Mechanistic Investigations of the Steel Tire-cord-Rubber Interface

Brass-coated steel cords are extensively used as reinforcement material in radial tires, high-pressure hydraulic hoses and heavy duty conveyor belts. Bonding between rubber and steel cord is obtained via the formation of an adhesion interface layer during the curing process. The adhesion build-up mechanism involves the chemical reaction of sulfurating species contained in the rubber skim compound and copper of the brass coating, forming a CuxS layer at the rubber brass interface. Advances in mechanistic investigations are presented, using analytical techniques such as X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), atomic force microscopy (AFM) and optical microscopy (OM). XPS and AES provide chemical in-depth information, whereas OM and AFM highlight the morphology of the resulting interfacial layers. These investigations improve the understanding of the adhesion mechanism, both for adhesion build-up and for bond degradation.