Improvement of adhesive-bonding of elastomers by plasma surface modification

An attempt to replace a wet chemical modification of styrene-butadiene (SBS) elastomer surfaces to improve their adhesion to polyurethane adhesives, with a clean low-pressure plasma technique has been undertaken. The plasma has been generated by an RF discharge (13.56 MHz, plate electrode reactor) in oxygen (O2) or carbon dioxide (CO2) to create oxygen functionalities (>C=O~, OH~, COOH) on the elastomer surfaces. T-peel tests and FTIR spectroscopy have been utilized to investigate the surfaces. Some investigations of the aging processes taking place after plasma treatments have been also performed. It has been found that an important role in the plasma-improved adhesion is played by the chemical interaction between the modified SBS surfaces and polyurethanes. The peel strength for plasma treated samples in many cases is much higher than that for the wet chemical modification. It clearly indicates that the plasma treatment is a very promising method of improving the adhesion properties of SBS elastomers.