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2009, Volume 23 Issue 11 Publication date: 26 November 2009 Previous Issue Next Issue

Analysis and Development Trends of Clamping Mechanisms of Injection Molding Machines

2009, 23 (11): 1-6 ; DOI: 10.19491/j.issn.1001-9278.2009.11.001

Abstract ( 2406 )

The clamping mechanism was classified according to the number of templates, driving source, the transmission forms, and the mold structure, their function, construction, and performance characteristics were discussed. Four typical mechanisms, double-toggle, full hydraulic straight pressure, tie-barless, and two-plate were analyzed on their structural characteristics and application. The development trend of the typical clamping structure was also presented.

Research Progress in Silicon Flame Retardants

YE Long-jian QIAN Li-jun WANG Lan XU Guo-zhi

2009, 23 (11): 7-14 ; DOI: 10.19491/j.issn.1001-9278.2009.11.002

Abstract ( 1929 )

The research progress of silicon flame retardants and their application were reviewed. The thermal stability and fire retardant properties as well as flame retardant mechanism of both inorganic and organic silicon flame retardant systems were introduced, including those based on layered silicate, silica, cage-like polyhedral oligomeric silsesquioxane (POSS). Intrinsic flame retardant polymers were also discussed.

Study on Crystallization Behavior, Thermal and Mechanical Properties of PET/Talc Composites

2009, 23 (11): 15-20 ; DOI: 10.19491/j.issn.1001-9278.2009.11.003

Abstract ( 1855 )

The crystallization, thermal, and mechanical properties of PET/talc composite were studied using differential scanning calorimeter and thermogravimetric analysis. When the loading of talc was 0.5 wt%, the crystallization temperature was increased by 11.36 ℃ based on neat PET. Ozawa, Jeziorny, and Mo methods were used to describe the non-isothermal crystallization kinetics. It was found that Jeziorny and Mo methods could well describe the non-isothermal crystallization, while Ozawa was not suitable. Because of the good dispersion of talc in PET, the thermal property of PET was well maintained, and the tensile property was improved 12 %.

Effect of Compatibilizer on In-situ Microfibrillated Polypropylene/Poly(ethylene terephthalate) Blend

Yi Xin WANG Yu-ling Zhong Gan-ji Li Zhong-ming Ji Xu

2009, 23 (11): 21-25 ; DOI: 10.19491/j.issn.1001-9278.2009.11.004

Abstract ( 2408 )

In-situ microfibrillar reinforced composites based on blends of polypropylene (PP), poly(ethylene terephthalate) (PET), and compatibilizer propylene-g-glycidyl methacrylate (PP-g-GMA) were prepared via slit-extrusion, hot-stretching, and quenching. The effect of PP-g-GMA on the morphology of dispersed phase before stretching and microfibrils after stretching, mechanical properties, and crystallization behavior were studied using SEM, DSC, and mechanical testers. The addition of compatibilizer reduced and homogenized the sizes of dispersed phase before stretching, however，the aspect ratio of PET microfibrils was decreased. The compatibility was improved distinctly and thus improved mechanical properties. The PET microfibrils in the blends caused heterogeneous nucleation for PP, resulting in higher crystallization temperature and crystallization rate.

Study on Crystalline Properties of PP Composite Filled by Talc or Calcium carbonate

ZOU Yan WEN Bian-ying Bian-Ying

2009, 23 (11): 26-29 ; DOI: 10.19491/j.issn.1001-9278.2009.11.005

Abstract ( 1645 )

PP/Talc and PP/CaCO3 composites were prepared by melt mixing. Their crystal morphology and crystalline properties were studied using differential scanning calorimetry and hot stage polarized light microscopy. Results show that the influences of Talc and Calcium carbonate on the crystal morphology and crystalline properties of the PP matrix are different obviously. Talcum powder has clear heterogeneous nucleation effect, which could enable the number of polypropylene spherulite increased and the size reduced. In contrast, there is no significant nucleation of calcium carbonate is observed. For PP/Talc composite, both the Crystallization temperature and melting temperature raised; In PP/CaCO3 composite, the large and perfect spherulite formed, the black cross optical phenomena is observed clearly. Its crystal temperature reduced while its melting temperature is almost not affected.

