The effect of the nature of cross-links on stress-relaxation and elastic deformations of α-methyl styrene-butadiene vulcanizates

Six systems were employed to vulcanize α-methyl styrene-butadiene rubber SKMS-30, viz. sulphur-MBTS + DPG, sulphur-DEBTSA, sulphur-Zn dimethyl dithiocarbamate, sulphur-MBT, TMTD. and p-tert-butylphenol-formaldehyde resin-chlorosulphonated polyethylene. The resulting vulcanizates had good physicomechanical properties.The natures of the network structures formed by these vulcanizing systems were evaluated by stress-relaxation experiments at 130 in air. TMTD and phenolic resin form the most rigid networks. while sulphur-MBTS + DPG forms the most flexible one.Rubber samples vulcanized with different systems were subjected to a compression of 20% of the initial sample height for fixed periods at 100 and 130°. The instantaneous and retarded elastic recoveries were determined. The relation between the nature of the network structure and elastic recoveries of the rubber vulcanizate are discussed.