Study of vulcanization and degradation chemistry in natural rubber by solid-state C-13 NMR and physical property measurements

摘要

Sulfur-vulcanization and heat aging of natural rubber was investigated by solid-state C-13 NMR along with the measurements of physical properties.C-13 NMR detects all of the sulfurization occurring in natural rubber network including inter-and intra-molecular crosslink and pendant linkages,while physical measurements such as modulus at small strain and equilibrium swelling postulate only an amount of physically effective crosslinks.By comparing those two approaches,the efficiency of sulfur bonding in contributing to physical strength can be determined.It was found that the efficiency became lower for the samples with higher curing temperature,longer cure time,and also at higher sulfur level.