Page 254 - Handbook of Plastics Technologies

ELASTOMERS

4.46 CHAPTER 4

SCHEME 16

canization of CR is somewhat in doubt since it is a suspected carcinogen. A mechanism
for ETU acceleration is shown in Scheme 16.
Examples of recipes for metal oxide vulcanization are given in Table 4.8. It should be
noted that, in one case, calcium stearate was used instead of magnesium oxide to obtain
better aging characteristics.

4.5.1.10 Vulcanization by the Action of Organic Peroxides. Peroxides are vulcanizing
agents for elastomers, which contain no sites for attack by other types of vulcanizing
agents. They are useful for ethylene-propylene rubber (EPR), ethylene-vinylacetate copol-
ymers (EAM), certain millable urethane rubbers, and silicone rubbers. They are not gener-
ally useful for vulcanizing butyl rubber, poly(isobutylene-co-isoprene). Elastomers
derived from isoprene and butadiene are readily cross-linked by peroxides, but many of

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