Current Issue

2012, Volume 26 Issue 10 Publication date: 26 October 2012 Previous Issue Next Issue

Research Progress in Poly(lactic acid)/Layered Silicate Nanocomposites

Yuxia ZHANG Xue LIU Bengang LIU Xiangdong WANG

2012, 26 (10): 8-12 ; DOI: 10.19491/j.issn.1001-9278.2012.10.001

Abstract ( 1787 )

介绍了聚乳酸/层状硅酸盐纳米复合材料研究进展，阐述了聚乳酸添加纳米层状硅酸盐后结构与性能的变化，包括复合材料的微观结构、结晶性能、热性能、力学性能、流变性能、加工性能、阻隔性能、阻燃性能等的变化。

Research Development in Carbon Nanotubes-reinforced PMMA Composites

Yingchun JIAO Tongde SHEN Qin LIANG Yi ZHANG

2012, 26 (10): 16-23 ; DOI: 10.19491/j.issn.1001-9278.2012.10.002

Abstract ( 1718 )

The preparation methods of poly(methyl methacrylate)(PMMA)/carbon nanotubes(CNTs) composites were summarized, including insitu, melt blending, and solution blending methods. The mechanical property, electric performance, and thermal conductivity of the PMMA/CNTs composites were introduced. In the end, the problem and the future research direction of PMMA/CNTs composites were pointed out.

Epoxy Resin Intrinsically Flame Retarded by Silicon and Special Structure

Xiuwei JIA Hongying CHU Zhiguo LIU

2012, 26 (10): 24-30 ; DOI: 10.19491/j.issn.1001-9278.2012.10.003

Abstract ( 1537 )

Intrinsic flame retardant epoxy resins, including siliconcontaining and special structural epoxy resins were overviewed. Compared with traditional additive flame retardant systems, halogen and phosphorusepoxy resins, siliconcontaining and special structural epoxy resins gave rise to better flame retarding performance, higher physical properties, and could be seen as green flame retarding systems. In addition, a better flame retardancy of epoxy resins could be achieved through use of synergistic effects. However, complex synthetic routes and higher cost had limited the wide application of such systems.

Effect of Chain Extender and Crosslinking Agent on the Properties of Polyurethane Elastomer Based on NDI

Huijian FU Chengke YU Jianxun LUO Lixin MAO Liqun ZHANG

2012, 26 (10): 31-35 ; DOI: 10.19491/j.issn.1001-9278.2012.10.004

Abstract ( 1572 )

A series polyurethane elastomers was obtained through curing a prepolymer prepared from 1,5naphthalene diisocyanate (NDI) and polytetramethyleneetherglycol(PTMG), with trihydroxy polyether polyols(330N) as a crosslinking agent and a 1,4butanediol(BDO) as a chain extender. The effect of the crosslinking agent and chain extender on the properties of polyurethane elastomer based on NDI(NDIPUE) was discussed. With increasing contents of 330N, the glass transition temperature for soft segment of NDIPUE increased, the storage modulus decreased between 0 ℃ and 150 ℃, tensile strength and elongation at break of the NDIPUE increased firstly and then decreased; and its hardness went down also.

Study on the Reaction Kinetics and Rheological Behaviors of Poly(polyethylene glycolcocitric acid)

Xueyu ZHANG Zongyan GUI Chong LU Shujun CHENG

2012, 26 (10): 36-41 ; DOI: 10.19491/j.issn.1001-9278.2012.10.005

Abstract ( 1981 )

Poly(polyethylene glycolcocitric acid) (PEGCA) was synthesized via condensation reaction between citric acid and polyethylene glycol. Its reaction kinetics and rheological behaviors of the product were studied. It showed that the energy of activation was 61.9 kJ/mol and the frequency factor was 1.89×105 kg/mol·min. Measurements showed that the PEGCA samples were Newtonian fluid. The only exception was the sample prepared with the reaction temperature and time of 130 ℃ and 35 h, respectively, measured at 60 ℃, While the reaction time is 35 h,its nonNewtonian index and consistency were 1.3 and 1.3×106 mPa·sn, respectively. The relatively low viscous activation energy (31~40 kJ/mol) of PEGCA is showed that the reaction time had little effect on the viscous activation energy.

