Silica -Titania Glass Fibers from Polytitanosiloxanes: Effect of Polymerization Mechanism on Mechanical Properties

SiO2 -TiO2 glass fibers have been prepared via dry spinning of the viscous solutions of polytitanosiloxanes followed by steam treatment and pyrolysis at 500, 700, and 900 °C for 1 h under ambient condition. The polymer was prepared via polycondensation of partially hydrolyzed tetraethoxysilane (TEOS) and an acetylacetone-chelated titan compound at various H2O/TEOS and Si/Ti ratios. Gel fibers formed shown tensile strength as low as 200 MPa and increased around 3 times after pyrolysis. The higher degree of TEOS hydrolysis the higher tensile strength of the fibers. The polymer with higher Si/Ti ratio also provided stronger fibers due to more extensive siloxane network. Fibers with the highest tensile strength, 610 MPa, was obtained from the polymer synthesized with SiO2/TiO2 mol ratio 20 and pyrolysis temperature 700 °C.