Diffusion of Sulfur in Rubber in Relation to Vulcanization

Abstract The present work is a report concerning the diffusion of sulfur in rubber. Following a suggestion of Prof. W. Seith, it was originally planned to investigate only the diffusion of radioactive, bound sulfur. If such a diffusion took place at all, it would seem to be equivalent to a wandering of the sulfur bridges which crosslink the carbon chains of the polymerized isoprene molecules in the vulcanizate and impart elasticity to the rubber. However, since the sulfur bridges are not exactly defined, and other types of combined sulfur can be present in the rubber, such a conclusion is not quite justified. Before such measurements are undertaken, one should be familiar with the diffusion of free sulfur in the rubber. Furthermore, a possible thermodynamic equilibrium between the free and the bound sulfur might invalidate the measurements. It was thus necessary to first determine the possibility of the occurrence of this equilibrium as well as the rate at which it is established. The diffusion experiment...