Four Liquid Containing The Thermal Sensitivity Of The Exploratory Study

Thermal sensitivity is a measurement on how easily chemical reaction can happcn, which can be expressed by the parameters of onset temperature,5 s delayed explosion temperature and VST.Generally,liquid energetic materials are too volatile to get the parameters above.So,the thermal sensitivity and decomposition of four liquid explosives, nitromethane(NM),n-propyl nitrate(NPN),isopropyl nitrate(IPN)and 2-ethylhexyl nitrate(EHN)are studied by Accelerating Rate Calorimeter(ARC)and Differential Scanning Calorimeter(DSC)in this paper.First of all,the decompositions of the tour liquid explosives are studied by DSC and ARC.Kinetic and thermodynamics parameters are calculated and analyzed.The influence of the experimental conditions and their thermal hazards are both compared and considered.According to the decomposition onset temperatures of both DSC(T_dse) and ARC(T_arc)),it can be founded that,at the start of thermal decomposition,EHN is the most sensitive,NPN is less sensitive than EHN and more sensitive than IPN,and NM is the least sensitive.Secondly,on the basis of the ARC data,0.5min,1min and 5min are chosen as the time to maximum rate(TMR)to calculate their corresponding temperatures.The temperature where TMR equals to 0.5min is selected as a criterion for thermal sensitivity evaluation when it goes to thermal explosion.By the criterion,it can be founded that NPN is the most sensitive,EHN is less sensitive than NPN,but close to IPN,NM is the least sensitive.Self-accelerating decomposition temperature(SADT)of the four liquids in three different containers are estimated according to the time constantτand the curve of TMR vs Temperature.Bond Dissociation Energy(BDE)calculated by the quantum chemical calculations are used to obtain T_ARC,with the expression as:T_ARC= 1.311BDE—70.At last,the decomposition of EHN with acids are studied,and the results is shown as follows:sulfuric acid can decrease the onset temperature of decomposition and increase thermal sensitive;Nitric acid can accelerate the decomposition of EHN,enhance thermal sensitive;Mixed acid(m_H2SO4:m_HNO3= 2:1)is of the influence similar to sulfuric acid except the influence is weaker.