The Long-Term Effectiveness of Chemical vs. Polymeric Antiozonants in Rubber.

摘要

Chemical and polymeric (EPDM) antiozonants were evaluated in unsaturated elastomers. Vulcanizates inhibited with chemical antiozonants were found to have taken a pronounced set after five years or more of outdoor exposure at Rock Island, Illinois, and exhibited no ozone resistance when restressed and reexposed to ozone. Vulcanizates inhibited with polymeric antiozonants also took a pronounced set in certain cases (depending upon the type of curing system employed), but all peroxide or sulfur-accelerator-peroxide cured vulcanizates retained their ozone resistance when restressed and reexposed to ozone. Polymeric antiozonants have proved to be more effective than the chemical type in those instances where chemical antiozonants function poorly or not at all. When certain unsaturated elastomers are blended with a fast-curing EPDM (FC-EPDM) and a sulfur-accelerator-peroxide-curing system is employed, stress-strain properties equivalent to those of the unsaturated elastomer alone can be obtained.