Prevulcanization Inhibitor the Chemistry of Scorch Delay

Abstract

Abstract Sulfenamide accelerators serve to perform two functions. They provide the necessary time period required to mix, process and shape rubber compounds. This portion of the overall vulcanization process is usually referred to as scorch delay. In addition, sulfenamides function as accelerators, in that once the crosslinking process has begun, they speed up this reaction. The delay period occurs because the sulfenamide must be converted to polythiobenzothiazoles, the precursors to crosslinking, before crosslinking can take place. The overall reaction of sulfenamide with sulfur is an autocatalytic process with MBT the autocatalyst. The role of PVI in this scheme is to remove MBT from this autocatalytic sequence of reactions, thus delaying those reactions which preceed crosslink formation.