THERMAL OXIDATIVE-DEGRADATION OF AES

Abstract The thermal oxidative degradation of an AES blend formed by a mixture of ethylene-propylene-diene (EPDM) rubber, styrene-acrylonitrile (SAN) copolymer and SAN grafted on EPDM chains has been investigated both in conditions of total volatilization and at temperatures below decomposition. During degradation, chemical interactions between the different polymeric structures take place, particularly in the case of the graft copolymer. Under decomposition conditions the effect of the interactions is the reduction of the overall volatilization rate. The oxidation reactions start on the EPDM chains at temperatures below those at which the formation of volatile compounds takes place, with a mechanism typical of hydrocarbon oxidation. Higher reactivity of EPDM has been found in the graft copolymer and attributed to the presence of the SAN chains attached to diene units. During oxidation, crosslinking takes place at the same time with chain scissions and partial destruction of the graft structure.