Solubility study of curatives in various rubbers

The previous works on solubility of curatives in rubbers were mainly carried out in natural rubber. Not too much information available on dissimilar rubbers and this is important because most of the compounds today are blends of dissimilar rubbers. Although solubility can be expected to certain level by the previous studies, the current work provides a much precise view in the solubility behavior of curatives. Solubility of sulphur and several accelerators N-cyclohexylbenzothiazole-2-sulphenamide (CBS), N-dicyclohexylbenzothiazole-2-sulphenamide (DCBS), and 2-mercaptobenzothiazole (MBT) is measured in dicumyl peroxide vulcanised Styrene-Butadiene rubber (SBR), Acrylonitrile-Butadiene rubber (NBR) and Ethylene-Propylene-Diene rubber (EPDM) rubber at room temperature and at 60 °C. The experimental results can be correlated with the calculated solubility parameters δ  , as determined using the method of Hoftijzer and Van Krevelen. Results of Δ¯δ are used to judge the solubility of curatives in a specific rubber in blends.