Synthesis and properties of ceramic fibers from polycarbosilane/polymethylphenylsiloxane polymer blends

Kita, Kenichiro; Narisawa, Masaki*; Nakahira, Atsushi*; Mabuchi, Hiroshi*; Sugimoto, Masaki; Yoshikawa, Masahito

We synthesized ceramic fibers based on silicon carbide (SiC) from polymer blends of polycarbosilane (PCS) and polymethylphenylsiloxane (PMPhS). PMPhS was compatible with PCS up to 30 mass%. The polymer blend was formed a transparent melt at temperatures higher than 513 K and the softening point was also lowered by adding PMPhS. 15 mass% of PMPhS to PCS was the most suitable condition for obtaining thin fibers with an average diameter of 14.4 m and the ceramic yield of the cured fiber was 85.5% after pyrolysis at 1273 K. In spite of the small diameter, the resulting tensile strength at 1273 K was rather limited at 0.78 GPa. After high temperature pyrolysis at 16731773 K, a porous nanocrystalline SiC fiber with a unique microstructure was obtained with surface area of 70150 m/g.