Effect of Curing in Air on the Synthesis of Si-Ti-C-O Fiber

The curing process for the synthesis of Si-Ti-C-O fiber was investigated in air. In curing by heat-treatment in air of polytitanocarbosilane as precursor of Si-Ti-C-O fiber, Si-H bonds, which were included in main structures of polytitanocarbosilane, were reacted with oxygen atoms to form Si-O-Si bonds between main chains of the polymer. DTA curve of polytitanocarbosilane in air showed the exothermic peak at the most suitable temperature for the curing of this polymer. The exothermic peak shifted to the higher temperature as the molecurar weight of polytitanocarbosilane increased from 1560 to 1970. The increase in gel fraction and the weight residue at 1300°C in N2 of the cured fiber was observed with a rise in curing temperature. The tensile strength of Si-Ti-C-O fiber correlated closely to these gel fraction and the weight residue. The maximum strength value of Si-Ti-C-O fiber was exhibited when the cured fiber had gel fraction of more than 70wt% and the weight residue of more than 85wt%. Young's modulus of Si-Ti-C-O fiber, which was obtained from the cured fiber with gel fraction of 60 to 75wt%, led to be maximum. Its young's modulus, however, gradually became small in the case of the gel fraction of more than 75wt%, because of the increase in oxygen content in the fiber.