Study On The Impact Sensitivity Of Nitro Energetic Materials

Sensitivity of energetic materials refers to the difficulty level of explosion whenthey are stimulated by outside energy. Its value directly affects the storage,transportation and application of explosives. Sensitivity is an important index ofenergetic materials, which can be divided into thermal sensitivity, mechanicalsensitivity, shock sensitivity and so on according to different forms of energetic impact.And the impact sensitivity is often represented by H50, which means the drop height ofthe explosive when tested by using a2.5kg DWTT instrument and when the explosivereaches50%. In this thesis, we mainly investigate the sensitivity of energetic materialsby following two ways:（1） Base on electronic topological index, we divide molecularstructure into some structure units and use the number of units to predict sensitivity.（2）Base on the theories of quantum chemistry, predict sensitivity of energetic materials.First, on the groundwork of five descriptors, e.g., oxygen balance OB100, activityindex F, active hydrogen, α-CH, α-OH and symmetry, we introduced four kinds ofmolecular structure descriptors, including intramolecular hydrogen bond, the number ofchemical group on same carbon atom, the number of chemical group on adjacent carbonatom, the number of chemical group on interval carbon atom,. According to above ninedescriptors, the stepwise regression and support vector regression were utilized toconstruct models for156nitro energetic materials’ sensitivity, and other eightindependent samples were employed to further evaluate the established models. Theresults indicate that only oxygen balance OB100, activity index F, intramolecularhydrogen bond and α-CH are chosen as independent variables, which confirmed that theintramolecular hydrogen bond have great influence on the sensitivity of energeticmaterials.Second, Based on35samples, the lowest unoccupied molecular orbital energy（Elumo） and others variables were used to generate a model and predict sensitivity, theresults again illustrate that the intramolecular hydrogen bond has strong relevance withsensitivity. Soon afterwards, based on15molecular samples contained intramolecularhydrogen bond among the35samples, we modified the definition of intramolecularhydrogen bond and implemented further investigation. The related quantum chemistryparameters are calculated by Gaussian program based on DFT theory under the level ofB3LYP/6-31+G*. And the results demonstrate that, among the three descriptors about intramolecular hydrogen bond, the error of the model set by definitionND=∑Q_OQ_H/R_OH is minimum. Here, the QOand QHare Mulliken atomic charges ofO-Hoxygen atom and hydrogen atom, RO-His the distance of the hydrogen between oxygenatoms which formed intramolecular hydrogen bond.At last, in our research, we found that the molecular electronic topological indexand methods concerning with the study of sensitivity can also be used to regress theglass transition temperature of chemical moleculars, and the error of the constructedmodel is relatively less than the responded result. First, based on the electronic topologystructure index theory, we divided the molecular structure of57polyphenol molecularsinto several structure units, and used the units and relative molecular mass asindependent variables to predict the glass transition temperature of polyphenolmoleculars. Here after, we calculated the activity index F for each molecular, which wasintroduced by Yuming Xing used to predict the sensitivity of energetic materials. Andthen the orbital energy was calculated by Hyperchem. Totally7descriptors are used toconstruct model by stepwise regression. The results revealed that the number of OHgroup has the greatest influence on glass transition temperature, followed by the activityindex F and the highest occupied molecular orbital energy. Moreover, the predictederror is smaller than that reported in the original literature. Thus, the F index can beused to model and predict the glass transition temperature.