| Azo compounds refer to a class of compounds with azo bonds(–N=N–)in their molecules.They are widely used in industrial production and are often used as initiators for free radical polymerization.In addition,they can also be seen in dye,liquid crystal and even food additive industries.The azo groups of azo compounds will break under the action of light and heat,which is also the reason why they are used in the polymerization industry.However,a large amount of gas and reaction exothermic come with the rupture of azo bond,which often makes azo compounds face the danger of combustion and even explosion.Therefore,it is of great significance for the safety production of chemical enterprises to study the thermal safety of azo compounds,speculate their safe use temperature,understand their decomposition mechanism,and classify their ignition and explosion hazards.Azo compounds can be divided into oil–soluble compounds and water–soluble compounds according to their solubility.As a new generation of products,water-soluble azo compounds are not only better than the old ones in initiating efficiency,but also can be used in more production environments,so their use proportion has gradually increased.However,since most water-soluble azo is still in the research and development stage,its thermal safety problem is still unclear,and few people have carried out a complete thermal safety analysis on it,and the relevant research mainly focuses on their synthesis and application.In order to fill the research gap in this direction,this paper selects three water-soluble azo compounds commonly used in domestic factories,namely,2,2’-azobis(2-methylpropionamidine)dihydrochloride(AIBA),2,2’-azobis(2-(2-imidazoline-2-yl)propane)dihydrochloride(AIBI),and 4,4’-Azobis(4-cyanovaleric acid)(ACVA),and uses a variety of thermal analysis technologies to conduct a comprehensive assessment of their thermal stability,thermal hazards,pyrolysis mechanism,and other aspects,and compares the thermal hazards of three water-soluble azos by grades,provide relevant thermal safety parameters to give valuable reference for the safety production of chemical enterprises.The study starts with the thermal stability of three water-soluble azos.The weight loss process of the sample is analyzed by thermogravimetric analyzer,and the extrapolated initial decomposition temperatures are 166 ℃,194 ℃,125 ℃(AIBA,AIBI,ACVA)respectively.Combined with the detection results of differential scanning calorimeter and the relevant contents of dynamic analysis,it can be determined that the thermal stability of the three water-soluble azones from high to low is AIBI,AIBA,ACVA.The runaway reaction of the sample was studied through the adiabatic experiment,and it was found that all the three azos could undergo self-accelerating decomposition reaction,and had extremely high thermal hazard,which belonged to Grade Ⅲ unacceptable risk.Among them,the out of control of ACVA also directly led to the error and shutdown of the instrument.The product analysis experiment recorded the main decomposition products of three kinds of azo during thermal decomposition,inferred their possible pyrolysis mechanism,and graded the hazards of decomposition products.Many products have explosion and health risks.It is necessary to properly handle the accident site after the disaster to avoid secondary injury.In this study,several thermal analysis techniques were used for the first time to study the thermal decomposition of three water-soluble azo compounds,and their stability,thermal hazard and pyrolysis mechanism were systematically summarized,which has guiding significance for the subsequent research on thermal safety of water-soluble azo compounds and the synthesis of new azo compounds.Figure 38 Table 17 Reference 106... |
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