Study On Thermal Hazards Of Oil-soluble Azo Initiators

Azo compounds are always used as initiators and blowing agents.They are also typical self-reactive materials, which are capable of undergoing runaway reaction due to its self-heating during storage or transportation, which can cause serious accidents on fire and explosion. In order to ensure thermal safety of Azo initiators in the process of production, transportation, storage and usage, the most commonly used oil-soluble azo initiators, azobisisobutyronitrile(AIBN), azobismethybutyronitrile(AMBN), azobisdimethylvaleronitrile (ADVN) and dimethyl azobisisobutyrate(AIBME), are selected to research.Firstly, thermal decomposition characteristics of the four substances in nonadiabatic system were measured by using differential scanning calorimeter (DSC), and the variation of the kinetic parameters was calculated and revealed by isoconversional methods. Secondly, thermal decomposition characteristics of the four substances under adiabatic condition were measured by using accelerating rate calorimeter (ARC), and their explosion risks were compared. At last, based on Semenov and Frank-Kamenetskii theoretical models, by using the kinetic and thermodynamic parameters of ARC and the characteristic parameters and dimensions of25Kg standard packaging material, the self-accelerating decomposition temperatures were extrapolated in the case of both depletion ignored and depletion included.The results show that either in nonadiabatic system or adiabatic system, the exothermic decomposition reaction takes place parallel with the endothermic melting in the initial stage of the thermal decomposition reaction of AIBN, while the other three substances decompose in liquid phase completely. The decomposition reactions of the four substances are very complex, and do not follow a single reaction mechanism. The self-accelerating decomposition temperatures are all below50℃, so in the actual process of production, usage, storage and transportation, it is essential to strengthen temperature monitoring and take effective measures to cool them to the actual conditions. What is more, depletion has little influence on the self-accelerating decomposition temperatures and the depletion can be ignored.