Silicon carboxide fibers from gel spinning cyclosiloxane polymer precursors

A process for preparing a black glass fiber comprising:

• a) forming a soluble cyclosiloxane polymer by reacting in solution and in the presence of a catalytically effective amount of a hydrosilylation catalyst a silicon hydride group with a silicon olefinic group wherein 1) said silicon hydride and silicon olefinic group are present in the same cyclosiloxane monomer having the formula ##STR5## where n is an integer from 3 to about 20, R is hydrogen, and R' is an alkene having from 2 to about 20 carbon atoms and an olefinic carbon bonded directly to silicon, or 2) said silicon hydride and silicon olefinic groups are present on two or more, different cyclosiloxane monomers, at least one monomer having a silicon-hydride group and having said formula in which n is an integer from 3 to about 20, R is hydrogen and R' is an alkyl group having from 1 to about 20 carbon atoms and at least one monomer having a silicon olefinic group and having said formula in which R is an alkene having from 2 to about 20 carbon atoms and which has an olefinic carbon directly bonded to silicon and R' is an alkyl group having from 1 to about 20 carbon atoms;
• b) forming a spinning solution from the solution containing a soluble cyclosiloxane polymer;
• c) spinning the spinning solution to give a polymeric cyclosiloxane fiber;
• d) heating the polymeric cyclosiloxane fiber at a temperature of about 50.degree.-200.degree. C. and for a time sufficient to form a hardened polymeric cyclosiloxane fiber;
• and
• e) heating the hardened polymeric cyclosiloxane fiber at a temperature of about 700.degree. C. to about 1400.degree. C. in a non-oxidizing atmosphere for a time sufficient to pyrolyze the polymeric fiber into a black glass fiber.