Effect of blend ratio and testing rate on the adhesion properties of pressure-sensitive adhesives prepared from epoxidized natural rubber 25/acrylonitrile–butadiene rubber blend

Abstract

The dependence of adhesion properties, that is, viscosity, tack, peel strength, and shear strength of epoxidized natural rubber (ENR 25)/acrylonitrile–butadiene rubber blend pressure-sensitive adhesive on blend ratio and testing rate was studied using coumarone–indene resin and toluene as tackifier and solvent, respectively. The rubber blend ratio was fixed at 0, 20, 40, 60, 80, and 100% of ENR 25 content. Four different thicknesses, that is, 30, 60, 90, and 120 μm, were used to coat the polyethylene terephthalate (PET) film. The viscosity of adhesive was determined by a Brookfield viscometer, whereas loop tack, peel strength, and shear strength were measured using a Lloyd adhesion tester operating at 10–60 cm/min. Results show that the viscosity of the adhesive decreases with increasing % ENR 25, whereas loop tack and peel strength pass through a maximum value at 20% ENR 25, an observation which is attributed to the optimum wettability and compatibility of adhesive at this optimum ENR 25 content. For the shear strength, it increases steadily with % ENR 25 due to the constant increase in cohesive strength. Adhesion property also increases with coating thickness and rate of testing at a fixed blend ratio.