Adjustable biodegradation for ceramic fibres derived from silica sols

Biodegradable silica fibres were prepared from TEOS-derived silica sols by dry spinning. The spinnability of the sols and its influence on the green s tate fibre structure were investigated. The same sols can be used to prepar e different fibre structures depending on the process stage, temperature an d viscosity. The spinning moment was found to be important in order to cont rol the biodegradation. Influence of catalysts (HNO3 and/or NH3) as well as evaporation of the liquid on the process were investigated. They did not h ave an influence on the spinnability, but they reduced the overall reaction time. The prepared green state fibres were aged for 1 and 3 months indicat ing stable structure as a function of ageing time according to the biodegra dation experiments, except in the case of high catalyst concentration. A po rous structure was revealed using transmission electron microscopy. Heat-tr eatment of the fibres induced remarkable differences in the fibre bulk stru cture according to FT-IR measurements. (C) 2000 Elsevier Science Ltd. All r ights reserved.