Study On Thermal Hazard And Thermal Decomposition Mechanism Of DNPT

N,N'-dinitrosopentamethylenetetramine?DNPT,foaming agent H?,which is a widely used as blowing agent in the rubber industry,tends to be unstable when affected by high temperature and specific impurities.At least four DNPT deflagration accidents have occurred at home and abroad,causing at least 15 deaths and 25 disability and huge economic losses.Therefore,this paper selected DNPT as the research object,and used two means conCluding experiment and simulation to study the thermal stability of DNPT.The thermal stability of DNPT was studied from different angles by differential scanningcalorimeter?DSC?and thermogravimetric analyzer?TG?in the experimental section.Firstly,DSC was used to study the thermal decomposition of N,N'-dinitrosopentamethylenetetramine at a heating rate of 2oC/min,4oC/min,6oC/min,8oC/min,10oC/min and 12oC/min,and the corresponding heat flow-temperature curves were obtained.The study showed that with the increase of heating rate,the exothermic peak in the curve moved towards a higher temperature,and the temperature hysteresis occurred.The apparent activation energy of DNPT was measured by Kissinger method as 160.83 kJ mol^-1.The TG-IR?Thermogravimetry-Infrared Sectrometer?equipment was used to study the weight loss of DNPT at the heating rate of 1oC/min,3oC/min,5oC/min.Studies have shown that thermal weight loss curves of DNPT had good consistency at different heating rates.The weight loss curve consists of two stages:the first stage was the dehydration process;the second stage was the process of thermal decomposition.The apparent activation energy E obtained by Friedman method was 165.35 kJ/mol.At the same time the spectrum of the product was obtained by an infrared analyzer when the decomposition rate reached the maximum.According to the spectrum,the functional groups present in the product were judged.The conClusion of the spectrum diagram effectively guided the work of the simulation part.According to the environment of production,transportation,storage,use,and emergency of DNPT,DSC was used to study the thermal decomposition of DNPT under the influence of impurity water,acid,alkali,and Fe³⁺.The simulation section used Gaussian to perform structural optimization,energy,and frequency calculations on DNPT molecules under selected density functional theory?DFT-B3LYP?and basis set 6-311++G?D?.The DNPT stable configuration and single point energy data were obtained through simulation.The possibility of breakage in the pyrolysis process of DNPT was optimized-frequency calculation.Through the calculation and comparison of the bond dissociation energy,the process of thermally decomposing and breaking bonds was found out.Finally the most likely path of DNPT thermal decomposition was predicted.The theoretical activation energy Ea?of DNPT calculated from the broken-bond process in the simulation is 147.75 kJ/mol.The thermal decomposition properties of DNPT can be further understood by simulatingthe thermal stability and decomposition mechanism of DNPT Those results have an important role in promoting the safety of DNPT during transportation,storage,using,and emergency response.