Thermal hazard evaluation conjoined with product analysis of two water-soluble azo compounds

Azo compounds are widely used in polymerization as an initiator for chain polymerization reactions. Although they have excellent initiating properties, the thermal instability and associated risk of ignition and explosion cannot be ignored. This paper aimed to decode the thermal behavior and evaluation thermal hazards of two water-soluble azo initiators 2,2′-azobis(2-methylpropionamidine) dihydrochloride (AIBA) and 2,2′-azobis(2-(2-imidazoline-2-yl) propane) dihydrochloride (AIBI). Thermogravimetric analysis and adiabatic experiments were used to investigate the decomposition process of these two azos under atmospheric and adiabatic conditions. The apparent activation energy ( E a ) and time to maximum rate under adiabatic conditions ( TMR ad ) were obtained based on above experiments. Decomposition products and mechanisms of AIBA and AIBI were preliminarily studied using a thermogravimetric analyzer coupled with Fourier transform infrared spectrometer system. Results showed that most decomposition products of AIBA and AIBI still existed in the form of organic compounds under nitrogen conditions. Furthermore, the leakage of pyrolysis gas (such as ammonia) should be prevented from causing environmental pollution.