Influences of Interface Control on Thermal and Dynamic Thermal Mechanical Properties of PLA/Bamboo Fibers Composites

Xingong LI Xia ZHENG Yiqiang WU Yunchu HU

2012, 26 (10): 42-49 ; DOI: 10.19491/j.issn.1001-9278.2012.10.006

Abstract ( 1387 )

Composites of poly(lactic acid)（PLA） and bamboo fibers（BF）were prepared via injection molding. The interface in the composites was modified using alkali（NaOH）, isocyanate (MDI) , and NaOH+MDI treatments. The thermal and dynamic thermal mechanical properties of the composites were investigated. All three interface control methods improved the thermal and dynamic thermal mechanical properties of PLA/BF composites, with the synergistic effect between NaOH and MDI being the most effective.

Synergistic Effect of Boron Nitride and Magnesia on the Properties of Thermally Conductive and Electrically Insulative PA10T Composites

Zhiqiang JIANG Qingfeng YI Jiehong MAI Sujun JIANG

2012, 26 (10): 46-49 ; DOI: 10.19491/j.issn.1001-9278.2012.10.007

Abstract ( 1321 )

Thermally conductive and electrically insulative poly(decamethylene terephthalamide)(PA10T) composites were prepared using an instantagglomerated boron nitride (BN) powder and a microspheric magnesia (MgO) powder as fillers. A few amount of chopped glass fiber was loaded to improve the strength. Keeping the total filler loading of chopped glass fiber and fillers at 10 wt % and 60 wt % respectively, the effect of the weight ratio of BN to MgO on the thermally conductive and mechanical properties as well as flow abilities of the composites was studied. It was observed that the two thermally conductive fillers had an enormously synergistic effect on the thermal conductivity when the weight ratio of BN to MgO was 20 to 40. In this case, the throughplane thermal conductivity was as high as 3.5 W/m·K. A higher weight ratio of BN to MgO usually led to poorer mechanical and flowing properties.

Study on the Molecular Orientation Distribution in Structure of Injected Molded PP/PET Blends

Xin YI Zhongming LI

2012, 26 (10): 50-56 ; DOI: 10.19491/j.issn.1001-9278.2012.10.008

Abstract ( 1493 )

In this study, the molecular orientation distributions and crystalline structure in the thickness direction of injection molded PP/PET blends were characterized by twodimensional wideangle Xray scattering (2DWAXS). It showed that the orientation parameters for PP/PET blends were lower than neat PP in every layer. Furthermore, the distinction of orientation parameters of the blends between skin layer and core region was also smaller than pure samples. In the sample of compatibilized PP/PET, the orientation parameter along the thickness was about 0.3～0.4, which indicated that the skincore structure of this sample was greatly restrained. Addition of carbon nanotubes(CNTs) accelerated the crystallization rate of PET dispersed phase, and increased the crystallinity. After addition of CNTs, its bending modulus was 20 % higher than pure PP.

Effect of Rare Earth βnucleating Agent on Mechanics and Crystallization Properties of PP/OBC Blends

Peng CHEN Huaji ZHANG Wen ZHANG Xiao CHEN Yongxin SHEN

2012, 26 (10): 57-61 ; DOI: 10.19491/j.issn.1001-9278.2012.10.009

Abstract ( 1465 )

Blends of PP/ethyleneoctene block copolymer (OBC) were prepared containing a rare earth compounds (WBGⅡ) as a βnucleating agent. The effects of WBGⅡ on crystalline behavior, crystalline form, crystal morphology and mechanical properties of the blends were studied. With increasing OBC content, the notched impact strength and elongation at break of PP/OBC blends increased significantly, while tensile and flexural strengths of blends decreased. The PP/OBC blend containing 1.0 % WBGⅡ masterbatch and 15 % OBC gave rise to a βphase melting peak at 152 ℃, and a βform content of 21.94 %. The crystallization temperature of the blends increased by 10.88 ℃, notched impact strength and the elongation at break increased by 264.82 % and 367.66 %, respectively, compared with neat PP.

