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2010, Volume 24 Issue 07 Publication date: 26 July 2010 Previous Issue Next Issue

A Concept of Differential and Integral Method in Advanced Processing of Polymer Materials

YANG Weimin

2010, 24 (07): 1-6 ; DOI: 10.19491/j.issn.1001-9278.2010.07.001

Abstract ( 1623 )

In order to solve the bottleneck problems in the micro-precision and macro-complex processing technologies, a concept of differential and integral method for advanced processing of polymer materials was proposed. Based on this concept, principles of injection molding, extrusion, electrostatic spinning, nano-composite processing, and structure innovation of polymer products were studied, a series of new methods of polymer processing and molding, new equipments, and new technologies of product application were invented. Some industrial application results proved that the concept of differential and integral method was a valuable guide to break through the restriction of traditional manufacturing mode, and to develop new method of polymer processing and new technology of polymer products application.

Research Progress in Synergistic Agents of Intumescent Flame Retardants Containing Ammonium Polyphosphate

QU Hongqiang WU Weihong WU Hongjuan XU Jianzhong

2010, 24 (07): 7-12 ; DOI: 10.19491/j.issn.1001-9278.2010.07.002

Abstract ( 2345 )

Progress in the synergistic agents of ammonium polyphosphate (APP) intumescent flame retardant (IFR) system was reviewed. The application of IFR and its synergistic agents in polymer materials was introduced. Four categories of synergistic agents for IFR containing ammonium polyphosphate, such as zeolite, metal oxide and metal salt, metal hydroxide, and expanded graphite were introduced. The flame retardancy and the flame retardant mechanism were also discussed. It was shown that the efficiency of the IFR could be remarkably improved by the addition of synergistic agents, and the harm to the matrix and the loading level were also decreased. The study on the synergistic agents also promoted the study on surface modification and micro-encapsulation of APP.

Research Progress in Novolac-type Phenolic Resin in Foreign Countries

LI Shasha QI Shuhua LIU Nailiang LU Wenshu LI Mengtao XU Dengshun

2010, 24 (07): 13-18 ; DOI: 10.19491/j.issn.1001-9278.2010.07.003

Abstract ( 2191 )

The foreign research work on the curing behavior of novolac-type phenolic resins were reviewed, including numeral simulation and experimental studies using infrared spectroscopy, nuclear magnetic resonance, differential scanning calorimetry, thermogravimetric analysis, and scanning electron microscope. The modification studies of novolac-type phenolic resins were also summarized. For example, the toughness was improved by adding polyamide and phenolic compatibilizer; the flame retardancy was enhanced by diazo coupling or esterification; the thermal and mechanical properties were increased interpenetration, and the thermal stability was promoted by blending with inorganic nanoparticles and layers.

Preparation of Monomer Casting Polyamide 6-Polyether Block Copolymer/Nano-carbon Black Composites and Their Non-isothermal Crystallization Behavior

LIN Xuan ZHOU Hongjun YIN Guoqiang ZENG Yuping

2010, 24 (07): 19-23 ; DOI: 10.19491/j.issn.1001-9278.2010.07.004

Abstract ( 1991 )

Monomer casting polyamide 6-b-polyether block copolymer/nano-carbon black composites were prepared by in-situ anionic polymerization, and their mechanical properties and non-isothermal crystallization behavior were investigated. Mechanical property test indicated that the toughness and wear resistance of polyamide 6 were significantly improved, but its tensile strength was reduced by the introduction of polyether and carbon black. When the polyether content was 10 %, the impact strength of the composite was 120 %, which was higher than that of neat polyamide 6. When polyether content was 15 %, the wear volume ratio of the composite decreased by 89.7 % compared with neat polyamide 6. Differential scanning calorimetry indicated that with the addition of polyether and nano-carbon black, crystallization peak temperature decreased, and crystallization rate slowed down, and crystallization activation energy reduced. The polyether did not act as a nucleating agent for the polyamide 6.

