Environmental friendly surface treatments of styrene–butadiene–styrene rubber: alternatives to the solvent-based halogenation treatment

Abstract

Corona discharge and ultraviolet (UV) radiation treatments have been used as environmental friendly alternatives to the common surface treatment of halogenation for a styrene–butadiene–styrene (S6) rubber. The corona energy and the length of treatment under UV radiation of the S6 rubber have been studied and the surface modifications produced have been assessed by contact angle measurements, ATR-IR spectroscopy, XPS and SEM. Adhesion properties were obtained from T-peel tests of surface treated S6 rubber/polyurethane adhesive/leather joints. Corona discharge and UV radiation treatments modified the S6 rubber surface by creating C–O, C=O and COO − moieties that improved wettability. The extent of the surface modifications of S6 rubber was different by treatment with UV radiation or corona discharge. The higher the corona discharge energy or the higher the length of the UV radiation treatment, the more marked modifications were achieved on the S6 rubber surface. On the other hand, corona discharge and UV radiation treatment produced different morphologies on the S6 rubber surface. The poor adhesion obtained with the corona discharge treatment has been ascribed to a lack of surface roughness and/or the creation of weak boundary layer on the S6 rubber. On the contrary, UV radiation treatment produced cracks on the S6 rubber surface that favored the mechanical adhesion. The modifications produced by both treatments were compared to those produced by the solvent-based halogenation treatment.