Adhesion behavior of natural rubber-based adhesives crosslinked by benzoyl peroxide

The loop tack, peel, and shear strength of crosslinked natural rubber adhesive were studied using coumarone-indene and toluene as the tackifying resin and solvent, respectively. The concentration of benzoyl peroxide-the crosslinking agentwas varied from 1 to 4 parts per hundred parts of rubber (phr). A SHEEN hand coater was used to coat the adhesive on the polyethylene terephthalate substrate at various coating thickness. Loop tack, peel, and shear strength were measured by a Llyod adhesion tester operating at 30 cm min-1. Result shows that loop tack and peel strength of the adhesive increases up to 2 phr of benzoyl peroxide concentration after which it decreases with further benzoyl peroxide content. This observation is attributed to the optimum crosslinking of natural rubber where optimum cohesive and adhesive strength occurs at 2 phr peroxide loading. However, for the shear strength, it increases with increasing benzoyl peroxide concentration where higher rate of increase is observed after 2 phr of peroxide content, an observation which is associated to the steady increase in cohesive strength of crosslinked rubber. In all cases, the adhesion properties of adhesives increase with increase in coating thickness. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012