Thermal Stability And Thermal Safety Of Isopropyl Nitrate

As an important branch of energetic materials,the thermal stability of nitro compounds has always been the focus of attention of researchers,managers,and users.As one of the main components of cloud blasting agents,isopropyl nitrate is also used as a diesel fuel additive.One of the components of the propellant has always lacked comprehensive thermal stability and thermal safety knowledge of the system.This paper takes isopropyl nitrate as the research target,and under the experimental environment provided by a variety of different calorimeters(DSC,ARC,Phi Tec II),the main researches are:1)The initial decomposition temperature Tonset,the heat of thermal decomposition Basic thermal behavior represented by ?H and thermal decomposition process;2)Thermal decomposition kinetics represented by process conversion rate ?,apparent activation energy E,exponential factor A,and reaction order n;3)Maximum adiabatic process Reaction rate time TMRad,adiabatic temperature rise ?Tad,self-accelerating decomposition temperature SADT as a representative of thermal safety;4)Thermal stability represented by isothermal storage temperature,storage quality,storage location,and long-term storage experiment;5)Compatibility represented by water-ester mixing calorimetry.1.DSC performed thermal sweeping of isopropyl nitrate at different heating rates,and the results showed that under different heating rates,the heat release heat of isopropyl nitrate was relatively stable,with an average value of 2815 J·g-1,and the initial decomposition temperature was concentrated in At around 140?,at a heating rate of 1?/min,the peak temperature of isopropyl nitrate and Tonset are the lowest,which are 197.03? and 183.37?,respectively.The thermal decomposition process is divided into three obvious stages.2.In the simulation of the DSC reaction process by thermodynamics,the initial temperature of 85?,under the condition of ?=1,the adiabatic temperature rise is 1407.5?.The Friedman model-free model obtains the apparent activation energy that varies with the conversion rate,which reaches the maximum value at the conversion rate of 0.2,which is 161 kJ·mol-1,and then stabilizes at Above 130 kJ·mol-1,this is the result of the coupling of multiple continuous behaviors in the thermal decomposition step.The simulated value of TMR under 125? isothermal environment is 6.68 h,and the thermal decomposition conversion rate of 24 h is 0.136.The commonly used highdensity polyethylene material packaging has a heat transfer coefficient of 2.8386 W·m-2·K-1.Under the United Nations standard 25 kg packaging,the SADT value is 68?.3.In the experiment of ARC adiabatic process,the initial exothermic temperature of isopropyl nitrate was 146.5?,and the adiabatic temperature rise reached 89.8?.The zero-order kinetics was used to analyze and predict the adiabatic exothermic process of ARC,TD8 and TD24 of isopropyl nitrate are 120.5? and 110.7? respectively.In the simulation of the reaction process,the initial temperature of 85?,under the condition of ?=1,the adiabatic temperature rise is 1407.5?.At the same time,in order to explore the thermal decomposition of isopropyl nitrate in the whole process,a small mass sample was taken for adiabatic experiment.Under the same test conditions,the complete process has a more continuous exothermic phase and a longer induction period.The complete exothermic process is divided into two stages:140?-217? and 217?-235?.After being corrected by the ? factor,the heat release heat of the complete process is 3176.3 J/g,which is close to the DSC test result(2891 J/g).The ?Tad' of the complete process can reach 1587.67?,which is much higher than the previous exothermic process.4.Since water catalyzes the hydrolysis of esters,by designing samples with different moisture content,the thermal behavior of the mixed system is judged,and the compatibility of water and isopropyl nitrate is explored.As the water content increases,the ?Tad' of the system gradually decreases,while the induction period is shortened,and the corresponding maximum temperature rise rate and pressure rise rate increase.Under higher water content,the thermal decomposition of the system accelerates,and finally reaches a higher temperature.Low termination temperature.In the TMR changes of IPN with different moisture content,higher moisture content shows lower TMR.In samples without water,TD24=102?,corresponding to 10%,30%,and 50%water content systems,TD24 is respectively 92?,78?,70 ?,reflecting the promoting effect of water on the thermal decomposition of IPN.5.The long-term storage experiment of isopropyl nitrate is used to explore its thermal stability,and an isothermal calorimetry experiment that simulates long-term storage is carried out using a bench-top calorimeter Phi Tec II.When 120? is selected,the sample has obvious liberation gas.However,no significant liberation gas was observed by lowering the temperature and extending the test time.When formulating stability standards,it is necessary to consider selecting the test environment temperature based on the thermal characteristics of different substances;below 100?,with an appropriate extension of the constant temperature time,the decomposition of isopropyl nitrate and the production of gas are weak,all below 0.1 mL/g.