Cure Modification Effected by 2-Iminothiophthalimides in the Vulcanization of NR Accelerated by Thiocarbamyl Sulfenamides and Dibenzothiazyl Disulfide

Abstract

Abstract Studies have been made on the effect of N-oxydiethylene thiophthalimide (ODTP) and N-cyclopentamethylene thiophthalimide (CPTP) as retarders in the vulcanization of NR. N-oxydiethylenethiocarbmyl-N′-cyclopentamethylene sulfenamide (OTCS) and N-oxydiethylene thiocarbamyl-N′-oxydiethylene sulfenamide (OTOS) have been used separately with MBTS to form the binary systems of accelerators. Retardation exhibited by the combinations OTCS-MBTS-ODTP and OTOS-MBTS-CPTP is noteworthy. In these systems, both CBDS and OBDS are formed. The enhanced activity with regard to torque, scorch, modulus, tensile strength, etc. is believed to be due to the presence of CBDS and OBDS. Probable reactions for the formation of various compounds responsible for acceleration and retardation of vulcanization of NR have been explored. It has been observed that ODTP and CPTP provide better cure-retardation than CTP and in almost all the cases, the cure rate and torque values of the resulting vulcanizates are increased. In the case of filled vulcanizates containing HAF, it seems that the nature of the reaction is of the same kind as observed in the case of gum stocks but differs only in degree. The physical data of the vulcanizates containing HAF also indicate that both ODTP and CPTP excel CTP in many respects.