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 mm, 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.