Thermal Conductivity Mechanism and Flameretardant Properties of HNTs Insitu Hybrid Composites

Diansong GAN Xingming ZHENG Ping NING Xionggang WANG Kaihuan DENG

2012, 26 (10): 62-65 ; DOI: 10.19491/j.issn.1001-9278.2012.10.010

Abstract ( 1553 )

Polyamide 66/thermotropic liquid crystalline polymer/halloysite nanotubes (PA66/TLCP/HNTs) Insitu hybrid composites were prepared by means of melt blending. The thermal conductivity mechanism, flameretardant properties as well as the morphologies of the composites were investigated. The thermal conductivity properties and limited oxygen index were improved as the amount of HNTs increased and a thermal conductive net was formed at a HNTs content of 30 wt %, in which HNTs and TLCP dispersed well in PA66 matrix. When the content of HNTs increased to 40 wt %, the thermal diffusivity, thermal conductivity, and limited oxygen index were increased by 27 %, 134 %, and 42 %, respectively.

Study on Effect of SEBS and SEBSgMAH on Properties of PPO/PA66 Alloy

Shihong CHEN Wenhu LIANG Xiuqing MA Kuisheng WANG Chongliang CHEN

2012, 26 (10): 66-69 ; DOI: 10.19491/j.issn.1001-9278.2012.10.011

Abstract ( 1616 )

Alloys of polystyrene oxide (PPO) and polyamide 66 (PA66) were prepared via twinscrew extrusion and toughened with styteneethylenebutadienestyrene block copolymer(SEBS) and maleic anhydride grafted styreneethylenebutadienestyrene block copolymer(SEBSgMAH). Effects of SEBS and SEBSgMAH on properties of PPO/PA66 alloys were studied through mechanical property test, scanning electron microscopy(SEM), and water absorption. It showed that the toughness of PPO/PA66 alloys with SEBSgMAH was improved obviously, meanwhile its water absorption decreased.

Crystalline Morphology and Mechanical Property of Polyethylene Parts Prepared by Gas assisted Injection Molding

Quanping ZHANG Long WANG Kai ZHANG Nan SUN Ruiyan ZHANG Jingjing WU Mingbo YANG

2012, 26 (10): 70-83 ; DOI: 10.19491/j.issn.1001-9278.2012.10.012

Abstract ( 1661 )

The effects of polyethylene molecular parameters and processing conditions on crystalline morphology of gasassisted injection molded (GAIM) polyethylene and relationships between the crystalline morphology and mechanical property were introduced. Due to the enhanced shear fields induced by melt short shot and gas penetration, polymer chains were partially oriented along the flow direction and the hierarchical crystal structures were further formed in parts during the subsequent cooling stage of GAIM process. In this paper, combined molecular parameters of polyethylene with molding process, the formation mechanism of hierarchical morphology during GAIM was explored.

Experimental Study on the Law of Smoke Release of Cable Under Overload Condition

Xuebao WANG Yang YANG

2012, 26 (10): 91-95 ; DOI: 10.19491/j.issn.1001-9278.2012.10.014

Abstract ( 1310 )

In this paper, the law of smoke release of cables under overload condition that frequently occurred in civil buildings was studied. The influence of overload current, conductor material, nominal sectional area, and the hardness of the cable on smoke release was discussed. It was found that the amount of smoke increaed with the increase of overload current. More smoke generated from coppercorewires than aluminum counterpart with the same diameter. The cables with smaller diameter and soft core were easier to release smoke than those with larger diameter and hard core.

Effects of Surface Tension on Microextrusion Flow

Zhihong FU Yuhui CHEN Xionghui XIAO

2012, 26 (10): 96-100 ; DOI: 10.19491/j.issn.1001-9278.2012.10.013

Abstract ( 1432 )

A numerical method to simulate surface tension in the micro circle extrusion flow has been developed based on software Polyflow. It showed that the surface tension becomes a more important role as the dimension of the extrusion die becomes smaller. As the surface tension coefficient increased, the extrudate swelling ratio, the meltpressure at the exit and entrances of the die, and the negative pressure of free surface at exit all increased. As the contact angle increased, the negative pressure of free surface at exit increased first and then reduced, with the first two parameters decreased.

