Impact of fuel/oxidizer ratio of NaN3 and KNO3 airbag gas generants on toxic emission and performance.

• The work gives a methodology to arrive at the optimal mixture for airbag gas generants using DSC-TGA, which will give better performance with minimum toxic residues. • The work depicts the major performance parameters to be evaluated for an effective airbag gas generant. • Tank testing using lower volumes and full-fledged 28.3 L vessels is done for NaN 3 /KNO 3 mixtures for the first time. • For the first time, the maximum pressure developed during decomposition of the fuel/oxidizer mixtures on a closed vessel test was compared with theoretically calculated maximum pressure. This paper reports the experimental methodology to arrive at an optimal weight composition of NaN 3 /KNO 3 airbag gas generants based on thermal studies using Differential Scanning Calorimetry/Thermogravimetry analysis. The residual analysis showed that the fuel oxidizer mixture of 62.5/37.5 by weight percentage can be used as the optimal composition for airbag gas generants, as it produced minimum residues after decomposition reaction. Spectroscopic studies using SEM-EDS showed that the optimal composition had zero residues of toxic NaN 3 compared to all other compositions tested. The heat energy released was found to be more in the air atmosphere due to the complete decomposition of mixtures compared to the nitrogen atmosphere. In this study, the ballistic properties such as time to peak pressure and peak pressure generated on ignition of the mixture were measured using the closed vessel test and the 28.3 lit full-fledged tank test. For the first time, the maximum pressure developed during decomposition of the fuel/oxidizer mixtures on the closed vessel test was compared with the theoretical maximum pressure value calculated using the ideal gas equation assuming that the process was adiabatic. The applicability of using the constant volume closed vessel test chamber for performance testing of auto airbag systems was also addressed. [ABSTRACT FROM AUTHOR]