The Investigation Of Carbon Nanotube-Polymer Composites

The super high strength, ductility, Young's modulus nanometer scale and large aspect ratio of carbon nanotubes (CNTs) make it an ideal reinforcement additive for composites. At the same time, the good electrical conductivity, high thermal conductivity, good thermal and chemical stability of carbon nanotubes could make the composites versatile.In this paper, 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.The carbon nanotube/silicone rubber and carbon nanotube/polypropylene composites were prepared by solution-evaporation method assisted by high-energy sonication. The mechanical, electrical and thermal properties of composites were investigated systematically. The results indicated that the incorporation of carbon nanotubes could enhance the strength, conductivity and thermal stability of composites. The resistivity of carbon nanotube/silicone composite showed strong negative temperature coefficient effect and were sensitivity to force. The carbon nanotubes enhanced the nucleation of polypropylene crystallization and made the crystal smaller and enen. The resistivity of carbon nanotube/polypropylene composite showed strong positive temperature coefficient. Very low concentration of carbon nanotubes could greatly enhance the thermal stability of polypropylene in nitrogen at high temperature.