FORMATION OF VULCANIZATION STRUCTURE OF RUBBER IN THE PRESENCE OF VARIOUS VULCANIZATION ACTIVATORS

Abstract

The in situ formation of active vulcanization agents (ДАВ) and the kinetics of vulcanization (КВ) of rubber compounds based on SKI-3 were studied in the presence of mercaptobenzthiazole (2-MBT) and various vulcanization activators. On the first stage, zinc mercaptide was synthesized by the reaction between zinc chloride and 2-MBT in the presence of excess NaOH. At the second stage, alloys of zinc mercaptide with stearic acid were obtained. Using a program created by Mathcad Software, the rate and cure constants: k₁ (curing induction) and k₂ (curing main process), the time of the induction period t_i, and the dissociation time of the ДАВ tdis were calculated. It has been concluded based on the difference in the dependences of t_i and k₂ on the initial concentrations of the accelerator, activator, and sulfur, that the reactions responsible for crosslinking and characterized by k₂ actually proceeded in isolation from those processes that occurred during the induction period. It was shown that the use of ДАВ in the form of pre-prepared alloys improves vulcanization properties and shortens the duration of vulcanization. It has been established that due to the permanent regeneration of the sulfurizing complexes during the curing process, the fraction of the introduced elemental sulfur increases, expended on the formation of crosslinks through vulcanization system. The use of such products in more active physical and chemical forms of zinc derivatives open the possibility for reduce zinc oxide amounts in comparison with zinc oxide itself.