THERMAL-OXIDATION OF EPDM TERPOLYMER AND VULCANISATE

Thermal ageing tests were made in the range 110-160-degrees-C, on an ethylene-propylene-hexadiene terpolymer and with a filled, stabilised and vulcanised industrial rubber based on it. Carbonyl build-up, weight loss, density, chemiluminescence and removable fraction kinetic curves reveal an induction period whose duration is almost independent of the measurement method. These results suggest that the hypothesis of spatially heterogeneous (at small scale) oxidation is to be rejected in this case. They reveal the interest of density measurement for the detection of the end of the induction period, and the fact that variations of the soluble fraction -are due to changes of the solubility parameter rather than to changes of the molecular weight/crosslink density.