Effects of incompatible substances on the thermal stability of dimethyl sulfoxide

•DMF, NaOH, KBr and FeCl3 were chosen as incompatible substances.•Thermal stability of DMSO mixed with above substances was studied using ARC.•Hazard indicators were obtained.•Decomposition mechanism was discussed.

Thermal decomposition of pure dimethyl sulfoxide (DMSO) and DMSO in the presence of different incompatible substances including N,N-dimethyl formylamine, NaOH, KBr and FeCl3 were investigated using accelerating rate calorimeter. Hazard indicators such as onset temperature Tonset, adiabatic temperature rise ΔTad, maximum pressure Pmax at Tfinal, residual pressure Presidual at 50 °C, maximum rate of pressure-rise (dP/dt)max and self-heating rate (dT/dt)max have been determined directly. Activation energy Ea of decomposition reaction and time to maximum rate TMRad of pure and impure DMSO have been studied from the measured self-heating rate data by assuming a zero-order reaction. Moreover, the decomposition mechanisms of pure and impure DMSO have also been discussed.