聚丙烯／热致液晶聚合物／玻璃纤维混杂复合材料的制备及性能研究

提出了一种制备原位混杂复合材料的新途径。将聚丙烯(PP)、热致液晶聚合物(TLCP)与玻璃纤维(GF)在高于TLCP熔点的温度下熔融共混挤出，经适当拉伸，然后造粒，得到TLCP成纤良好的PP／TLCP／GF复合材料粒料。将其在不同温度下注射成型，考察了成型温度对所得混杂复合材料中TLCP组分的形态及材料力学性能的影响。结果表明，注射成型温度对最终复合材料中TLCP形态及材料的力学性能有明显的影响。当注射温度为200℃和220℃，即低于TLCP的熔融温度较多时，所得混杂复合材料中TLCP组分保持了较好的微纤结构，复合材料具有良好的力学性能。注射成型温度为240℃时，复合材料中TLCP相开始出现熔融回缩；而当加工温度高于260℃后，TLCP分散相主要成球形。随注射成型温度升高，混杂复合材料的力学性能逐渐下降。在基体中加入聚丙烯接枝马来酸酐(PP-g-MAH)作为增容剂，可以同时改善PP与TLCP、PP与GF之间的界面黏结，从而有利于混杂复合材料力学性能的提高。     

热致性液晶高分子增强复合材料研究进展

从材料组成、共混加工、形态结构及材料性能诸方面对热致液晶高分子聚合物(TLCP)增强复合材料的最新研究进展进行了综述,并指出该材料良好的应用开发前景。     

PA纤维／环氧树脂超混杂复合材料的层压成型工艺

本文研究了ＰＡ纤维／环氧基体超混杂复合材料的层压工艺,确定了超混杂复合材料的铺层叠合及工艺条件,在此工艺条件下制备的复合材料具有优异的性能。     

树脂基超混杂复合材料成型工艺研究

本文系统研究了金属纤维 /树脂基超混杂复合材料层压成型工艺(即SHCM)的铺层设计和铺层工艺 ,探讨并确定了固化工艺和后固化处理参数 ,从而使材料具有优异的性能。     

低成本多功能超混杂复合材料及其应用

介绍研究、开发的低成本、多功能树脂基超混杂复合材料及其产品的应用前景。     

混杂纤维复合材料的力学性能研究

采用盐酸和乙酸对金属纤维表面进行活化处理后，使之与环氧树脂的粘结性大为改善。研究了玻璃纤维与金属网混杂增强环氧树脂复合材料的力学性能。     

混杂纤维复合材料热性能异性研究

本文对碳纤维，玻璃纤维混杂纤维复合材料进行了热膨胀系数计算，计算结果表明，环向碳纤维的加入可使碳纤维增强复合材料的纵向热膨胀系数趋于正值，而同等厚度环向玻璃纤维的加入却使碳纤维增强复合材料的纵向热膨胀系数更趋于负值，从而增加了复合材料零膨胀设计范围。     

天然纤维混杂增强聚合物基复合材料的研究进展

天然纤维混杂增强聚合物基复合材料因其密度低、能耗少、阻尼性能和抗噪声性能优异而在汽车轻量化、能源化工装备及家电轻薄化等领域应用较广。结合影响天然纤维混杂增强聚合物基复合材料力学性能的影响因素,对其研究进展进行了综述,并对其发展前景进行了展望。     

混杂纤维增强复合材料梁挠度计算理论研究

本文针对目前土木工程中最新出现的混杂纤维树脂基复合材料梁,以3组不同碳纤维含量的混杂纤维拉挤型材薄壁梁构件作为研究对象,通过模型试验、有限元数值分析和理论分析进行对比。研究表明,与相同截面玻璃钢相比,上下翼缘采用碳纤维增强的混杂纤维拉挤型材抗弯刚度有明显提高,但是抗剪切变形能力提高有限。在进行混杂纤维树脂基复合材料梁的挠度计算时须采用考虑横向剪切变形对挠度影响的铁木辛柯梁理论。     

混杂纤维浆状模塑(JMC)复合材料及其成型工艺

本文提出一种浆状模塑料的复合材料作成型工艺,以广泛适用开发和扩充新的增强材料广谱混杂使用,是一种环保,可持续发展而又易实现机械化的新工艺。     

Effect of a filler on the rheological and mechanical properties of the liquid‐crystalline polyester–poly(methyl methacrylate) blends

The rheological and mechanical properties of the blends of liquid‐crystalline polyester (LCP) and poly(methyl methacrylate) (PMMA) filled with aluminum borate whiskers have been studied. It was established the combined action of reinforcing LCP and filler onto the property of PMMA matrix leads to marked reinforcing of PMMA. At 10% of filler and 30% of LCP, the tensile strength of PMMA increases by 30% and elasticity modulus by 110%, the processability being no worse. The viscosity of the blend PMMA + 30% LCP + 10% filler practically is the same as the PMMA melt viscosity at 220°C. With increasing concentration of LCP up to 30%, the filler effect in binary matrix becomes more essential. The possible reason is the preferential adsorption of LCP at the filler interface (surface segregation) and additional ordering of LCP near the surface, possible, due to additional stretching of nematic phase in the convergent flow zone. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 993–999, 2000     

The crystallization rate of poly(ethylene terephthalate) accelerated by co[poly(butylene terephthalate‐p‐oxybenzoate)] copolyesters

