Organic Sulfides as Vulcanizing Agents of Rubber

Abstract 1. It has been demonstrated that a number of organic sulfides possess the property of breaking down under vulcanizing conditions in a rubber compound to produce a cure. 2. Although several scores of sulfur-containing organic compounds other than those discussed in this paper or described in other papers have been tested, as yet there appear possible no generalizations to serve as a guide to further exploratory studies. 3. Organic sulfur compounds which are unstable under temperature conditions higher than normal do not liberate all of their sulfur in all cases. 4. Organic sulfur compounds employed alone as vulcanizing agents usually produce slower-curing rubber stocks than does sulfur, and at the same time lessen greatly the tendency of the stock to scorch. 5. Stocks of satisfactory physical properties, superior aging characteristics, and outstanding freedom from scorchiness are obtained by the use of a fractional part of the normal sulfur requirement together with a sulfur liberator. 6. Morpholine disulfide is a good example of a sulfur liberator, and exhibits its greatest effects in conjunction with a mercaptobenzothiazole type accelerator. 7. Morpholine disulfide gives satisfactory cures when used in place of sulfur in natural rubber, GR-S rubber, and Hycar-OR, but gives slow cures in GR-I rubber.