Studies on the reactions between thiocarbamyl sulfenamide and 2‐(iminodithio)benzothiazole accelerator system in the early stage of vulcanization of NR

Abstract

AbstractInvestigations on the interactions of the synergistic pair of accelerators comprising of thiocarbamyl sulfenamide and 2‐(iminodithio)benzothiazole have been carried out through hplc. N‐cyclopentamethylene thiocarbamyl‐N'‐oxydiethylene sulfenamide, N‐oxydiethylenethiocarbamyl‐N'‐cyclopentamethylene sulfenamide (OTCS), 2‐morpholinodithiobenzothiazole, and 2‐piperidinodithiobenzothiazole (PDB) have been selected as the reactants which, when suitably combined, provide most effective accelerator systems capable of generating heat and age resistant vulcanizates. The OTCS–PDB system has been found to yield vulcanizates which exhibit the greatest crosslink density, scorch safety, and highest modulus and tensile strength. An attempt has been made to explain the higher activity of the binary systems studied as compared to that obtained from comparable thiocarbamyl sulfenamide plus dibenzothiazyl disulfide system. Zin–dithiocarbamates have been found to influence the curing reactions depending upon the composition of the mixed accelerators. Cyclohexyl thiophthalimide, a versatile cure retarder, reacts with the accelerators to yield cyclohexyl thiomorpholine and cyclohexyl thiopiperidine, as the case may, which also have a profound effect upon cure retardation as noticed in the present investigation.