ESR-INVESTIGATIONS OF THE THERMAL-OXIDATIVE AGING IN SBR

The thermal-oxidative aging of technical SBR vulcanizates was characte rized and monitored in ESR experiments. Under the thermal load the for mation of a long-lived radical species was observed. Different individ ual processes which superimposed to the complex aging process were inv estigated with respect to their dependence on temperature, crosslink d ensity, filler content and antidegradants. The thermally induced recom bination of radicals proved to be independent of crosslink density and carbon black content. The thermal-oxidatively induced formation of ra dicals followed two successive mechanisms. The first exhibited a stron g temperature dependence, the second was substantially affected by the variation of crosslink density.