Kinetic aspects of water sorption in polyester-resin/glass-fibre composites

Solubility and diffusivity of wafer in sheet-moulding compound (SMC) materials based on polyester-resin/glass-fibre composites with variable content of fibres, filler (CaCO3) and other low-molecular-weight additives have been studied The main scope is the finding of a realistic approach to describing water sorption behaviour as a function of the hydrophilic character of the matrix, the mechanical properties of the material and the water solubility of fibres, fillers and low-molecular-weight compounds (solutes). The model previously proposed for simultaneous water sorption in and solute release from moderately hydrophobic materials has been generalised here in order to take into account experimental findings on chemical and physical processes induced by water penetration into the composites A method is developed that is based on the use of thermodynamic and kinetic parameters of water sorption/desorption for the physico-chemical characterisation of SMC materials. (C) 1997 Published by Elsevier Science Limited.