Study on the Relationship Between Compositions and Properties of CPVC/ABS/CPE Ternary Blends

MA Jun YUAN Maoquan MU Nanxiang HU Meihua WANG Jian WU Dezhen

2010, 24 (07): 24-27 ; DOI: 10.19491/j.issn.1001-9278.2010.07.005

Abstract ( 1926 )

In this paper, the relationship between compositions and properties of chlorinated poly(vinyl chloride)/acrylonitrile-butadiene-styrene copolymer/chlorinated polyethylene (CPVC/ABS/CPE) ternary blends was studied. The torque of CPVC/ABS/CPE decreased and thus the plasticizing time was reduced significantly with increasing content of ABS. When the weight ratio of CPVC to ABS was 7:3, the CPVC/ABS/CPE ternary blends displayed the best mechanical properties. CPE had good toughening effects on CPVC/ABS/CPE ternary blends, and the optimum dosage was 15 phr.

Preparation of Polyaniline/ Schiff Base Nanorods Composites and Their Conductive Properties

DUAN Guochen QI Shuhua WU Xinming QI Haiyuan ZHANG Yi

2010, 24 (07): 28-33 ; DOI: 10.19491/j.issn.1001-9278.2010.07.006

Abstract ( 2014 )

Polyaniline/schiff base composites were prepared via seeding polymerization. The influence of Schiff base dosage, concentration of acid and the organic medium on the properties of composites was investigated. Structure and morphology of the composites were characterized using FTIR，UV-Vis and SEM. It was demonstrated that the conductivity of polyaniline/schiff base composite could reach 1.201S/ cm. In comparison with polyaniline (9.21×10^-6 S/cm), its conductivity increased by the order of magnitude of six at room temperature, under the condition of 15 % schiff base, 2 mol/L HCl concentration and in Ethylene glycol. In addition, the dispersion and heat resistance properties of polyaniline/schiff base were better than that of polyaniline obviously.

Study on Microstructure and Electrical Properties of CER/TMPTMA with Interpenetrating Networks

DUAN Jingkuan JIANG Pingkai

2010, 24 (07): 34-40 ; DOI: 10.19491/j.issn.1001-9278.2010.07.007

Abstract ( 2262 )

Novel interpenetrating polymer networks (IPNs) based on cycloaliphatic epoxy resin (CER) containing cyclohexene oxide groups and trimethylolpropane trimethacrylate (TMPTMA) were synthesized in this paper. The influences of TMPTMA content on the electrical properties of CER/TMPTMA were also studies. The results showed that the AC resistivity values of the cured CER/TMPTMA IPNs at different temperatures were related to both the formulation and microstructures of the systems. With the increase of TMPTMA content, the breakdown strength of CER/TMPTMA and its shape parameter of Weibull distribution increased gradually. The increase of shape parameter indicated that homogeneity of CER/TMPTMA was improved gradually and mechanism of dielectric breakdown tended to uniform.

Preparation and Properties of Environmentally-frendly Modified Furfural Epoxy Grouting Materials

GAO Nan ZHANG Yafeng KUANG Jianzheng CHEN Yufang XU Yuliang ZHOU Hua

2010, 24 (07): 41-46 ; DOI: 10.19491/j.issn.1001-9278.2010.07.008

Abstract ( 1940 )

A new type of 3-furyl-2-hexyl-acrolein (FHA) with high boiling point and low volatility was synthesized and used as diluent in epoxy grouting material. Effects of diluent ratio, diluent, curing agent, and accelerator on properties of epoxy resin grouting material were studied to get the optimum recipe. Diluent ratio of 2:1 to 1:1, diluent addictive amount of 20 % to 30 %, curing agent of 8.16 % to 11.76 %, and accelerator of 0.2 % to 0.4 % were selected to make the optimum physical and mechanical properties of epoxy grouting material. It was shown that this environmentally-friendly epoxy grouting material with comprehensive properties could replace the toxic and volatile furfural in the epoxy grouting material.

