Abstract: Bis(trinitroethyl-N-nitro) ethane (BTNE) is a compound that decomposes thermally in solid state. We have reported the first study of thermal decomposition of crystals of BTNE prepared through various methods of recrystallization. In this work nonisothermal kinetics of the decomposition of BTNE crystals(10 samples)was investigated in more detail.
The unpurified samples of BTNE prepared in laboratory were recrystallized respectively from acetic acid glacial, absolute alcohol, nitromethane, dichloroethane, acetone, butanone or distilled water and ten samples of BTNE were prepared for investigation.
Nonisothermal kinetics study on these crystals was carried on with a Rigaku TG-2000 Thermal Analizer. DSC curves with various heating rates (φ=1.25, 2.50, 5.0, 10.0 ℃·min~(-1))were treated mathematically with equations of Kissinger H.E. and Ozawa T. for the evaluation of the aqqarent energy of activation (E) and then with that of Rogers R.N. and Smith L.C. for the evaluation of the pre-exponen-tial factor (A). In Table 1 the values of E and A for various crystalline samples of BTNE are demonstrated.
On the basis of values of E and A in Table 1 the reaction constants of rate (k) at 120 ℃ are calculated as listed in Table 2. The data in Table 2 show that there exist great differences of k value among samples of BTNE. For example, at 120 ℃ the difference of k between BT-8 and BT-5 amounts to more than two orders of magnitude. Based on these properties, one can evaluate, regulate and control the thermal stability of crystalline BTNE for for its processing and storage. It appears that the phenomenon above mentioned depeds upon the solutility of BTNE in solvent and conditions of recrystallization. The large the value of k, the higher the solubility of BTNE in the pertinent solvent. The four kinds of BTNE having the highest value of k are prepared by method of fast recrystallization. The process of recrystallizaion may change the reactivity of crystalline BTNE.
Generally speaking, process of recrystallization may influence the crystal modification or habit of solids, meanwhile crystals with diversified modification or habit show different reactivity. It is therefore necessary to study the properties of crystals of BTNE prepared by different methods of recrystallization.