Correlation of crosslink density with pyrolysis pattern of natural rubber vulcanizates with efficient vulcanizing cure system

Correlation between the crosslink density and the product ratio of isoprene dimer species to isoprene formed from pyrolysis of NR vulcanizates was studied using pyrolysis-gas chromatography (pyrolysis-GC). The major products of the isoprene dimer species were 1,4-dimethyl-4-vinylcyclohexene and 1-methyl-4-(1-methylethenyl)-cyclohexene formed from natural rubbers having head-to-head and head-to-tail linkages, respectively. It was found that the relative abundance ratio of the isoprene dimer species to the isoprene decreased in proportion to an increase of the crosslink density of the vulcanizate. (C) 1999 Elsevier Science B.V. All rights reserved.