Toughening Mechanisms of PVC/SAN/ABS Blends

2009, 23 (11): 30-33 ; DOI: 10.19491/j.issn.1001-9278.2009.11.006

Abstract ( 1761 )

ABS grafted copolymer was prepared by grafting styrene and acrylonitrile onto PB seed latex in emulsion polymerization, with which PVC/SAN/ABS blends were prepared. Keeping constant ABS fraction, the weight ratio of SAN to PVC varied from 70.5/17.5 to 18/70. Transmission electron microscope (TEM) showed that SAN component promoted the crazing and PVC the shear yielding. Scanning electron microscope (SEM) observation of the fractured surface revealed that voids and plastic flow were enhanced with increasing PVC content. Small angle X-scattering (SAXS) showed that SAN increased the scattering intensity, which was attributed to crazing.

Study On Gelation Properties of Environmentally-friendly PVC Plastisols

XU Guo-Min TAN Hong

2009, 23 (11): 34-37 ; DOI: 10.19491/j.issn.1001-9278.2009.11.007

Abstract ( 1603 )

The gelation property of environmental-friendly PVC plastisols was measured by torque rheometer and rotary viscometer. The effect of PVC resin, plasticizer, and blending resin on the gelation time were investigated. High molecular weigh or round shaped resin resulted in long gel time, whereas sheet shaped resin gave short gel time. The higher the compatibility between the resin and plasticizer, the shorter the gel time. The gel time increased with increasing loading of blending resin. When the loading of blending resin was 40phr, the gel time was 28 min, which contrasted to 18 min of the neat system.

Effect of Graft Copolymer of Polypropylene on the Properties of PP/EVOH Blend System

WANG Shi-Yin Min-lian CHENG

2009, 23 (11): 38-43 ; DOI: 10.19491/j.issn.1001-9278.2009.11.008

Abstract ( 2162 )

Polypropylene was grafted with maleic anhydride (MA) and (TIAC) was prepared in a twin-screw extruder and used as a compatibilizer for PP/EVOH blends. The compatibility, rheological properties, crystal properties, mechanical properties, and barrier properties of the blends were studied. The grafting degree was increased by 13% through the grafting of TIAC. Infrared spectra analysis indicated that the compatibility was improved by the esterification between compatilizers and EVOH. Scanning electron microscopy observation revealed the smaller size of the dispersed phase. Rheological experiments indicated that the TIAC grafting suppressed the degradation of PP. Differential scanning calorimetry analysis showed that the crystallization temperatures of PP and EVOH in the compatibilized blend were higher than those in the uncompatibilized blends. The incorporation of TIAC had little effect on the mechanical properties, however, showed major effect on the barrier property. When the loading of TIAC was 0.4 phr, the barries property was increased by 28%.

Thermal Conductivity of Polyimide Composites Modified with Graphite and Carbon Fiber

2009, 23 (11): 44-47 ; DOI: 10.19491/j.issn.1001-9278.2009.11.009

Abstract ( 1415 )

In this work, the mechanical properties and thermal conductivity of polyimide/graphite/ carbon fiber (CF) ternary composites were investigated. The synergistic effects between graphite and CF was studied with pseudo-binary system model. With increasing CF content, the tensile strength of PI/graphite/CF composite increased first and subsequently decreased. When the content CF was 11.8vol%, the tensile strength reached 66.37 MPa. The flexural strength of composite increased with increasing CF content. When the CF content was 24.6vol%, the flexural strength was 103.3MPa. The thermal conductivity of composites increased nonlinearly, which indicated that graphite and CF had a synergistic effect. SEM indicated when the volume of CF was 34.1%, thermally conductive pathway was formed by the crossover of CF and graphite resulting in a thermal conductivity of 0.512 W/(m·K), which was two times of the calculated value.

Preparation and Properties of Organic Bentonite Compound High Oil Absorption Resin

2009, 23 (11): 48-52 ; DOI: 10.19491/j.issn.1001-9278.2009.11.010

Abstract ( 1496 )

Bentonite was pre-treated and organically modified with HDTMAoBr, which was introduced into a polymerization system of acrylate monomer, crosslinker, and initiator resulting in a high oil-absorbing resin. The addition of 1.5wt % of the modified bentonite led to an oil-absorbing degree of 14.1 g/g. The optimal recipe was obtained via orthogonal experiments. The organic bentonite was well compatible with the acrylate resin, the thermal stability of the latter was improved.

