Investigation Of Inflammable And Explosive Hazardous Chemicals Identification Method Using Differential Scanning Calorimetry (DSC)&Establishment Of DSC Database

Handling,carrying and transporting of inflammable and explosive hazardous chemicals illegally would pose a great threat to public social security,a rapid detection and identification of those dangerous chemicals could provide a great convenience for regulation and control.For the rapid detection and identification of dangerous and prohibited chemicals,a new identification method based on Differential Scanning Calorimetry(DSC)was proposed in this study.Firstly,the influence of sample mass and heating rate on DSC test results under linear temperature increase condition was investigated and the quantitative description of the influence was carried out based on the basic detection theory of DSC test and thermal kinetics analysis,which could provide a foundation for material identification.Besides,in order to validate the identification ability for a serious of chemicals with similar molecular structure by DSC spectrogram,three kinds of inflammable and explosive hazardous chemicals were selected and tested under different heating rate conditions,then according to these data,thermal decomposition parameters such as activation energy(Ea)and pre-exponential(A)factor were respectively calculated based on Friedman and Malek method.By using quantum chemistry method,the most stable molecular structure,bond dissociation energy(BDE)and HOMO-LUMO energy gaps(AE)were optimized and calculated,then the relationship between molecular structure and thermal decomposition properties was investigated according to the principle of chemical bond dissociation.At last,DSC spectrogram extrapolation method and BP neural network method were carried out to identify the inflammable and explosive hazardous chemicals with DSC spectrogram,and the corresponding DSC spectrogram database was established based on Sqlite3 database server.The results shows that when the heating rate is constant,the relationship between heat flow(q)and sample mass(m)at the same conversion rate of DSC spectrogram could be described as a linear relationship;when the sample mass(m)is constant,the reciprocal of temperature(1/T)has a linear relationship with the logarithm of heating rate(In(?))and heat flow(q)also has a linear relationship with the value of heating rate(?),while the temperature and heat flow is the value at same conversion rate of DSC spectrograms.Thermal decomposition property investigation of azo-nitrile compounds,azo-dicarboxylate compounds and organic peroxides show a good identification ability of DSC spectrogram under linear temperature increase condition.Furthermore,quantum chemistry calculation result shows that the molecular structure has some connection with thermal decomposition properties,which could be described as higher bond dissociation energy(BDE)indicates higher onset temperature and higher HOMO-LUMO energy gaps(AE)indicates higher activation energy(Ea).DSC spectrogram identification result of different inflammable and explosive compounds shows that both DSC spectrogram extrapolation method and BP neural network method have a high identification accuracy with DSC spectrograms under different test conditions,which could prove the potential application to identify the inflammable and explosive hazardous chemicals.