Rubber-sulphur reaction moulding

On heating a chemical reaction took place between the rubber and sulphur which resulted in production of tough elastic rubber that retained its moulded shape. Natural rubber is plastic in nature while vulcanised rubber is elastic. This vulcanisation process led to a rapid development of rubber industry. 

The cure and tensile properties of sulphur vulcanised styrene-butadiene rubber filled with a conventional furnace black or a fluorinated black have been determined. Compositions with the fluorinated black and normal curative levels exhibit retarded cure compared to corresponding ones with the furnace black. This is due to a reaction between the sulphenatnide accelerator and the fluorinated black. Notwithstanding, a fluoro-filled composition with no curatives substantially crosslinks when moulded at 150 deg.C. Thus, fluoro-black filled specimens have competing effects toward crosslinking. On the one hand, crosslinking is inhibited by reaction with the accelerator, while on the other, the fluoro-black itself can cause crosslinking. 2 refs. 

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