Abstract
The mechanism for crosslinking of various EPDM rubbers has not yet been clearly established, though the mechanism is assumed to be based on the recombination of two polymer radicals produced by the extraction of hydrogen from activated methylene, methyne or methyl groups neibouring the olefinic double bond in EPDM molecules. This study was intended to elucidate the crosslinking mechanism of three tyeps of EPDM, i. e., dicyclopentadiene, ethylidene norbornene, and 1, 4-hexadiene types by using an electron spin resonance spectrometer. The experimental procedure was based on the so-called spin trapping method by using 2, 4, 6-tri-tertbutylnitrosobenzene as a radical trapping agent and benzoyl peroxide as a radical initiator for EPDM in n-heptane solution to afford the molecular structure of polymer radicals. This study enables us to elucidate the moleculer structure of the crosslinking point. The difference hed seen the cure rates of the three types of EPDM was referred from the results.
