Dilatometric measurement of the rate of vulcanization of crêperubber by sulphur monochloride.

Abstract

THE ‘cold’ vulcanization of rubber by sulphur monochloride is believed to consist essentially of the cross-linking of adjacent poly-isoprene units by a series of sulphide bonds. Chemical analysis of the product1 suggests that the cross-linking process is analogous to the ‘mustard gas’ reaction of ethylene with sulphur monochloride; thus, Nothing is known, however, about the kinetics of this vulcanization process. General considerations lead one to expect that such a reaction, involving polymer aggregation, should be accompanied by an increase in the density of the rubber; moreover, by choosing a suitably delicate technique, it should be possible to utilize such density changes for rate-determinations. A dilatometric method seemed most suitable, and the experiments described here show that the vulcanization process is, indeed, accompanied by a decrease in volume of the reaction mixture, and that the reaction may be followed quantitatively using a tap-dilatometer2.