Chemorheology of irradiation-cured natural rubbers: 2. Stress relaxation mechanisms of sulphur-containing cured systems in air

摘要: Abstract Stress relaxation mechanisms in air were investigated for irradiation-cured natural rubbers (NR) containing the various levels of sulphur, relation to crosslinked structure. All stress curves these vulcanizates except sulphur-free sample sum two exponential terms. The rate long time region increased with increasing sulphur contents, spite having same initial chain density. This behaviour could be explained by introducing assumption, that this system has independent networks, i.e. one ( N p (O)) based on polysulphide cross-linkages and another c , m mono- di-sulphide linkages carbon—carbon bonds. (O) contents decreased contents. q t ) (the number moles main scission) agreement each other, However, value was larger than sample. similar tetramethylthiuram disulphide NR, which crosslinking sites consisted di-sulphides