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

Oxidative degradation of ethylene propylene diene (EPDM) rubber contai ning varying amounts of ethylene units has been carried out using phas e-transferred permanganate as oxidant. The oxidised products have been characterised by IR spectroscopy. The degradation behaviour of EPDM r ubbers has been studied by thermogravimetry in air. A comparison of th e 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 differ ential scanning calorimetry shows that T(onset) values decrease signif icantly on oxidation. The measurement of glass transition temperature (T(g)) suggests an increase in T(g) due to oxidation. Scanning electro n microscopy (SEM) observations indicate surface roughening due to oxi dation.