Louis-Simon Lussier

Thermal stability and formation barrier of a high-energetic material N8 polymer nitrogen encapsulated in (5,5) carbon nanotube

We report the density functional theory total energy calculations of thermal stability and formation barrier of polymer nitrogen confined in carbon nanotubes (CNT). The analysis suggests that N8 polymer nitrogen encapsulated in (5,5) carbon nanotube [N8@CNT(5,5)] is thermally (meta)stable at a finite temperature up to energy scale of at least 5000 K, similar to nitrogen molecule gas phase confined in CNT [N2@CNT(5,5)]. The energetic difference between these two phases of N does not significantly change with temperature. A barrier of 1.07 eV was found for the formation of N8@CNT(5,5) from N2@CNT(5,5), while the dissociation barrier was found to be 0.2 eV. Snapshots of the reaction pathway show that the transition state is composed by a N2 and a N6 inside a CNT(5,5).

Spectral artifacts from non-uniform samples analyzed by terahertz time-domain spectroscopy.

We report the impact of the spatial coherence distortion on the measured absorption spectra and the identification of materials analyzed by terahertz time-domain spectroscopy. It is shown that the deformation of the terahertz beam wave front can result into the overestimation of the electromagnetic absorption, the generation of artificial absorption peaks and even to the disappearance of characteristic absorption peaks. Obtaining clear absorption spectra without artifacts is crucial for applications based on terahertz imaging and spectroscopy.

Effects of Interface Interactions on Mechanical Properties in RDX-Based PBXs HTPB-DOA: Molecular Dynamics Simulations

Atomistic molecular dynamics simulation was carried out to study interface interactions between a crystal structure and a plastic bonded explosive (PBX) system. In this work, the polymer is hydroxyl-terminated polybutadiene (HTPB), the plasticizer is dioctyl adipate (DOA) and the crystal phase is hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). Experimental RDX crystallo-graphic data show that (020 ), (200 ) and (210 ) crystal faces usually dominate, and these were therefore only these were studied. Interface models were built and interfacial bonding energies calculated to investigate HTPB/RDX adhesion properties in the (DOA+HTPB)/RDX system. Mechanical properties such as Poissons ratio, Young, bulk and shear moduli were also predicted. The most favourable interactions occur between HTPB-DOA and the RDX (020) crystal face: obtaining crystals with prominent (020) faces may provide a more flexible mixture, with a lower Youngs modulus and an increased ductility.

Predictions of thermodynamic properties of energetic materials using COSMO-RS

Abstract In this work, conductor-like screening for real solvents (COSMO-RS) calculations were carried out using COSMOtherm program in conjunction with Gaussian03 packages. The objective was to predict thermodynamic properties for two nitrogen-rich energetic materials which are less harmful for the environment than the conventional ones, namely 3,6-di(hydrazino)-1,2,4,5- tetrazine (DHT) and 3,3’-azo-bis(6-amino-1,2,4,5-tetrazine) (DAAT) for which no experimental data are available to our best knowledge. COSMO-RS approach is a combination of quantum chemical and statistical thermodynamic basis, which allow a physically meaningful description of molecular interactions between pure molecules and solvents in solution. Recently, this approach has been used for the prediction of an enormous number of physicochemical properties especially aqueous solubility, Henry’s law constant, vapor pressure and partition coefficient. The vapor pressure of pure compounds is one of the most important thermodynamic properties required for the chemical process design as well as for the fate assessment of pollutants in the environment. To validate the accuracy of COSMO-RS approach for the two molecules of interest, six reference energetic molecules have been studied, for which experimental data are available, such as cyclotetramethylene-tetranitramine (HMX), 2,4,6-trinitrotoluene (TNT), cyclotrimethylenetrinitramine (RDX), 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), 1,1-diamino-2,2-dinitroethylene (FOX-7) and n-methyl-p-nitroaniline (MNA). From predicted results, a good agreement has been noted. DAAT molecule shows a lower volatility in the medium so that a low detectability compared to the DHT and other reference molecules. Both DHT and DAAT showed negative logarithmic values of Octanol-Water partition coefficients, this means that they don’t have the tendency to enhance the bioaccumulation process in soils.