Abstract
Apparent dynamic moduli S and loss moduli S of various raw diene rubbers were determined on the basis of measured torque S* and loss angleδat6cpm of frequency and±3degrees of amplitude, using the Curelastometer, i. e., oscillating die curemeter.The experiments yielded the characteristic relationship between S and S for the respective rubbers.
The moduli S, S and stress relaxations of cis-1, 4-polybutadiene stocks were also determined continuously in the process of vulcanization. Curing systems used were dicumyl peroxide (DCP), tetramethylthiuramdisulfide-zinocx ide (TT-ZnO) and diphenylguanidine-suefur (DPG-S). The moduli S increased with an increasing crosslink densityνdetermined by equilibrium swelling measurements. The values of S also increased with the progress of vulcanization, but gave maximum value at definit ν, beyond which S decreased with an increasing the crosslink density.The relation was influenced by the type of curing system, and S increased in the order of DPG-S>TT-ZnO>DCP at the same νvalues in the range of S≤20 kg-cm.
The DCP vulcanizate showed the lowest relaxation, but relaxed to some extent at lower range of ν.
Some discussions were made on these results in connection with the structure of the crosslinks.
