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ABSTRACT
A polymer binder comprising of a blend of Poly (2-methyl-5-vinyl tetrazole) (PMVT) and poly (3- nitratomethyl-3-methyl oxetane) (PLN or Poly NIMMO), has been made using solution blending method. The blend of PMVT and PLN in the various ratios was prepared and characterized. The blend in all proportion could form flexible elastic films and showed a single T^sub g^ varying from -30 °C to -20 °C, indicating the complete miscibilility of the components. T^sub g^ could be further lowered by addition of suitable plasticizer. Detailed thermal analysis of the blends was carried out using DSC and TGA. IR spectra showed strong hydrogen bonding between the two polymers. The blend is found to be thermally stable and insensitive to impact and friction stimuli. This blend may find application in high energy, reduced sensitivity propellant and plastic bonded explosive compositions with improved mechanical properties.
KEYWORDS: Energetic binder, Insensitive munitions, Tetrazole polymer, Blend.
1. INTRODUCTION
Recent advances in propellant research are aimed at developing high energy polymeric binders with better performance than the existing widely used HTPB binder. Approach to high energy, low sensitivity explosive and propellant formulations i.e. insensitive munitions,[1-2] involves the use of insensitive energetic polymers as binder ingredients. These binders are expected to remain tough and soft especially in the time frame of an impact. They need to possess a low glass transition temperature. Insensitivity of the energetic composition can be improved either by reducing the percentage of explosive components of compositions like crystalline nitramine as well as by using moderately energetic insensitive binder such as PMVT. The latter approach is more viable as it imparts insensitivity characteristics to the composition without reducing their performance. I.B Mishra et al.[3] reported the blend of PMVT and Poly Ethylene Glycol (PEG) as binder for Plastic Bonded Explosives (PBX). But PEG being non energetic in nature, reduces the energy and thus overall performance of the composition. Moreover, Tg of this blend is not in the range as required for binder applications. On this basis, properties of a blend of PMVT and an energetic polymer namely poly (3-nitratomethyl-3-methyl oxetane) (PLN) has been observed during this study. This paper reports the preparation, characterization, thermal studies and sensitivity characteristics of the blend of PMVT and PLN.
2. EXPERIMENTAL
2.1 Materials