the performance of natural rubber based products , such as engine mounts which are susceptible to degradation caused by heat , oxidation , ozone attack or ultraviolet radiation is significantly improved by coating exposed surfaces of the product with a polymeric material having excellent heat and oxidation resistance properties . by applying such polymeric coatings having high resistance towards oxidation under excessive heat , the c ═ c bonds of the natural rubber are protected from oxygen and ozone attacks , thereby allowing its strain - crystallization characteristic properties to be retained .