Characterization of Adhesion Interlayer Between Rubber and Brass by a Novel Method of Sample Preparation

Abstract

Abstract Instrumental characterization of an adhesion interface in a rubber-brass system often faces a difficulty in exposing a clean surface due to a stick of rubber residue on a brass surface. We have succeeded in isolating an interface from the rubber matrix by inserting a filter paper between rubber and brass during the vulcanization. Clean interface was obtained by removing the filter paper after the vulcanization, enabling a detailed characterization of the interface by XPS and SEM-EDX from a practical rubber formulation. Formulation of cobalt naphthenate did not contribute to a formation of adhesion interlayer in an initial stage of cure, but greatly affected the composition of copper sulfide during the vulcanization. It was found that a dosage of cobalt improved a growth of interface at aging. Copper sulfide particles were found to be spherical at the interface for unaged specimens. It was revealed that excess growth of copper sulfide was a main feature at a humidity aging, while the growth of zinc oxide was eminent under a hot water aging. Scheme of an aging reaction was considered to depend on an interaction between brass and external factors such as heat, water, and oxygen.