S. Prem Felix

Studies of energetic compounds, part 29: effect of NTO and its salts on the combustion and condensed phase thermolysis of composite solid propellants, HTPB-AP

Abstract The effect of 5-nitro-2,4-dihydro-3H-1,2,4-triazole-3-one (NTO) and two of its transition metal salts, namely Cu(NTO) 2 and Fe(NTO) 3 , during the combustion of composite solid propellants (CSPs) of hydroxyl-terminated polybutadiene (HTPB) and ammonium perchlorate (AP) has been studied. The activities of Cu(NTO) 2 and Fe(NTO) 3 have been compared with those of CuO and Fe 2 O 3 at their equivalent metal concentrations. The processing parameters and mechanical properties of the propellants were also evaluated using Cu(NTO) 2 and Fe(NTO) 3 as additives, and a comparison has been made with that of copper chromite (CC) and active iron oxide (AIO) at pilot plant scale. The safety aspects of using these energetic salts as burning-rate modifiers have been studied in terms of the impact-sensitivity of the modified propellants. An attempt has been made to evaluate experimentally the condensed phase activity of these additives during the slow thermolysis of propellants, as well as AP. Rapid thermolysis of the propellants and AP has been studied using measurements of ignition delay.

Studies on energetic compounds: 25. An overview of preparation, thermolysis and applications of the salts of 5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (NTO)

The research work reported on the preparation, characterisation and applications of more than 50 salts of NTO has been reviewed thoroughly. A broad classification and sub classification of all these compounds has been given on the basis of nature of the compounds with which NTO forms salts. Attempt has been made to discuss the structure of these salts by summarising analytical data reported from 13C NMR. The structure as determined by IR spectroscopy as well as XRD has also been discussed briefly. A generalised mechanism for the thermolysis of the metal salts has also been given and any deviation from this has been narrated in particular cases. The kinetic details, thermodynamical and thermochemical data as well as performance parameters have also been reviewed. Thus, the futuristic potentials of these salts are analysed critically and further studies have been suggested.

Studies on energetic compounds part 28: thermolysis of HMX and its plastic bonded explosives containing Estane

The thermolysis of HMX, Estane and two of their plastic bonded explosives (PBXs) namely HXE 9505 and HXE 9010 were investigated using non-isothermal TG–DTG and DSC under an inert gas (N2) atmosphere. Non-isothermal TG, isothermal TG and DTA were also undertaken in air atmosphere on the above-said samples. Lowering of decomposition temperature of HMX has been observed when Estane was coated over it, to make their PBXs. The extent of lowering was increased as the amount of Estane increased in the PBX. Kinetic analyses of isothermal TG data has been made by using model fitting methods as well as by using a model free isoconversional method. The merits and demerits of both modes of kinetic analysis have been critically evaluated by making use of the kinetic parameters obtained there from to explain the thermal characteristics of the samples studied. Explosion delay measurements have been made on HMX and its PBXs and the kinetic parameters were also evaluated from this data.

Studies on energetic compounds. Part 32: crystal structure, thermolysis and applications of NTO and its salts

The research reports dealing with crystal structure, thermolysis and applications of 5-nitro-2,4-dihydro-3H-1,2,4-triazole-3-one (NTO) has been thoroughly reviewed here. Stress has been given to theoretical considerations of both, structure and thermolysis of NTO. The experimental and theoretical aspects of crystal structure of various NTO salts have been discussed. The works reported on solubility and crystallisation of NTO has also been mentioned. The various experimental methods and reported mechanisms for initial thermolysis reactions has been briefly mentioned so that to have a background for the discussion of theoretical considerations. The theoretical considerations on the decomposition of NTO have been critically reviewed and the new insights that are obtained from these works have been highlighted. The reported parameters available in the literature on sensitivity and performance of NTO have been summarised. An overview has been presented on the various studies dealing with applications of NTO as a high-energetic material, which reveals the potential of this compound for various applications.

