Viscosity and Peel Strength of SMR 10-Based Pressure-Sensitive Adhesives

The viscosity and peel strength of a natural rubber-based pressure-sensitive adhesive was studied. One grade of natural rubber (SMR 10) and coumarone-indene resin were used as the elastomeric material and tackifier, respectively. Throughout the experiment, toluene was used as the solvent to prepare the adhesive. The effect of mastication time of rubber and tackifier concentration on the viscosity and peel strength of adhesive on various substrates was systematically investigated. The viscosity was measured using a HAAKE Rotary Viscometer. T-Test, 90° Adhesion To Steel (ATS), and 180° Adhesion To Steel (ATS) Tests were used to determine the peel strength of the adhesive. The results indicate that the viscosity of the adhesive increases with the resin content but decreases with mastication time. The peel strength generally increases with an increase in resin content except for the 20 min masticated sample. For all concentrations of the resin tackifier studied, the 10 min masticated sample exhibits the highest peel strength as compared to the corresponding values of the other masticated samples. This observation is attributed to the optimum wetting and formation of mechanical interlocking, and anchorage of the adhesive in pores and irregularities in the substrate for the former sample.