Use of sulfur bearing rubber accelerators for curing polyacrylic rubber in presence of metal oxides.

Abstract

Studies of vulcanizate properties of polyacrylic rubber (Nipol AR 51) with metal oxides and S-accelerators are made with a view to elucidate the vulcanization mechanism. The used S-bearing accelerators are ethylene thiourea (I), mercaptobenzothiazole (II), dibenzothiazyl disulfide (III), tetramethylthiuram disulfide (IV), zinc diethyldithiocarbamate (V), N-cyclohexylbenzothiazyl sulfenamide (VI), N,N-dicyclohexylbenzothiazyl sulfenamide, N-oxydiethylene benzothiazyl sulfenamide (VII), and N-tert-butylbenzothiazyl sulfenamide (VIII). From rheograms it is obsd. that VI/PbO cure system gives the highest state of rate of cure. VII and VIII give comparable state of cure with II, III, and I systems in presence of PbO. IV and V are less active than others. Sulfenamides are not influenced by methylenedianiline while others are influenced remarkably. Formation of PbS and PbCl2 in the vulcanizate are confirmed by x-ray diffraction patterns and XPS. Ether type of crosslink was confirmed by IR spectra anal. Based on the expt. results a mechanistic scheme was put forward. [on SciFinder(R)]