Thermal hazard analysis of the dual initiator-initiated styrene polymerisation with ethylbenzene as diluent

Styrene polymerization is a strong exothermic reaction, where the reactants, initiators and diluents are flammable and explosive substances. Once the reaction is out of control, it is extremely easy to cause fire and explosion accidents. In order to analyze the thermal hazards of styrene polymerization reactions, the thermal behaviors of reactions at different reaction conditions are investigated in this paper. Differential scanning calorimeter (DSC) and adiabatic rate calorimeter (ARC) were used to study thermal behavior of styrene polymerization reactions initiated by dual initiators (azodiisobutyronitrile/tert-butyl peroxybenzoate) with different ratios. Reaction calorimetric experiments were performed via reaction calorimeter (RC1e) to analyze the process hazard and calculate thermal hazard parameters. Subsequently, the thermal decomposition properties of the polymerization products were studied by simultaneous thermal analyzer (TGA–DSC). Moreover, the apparent activation energy (E_a) during product decomposition was calculated by Starink and Friedman methods. The results show that the presence of initiators increases the risk of thermal runaway of the reaction. The thermal hazard of styrene polymerization can be reduced due to the addition of ethylbenzene. The most serious consequences of thermal runaway were caused at an early stage. It can be concluded that the reaction of the system containing AIBN initiator reacts at a lower temperature, while the reaction of the system with TBPB is relatively lagged. This study is valuable for the selection of initiator in the polymerization reaction process.