DSC study of the interaction of 2‐mercaptobenzothiazole, sulphur, ZnO and stearic acid in the absence of rubber

Abstract

AbstractThe interactions between mixtures of 2‐mercaptobenzothiazole (MBT), sulphur, ZnO and stearic acid were studied by DSC in the absence of rubber. MBT was thermally stable up to its melting point of 174°C, but molten MBT reacted with ZnO as well as with molten zinc stearate, to form zinc mercaptobenzothiazole (ZMBT). The reactions did not go to completion, presumably as further reaction was hindered by solid ZMBT which was thermally stable up to its melting point of 330°C. MBT dissolved in molten sulphur and no thermal events that could be attributed to MBT/sulphur interaction were detected. A mixture of MBT/sulphur/ZnO heated to 190°C yielded ZMBT, together with residual MBT and sulphur (residual ZnO was not measured). In a mixture of MBT/ZnO/stearic acid, the formation of zinc stearate occurred at a lower temperature than in the absence of MBT and preceded the formation of ZMBT.