Fundamental adhesive studies of block copolymers

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Virginia Polytechnic Institute and State University

Models of multiple component, multiple phase adhesives were developed to examine the conflicting demands placed on modern adhesion technology. Styrene and isoprene based block copolymers were investigated 511 order to understand their adhesive properties. The structure of the microphase separated morphology of the materials studied was found to influence the adhesive behavior in applications as hot melt/structural type adhesives and as pressure sensitive adhesives.

The thermal and the dynamic mechanical behavior of linear styrene/isoprene/styrene triblock copolymers (40% and 50% by weight styrene) was determined for free films and for films bonding together two rigid adherends. Damping phenomena indicated a broader mechanical relaxation spectrum occurring at higher i temperatures in the bonded assemblies.

Microphase separation in the melts of these triblock materials was interpreted as contributing to the formation of residual stresses in both free films and bonded joints under appropriate thermal and pressure histories, illustrating the importance of sample preparation. in the evaluation of multiple phase adhesive systems.