Thermal and Kinetic Studies of Trinitrotoluene (TNT) and Amatol Vis-a-Vis Oxygen Balance

Abstract

Trinitrotoluene (TNT) is considered as one of the most useable explosive for the military use but it has some drawbacks of negative oxygen balance which is about negative 74% which forms the unburnt carbon in the form of soot due to which maximum potential of the explosive cannot be explored. To address this problem 80/20 amatol has been used which has positive oxygen balance which comes out to be positive 1.2%. Due to this positive oxygen balance it has more blast effects than the TNT due to the high volume of gasses released after the detonation. In the study oxygen balance vis-a-vis thermal and kinetic parameters of the TNT and amatol has been analyzed. This study also highlights the effects of increasing heating rates on the temperature changes of the TNT and amatol. For thermal study of TNT and 80/20 amatol, DTA/TGA techniques have been used in the form of simultaneous thermal method. In case of TNT thermal analysis, it is found that with the increase in the heating rate thermal decomposition temperature and activation energy increases till heating rate of 200C/min after that decomposition temperature and activation energy reduces at heating rate of 250C/min. This effect is similar to the DDT phenomenon which takes place due to increase in heat rate due to which heat generated is more than the heat liberated which results in the increase of internal temperature and reduction in the activation energy, here as well, as the heating rate is increased beyond 20 0C/min more heat is generated resulting in the reduction of activation energy of TNT. In case of amatol thermal analysis, it is found that with the increase in the heating rate there is increase in the thermal decomposition temperature and contrary to that it is found that there is decrease in the activation energy with the increase in the heating rate. Some of the reasons of such trends are thermal lag, furnace temperature, higher heat dissipation and heating rate. From the data it is found that TNT decomposition temperature is 2400C/min and that of amatol it comes out to be about 2450C/min which clearly shows that amatol is found to be more safe in handling than the TNT. In the nutshell, this study shows that amatol is having more blast effect than the TNT and also amatol is found to be more safe in handling due to the higher decomposition temperature than the TNT.