FAILURE ANALYSIS OF SURFACE-TREATED UNVULCANIZED SBS RUBBER POLYURETHANE ADHESIVE JOINTS/

The surface of an unvulcanized styrene-butadiene-styrene (SBS) rubber (S0) was chlorinated with 0.5-7 wt% trichloroisocyanuric acid (TCI) so lutions. The adhesion strength of surface-treated SO rubber/polyuretha ne polyurethane adhesive joints was obtained from T-peel tests. The fa iled surfaces after peeling were characterized by ATR-IR spectroscopy, contact angle measurements, SEM coupled with EDX analysis and XPS. Th e untreated SO rubber shows no adhesion because of a lack of compatibi lity with the polyurethane adhesive. Chlorination of SO rubber with 0. 5 wt% TCI produced a noticeable increase in T-peel strength which was due to the formation of C-Cl and C-O species on the rubber surface, th e failure of the joint being produced at the chlorinated surface (weak boundary layer). Treatment of SO rubber with greater concentrations o f TCI, up to 2 wt%, resulted in a decrease in the joint strength becau se the locus of failure was directed deeper into the chlorinated layer . On the other hand, the treatment of SO rubber with 7 wt% TCI produce d different joint strength values in replicate joints that were tested under similar experimental conditions, mainly owing to differences in the locus of failure in the joints. Failure occurred randomly through out the adhesive, the interface or the surface chlorinated layer. (C) 1997 Elsevier Science Ltd.