Haridwar Singh

Important aspects of behaviour of organic energetic compounds: a review.

The importance of a prediction tool increases with greater relevance for synthesis, performance and vulnerability predictions. Some important aspects of performance behaviour and their theoretical calculations, which are indispensable in recognising energetic molecules of interest, are described here. This review also discusses on factors influencing sensitivity and overall stabilities of organic energetic compounds especially on nitroaromatics and nitramines, and exceptions to this relationship suggest other factors playing roles in specific instances.

Glycidyl azide polymer (GAP) - an energetic component of advanced solid rocket propellants - a review

Abstract This paper reviews physico chemical, thermal, mechanical and ballistic characteristics of glycidyl azide polymer (GAP) and GAP based solid propellants. GAP offers propellant system with superior ballistics and high performance. Its potential as an energetic additive is attributed to the highly exothermic scission of -N3 bond structure accompanied by the release of energy of the order of 685 kJ/mole. Inclusion of GAP in propellant compositions leads to an improvement in their mechanical properties.

Synthesis, characterization and thermal studies of (Ni/Co) metal salts of hydrazine: potential initiatory compounds

Nickel hydrazinium nitrate (NiHN) and cobalt hydrazinium nitrate (CoHN) were prepared by reacting their respective metal nitrates with hydrazine hydrate at 25 and 65 degrees C. The compounds were characterized by metal content and infrared (IR) spectroscopy. Differential thermal analysis (DTA) results suggest that the nickel complex is relatively more stable than the cobalt complex. The activation energy determined by DTA and ignition delay measurements corresponds to an energy of activation (E(a)) of 80+/-4 kJ/mol for NiHN and that of 150+/-8 kJ/mol for CoHN. Thermo gravimetry (TG) also revealed more rapid decomposition of NiHN than that of CoHN in the temperature region of 215-235 degrees C. High temperature Fourier transform-infrared (FT-IR) studies indicated rupture of the Ni-Co-N bond as the primary step in the thermolysis. As regards sensitivity to mechanical stimuli, NiHN was found to be less impact sensitive while CoHN exhibited less friction sensitivity. The study revealed that NiHN could be used alone as well as in combination with oxidizer/fuel as initiators depending upon the specific requirements. The effect of silver azide and glass on the sensitization of NiHN was also studied. CoHN appears to be an effective ballistic modifier in enhancing burning rates of composite propellants.

Hydrazinium nitroformate (HNF) and HNF based propellants: A review

Abstract This paper reviews the studies carried out so far on HNF, which is emerging as potential oxidizer for futuristic propellant systems. Methods of synthesis of HNF including efforts to obtain HNF of desired particle size/shape have been discussed in detail. As purity of HNF has bearing on its thermal, physical and chemical characteristics, process parameters are being optimized to obtain high quality HNF with reproducible characteristics. Potential of HNF based propellants as propulsive force to missiles and space vehicles is also discussed in this paper. Problem areas in processing HNF based propellants have also been identified.

Studies on thermoplastic elastomers based RDX-propellant compositions

Abstract This paper presents the results obtained during studies on 80% RDX propellant systems based on thermoplastic elastomers (TPEs) namely ethylene-vinyl acetate (EVA), triblock copolymers of styrene-butadiene/styrene-isoprene (Kraton), poly-urethane-ester-MDI (Estane) and copolymer of polybutylene terephthalate - polyether glycol (Hytrel) as binders, Dioctyl phthalate (DOP), triacetin (TA) and glycidyl azide polymer (GAP) were incorporated as plasticizers in the formulations. An attempt has been made to correlate structural features of TPEs with mechanical properties as well as glass transition temperature (Tg). Results obtained suggest that TPE-based RDX-propellants have the advantage of high insensitivity to impact and friction stimuli vis-à-vis nitrte ester based conventional propellants. EVA based propellents gave the best results in this regard. Ignition temperature for all the compositions was >200°C. EVA, Hytrel and Estane based formulations were found to be more energetic than Kraton based formulations. Incorporation of GAP resulted in the improvement in ballistics (Impetus and burn rates) as compared to DOP plasticised formulations. TA based compositions gave an intermediate value. Thermal decomposition pattern was determined by applying Differential Thermal Analysis (DTA) and Differential Scanning Calorimetry (DSC). An attempt has been made to explain the trends observed on the basis of the evidences generated during this study and theories proposed by other researchers.

