Quantitative analysis of azodicarbonamide, a chemical-blowing agent for foamed plastics by differential scanning calorimeter

A differential scanning calorimeter (DSC) was used for the quantitative ana lysis of chemical blowing agents such as azodicarbonamide (azo) in commerci al formulations. The DSC results are comparable to those obtained by the co mmonly used evolved gas analysis (EGA) technique. Advantages of DSC over th e current technique are: ease of operation, shorter analysis time, environm entally safe, and the quantitative analysis is independent of additives suc h as UV and antioxidant stabilizers which are normally present in carrier r esins. DSC technique is also effective in measuring azo concentrations up t o 2% by weight, which is a limitation of the EGA technique. DSC can also be used to obtain the onset of the decomposition temperature and rate of deco mposition of azo compounds containing group II and group IV metal salt acti vators, such as zinc oxide and zinc stearate, DSC also has the potential to detect the level of undecomposed blowing agent present in processed foam p roducts.