INVESTIGATION OF THE INFLUENCE OF STEARIC ACID ON RUBBER–BRASS ADHESION

Abstract

Abstract The influence of stearic acid loading on the adhesion of rubber to brass-plated steel wires was investigated. The so-called squalene method was employed to investigate the adhesion interface built up during the vulcanization reaction. Variation of the stearic acid loading has a direct influence on the bonding interface and at the same time also has a strong influence on the rubber properties. The surface of the sulfidated wires was analyzed using optical, focus variation, and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. Increasing amounts of stearic acid accelerated the sulfidation reaction. Furthermore the focus variation microscopy data were used to calculate roughness parameters of the sulfidated wires. Rubber properties and adhesion values were measured for natural rubber compounds with variable amounts of stearic acid. In most cases the adhesive strength exceeded the cohesive strength of the rubber.