Mechanical and Transport Properties of Colloidal Silica-Unsaturated Polyester Composites

Abstract

Colloidal silica-reinforced polyester composites with different volume fractions of colloidal silica are investigated for morphology, tensile strength, and flexural strength. Morphology is studied using scanning electron microscopy. Mechanical properties are studied with respect to varying filler content i.e., from 0.5 to 2.5% (by wt.) and it is found that the tensile and flexural strengths increase initially with increasing filler content and then start to decreasing with the increase in filler content. There are several explanations for these effects, which are discussed in terms of reinforcing mechanisms. In addition, the effect of various aggressive solvents is studied. It is found that the chemical absorption increases with increasing filler content. The kinetics of swelling and sorption has also been studied for carbon tetrachloride, toluene, xylene, and formaldehyde at 30 C. Diffusivity coefficient decreases and sorption coefficient increases with increasing filler content. In addition, the mode of transport is observed to be non-Fickian. The effect of solvents on the diffusion behavior of the composites is also studied. It is found that the equilibrium degree of swelling increases with the increase in the solubility parameter of the solvent and is maximum in the solvent, which has the solubility parameter value near to that of the polyester resin. As solubility parameter value deviates more from that of the resin, the equilibrium absorption value decreases.