2004 Volume 77 Issue 3 Pages 79-84
Instrumental characterization of an adhesion interface in a rubber-brass system often faces a difficulty in exposing the clean surface due to the stick of the rubber residue on the brass surface. We have succeeded in isolating the 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 the detailed characterization of the interface by XPS from a practical rubber formulation.
Formulation of cobalt naphthenate did not contribute to the 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 the dose of cobalt improved the nature of interface at aging.
It was revealed that excess growth of copper sulfide was a main feature in the humidity aging, while the growth of zinc oxide was eminent in the hot water aging. Scheme of the aging reaction that depends on the interaction between the brass and external factors such as heat, water, and oxygen was considered.
In conclusion, the XPS analysis using the specific sample preparation shown in this study was found to be a powerful technique to characterize the adhesion Interlayer in not only model systems but also practical rubber formulation systems.
