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W. M. Rzymski, M. Mikrut, J. Magryta, B. Wolska

Curing of acrylonitrile-butadiene rubber with tetraisobutylthiuram disulfide

Polimery 2005, No 10, 718



Summary

The results of vulcametric measurements (Fig. 1), equlibrium swelling, sol fraction content, network density (on the basis of elasticity constants) (Table 1) as well as of mechanical properties (Table 2 and Fig. 3) show that tetraisobutylthiuram disulfide (TiBTD), used by us, is effective curing agent for acrylonitrile-butadiene rubber (NBR) only in the presence of ZnO [equations (1)-(3)] and stearic acid as curing activators. NBR curing with TiBTD at temp. 433 K characterizes by "marching" modulus for stearic acid content <0.9 phr and by reversion for stearic acid content higher than optimal (>1.2 phr). At constant amount of ZnO (4 phr) the network density of a rubber cured with TiBTD (0.20 mol/kg of rubber) is a linear increasing function of stearic acid content in the blend (Fig. 2). Stearic acid presence increases the efficiency of TiBTD curing activity even 4-5 times. NBR curing is accompanied with bonding of some products of disulfide decomposition with elastomer [equation (4)]. NBR networks obtained with TiBTD in the presence of ZnO and stearic acid contain only mono- and disulfide cross-bonds while polysulfide bonds are missing.


Key words: acrylonitrile-butadiene rubber, curing, tetraisobutylthiuram disulfide, curing activators, zinc oxide, stearic acid


W. M. Rzymski, M. Mikrut, J. Magryta, B. Wolska
Curing of acrylonitrile-butadiene rubber with tetraisobutylthiuram disulfide