Preparation and Properties of PTT/mPE Blends

2009, 23 (11): 53-57 ; DOI: 10.19491/j.issn.1001-9278.2009.11.011

Abstract ( 1969 )

The rheology, crystallization, and melting behaviors of PTT/mPE blends prepared by twin-screw extruder were studied. The influence of compatibilizer on the phase morphology of the blends and their mechanical property were also studied. All PTT/mPE blends were pseudo-plastic fluid, and their apparent viscosity decreased rapidly with increasing PTT content. The more content the mPE, the less the temperature sensitivity, and the poor the processability of the blends. Although PTT and mPE crystallized separately, the presence of mPE increased the crystallization temperature. However, PTT did not affect the crystallization behavior of mPE. The morphology of the fractured surface suggested that EPDM-g-MAH constituted a good compatibilizer for PTT and mPE. The blend possessed improved impact strength due to the toughening effect of mPE component.

Preparation of Rigid Polyurethane Foam with PIPA Polyol

DING xuejia

2009, 23 (11): 58-62 ; DOI: 10.19491/j.issn.1001-9278.2009.11.012

Abstract ( 1897 )

Polyisocyanate polyaddition (PIPA) polyol was synthesized and was characterized with Fourier transform infrared spectrometry (FTIR) and gel permeation chromatography (GPC). The optimal recipe was found to be determined as polyol A/TEA/TDI=110/10/9（w）. The rigid polyurethane foam was prepared with PIPA polyol, and the effect of foam stabilizer on the foaming time, cell structure, and mechanical properties like compression, bending and impact strengths of the product were studied. When the content of foam stabilizer was 1.0 pphp, the impact strength was 23% higher than that based on unmodified polyol.

Effect of Heat Stabilizers and Lubricants on Properties of CPVC Resin

2009, 23 (11): 63-68 ; DOI: 10.19491/j.issn.1001-9278.2009.11.013

Abstract ( 1632 )

The effects of calcium-zinc composite stabilizer, organo-tin stabilizer, and other thermal-resistant additives on the dynamic thermal stability of chlorinated poly(vinyl chloride)(CPVC) resin were studied. The effects of inner and external lubricants on the processing behavior of CPVC was investigated. A formulation of CPVC compound used for plastic pipes was suggested, and resulted mechanical properties were compared with those of the commercial products.

Experimental Research and Prediction of Expansion Ratio of Foamed EVA Plastic

2009, 23 (11): 69-74 ; DOI: 10.19491/j.issn.1001-9278.2009.11.014

Abstract ( 2009 )

In the paper, adopt Taguchi DOE method and BP (Back Propagation) neural network technology, the effects of four factors, molding temperature, molding time, injection pressure, and molding pressure on the expansion ratio of EVA were studied with a four-level orthogonal experiment. It was concluded that the effect of molding temperature was the most obvious, that of molding time the second, and those of injection pressure and molding pressure are smaller. Taking molding temperature, molding time, and injection pressure as the parameters, another orthogonal experiment was carried out for different shapes and sizes of the standard sample molds. The experiment results were used as neural network sample data, and expansion ratio of EVA plastic could be predicted more accurately using after trained neural network.

Analysis of Injection Molding Flow of Inner Decoration Button Lid Based on Moldflow

ZHAO Long-Zhi

2009, 23 (11): 75-79 ; DOI: 10.19491/j.issn.1001-9278.2009.11.015

Abstract ( 1931 )

The flow process in the injection molding of button lid of the automobile inner decoration was simulated using Moldflow. A double surface grid model was formulated based on the body model in the virtue of Pro/E soft. By analyzing the gating location, temperature field and pressure at the gating location，the reasonable pouring system was obtained. The central symmetry layout of the part ensured the pressure center consistency and the uniform distribution of the pressure in the runner. During the moulding, the temperature ranged between 196℃ and 234℃. The highest temperature located at the center of main runner and the lowest temperature at the side of the small flank, which provided a reference for the design of cooling system of the mould.