Degradation Mechanism of ABS by Thermal Degradation Kinetics

YANG Youcai LI Rongxun LIU Guangye

2010, 24 (07): 47-50 ; DOI: 10.19491/j.issn.1001-9278.2010.07.009

Abstract ( 1601 )

In air atmosphere, the mass loss of ABS resin at four different heating rates was investigated using TGA. The kinetics of thermal degradation was described using Flynn-Wall-Ozawa and Kissinger methods. It showed that there were two degradation stages; the first stage between 350 and 450 ℃ was the rapid degradation with activation energy (Ea) about 200 kJ/mol; the cross-linking reaction coupled with the degradation. When the mass loss in the range of 80 %~90 %, char formation was observed with Ea increasing to 262.81 kJ/mol. The second stage was the oxidation of carbon with Ea decreasing to 130 kJ/mol, so the carbon had a poor thermal stability. The reaction order of ABS thermal degradation was found to be 0.946, so the mechanism of ABS thermal degradation was controlled by the processes of random nuclear formation and growth. The thermal degradation occurred in the bulk rather than surface of ABS, so the gas of thermal degradation could not be burnt completely and lead to black smoke and dripping.

Study on Epoxy-terminated Silicone Modified Epoxy Resins

LI Hongjing LIU Weiqu WEI zhenjie WANG Zhengfang MA Songqi

2010, 24 (07): 51-54 ; DOI: 10.19491/j.issn.1001-9278.2010.07.010

Abstract ( 1520 )

Bisphenol A epoxy resin was modified by epoxy-terminated silicone. The impact strength, tensile strength, elongation at break, and glass transition temperature of the composites were investigated. The morphology of fracture surfaces was observed using SEM. The effects of modification methods and silicone content on material performance were discussed. After direct mechanical blending with epoxy-terminated silicone, the thermal resistance of epoxy resin was unchanged and the mechanical property declines clearly. When epoxy-terminated silicone was introduced via co-curing at 5 phr, the glass transition temperature of the system reached 177.35 ℃，which was higher than that of unmodified EP with 2.67 ℃. In addition to improved thermal resistance, the tensile strength almost remains unchanged and elongation at break increased from 7.6 % to 16.7 %, the impact strength increased from 20.23 KJ/m2 to 27.19 kJ/m2. A significant toughening was evidenced by the improvement of toughness and was supported by the SEM micrographs of the stretched section of cured epoxy resin.

Study on Optimal Design of Gas Channel in Gas-assisted Injection Molding

FU Qingxing CHENG Xiaofeng LI Yi LIANG Jicai

2010, 24 (07): 55-59 ; DOI: 10.19491/j.issn.1001-9278.2010.07.011

Abstract ( 1436 )

Numerical simulation and laboratory experiments were carried out to analyze two kinds of polystyrene plates with either semi-circle or rectangular gas channel. Based on the main processing parameters such as gas penetration length, gas channel shape, residue thickness, and gas channel defects, the evaluating standard of the quality of gas channel was established. For semi-circle gas channel, the radius was 2 times that of the plate wall thickness, and the quality of gas channel was the best. For rectangular gas channel, when the width of gas channel and the wall thickness kept constant, the quality of gas channel would improve with increase of the height and width of gas channel increased; when the height of gas channel was 2 times of the width of gas channel, and the width of gas channel was the 2 times of the plate wall thickness, the quality of gas bubble was the best.

Effect of MAPE Contents on Impact Strength of WPC Based on PE

ZHANG Qingfeng LV Qun CAI Peixin LAI Guoqiao

2010, 24 (07): 60-63 ; DOI: 10.19491/j.issn.1001-9278.2010.07.012

Abstract ( 2139 )

The wood-plastics composites (WPC) were prepared via compression molding using a blend of high density polyethylene (PE-HD) and maleic anhydride grafted polyethylene (MAPE) as the matrix and wood flour as filler. The effects of the contents of MAPE on the impact strength of the matrix and WPC were investigated. It was shown that the change of MAPE contents had significant influence on the impact strength of the matrix and WPC. When the contents of wood flour was 30 %, the impact strengths of WPC decreased with increasing MAPE contents; whereas at 70 % of wood flour loading, the impact strength of WPC increased with increasing MAPE contents.

