Using dynamic and adiabatic methods for thermal hazard evaluation of styrene bulk polymerization initiated by AIBN

Polystyrene is a multifunctional plastic used to manufacture consumables with a wide range of applications. Some azo compounds can produce free radicals when heated, which can be used as initiators for styrene polymerization. However, thermal runaway could occur during the styrene bulk polymerization initiated by azodiisobutyronitrile (AIBN) due to the release of a large amount of heat. To obtain thermal hazard properties, differential scanning calorimetry (DSC) and accelerating rate calorimetry (ARC) were applied to this investigation. The DSC experimental results showed that the extrapolated onset temperature and exothermic peak temperature decreased gradually after adding the initiator, which indicated initiator AIBN promoted the polymerization. ARC experiment decoded dynamic thermal parameters such as apparent activation energy, adiabatic temperature rise, initial runaway temperature, maximum temperature and polymerization heat of the hybrid system. Finally, the experimental and calculation results showed that the heat released by the polymerization reaction was basically unchanged at different heating rates; as the initiator concentration increases, the heat released by the polymerization reaction also increases, the polymerization temperature is controllable below 35.1 ℃. These results are critical for reducing the risk of loss of control and designing intrinsically safer styrene production, storage and transport processes.