Poly(ethylene terephthalate) (PET) was blended with three different kinds of co[poly(butylene terephthalate‐p‐oxybenzoate)] copolyesters, designated B28, B46, and B64, with the level of copolyester varying from 1 to 15 wt %. All samples were prepared by solution blending in a 60/40 by weight phenol/tetrachloroethane solvent at 50°C. The crystallization behavior of samples was then studied via differential scanning calorimetry. The results indicate that these three copolyesters accelerate the crystallization rate of PET in a manner similar to that of a nucleating agent. The acceleration of PET crystallization rate was most pronounced in the PET/B28 blends with a maximum level at 10 wt % of B28. The melting temperatures for the blends are comparable with that of pure PET. The observed changes in crystallization behavior are explained by the effect of the physical state of the copolyester during PET crystallization as well as the amount of copolyester in the blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 587–593, 2000     

Non-isothermal Crystallization of Poly(ethylene terephthalate) with Poly(oxybenzoate-p-trimethylene terephthalate) Copolymer

The influence of a poly(oxybenzoate-p-trimethylene terephthalate) copolymer, designated T64, on the non-isothermal crystallization process of poly(ethylene terephthalate) (PET) was investigated. All samples were prepared by solution blending in a 60/40 by weight phenol/tetrachloroethane solvent at 50°C. The solidification process strongly depended on cooling rate and composition of system. The crystallization rate of blends was estimated by crystallization rate parameter (CRP) and crystallization rate coefficient (CRC). From these results of CRP and CRC, it was predicted that the overall non-isothermal crystallization rate of PET would be accelerated by blending with 1–15 wt% of T64. The acceleration of PET crystallization rate was most pronounced in the PET/T64 blends with 5 wt% T64. The observed changes in crystallization behavior are explained by the effect of the physical state of the copolyester during PET crystallization as well as the amount of copolymer in the blends. An Ozawa plot was used to analyze the data of non-isothermal crystallization. The obvious curvature in the plot indicated that the Ozawa model could not fit the PET/T64 blend system well, and there was an abrupt change in the slope of the Ozawa plot at a critical cooling rate.     

Properties of ternary in situ polycarbonate/polybutylene terephthalate/liquid crystalline polymer composites

Ternary in situ polycarbonate (PC)/polybutylene terephthalate (PBT)/liquid crystalline polymer (LCP) composites were prepared by injection molding. The liquid crystalline polymer used was a versatile Vectra A950. The matrix of composite was composed of PC/PBT 60/40 by weight. A solid epoxy resin (bisphenol type‐A) was used as a compatibilizer for the composites. Dynamic mechanical analysis (DMA) showed that epoxy resin was effective to improve the compatibility between PC and PBT, and between PC/PBT and LCP, respectively. Tensile tests revealed that the stiffness of composites shows little change with the LCP content up to 10 wt %. Above this concentration, the stiffness tended to increase with increasing LCP content. Furthermore, the tensile strengths appeared to increase with increasing LCP content, and their values were close to those predicted from the rule of mixtures. Scanning electron microscopic examination showed that LCP ribbons and short fibrils were developed in the composites containing LCP content ≤10 wt %. However, fine and elongated fibrils were formed in the skin and core sections of the composites when the LCP content reached 25 wt % and above. Thermogravimetric analysis indicated that the thermooxidative stability of the PC/PBT 60/40 blend tended to improve with increasing LCP content. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1827–1835, 1999     

A novel microstream injection molding method for thermotropic liquid crystalline polymers to promote mechanical isotropy: A matrixing microbeam X-ray study

The effects of flow-altering inserts and mold cavity geometry on the mechanical properties of an injection molded liquid crystalline polymer were studied to produce parts with properties approaching macroscopically isotropic state. By inserting fine metal mesh barriers to the gates of the mold cavities, a large number of highly oriented microstreams are produced. After their creation these highly oriented streams of differing flow vectors intertwine and this texture remains reasonably intact even after substantial shearing and extension history imparted on them during ensuing flow into the cavity. This method is effective in the interior away from the skin regions formed under the shearing flow during injection. The local molecular orientation was determined using a matrixing microbeam WAXS technique that allows precision movement of the sample in the microbeam X-ray. Samples produced with the 1.0 mm² mesh showed large variations in the local symmetry axis with respect to the machine as measured by microbeam X-ray diffraction incrementally from the edge to the core of the parts. In comparison, samples with no mesh insert showed only gradual changes in the tilt angle (angle between local symmetry axis and flow direction). The modulus and tensile strengths of all samples with the 1.0 mm² mesh inserts were found to approach virtual global mechanical isotropy.     

Crystallization and compatibilization of polypropylene–liquid crystalline polyester blends

A liquid crystalline polyester, LC3000, has been blended with polypropylene. These polymers form an incompatible and immiscible blend. Polypropylene grafted with epoxy via glycidyl methacrylate forms an effective compatibilizer. The dispersed liquid crystalline polyester particle size was decreased when the compatibilizer was used. The polyester influenced the morphology of the polypropylene continuous phase by increasing the nucleation, and the effect was enhanced when the compatibilizer was present. This was demonstrated using continuous cooling DSC where the crystallization temperatures were increased. Isothermal crystallization showed decreased crystallization half‐times with the polyester present, and these were further reduced with compatibilizer. Avrami analysis showed that the exponent values increased by an average of 0.1–0.2, so nucleation was assisted by the LC3000, and the rate coefficients were increased. The continuous cooling and isothermal DSC measurements provided complementary results. Optical microscopy showed that the spherulite size of the polypropylene was reduced. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2229–2236, 2000