B. L. Korsounskii

Comparative Investigation of Thermal Decomposition of Various Modifications of Hexanitrohexaazaisowurtzitane (CL-20)

The thermal decomposition kinetics of different polymorphs of CL-20 (α, γ and e) has been investigated by thermogravimetry, IR spectroscopy and optical and electronic microscopy. The reactions proceed with self-acceleration and can be described by a kinetic law of first order with autocatalysis. Already at the earliest stages of decomposition (≤1%) phase transitions take place from αγ and from eγ. For this reason the observed decomposition is related to the decomposition of γ-CL-20. On the other hand, the kinetics of decomposition depends on the initial polymorphic state, so that the thermal decomposition increases in the series: α<γ<e. Experiments with different samples of α-CL-20 demonstrate that different rates of decomposition are observed for the same polymorph depending on the mean size and the size distribution of the crystals and their morphological features. In some cases the thermal stability of α-CL-20 can be increased by previous annealing. It is concluded that the thermal decomposition of CL-20 is purely a solid-state process. Microscopical and spectroscopical analysis of the condensed CL-20 decomposition product (formed after prolonged heating at high temperature) show that it has a network structure and consists mainly of carbon and nitrogen.

PREPARATION AND PROPERTIES OF SORBENTS BASED ON SILICA GEL CONTAINING COVALENTLY LINKED FULLERENE C60

Sorbents containing 10–12 % fullerene C60 were prepared by the reaction of C60 with γ-aminopropylsilica gel. C60-Silica gel possesses good chromatographic properties for the separation of aromatic, nitro, and heterocyclic compounds in the regimes of normal and reversed-phase HPLC.

Kinetics of reversible polymorphic transitions in high-energy compounds. Phase transformations in octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine

The kinetics of reversible phase transitions (PTs) in various polymorphs (α, β, γ, δ, and ɛ) of polycrystalline octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) is investigated by means of differential isothermal and scanning calorimetry. The rate of the β → δ PT is limited by the nucleation process occurring during the induction period. In a general case, the distribution density for the induction times is a superposition of continuous and discrete functions. The reverse δ → β PT obeys the first-order kinetic law. The effects of mechanical exposure on the kinetics and the PT products of the different polymorphs of HMX is investigated by FTIR spectroscopy.

Mechanism of the primary stages of decomposition of aliphatic nitro- and fluoronitronitramines

The primary stage of the decomposition of compounds RN(NO2)CH2C(NO2)2X is the homolytic cleavage of the C−NO2 bond, at X=NO2 and N−NO2 bond at X=F. The inductive effect of substituents decreases the dissociation energies of the C−N and N−N bonds by 1–2 kcal mol−1. Kinetic effects caused by the spatial interaction of groups and by stepwise decomposition of polyfunctional compounds are described.

Kinetics of reversible polymorphic transition in energetic materials. Phase transitions α → β and β → α in 1,1-diamino-2,2-dinitroethylene

Differential scanning calorimetry and isothermal calorimetry are used to study the kinetics of the α → β polymorphic transformation (PT) in 1,1-diamino-2,2-dinitroethylene (DADNE). The kinetics of the β → α PT in DADNE is investigated by infrared spectrophotometry. The α → β phase transition is described by the first-order autocatalysis equation. The activation energy and the rate constant are determined. The rate of the β → α PT is described by the kinetic law for two parallel first-order processes. The rate constants for these processes are obtained.

Thermal decomposition ofC-iodotetrazoles

Thermal decomposition of 1-substitutedC-iodotetrazoles in melt and solutions has been investigated. Thermal stabilities, kinetic and activation parameters, and compositions of products of thermolysis ofC-iodotetrazolcs depend on the substituent nature. The scheme of thermolysis ofC-iodotetrazoles has been suggested.

Crystallization and phase homogeneity of [1,2,5]oxadiazolo[3,4-e][1,2,3,4]tetrazine-4,6-dioxide–2,4-dinitro2,4-diazapentane molecular complex

The thermally reversible processes of melting and crystallization of the [1,2,5]oxadiazolo[3,4-e][1,2,3,4]tetrazine-4,6-dioxide–2,4-dinitro-2,4-diazapentane equimolar molecular complex produced in various technological modes of its isolation from the melt are studied and optimized by using turbidimetry, optical microscopy, and differential scanning calorimetry. The kinetic factors of the stepwise crystallization of the complex related to both the formation of nucleation sites and growth of the crystals are identified. A colorimetric method for controlling the phase purity and evaluating the content of impurities in the molecular complex after their preliminary identification by infrared spectroscopy is developed.

Thermal decomposition of 2,4-diazido-6-trinitromethyl-1,3,5-triazine, 2,4-dimethoxy-6-trinitromethyl-1,3,5-triazine, and 2,4-diazido-6-methoxy-1,3,5-triazine

The thermal decomposition of 2,4-diazido-6-trinitromethyl-1,3,5-triazine, 2,4-dimethoxy-6-trinitromethyl-1,3,5-triazine, and 2,4-diazido-6-methoxy-1,3,5-triazine in a melt was studied by differential scanning calorimetry, thermogravimetry, manometry, mass spectrometry, and IR spectroscopy. The kinetics of these reactions was investigated, and the activation parameters were determined. The gaseous products of the decomposition of 6-trinitromethyl-2,4-diazido-1,3,5-triazine were N2, NO, N2O, CO, and CO2 in a molar ratio of 1: 2: 1: 0.6: 1 and pronounced amounts of NO2. A comparison of kinetic data for the compounds under study indicated that the azide groups in 2,4-diazido-6-trinitromethyl-1,3,5-triazine were thermally more stable than the trinitromethyl group.

Separation of C60 and C70 fullerenes on silica modified by polyaromatic and π-acid aromatic compounds

Separation of C60 and C70 fullerenes by HPLC was studied using sorbents synthesized by reaction of perylenedicarboxylic anhydride, dimethoxyviolanthrene, the tetramer of chromotropic acid with formaldehyde (TCA), trinitrobenzoyl chloride, or chlorotrinitrobenzene with γ-aminopropyl silica. These sorbents possess satisfactory chromatographic properties. The sorbent based on TCA is effective for separation of preparative amounts of fullerenes.