AbstractReplica electron microscopy has been used to elucidate the physical mechanisms by which various additives afford ozone resistance to natural rubber. There exist two classes of chemical antiozonants, namely, those that enhance the critical energy required for ozone cracking and those that retard the rate of crack growth; representatives of these two classes were used in the investigation. The process involved in the first of these protective mechanisms was found to be the formation at the exposed surface of an inextensible layer some 100 A. thick and inert to further ozone attack. That giving rise to rate retardation also involved the formation of a surface layer, but the layer was susceptible to further ozonolysis and, eventually, complete degradation.
展开▼
