Thermal analysis and pyrolysis products analysis of 4,4′-azobis (4-cyanovaleric acid) by using thermal analysis methods and combination technology.

4,4′-Azobis (4-cyanovaleric acid) (ACVA) is known as a kind of water-soluble azo initiator which was widely used in the radical polymerization process. As same as other azo compounds, ACVA may also trigger thermal runaway accidents at high temperatures due to its specific –N=N– structure. To qualify its pyrolysis characteristics, thermogravimetric analysis and differential scanning calorimetry were applied to this investigation, moreover, the TGA-FTIR combination technology was used in the product analysis part. The results showed that ACVA has a complex decomposition process, there are four mass loss stages during its pyrolysis, the heat release mainly occurred in the first and final decomposition stage and the heat flux in the middle stages was very disordered. Different decomposition stages were accompanied by different decomposition products, and some of them were considered toxic, such as HCN and CH4. Thermokinetic parameters such as apparent activation energy (Ea) were also calculated in this paper by using Kissinger–Akahira–Sunose (KAS) method. Surprisingly, ACVA has the lowest Ea (91 kJ mol⁻¹) and the highest heat release (4706 J g⁻¹) compared with some commonly used azos, which means it will more easily suffer a serious runaway accident. All these studies can give us a comprehensive understanding of the thermal decomposition of ACVA to prevent accidents. [ABSTRACT FROM AUTHOR]

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