Epoxidation reaction of natural rubber: kinetic parameters and mathematical models

Abstract Epoxidized natural rubber (ENR) is commonly used to improve durability, abrasion resistance and grip, and to increase compatibility with fillers for industrial products. They are increasingly used in the fields of green tire manufacturing, composites, adhesives and sealants, waterproofing and insulation, and medical equipment. The study aimed to determine the model and kinetic parameters of the epoxidation reaction of natural rubber using hydrogen peroxide and formic acid to generate peroxyformic acid in situ as an oxidizing intermediate, and formic acid acts as a catalyst. Using 10% 4-(2,4-dimethylheptan-3-yl) phenol (NP9) helps to stabilize the rubber latex and prevent coagulation at a pH of 4.7. The study assessed the interactions of species in a simultaneous multi-reaction system and developed mathematical models to describe the kinetics of the simultaneous multi-reaction system for the epoxidation of natural rubber, determining the reaction rate constants for the two peroxoacid stages (k 1 = 0.57 h −1 , k −1 = 0.44 h −1 ) and the formation of epoxides from performic acid (k 2 = 5.05 L · mol −1 · h −1 ) . The results obtained are the basis for research on the synthesis reaction of new material ENR-Silica applied in the production of “green” tires.