Adhesive properties of thiol-acrylate-epoxy composites obtained by dual-curing procedures

Abstract

Composite materials were prepared using a thiol-acrylate-epoxy dual-curing system filled with Boron Nitride (BN) agglomerates. The adhesive properties obtained with two different acrylate ratios (ra) were tested to characterize differences and applicability of final thermosets. The effect of bondline thickness, BN wt% and curing procedure on the adhesive strength was evaluated for both acrylate ratios ra by means of lap-shear tests. Materials with viscous intermediate (ra = 0.2) results were observed to have the best performance reaching a maximum of almost 5 kN with 20 wt% of BN. On the other hand, materials with an intermediate gelled network (ra = 0.5) showed a high accuracy in dimension control but lower values of adhesive strength were obtained. A decrease of adhesive strength with the increase of thickness was found for both ra, while the increase of BN wt% lead to higher adhesive strength. The beneficial effect of dual-curing processing on the adhesive properties of liquid intermediate materials was also experimentally demonstrated.