Effects of Processing Parameters on Wall Thickness of Water-assisted Molded Curved Tubes

LIU Xuhui HUANG Hanxiong

2010, 24 (07): 64-68 ; DOI: 10.19491/j.issn.1001-9278.2010.07.013

Abstract ( 2013 )

The effects of eight processing parameters on the residual wall thickness of water-assisted injection molded parts were investigated. The processing parameters were melt temperature, mold temperature, short-shot size, water injection delay time, water pressure, water temperature, melt filling speed, and pressure. The experiments were carried out on a lab-developed water injection system and a mold with curved circular pipe cavity. The material used for the experiments was polypropylene. It was found that some processing parameters had effects on the wall thickness invariance of the curved sections. When the water injection time increased and the water pressure and melt temperature decreased, the wall thickness invariance of the short-shot filling section reduced. The wall thickness invariance became larger with increasing melt temperature.

Analysis of Injection Molded Automobile Bumpers Based on Moldflow

LI Yongquan LI Feng SUN Jin

2010, 24 (07): 69-73 ; DOI: 10.19491/j.issn.1001-9278.2010.07.014

Abstract ( 1933 )

Based on Moldflow software, the filling, packing, cooling, and warping of a front bumper was simulated using a scaled down model. The used material was high impact polypropylene K9015 provided by Yangzi Petrochemical. The reason causing warping was explored with two injection schemes. It showed that the injection times was the same for two schemes. When the three gates were located on the same side of the product, better quality of appearance and more accurate assembly were obtained. Both schemes caused large warpage, however, which could be reduced by optimizing the packing curve.

Study on Smoke Release Rate of Cable during Burning

YANG Shousheng HE Yi

2010, 24 (07): 74-77 ; DOI: 10.19491/j.issn.1001-9278.2010.07.015

Abstract ( 1584 )

In order to find out the characteristic smoke release rate and their relation with other parameters, the rate of smoke release in combustion of YJV4×6 cables was analyzed using a cone calorimeter. It showed that the combustion behavior was different at different radiation intensity. The greater the radiation intensity, the higher the smoke release rate. In addition, the heat release rate lagged behind the smoke release rate, and the smoke release rate increased with increasing mass loss rate. In a steady state, the combustion was characterized by decreasing of smoke release rate and increasing the heat release rate.

Effect of Suberic Acid/Calcium Stearate Bi-component Nucleating Agent on β Crystal in Isotactic Polypropylene

XUE Jianfeng DOU Qiang

2010, 24 (07): 78-82 ; DOI: 10.19491/j.issn.1001-9278.2010.07.017

Abstract ( 1505 )

Isotactic polypropylene (iPP) containing a binary nucleating agent of suberic acid/calcium stearate (SA/CaSt) was isothermally crystallized at 120 ℃ for 30 min in order to study the influence of the latters on the content of β crystals. It was found that when SA contents was 0.15 % and that of CaSt was more than 0.525 %, β crystals were observed in iPP. When CaSt contents were 0.675 %, β crystals contents showed a maximum. Analysis of FTIR indicated that an in situ chemical reaction occured between SA and CaSt during the melting blending, and a high effective β nucleating agent (calcium suberate) was produced.

Friction and Wear Properties of Nano SiO₂ and Glass Fiber Reinforced Polyamide 6 Composites

ZHANG Jing YANG Hemei GU Hongyan

2010, 24 (07): 83-86 ; DOI: 10.19491/j.issn.1001-9278.2010.07.018

Abstract ( 1963 )

The friction and wear properties of PA6 composites filled with nano-SiO2 and glass fibers were investigated with MM-200 wear tester. The results showed that the addition of nano-SiO2 and glass fiber could considerably improve the friction and wear properties of PA6. The best mass fraction was obtained by adding 5 % of SiO2 and 20 % of glass fiber. SEM of worn surfaces of PA6 and the composites showed that obvious ploughing and adhesion marks. When the load was low, the main wear mechanism was the abrasive attrition. When the load was high, the main wear mechanism was fatigue.

