Dissertation > Industrial Technology > Chemical Industry > Basic Organic Chemistry Industry > The production of various types of organic compounds ( . 技) > Nitrogen compounds

Study on Preparation and Modification of Azodicarbonamide

Author ZhaoMeiJie
Tutor PanWang
School Hebei University of Technology
Course Hebei University of Technology
Keywords Hydrazine hydrate Biurea Azodicarbonamide PVC resin Inorganic nanopowder Complex foaming agent
Type Master's thesis
Year 2011
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Azodicarbonamide (trade name : foaming agent ADC) is a non-toxic , tasteless , non-polluting , orange - yellow azo blowing agents , its biggest feature is a molecule containing -N = N- structure , Heating may release large amounts of N2 gas evolution up to 200 ~ 250 ml / g, a widely used chemical foaming agent . Currently, the synthesis process of the azodicarbonamide is mainly synthesized by the condensation of hydrazine hydrate by the acid method biurea , biurea synthesized by oxidizing agent azodicarbonamide . Acid prepared biurea to adding large quantities of sulfuric acid in the reaction system to adjust the pH value is acidic , severe corrosion of the equipment , are difficult to recover and dispose of ammonium sulfate generated . With hydrochloric acid to adjust a pH of the hydrazine hydrate solution weakly alkaline , rather than adjusting the pH value of the reaction system , and reduces the amount of hydrochloric acid . Also studied using high concentrations of hydrazine hydrate and the direct synthesis of Urea biurea process , this process does not use an acid , the corrosion of the equipment smaller , friendly to the environment . Orthogonal experimental method to study the optimum conditions for the synthesis azodicarbonamide , under optimum conditions , the auxiliary ultrasound, to improve the the azodicarbonamide the gas evolution . Azodicarbonamide decomposition temperature of 195 to 220 ° C , far exceed the plasticizing temperature of the PVC resin (about 170 to 175 ° C ) , therefore need to be added in the azodicarbonamide activators, reducing azodicarbonamide decomposition temperature, in order to meet the processing requirements of the PVC resin . Zinc oxide zinc ions having the acceptance of the ability of a lone pair of electrons that can accept the azodicarbonamide the nitrogen atom and the carbonyl oxygen atom lone pair of electrons , reduce the decomposition temperature of the azodicarbonamide , is a relatively excellent activators. In this paper, the sol - gel method to prepare nano ZnO -SiO 2 < / sub > powders , nano ZnO-SiO 2 powder was added to the azodicarbonamide , preparation mixed blowing agents. Mixed blowing agent decomposition temperature , gas evolution , and is conducive to the processing of PVC resin foam , so it has a certain application prospects .

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