Source Year: 1996

Ozone cracking in elastomers can be characterized by two parameters : a threshold condition and a characteristic rate of growth. Many chemical additives can reduce growth rate but the most potent also effectively raise the threshold by forming a protective layer on the surface. Elastomers that have relatively high glass transition temperatures, and hence high internal viscosity (which retards diffusion), such as nitrile rubber or epoxidized natural rubber, are found to be more difficult to protect than lower glass transition materials, such as natural rubber or styrene-butadiene rubber.