Effect of incompatible substances on the thermal stability and decomposition products of 2,2-azobisisobutyronitrile and 1,1′-azobis(cyclohexanecarbonitrile)

Abstract

2,2-Azobisisobutyronitrile (AIBN) and 1,1′-azobis (cyclohexanecarbonitrile) (ABCN) are two common azo initiators in the polymerization industry. In the chemical process, incompatible substances are commonly in contact with azo initiators. However, the thermal stability and decomposition process of azo compounds may change. In this study, the effects of common incompatible substances (hydrochloric acid (HCl), sodium hydroxide (NaOH), ferric oxide (Fe2O3), and water (H2O)) on the thermal stability and decomposition products of AIBN and ABCN were investigated. Thermal activity monitor IV (TAM IV) was utilized to investigate the thermal behavior of AIBN and ABCN industrial applications and storage processes. Several parameters such as the maximum peak power (Qmax), time to maximum rate under isothermal conditions (TMRiso), and heat of decomposition (ΔHd), were used to evaluate the effect of incompatible substances on the thermal stability of AIBN and ABCN. The results show that HCl will significantly reduce the thermal stability of AIBN and ABCN and increase the thermal risk in industrial applications. Accelerating rate calorimeter (ARC) was utilized to simulate the thermal runaway of the industrial application process. The real thermal runaway behavior was obtained by correcting the ARC experimental data with thermal inertia (φ). The decomposition products affected by incompatible substances were explored by Fourier transform infrared spectrometer (FTIR). After AIBN or ABCN were mixed with the incompatible substances, in addition to the free radicals and nitrogen generated, there may be 2-propenenitrile, 2-methyl-, hydrazinecarboxamide, and 4-cyano-1-cyclohexene. The process safety parameters can provide a valuable reference for industrial loss prevention.