Explosion mechanism of azobisisobutyronitrile doping with sodium bicarbonate modified dry water

Abstract

Azobisisobutyronitrile (AIBN) plays a key role as a typical initiator or a foaming agent in the industries of plastics, pharmaceuticals and semiconductors. The autocatalytic property and high instability of AIBN make it risky to explode when subjected to heat. In this paper, the explosion characteristics and mechanism of AIBN dust were thoroughly investigated. During the explosion process, two carbon‑hydrogen bonds are broken and release N₂ leading to a rapid increase in explosion pressure. The optimum concentration of AIBN is 600 g/m³, at which time the P_max is 735.51 kPa and the (K_st)_max is 173.02 bar·m/s. In order to effectively inhibit the explosion of AIBN, SiO₂ and NaHCO₃ were selected as coating materials to develop a novel inhibitor modified sodium bicarbonate dry water powder (SBDW). When the concentration reached 400 g/m³, it was able to completely inhibit the explosion of AIBN. The kinetic model of AIBN/SBDW/air explosion reaction was constructed to reveal the key free radical mechanism of NaHCO₃ capturing AIBN combustion and explosion process. Considering the chemistry, inhibitors can hinder the combustion and explosion reaction of AIBN by despoiling H, O and OH. A novel insight into the characteristics and inhibition of AIBN dust explosion was provided, and is of great value for the safe application of azo compounds.