The Protection of Rubber against Atmospheric Ozone—Cracking

The cracking of rubber by atmospheric ozone is now a well-known phenomenon and for a number of years rubber scientists and technologists have devoted considerable effort to combating it. While the differences of opinion and the confusion of data in this work are sometimes more conspicuous than the successes, nevertheless, there has been considerable success. In spite of the existence of large areas of uncertainty, much progress has been made. A new word, “antiozonant”, has been added to the vocabulary of the rubber man. The substances so designated, together with waxes already well known, enable the compounder to protect natural and synthetic rubbers against both static and dynamic exposure to a fair degree, and this in spite of the fact, now recognized, that certain urban atmospheres may contain much higher concentrations of ozone than were formerly considered normal. In addition, the synthetic polymer chemist has made available a number of commercial rubbers which, because they are saturated, are not at all vulnerable to ozone attack, and serve in many special applications in which extreme resistance to ozone is necessary. The purpose of this paper is to review the present status of the antiozone work.