Research on Properties of Cable Jacket Flame Retarded by Mg(OH)₂ /Al(OH)₃

Xinpeng HOU Yang JIAO Tiejun LI Wei TANG Shan CAO

2012, 26 (10): 96-100 ; DOI: 10.19491/j.issn.1001-9278.2012.10.015

Abstract ( 1270 )

Using a blend of lowdensity polyethylene/ethylene vinyl acetate/ethylene propylene diene monomer(PELD/EVA/EPDM) as a basic resin, Mg(OH)2/Al(OH)3 and Mg(OH)2 as two kinds of flame retardants, cable jacket was produced and the effects of flame retardants on mechanical properties were studied. It showed that, tensile strength and limited oxygen index were increased and elongation at break was decreased with increasing Mg(OH)2 to Al(OH)3. When Mg(OH)2 was used, limited oxygen index was directly proportional to the loading of Mg(OH)2, tensile strength and elongation at break were inversely proportional to the loading of Mg(OH)2. When the content of Mg(OH)2 was between 40~50 phr, limited oxygen index reached to more than 29 %, mechanical properties were superior to those based on Mg(OH)2/Al(OH)3 system.

Packing Pressure of Isosteric Control Method Based on PVT Character of Polymer

Shenggui ZHANG Pengcheng XIE Xuetao HE Yumei DING Weimin YANG

2012, 26 (10): 101-106 ; DOI: 10.19491/j.issn.1001-9278.2012.10.016

Abstract ( 1429 )

Based on the independence of pressure(P)temperature(T)specific volume(V) relationship of polymer to processing mode, using the modified double domain Tait state equation, a isovolume pressureholding curve was proposed. The injection pressureholding was simulated using Moldflow software, a cooling pressureholding curve of products was extracted. With such a curve we could transfer the pressuretemperature curve into a pressuretime one. Comparison among various pressureholding modes showed that the quality of products could be significantly improved through isovolume pressureholding method.

Preparation of Nanozinc Hydroxylstannate and Its Application in Flexible PVC

Zhiwei LI Yongshan HUANG Xiaohong LI Zhijun ZHANG

2012, 26 (10): 107-111 ; DOI: 10.19491/j.issn.1001-9278.2012.10.017

Abstract ( 1273 )

Nanozinc hydroxystannate (nanoZHS) was synthesized via chemical precipitation method. Xray diffraction(XRD), Xray photoelectron spectroscopy (XPS), and transmission electron microscope (TEM) showed that the product was in the form of nanocubic singlecrystals having particle size of 50～60 nm. PVC/ZHS nanocomposites was prepared via a blending method. TG and DTA showed that nanoZHS could catalyze the dehydrochlorination of PVC and promote early crosslinking leading to rapid charring and increase thermal stability of char layer. When the addition of nanoZHS increased, limiting oxygen index increased from 23.8 % to 32 %. However, tensile strength and elongation at break of the composites would be dropped when nanoZHS was added to PVC.

Research on Recycle PEHD Toughened by Sericite Surfacetreated by Resin Acid

Zhengnian CHEN Zhuqing TAO Lang XIAO Qiang WANG Zhaoliang LIU

2012, 26 (10): 112-115 ; DOI: 10.19491/j.issn.1001-9278.2012.10.018

Abstract ( 1331 )

In this paper, recycled highdensity polyethylene (RPE) was compounded with sericite powder, resin acid and a dispersant via a twinscrew extruder resulting in a RPE/sericite composite. The tensile, flexural, impact, and microstructure properties of the composite were measured to identify the effect of sericite loading on these properties. It showed that the sericite flake modified with 6～8 phr resin acid were finely dispersed in RPE matrix with almost no effect on the melt point and crystal temperature of RPE composite. With increasing contents of sericite powder, the tensile strength reduced, Izod impact and flexural strengths increased first and then decreased. When the content of sericite was 15 phr, the comprehensive mechanical property was optimal.

Study on Servo Pump Multiloop Hydraulic System Control Technology of Injection Molding Machine

Jianhong WEI

2012, 26 (10): 116-120 ; DOI: 10.19491/j.issn.1001-9278.2012.10.019

Abstract ( 1419 )

The multiloop control system in German Bosch Rexroth servo pump was studied, including electric control and hydraulic drive. This technique was applied to the injection molding machine, and an improved scheme was proposed. Through the application of advanced electric control and hydraulic transmission, more stable performance, more reliable operation, and convenient application were realized.