Microscopic Studies on Degradation of the Cross-linked Polymers. (III)

Experimental Results for Vulcanized Natural Rubber

Abstract

Several samples of natural rubber vulcanizates were prepared. A and B samples are cured with sulfur, and C is cured with TMTD (tetramethyl thiuram disulfide) and D is natural rubber cured with peroxide.
The cross-linking densities, n (0), were measured for these four samples extracted with : acetone and unextracted. The values of n (0) calculated by the Flory-Rehner swelling method were compared with those obtained by the mechanical means.
The probabilities of the ratio of both scissions were indicated by k_A, k_B and k_c for three samples except D. The degradation of the polymer structures was discussed for the values of k_A, k_B, k_C obtained from the theoretical equation derived in the former paper.