ADHESION OF ELASTOMERS, WITH SPECIAL REFERENCE TO TRIBLOCK COPOLYMERS

Results of a study are presented which show that several physical and chemical factors affect the strength of adhesion (as measured by a peeling method) for elastomers adhering to rigid substrates. These factors include: the thickness of the elastomer layer (and of an adhering backing, if present); the rate of detachment and the test temperature; and the presence of chemical bonds between elastomer and the substrate. Adhesion of thermoplastic elastomers, i. e. , SBS triblock copolymers, applied as hot melts, is much stronger than for the corresponding random copolymers, crosslinked in situ. These materials also show higher cohesive (tear) strength. Both effects probably arise from the same cause: an energy-dissipation process which operates at large stresses and prevents brittle fracture. This process is thought to be plastic yielding of the polystyrene domains.