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 state fibre structure were investigated. The same sols can be used to prepare different fibre structures depending on the process stage, temperature and viscosity. The spinning moment was found to be important in order to control the biodegradation. Influence of catalysts (HNO3 and/or NH3) as well as evaporation of the liquid on the process were investigated. They did not have an influence on the spinnability, but they reduced the overall reaction time. The prepared green state fibres were aged for 1 and 3 months indicating stable structure as a function of ageing time according to the biodegradation experiments, except in the case of high catalyst concentration. A porous structure was revealed using transmission electron microscopy. Heat-treatment of the fibres induced remarkable differences in the fibre bulk structure according to FT-IR measurements. (C) 2000 Elsevier Science Ltd. All rights reserved.