Combustible cartridge case formulation and evaluation

Abstract The formulation of combustible cartridge case was studied by changing the percentage of ingredients namely; nitrocellulose (NC), nitroguanidine (NiGu), cellulosic fibres, dibutylphthalate (DBP) and diphenylamine (DPA). A composition containing around 55% nitrocellulose & balance cellulosic fibers and nitroguanidine along with 3.5 parts dibutylphthalate & 1 part of diphenylamine was found compatible with triple base multi-tubular propellant, besides having reasonably good mechanical and ballistic properties.

Studies on thermal stability, autoignition and stabilizer depletion for shelf life of CMDB propellants

Abstract This paper reports the results of thermal stability of composite modified double base propellants (CMDB) by using tests applicable for double base propellants (DBP) and shelf life estimation of CMDB propellants by application of the autoignition test and monitoring stabilizer depletion by high performance liquid chromatography (HPLC). The Abel heat test results suggest the stability of CMDB propellants with or without additional stabilizer, whereas the Methyl Violet test indicated that CMDB propellants without resorcinol do not have stability comparable with DBP. Results of the Vacuum stability and B and J tests showed stability of CMDB propellants with resorcinol within acceptable limits. Aging did not change the DTA pattern to any appreciable extent. Autoignition test results gave a shelf life of 27.1 and 157.8 years for CMDB propellants at 40 and 30°C respectively. 2-NDPA depletion studies indicated a half life of 6–7 years and 26–30 years respectively for CMDB propellants at 40 and 30°C whereas carbamite depletion yielded a half life of 8–9 and 40–42 years. The activation energy ( E ) for aging of CMDB propellants was found to be 33 ± 1 kcal/mol.

Influence of metal salts of 4-(2, 4, 6-trinitroanilino) benzoic acid on the burnining rate of double base propellants

Abstract Cobalt, Nickel, Copper and Lead salts of 4-(2, 4, 6-trinitroanilino) benzoic acid have been evaluated as ballistic modifiers in double base propellant formulations. Measurements showed considerable increase in burning rate over the control propellant, in presence of salts at all pressures in the range 3.43 – 8.82 MPa. The effect of the lead salt, however, was more pronounced and showed a burning rate increase of 50 – 60%; the lower pressure ranges showing higher burning rate enhancement. The salts decompose exothermically: cobalt salt at 270°C (initiation), nickel salt at 300°C, copper salt at 240°C and lead salt at 260 °C.

Ballistic and mechanical properties of HTPB based composite propellants

Abstract This paper reports the results of the effect of solids loading on ballistic and mechanical properties of hydroxy terminated polybutadiene composite pro

Effect of high energy materials on the thermal stability and shelf life of CMDB propellants

Abstract The results of thermal stability tests indicate higher stability of cyclotrimethylene-trinitramine (RDX), pentaerythritol-tetranitrate (PETN) and their combined formulations with composite modified double base (CMDB) propellants than ammonium perchlorate (AP) containing CMDB propellants. Gas kinetic studies also reveal a similar trend. Activation energies as computed from isothermal gravimetric analysis in the range of 60-80°C, are about 35 kcal/mol for RDX and PETN based compositions, whereas for AP-RDX and AP-PETN based formulations they are about 30 kcal/mol. Autoignition test results also give lower activation energies for AP based CMDB systems. A shelf life of 65-164 year has been obtained for RDX and PETN based CMDB propellants, while on the otherhand the shelf life for AP based formulations ranges from 13-19 year.