Chemical Modifications of Rubber Surfaces: XPS Survey of the Reactions of Trichloroisocyanuric Acid at the Surfaces of Vulcanized Elastomers

Abstract

Abstract X-ray photoelectron spectroscopy (XPS or ESCA) was used to examine the outermost 100 A˚ of selected elastomer substrates, and to classify the predominant reactions that occur there between the substrates and trichloroisocyanuric acid (TCICA). About four monolayers deep, this surface region represents the locus of interfacial and adhesive processes. From these experiments, we concluded the following: (1) at the outermost surface of NR, substitution reactions of TCICA predominate, but a minor amount of addition is also evident; (2) addition and substitution reactions compete on the surfaces of the butadiene-containing polymers, BR and SBR; (3) no detectable functionalization by TCICA takes place on EPDM or CIIR — polymers which lack sufficient olefinic sites for surface modification; (4) isocyanuric acid or other nitrogenous residues are present on treated surfaces before washing; (5) reconstruction of functionalized surfaces may occur upon swelling for extended periods; (6) surface oxygen levels in these experiments were variable, and could not be relied upon as indicators of the functionalization chemistry.