A Study on the Decomposition Characteristics of Blowing Agent Azodicarbonamide in Ethene-Butene Copolymer

Fan YANG

2009, 23 (11): 80-84 ; DOI: 10.19491/j.issn.1001-9278.2009.11.016

Abstract ( 1512 )

The decomposition characteristics of blowing agent azodicarbonamide (AC) in Ethene-Butene copolymer were studied using FTIR、TGA, and DSC analyses. During the decomposition of AC at a constant heating rate, three stages of weight loss could be were identified and 63wt % of gas was released. The onset decomposition temperature of AC decreased with the addition of zinc oxide and/or zinc stearate, with zinc stearate being more effective than zinc oxide. When both were present, the activation effect was mainly due to the formation of zinc stearate. DCP decreased the onset decomposition temperature of AC slightly.

Study on a Novel Ca/Zn Compound Thermal Stabilizer for Rigid PVC

2009, 23 (11): 85-88 ; DOI: 10.19491/j.issn.1001-9278.2009.11.017

Abstract ( 1969 )

In this paper，the thermal stabilizer of Ca/Zn system for rigid PVC was studied by static and dynamic experiments and compared with four commercial ones. Its synergistic effect with organic auxiliary heat stabilizer and functional assistant was determined. It was found that the initial color and long-term thermal stability depended mainly on the ratio of calcium and zinc stearates. When the two stearates were heated at 180 ℃ for 5 minutes, the synergistic effect was enhanced and a dynamic thermal stabilizing time of 30 min was observed. PVC materials containing such stabilizing system possessed good processablity.

Study on Functionalization of PPR and Its Toughening Effect on Recycled PET Flakes

Zhao Qing

2009, 23 (11): 89-93 ; DOI: 10.19491/j.issn.1001-9278.2009.11.018

Abstract ( 1574 )

Maleic anhydride (MA) was grafted onto polypropylene random copolymer (PPR) with a grafting reactive extruder, and the grafted product (PPR-g-MAH) was used as a toughening agent for recycled PET flakes (r-PET) in a condensation reactive extruder. The optimal recipe for PPR-g-MAH was obtained as: 3 % of MAH, 0.03 % of initiator DCP. The mechanical properties of r-PET/PPR-g-MAH alloy were optimal when grafting rate was 4.2 mmol/100g and PPR-g-MAH content was 10 %. SEM showed that with MA grafted, PPR achieved a finer dispersion in r-PET compared with neat PPR.

Design of Two-shot Injection Mould for Ergonomics Mouse's Bottom Case

Yong-Quan Zhou

2009, 23 (11): 94-97 ; DOI: 10.19491/j.issn.1001-9278.2009.11.019

Abstract ( 2286 )

A two-shot mold for a bottom case of ergonomic mouse was designed based on UG6.0. Considering the features of complicated surface and two-shot injection, the design for slides and lifters, and TPE over-molding were discussed. The mold's trial run indicated that the design of the mold was reasonable, convenient in fabrication, and automatic in operation. The molding process Cpk was over 1.33, cycle time of molding was 43s, thus fully met the need of high quality and high efficiency of molding.

Forecast and Experiment Study of Melt Filled Length of Screw Assembled Field in an Intermeshing Co-rotating Twin Screw Extruder

2009, 23 (11): 98-102 ; DOI: 10.19491/j.issn.1001-9278.2009.11.020

Abstract ( 1828 )

A simulation of the assembled flow domain composed of screw elements and kneading blocks in an experimental intermeshing co-rotating twin screw extruder with 34 millimeter diameter has been carried on. The pressure distribution of three dimensional flow field at different screw phase angle was obtained. Then the variation of pressure of the observing point located in the assembled flow domain against the phase angle was analyzed. The melt filled length of assembled flow domain in the extruding process was forecasted at two different flow rates. Meanwhile an experiment was made to validate the analysis result. It showed that the melt filled length could be forecasted through the flow field simulation, with an error less than 10%. And in the forecasted filled length, the measured pressure fluctuation of observing point was got within the forecasted pressure fluctuation.