Study on Synergistic Retarding Effect of Intumescent Flame Retardant and Organic Montmorillonite on Polypropylene

LI Ying WANG Xiangdong

2010, 24 (07): 87-91 ; DOI: 10.19491/j.issn.1001-9278.2010.07.019

Abstract ( 2450 )

Polypropylene /intumescent flame retardant / organic montmorillonite (PP/IFR/OMMT) composites were prepared by direct melting intercalation. The synergistic flame retarding effect of OMMT and IFR was investigated. The composite was characterized by X-ray diffraction, limiting oxygen index, thermal analysis, etc. It was found that the layers of OMMT were intercalated by PP chain. There was a clear synergistic retarding effect between OMMT and IFR. When 2 phr of OMMT was introduced, the limiting oxygen index was 30 %, and the carbon residue increased obviously. With increasing contents of OMMT, the tensile strength, bending strength and impact strength of composites increased, and then decreased. When 3 phr of OMMT was introduced, the tensile strength, bending strength and impact strength of composites reached the maximum value.

Study on Migration Behavior of Nonvolatile Ultraviolet Absorbing Extractables from Microwave Susceptors Used in Microwave Popcorn Bags

YING Lu WANG Quanlin DAI Shuangyan LIU Zhihong

2010, 24 (07): 92-97 ; DOI: 10.19491/j.issn.1001-9278.2010.07.020

Abstract ( 1955 )

In this paper, microwave susceptors in the microwave popcorn bags were immerged into corn oil. When the system was heated in a microwave oven, some nonvolatile ultraviolet absorbing species were migrated into the corn oil. Such nonvolatile ultraviolet absorbing species were then extracted by hexane-acetonitrile. With water bath and a gentle nitrogen stream, the extract was dried and concentrated, and subsequently kept as a solution of dimethylacetamide of 2mL. The extract was finally separated with a high performance liquid chromatography and weighed. The weights of the extracts for four samples were 93.3, 134.1, 38.4, and 11.8μg/in2 respectively. Only one of these samples was below the FDA's safety limit standard of 20 μg/in2.

Study on Mixing Performance of Wave Twin-Screw Elements

WU Xuewei MA Xiuqing LI Yanhui TIAN Jun

2010, 24 (07): 98-101 ; DOI: 10.19491/j.issn.1001-9278.2010.07.021

Abstract ( 2284 )

The flow fields of wave-like and regular twin-screw element in an intermeshing co-rotating twin-screw extruder were simulated. Based on the simulation results, the weighted average shear stress, distribution of the maximum shear stress, distribution of the maximum stretching stress were compared for the two elements. The mixing performance of the two elements was also studied through the experiments. Numerical results were in agreement with experimental results. It was shown that the wave-like twin-screw element had a stronger dispersion mixing capability.

Boundary Element Analysis of Cooling Process in Injection Molds with Embedded Inserts

ZHANG Mingfei SHI Xianzhang ZHAO Zhenfeng LIU Chuntai

2010, 24 (07): 102-105 ; DOI: 10.19491/j.issn.1001-9278.2010.07.022

Abstract ( 2053 )

This paper was associated with cooling process of injection molding with an insert of high thermal conductivity. Based on boundary element analysis theory, mathematical models for molds and inserts were first formulated. Through a heat transfer analysis on the contact interface between the inserts and molds, a coupling integration analysis model was obtained. Through a case calculation and a comparison between the cooling processes of injection molds with and without inserts, the feasibility of the algorithm was confirmed, which could reveal how the insert affected the mold temperature.

Application of CAE Technology in Design of Injection Molds for Electric Water Heater Covers

KUANG Tangqing

2010, 24 (07): 106-110 ; DOI: 10.19491/j.issn.1001-9278.2010.07.023

Abstract ( 2317 )

An injection mould for covers of electric kettle was developed based on CAE technology in this paper. Two gate locations were determined by best gate location analysis. The optimal processing parameters were determined by the molding windows analysis as mold temperature 45℃, melt temperature 235℃, and injection time 1 s. The filling quality of the cover was examined after the filling process so as to adjust the injection pressure and the clamp force. The layout of cooling system was also optimized. Practical injection proved that CAE technology can be used to ensure the reasonable and efficiency of mold design, and high quality products can be obtained.