Vulcanization of Elastomers. 46. The Kinetics of Crosslinking

Abstract

Abstract The present article represents a first contribution to the investigation of the crosslinking kinetics of 1,5-polyenes, with sulfur as the vulcanizing agent. It is principally concerned with working out the pertinent methodology, and hence is a report on our experience with the “Agfa Vulcameter” (also called the Bayer Vulcameter). Using as an example the zinc benzothiazolyl mercaptide (ZnMBT)/zine stearate accelerated vulcanization of natural rubber with sulfur, which in any case runs with practically no reversion at moderate temperatures, and thus permits an experimental determination of the crosslinking end-values, we were able to show that crosslinking can be described quantitatively and qualitatively with the help of an Agfa Vulcameter. It was proved that the same reaction order and the same rates are obtained, as when the static modulus is used as the criterion for crosslinking. The scientific and practical importance of the results are pointed out.