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Optimization of Curing Agents for Linear Difunctional Glycidyl Azide Polymer (GAP), with and without Isocyanate, for Binder Applications

Agawane N. T., Soman R. R., Wagh R. M., Athar J., Talawar M.

Central European Journal of Energetic Materials

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2018

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Vol. 15, no. 1

206--222

EN

Glycidyl Azide Polymer (GAP) is one of the most potential energetic binders for rocket propellants and gas generator compositions. In the present paper GAP of molecular weight (Mn) ~2000 was cured with a mixture of di- and tri-isocyanates without a cross linker. The curing profile and time of curing was recorded using a rheometer. The minimum curing time was observed for samples cured with Desmodour N-100 alone, whereas the maximum curing time was observed for samples cured with a mixture of Desmodour N-100 and Isophorone Diisocyanate (IPDI) (1:1 w/w). It was observed that all of the samples cured well and were void or bubble free. The mechanical properties data showed that the tensile strength (TS) of GAP cured with Desmodour N-100 alone was 1.19 kgf/cm2, which is a minimum, while the maximum TS (3.66 kgf/cm2) was achieved with a mixture of N-100 and 4,4’methylenebis(phenylisocynate) (MDI). The percent elongation for a sample cured with Desmodour N-100 was 160, and was reduced to 64.27 when a mixture of MDI and N-100 was used. In order to study the curing of GAP without an isocyanate, GAP diol was cured with hexanediol di-acrylate. GAP was also cured with an alkyne-based curing agent i.e. bis-propargyl succinate (BPS), which showed improved curing. Comparative thermal studies of GAP cured with isocyanate and acrylate was carried out. Differential Scanning Calorimetry (DSC) and Simultaneous Thermal Analysis (STA) curves for all of the cured samples were recorded in order to study and compare the thermal decomposition behaviour of the cured GAP. Isocyanate cured GAP exhibited a single stage decomposition, with larger heat output. Acrylate cured GAP exhibited a two stage decomposition. Finally, a mixture of IPDI and Desmodour N-100 was selected for curing of GAP. Accordingly, curing was carried out and was tested in a small ballistic evaluation motor (BEM) to observe the combustion behaviour and burn rate. From the pressure-time profile it was found that this composition gave smooth burning with a pressure of ~3 kg/sec2 for 7 seconds of burn.

2

Thermal Analysis and Sensitivity Studies on Guanylurea Dinitramide (GUDN or FOX-12) Based Melt Cast Explosive Formulations

Badgujar D., Talawar M.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 2

296--303

EN

Guanylurea dinitramide (GUDN or FOX-12) is a stable salt of dinitramidic acid with good thermal stability, and is a good candidate for insensitive formulations. Thermal analysis reveals the compatibility of GUDN with benchmark explosives such as RDX and TNT in melt cast explosive formulations. The paper describes a thermal and sensitivity study of GUDN with RDX and TNT. In the present study GUDN was evaluated as a possible replacement for RDX/TNT based aluminized and non aluminized melt cast explosive formulations. The thermal properties of the composition were investigated as well as its sensitivity to impact and friction. Its thermal decomposition behavior was compared to a control composition based on RDX and TNT. The thermal and sensitivity results proved the worth of these compositions for melt cast explosive applications.

3

Physico-Chemical Characteristic of Sulfated Mixed Oxides of Sn with Some Rare Earth Elements

Jyothi T., Sreekumar K., Talawar M., Mirajkar S., Rao B., Sugunan S.

Polish Journal of Chemistry

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2000

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Vol. 74, nr 6

801-812

EN

A series of binary mixed oxides of tin with three rare earth elements viz. La, Ce and Sm were prepared by co-precipitation method and sulfate treatment was performed by treating the mixed hydroxides with sulfuric acid or ammonium sulfate. The physicochemical characterization has been done by XRD, BET-S.A., SEM, EDX, TG-DTA and IR spectroscopy. Adsorption of n-butylamine was used to probe the acidic properties of the catalysts. The strength and distribution of acid sites depend on the mixed metal oxide composition, as well as on the preparation method. The rare earth modified sulfated tin oxide catalysts are more active in the oxidative dehydrogenation of cyclohexanol and cyclohexane, compared to the corresponding mixed oxide systems and sulfated tin oxide. Among the different sulfated oxide systems investigated , cerium prooted catalysts displayed a better selectivity towards dehydrogenation products.