【作者】 胡静；

【导师】 陈小华；

【作者基本信息】 湖南大学 ， 材料物理与化学， 2005， 硕士

【摘要】 碳纳米管极高的强度、韧性及其纳米尺寸和极大的长径比,使其有望成为复合材料理想的增强体。同时,其优良的电导率、热导率、化学稳定性和热稳定性,也可能使复合材料多功能化。本文选择聚丙烯为基体材料,利用碳纳米管对其改性,研究改性后复合材料的力学、电学、热学及其结晶行为。首先采用溶胶-凝胶法制备镍催化剂,在此基础上用化学气相沉积法高产率地制备了碳纳米管。为了获得了比较纯净的碳纳米管,采用混合酸回流的方法除去了产物中的杂质,并使碳纳米管表面和端口产生了许多的缺陷和官能团,促进了碳纳米管对水和溶液的浸润性,这为进一步制备碳纳米管复合材料打下了基础。接着采用原位接枝法制备了碳纳米管/马来酸酐接枝聚丙烯复合材料,对所制备复合材料的力学、电学、光学、热学等性能进行了比较全面的研究。实验结果表明:碳纳米管的加入可以提高复合材料的强度、电学性能以及热稳定性。在碳纳米管含量较低的情况下就获得了力学性能和电学性能较好的复合材料。碳纳米管在聚丙烯中起到异相成核作用,促使晶粒细化。碳纳米管的加入,不仅提高了复合材料的电导率,同时提高了其力学性能。然后采用甲基丙烯酸丁酯对碳纳米管表面进行接枝聚合改性,制备了改性碳纳米管/聚丙烯基复合材料,并研究了改性碳纳米管及其复合材料的性能。实验结果表明:改性碳纳米管能够更为均匀的分布在聚合物基体中,使复合材料的结晶温度提高,成核速率增大,但结晶总速率降低。改性碳纳米管能够促使聚丙烯发生了由α晶型向β晶型的转变,更加有利于提高材料的机械性能。更多还原

【Abstract】 The super high strength, ductility, nanometer scale and large aspect ratio of carbon nanotubes (CNTs) make it an ideal reinforcement additive for composites. Also, the good electrical conductivity, high thermal conductivity, good thermal and chemical stability of carbon nanotubes could make the composites versatile. In this paper, polypropylene(PP) as matrix was modified by CNTs. The mechanical property, electrical conductivity, thermal conductivity and crystallization behavior of the composite were studied after modification. The catalyst was first produced by sol-gel method and the carbon nanotubes were high yield synthesized by the catalytic chemical vapor decomposition method. In order to get rid of the impurity, the as-CNTs were refluxed by nitric acid and muriatic acid. After refluxing, the carbon nanotubes were completely purified, the end and wall of carbon nanotubes were attached with carboxyl and hydroxyl groups. These functional groups could make carbon nanotubes hydrophilic. Then , the CNTs/MAH-g-PP composites were prepared by in situ graft method. The mechanical, electrical and thermal properties of the composite were investigated systematically. The results indicated that the incorporation of carbon nanotubes could enhance the strength, conductivity and thermal stability of composites. The carbon nanotubes enhanced the nucleation of PP crystallization and made the size of the spherulites smaller and even. Very low concentration of carbon nanotubes could greatly enhance the thermal stability of PP in nitrogen at high temperature. Finally, the modification of CNTs with poly(Butyl Methacrylate)(PMBA) by grafting polymerization method were studied to prepare PBMA-g-CNTs/PP composite. The properties of the composite were explored. The results showed that the CNTs encapsulated by PBMA could be dispersed more evenly in the matrix of PP and raised the crystallizing point and increased the nucleation rate of the composite, but the crystalline rate of the composite were reduced. The results also indicated that the introduction of the modified CNTs could cause the α-crytalline form of the composite be transformed to β-crytalline form so as to enhance the mechanical properties of the composite.更多还原