OXIDATIVE-DEGRADATION OF EPDM RUBBER USING PHASE TRANSFERRED PERMANGANATE AS OXIDANT

Oxidative degradation of ethylene propylene diene (EPDM) rubber containing varying amounts of ethylene units has been carried out using phase-transferred permanganate as oxidant. The oxidised products have been characterised by IR spectroscopy. The degradation behaviour of EPDM rubbers has been studied by thermogravimetry in air. A comparison of the IR spectra of EPDM and oxidised EPDM confirms the appearance of new peaks near 1735 cm-1 due to the [GRAPHICS] stretching vibration, which may arise from carboxyl, ester or ketone groups. Nonaqueous acid-base titration confirms the presence of carboxyl groups in oxidised EPDM. The onset temperature of oxidative degradation as determined by differential scanning calorimetry shows that T(onset) values decrease significantly on oxidation. The measurement of glass transition temperature (T(g)) suggests an increase in T(g) due to oxidation. Scanning electron microscopy (SEM) observations indicate surface roughening due to oxidation.