The Maximum Peel Strength of Pressure-Sensitive Styrene-Butadiene Emulsion Polymers

Peel strengths of five pressure-sensitive styrene-butadiene emulsion polymers, having different amounts of gel and different glass transition temperatures, have been determined as a function of temperature and peel rate. For each peel rate, the peel strength reaches a maximum at a particular temperature, and this maximum peel strength is associated with the change of the mode of failure from cohesive to adhesive. The maximum peel strength is found to be largely independent of the gel level and possibly of the glass transition temperature of the polymer within the domain of pressure-sensitive polymeric properties. The maximum peel strength appears to be dependent on the kind of substrates and the stabilization system of the emulsion polymers (surface free energy properties of the bonded interfaces).