Thermal Hazard Assessment of TBPB-Initiated Styrene Polymerization via Calorimetry, Kinetic Analysis, and Thermal Safety Software Simulation

Styrene polymerization is highly vulnerable to thermal runaway because of its strong exothermicity, viscosity increase, and deterioration of heat transfer during reaction. The thermal hazards of tert-butyl peroxybenzoate (TBPB) and TBPB-initiated styrene polymerization were investigated by differential scanning calorimetry (DSC), accelerating rate calorimetry (ARC), kinetic analysis, and Thermal Safety Software (TSS). The effects of TBPB dosage on runaway triggering, acceleration, and storage safety were evaluated using styrene/TBPB systems with mass ratios of 100:1, 100:2, and 100:10. Results showed that the addition of TBPB significantly increased the triggering sensitivity of styrene polymerization. Under adiabatic conditions, the exothermic onset temperature decreased from 105 °C for pure styrene to 75 °C for all TBPB-initiated systems. With increasing TBPB dosage, the time to maximum rate under adiabatic conditions (TMRad) decreased markedly, indicating a shorter intervention window during runaway development. Although the total heat release of the initiated systems changed only slightly, the high-dosage system exhibited more complex exothermic behavior, suggesting stronger coupling between initiator decomposition and styrene polymerization. TSS simulation further indicated that overheating could lead to severe runaway risk during storage and transportation. These results show that TBPB mainly reduces the thermal safety margin of styrene polymerization by lowering the runaway onset temperature and accelerating the runaway process.