Improvement in the properties of PAN-based carbon films by modification with cobaltous chloride

Carbon films were developed from polyacrylonitrile (PAN) modified with coba lt chloride. The modification was carried out by immersing PAN in a 5% coba ltous chloride (CoCl2) solution at 90 degrees C for 5 min, oven-dried, and then manufactured into films. The original and modified PAN films were oxid ized at 220 degrees C for 2 and 6 h in air, respectively, and finally carbo nized at 1300 degrees C. The density, microstructure, elemental analyzer, e lectrical conductivity, and morphology were all studied. According to the r esults, it was found that films modified with cobalt chloride have a greate r stacking height of carbon-layer planes (L-c), density, electrical conduct ivity, and nitrogen content after carbonization. Moreover, during the carbo nization stage, the cobalt ions promote a catalytic action. The carbon film s developed from the modified film not only improved electrical conductivit y by 12-38%, but also increased tensile strength by 29-36% and the tensile modulus by 69-110%. Therefore, carbon films having better mechanical proper ties can be obtained after such modification. (C) 1999 John Wiley & Sons, I nc.