Studies on energetic compounds: Part 36: evaluation of transition metal salts of NTO as burning rate modifiers for HTPB-AN composite solid propellants

Abstract Transition metal [Mn(II), Fe(II), Fe(III), Co.(II), Ni(II), Cu(II) and Zn(II)] salts of 5-nitro-2,4-dihydro-3H-1,2,4-triaole-3-one (NTO) have been incorporated as ballistic modifiers in composite solid probellants (CSPs) of hydroxyl terminated polybutadiene (HTPB) – ammonium nitrate (AN). The steady burning rate of the propellants was considerably increased by the additives, Zn(NTO) 2 being the most efficient one. The condensed phase thermolysis of such propellants was studied using non-isothermal TGA and DTA and the effect of additives is evident from these studies also. Also, the effect of these additives on the non-isothermal heating of AN from room temperature to ∼300°C was studied using TGA and DTA. The additives lowers the decomposition temperature of AN considerably. DTA studies show that the additives alter the phase transition temperatures of AN. Heats of combustion of the modified propellants were found to be higher than for the control one.

Studies on Energetic Compounds Part 23: Preparation, Thermal and Explosive Characteristics of Transition Metal Salts of 5‐Nitro‐2,4‐Dihydro‐3H‐1,2,4‐Triazole‐3‐One (NTO)

Five transition metal salts of 5-nitro-2,4-dihydro-3H-1,2,4-triazole-3-one, [namely M(NTO)n⋅mH2O where M is Ag, Hg, Cd, Cr, Fe where n=1,2,2,3,3 and m=1,2,2,8,2 respectively] were prepared and characterized (hereafter these compounds will be named as AgNTO, HgNTO, CdNTO, CrNTO and FeNTO, respectively). Their thermal decomposition was investigated by TG, DTA whereas explosive behaviour has been studied in terms of explosion delay, impact and friction sensitivities. Further, kinetic parameters have been derived using non-isothermal TG data and mechanism of thermolysis has also been proposed. It seems that dehydration takes place prior to the evolution of NO2 and the subsequent ring rupture yielding metal oxide. AgNTO on the other hand yields metallic silver. Dehydration in the case of HgNTO occurs in two steps: at each step one molecule is lost. All the salts are insensitive to impact and at the same time insensitive to friction up to 360 N.

Studies on energetic compounds part 15 : Transition metal salts of NTO as potential energetic ballistic modifiers for composite solid propellants

Abstract The combustion of hydroxyl terminated polybutadiene (HTPB) - ammonium perchlorate (AP) composite solid propellants has been studied using transition metal (Mn, Fe, Co, Ni, Cu and Zn) salts of 5-nitro-2,4-dihydro-3H-1,2,4-triazole-3-one (NTO) as energetic burning rate additives. The steady burning rate (r) was considerably enhanced with Cu(NTO)2 and Fe(NTO)2 whereas moderately enhanced with Zn(NTO)2 and Co(NTO)2 at low concentration (2% by wt.). Activity of these salts has been observed during isothermal decomposition of AP at 260°C. The values of ignition delay (tiJ), ignition temperature (Tign.) and activation energy for ignition (E*) for AP has also been lowered when these salts are added to it at 2% wt. concentration. The processing parameters as well as mechanical properties of the propellants with Cu(NTO)2 as additive have been studied in detail. The r of the propellants (both highly aluminized and less aluminized) with Cu(NTO)2 as additive at various concentrations, has been determined at high pressures, also shows its activity during combustion, The condensed phase activity of Cu(NTO)2 during propellant decomposition has also been studied using TG-DTG techniques.

Sulfonation of arylamines: Part 14. Kinetics of thermolysis of dichloroanilinium hydrogensulfate salts

Three dichloroanilinium hydrogensulfate (DCAHS) and two dichloroanilinium sulfate salts were formed while treating corresponding amines with excess amount of conc. sulfuric acid. These DCAHS salts were characterized by elemental analysis and spectral data. Thermolysis of these salts has been studied by using various thermo-analytical techniques under different conditions. All the salts on heating produce corresponding dichloroaminobenzene sulfonic acids (DCABSA) as intermediate product, which on further heating decomposes into gaseous products. The DCABSA were isolated and characterized by elemental and spectral analyses. Conventional model fitting methods and a model free isoconversional method were used to evaluate kinetic parameters for isothermal TG data and an attempt has been made to compare merits and demerits of both ways of kinetic approaches. The thermal decomposition pathway has also been suggested for DCAHS salts via solid-state sulfonation involving proton transfer as primary step.