Studies of triblock copolymer-tackifying resin interactions by viscoelasticity and adhesive performance

Various levels of a C5 aliphatic resin are blended into an elastomeric styrene-isoprene triblock copolymer, and viscoelastic studies and tack measurements of these polymer-resin blends are carried out. The function of the resin is to reduce the plateau modulus of the polymer and raise the glass transition temperature of the matrix phase. Some evidence from the thermomechanical properties suggests that two phases exist in the elastomer region, but the point is not proven. However, there seems to be none or a very minimal amount of resin intruding into the polystyrene domains. Assuming a simple and highly idealized model, a one-to-one correspondence between energy dissipation measured viscoelastically and debonding resistance measured by industry tests is obtained when the adhesives fulfill the Dahlquist criterion. It is found that the performance of pressure-sensitive adhesives in several industry tests is linearly correlated with the logarithm of loss modulus at the reduced frequency corresponding to the speed of the debonding test. (S.A.V.)