The effects of silica aerogel on the rheological behaviour and polymer matrix structure of Rigid Polyurethane foams

The incorporation of silica aerogel particles into the isocyanate used to prepare Rigid Polyurethane composite foams drastically modifies its rheological behaviour. changes from being a Newtonian fluid constant viscosity (0.3 Pa s at 25 °C) non-linear power-law material with complex decreasing 104 101 slope −1 versus frequency. change in response is caused by formation percolated network contents above 2.5 wt% aerogel. Moreover, addition significantly slows down modulus-build up kinetics and vitrification matrix approximately 4.5 min every 1 added. For foam 3.0 aerogel, combination high early reaction times coupled slow modulus build-up impedes drainage which leads decrease fraction struts matrix.