Behaviour of photopolymerized silicate-glass-fibre-reinforced dimethacrylate composites subjected to hydrothermal ageing: part I. Steady-state sorption characteristics.

Steady-state water sorption due to hydrothermal ageing (37 degrees C) was determined via gravimetric methods for both an unreinforced dimethacrylate copolymer network and for composites of the copolymer reinforced with two different silicate yarn products - S2-glass(R) and quartz. The copolymer sorbed 4.9+/-0.3 wt%, and the composites sorbed 0.5-2.5 wt%. For the two types of composites, two different positive linear correlations were established between the sorption gain and the copolymer content in the composites. In the case of the S2-glass(R) composites, the sorption gain was fully explained in terms of sorption in the copolymer; and normalization of these data by the mass fraction of copolymer yielded a constant sorption value matching that of the unreinforced copolymer. After normalizing the data for the quartz composites, an additional positive correlation was established between the water gain (per unit weight of copolymer) and the linear density of interfacial surface area. For both types of composites the sorption response was stable over a three-month ageing period. Copyright 1998 Chapman & Hall