheng XIE Yumei DING Weimin YANG

2013, 27 (12): 73-78 ; DOI: 10.19491/j.issn.1001-9278.2013.12.014

Abstract ( 1315 )

Experiment was carried out to study the effect of gate size and process parameters (eg. injection pressure and rate) on the melt filling behavior and tensile properties of PP injection molded parts in this paper. Three standard samples with rectangular gate of different size were taken as models, the filling process was observed by dynamic visualization experiment platform. By comparing and analyzing the melt filling behavior under different conditions, the conclusion was drawn that the gate size, injection rate and melt temperature significantly affected the filling speed of melt. The tensile test showed that the changes in the size of the gates would produce different influence on modulus and tensile strength of products. A suitable increase in the injection speed and pressure may improve the tensile properties of PP injection molding parts.

Study on Mechanical Properties and Flow Analysis of the Unsaturated Polyester Resin Wind Turbine Blade

Fang-Chen DONG

2013, 27 (12): 79-83 ; DOI: 10.19491/j.issn.1001-9278.2013.12.015

Abstract ( 809 )

A 3D model was formulated for wind turbine blade made of unsaturated polyester resin filled with organic montmorillonite (OMMT). Static and dynamic analysis were carried out using ProE/Mechanica, four vibration stage of the wind turbine blade were identified. The flow field during the injection molding was simulated with Moldflow software and the filling time and temperature were obtained. It was concluded that the blade would not cause resonance, even at the top of the blade where the wind was strongest. Injection molding was not suitable for the production of the blade, vacuum assisted resin transfer may be useful.

Synergism Between Intumescent Flame Retardant and Organic Montmorillonite in Polypropylene

2013, 27 (12): 84-88 ; DOI: 10.19491/j.issn.1001-9278.2013.12.016

Abstract ( 1138 )

Polypropylene (PP)/intumescent flame retardant (IFR) composites and PP/IFR/organic montmorillonite (OMMT) nanocomposites were prepared by melt blending method. Synergistic effect between IFR and OMMT on flame retardant properties in PP matrix and the mechanical properties of the composites were investigated. The synergistic flame retardant mechanism was explored. It was observed that PP/IFR/OMMT nanocomposites had a higher oxygen index and a lower peak heat release rate than PP/IFR composites. Especially, the material reached UL 94 V-0 level when 18.5% of IFR and 1.5% OMMT were introduced, while material without OMMT was zero level. SEM micrograph of char residue after combustion showed that OMMT played a reinforcing on the cell, so that the PP/IFR/OMMT nanocomposites exhibited better flame retardant performance than PP/IFR composites. The impact strength of PP/IFR/OMMT nanocomposites was improved, however, the tensile strength was declined based on PP/IFR composites.

Research on Experimental Methods of UV Artificial Accelerated Photoaging of Drip Irrigation Tape

mamatjan yimit

2013, 27 (12): 89-93 ; DOI: 10.19491/j.issn.1001-9278.2013.12.017

Abstract ( 901 )

The aging rate of drip irrigation tape in a cotton planting field was compared with that under a UVA-340 lamp. For artificial accelerated radiation, the strenth was 0.68 W/m2, blackboard temperature was 60 ℃, the condensing temperature was 60 ℃, expose time was 3 h, condensing time was 3 h, wind-blowing for 10 min, the reservation rate of elongation at break was 84.4 % after 12 days, while for the natural condition, the rate was 78.8 % after 150 days' exposure.

Mellt Flow Simulation in Injection Unit of Screw-plunger Injection Molding Machines

Xiuqing MA

2013, 27 (12): 94-97 ; DOI: 10.19491/j.issn.1001-9278.2013.12.018

Abstract ( 852 )

The method of strength check for the for-barrel of high pressure screw-plunger injector was introduced based on a case study. The stress and deformation of the for-barrel was analysed under maximum injection pressure by using finite element analysis software ANSYS. Finally, the flow state of the melt in injection unit under specific conditions was simulated. Such results provided a theoretical basis for the design of the for-barrel and the control of the injection speed.

Injection Mold Design of Glove Box Based on Moldflow Analysis

2013, 27 (12): 98-102 ; DOI: 10.19491/j.issn.1001-9278.2013.12.019

Abstract ( 950 )

In the design of injection mold of on-car glove box, the optimal gate location, filling time, injection pressure, clamping force were determined and the defects like weld bond ,cavitation, and warp were analyzed using software Moldflow. Subsequently, a four-number gating system, a 10 mm-diameter pipe cooling system, and other structures were designed using software UG. The optimal parameters were filling time 2.014 s, the largest injection pressure 43.97 MPa, and the clamping force 446.7 t. Such a design effectively reduced the production period of the glove box injection.

Design of Injection Mold for a large LCD TV panel

Zhou Jian-an

2013, 27 (12): 103-108 ; DOI: 10.19491/j.issn.1001-9278.2013.12.020

Abstract ( 935 )

The general scheme of an injection mold for a large LCD TV panel was determined. For better surface finish, a specific heating/cooling system and temperature control system were designed. The runner system, which starts from a pin valve hot runner system and turn to cold runner and tunnel gates, was obtained. Lifters which work for smooth injection and pulling side cores were used. The venting system and the material for cavity were introduced. The assembly drawing was shown and the mold's working process was described at last. The mold has been put into practice,obtaining high quality products.