S. Iyer

Bio: S. Iyer is an academic researcher. The author has contributed to research in topics: Shock sensitivity. The author has an hindex of 1, co-authored 1 publications receiving 16 citations.

Explosive desensitization studies via chemical group modification. Nitroso-Derivatives of RDX and 3-Amino-TNT

Abstract: With aims toward desensitizing RDX and TNT via molecular modification, mono- and trinitroso-derivatives of RDX and 3-amino-TNT were synthesized and subjected to sensitivity tests. Impact and shock sensitivity data show these compounds to be markedly desensitized. Explosive yield measurements indicate that the changes in power output due to these molecular modifications are minor.

Examining the Chemical and Structural Properties that Influence the Sensitivity of Energetic Nitrate Esters

Abstract: The sensitivity of explosives is controlled by factors that span from intrinsic chemical reactivity and chemical intramolecular effects to mesoscale structure and defects, and has been a topic of extensive study for over 50 years. Due to these complex competing chemical and physical elements, a unifying relationship between molecular framework, crystal structure, and sensitivity has yet to be developed. In order to move towards this goal, ideally experimental studies should be performed on systems with small, systematic structural modifications, with modeling utilized to interpret experimental results. Pentaerythritol tetranitrate (PETN) is a common nitrate ester explosive that has been widely studied due to its use in military and commercial explosives. We have synthesized PETN derivatives with modified sensitivity characteristics by substituting one –CCH2ONO2 moiety with other substituents, including –CH, –CNH2, –CNH3X, –CCH3, and –PO. We relate the handling sensitivity properties of each PETN derivative to its structural properties, and discuss the potential roles of thermodynamic properties such as heat capacity and heat of formation, thermal stability, crystal structure, compressibility, and inter- and intramolecular hydrogen bonding on impact sensitivity. Reactive molecular dynamics (MD) simulations of the C/H/N/O-based PETN-derivatives have been performed under cook-off conditions that mimic those accessed in impact tests. These simulations infer how changes in chemistry affect the subsequent decomposition pathways.

Impact sensitivity of polynitroaromatics

Abstract: A large number of polynitroaromatic compounds have been prepared in these laboratories over the last decade or so during programs to develop new energetic materials. This report documents their impact sensitivities and attempts to rationalize trends in terms of structure/property correlations.

Aminotetryls: Synthesis, spectral characterization, thermal decomposition and explosive properties

Abstract: This paper describes the synthesis and spectral investigations of two amino derivatives of N-methyl-N-(2,4,6-trinitrophenyl)nitramine (tetryl). Also discussed are the results from thermal decomposition studies on the three explosives, viz. tetryl, 3-aminotetryl (3 AT) and 3,5-diaminotetryl (3,5 DAT) and preliminary work on the explosive properties of the last two compounds. The aminotetryls have been prepared by the amination of the corresponding chlorotetryls. The yield was 87% for 3 AT, but was only 33% for 3,5 DAT, probably due to steric crowding around the benzene nucleus. The mass spectra show interesting differences in the electron impact fragmentation patterns of the three tetryls with the M+ ion relative intensities following the order 3,5 DAT > 3 AT > tetryl, which could be due to (a) resonance stabilization and (b) hydrogen bonding effects. Evidence for the latter is also found in the infrared spectra of these compounds. Arrhenius kinetic parameters derived from thermal decomposition studies of the three compounds are presented and show that 3,5 DAT is thermally less stable than 3 AT. Explosive sensitiveness tests indicate that the diamino compound is the most sensitive, the trend being 3,5 DAT > 3 AT > tetryl. This is contrary to the generally found desensitizing influence of NH2 groups on the thermal stability and explosive sensitiveness of trinitroaromatic energetic molecules. Mechanisms to account for the observed thermal decomposition behaviour and explosive sensitiveness patterns are discussed.

Computational Determination of Heats of Formation of Energetic Compounds

Abstract: A recently-developed density functional procedure for computing gas phase heats of formation is briefly described and results for several categories of energetic compounds are summarized and discussed. Liquid and solid phase values can be obtained by combining the gas phase data with heats of vaporization and sublimation estimated by means of other relationships. Some observed functional group effects upon heats of formation are noted.