High energetic propellants with synergistic mechanical strength are the prerequisites for aerospace industry and missile technology; though glycidyl azide polymer (GAP) is a renowned and a promising energetic polymer which shows poor mechanical and low-temperature properties. In order to overcome these problems, a novel energetic interpenetrating polymer network (IPN) of Acyl-terminated glycidyl azide polymer (Acyl-GAP) and hydroxyl terminated polybutadiene (HTPB) is effectively synthesized and characterized via an "in situ" polymerization by triazole and urethane curing system respectively. Acyl-GAP and Dimethyl 2, 2-di (prop-2-ynyl) malonate (DDPM) have been synthesized and well characterized by using FT-IR, 1 H NMR, 13 C NMR and GPC. The maximum tensile strength ~ 5.26 MPa and elongation 318 % are achieved with HTPB-PU/Acyl-GAP triazole in 50:50 weight ratios. The solvent resistance properties have been investigated by the equilibrium swelling method and the glass transition temperature (T g ), morphology and thermal stability are evaluated by DSC, SEM and TGA-DTG respectively. Thus, HTPB-PU/Acyl-GAP triazole is a futuristic binder for the composite solid propellant.
Novel energetic interpenetrating polymer network (EIPN) nanocomposite comprised of fMWCNTs covalently attached to HTPB and GAP by facile in situ polymerization technique.
To improve the thermo-mechanical properties of glycidyl azide polymer and hydroxyl terminated polybutadiene based propellants, a facile sequential polymerization approach was used to prepare an energetic hybrid polymer network by stepwise curation.
The high-performance solid propellants play very important role in defense industry, which required highly energetic binders with good mechanical properties. In order to get the activation parameters for energetic binders, In-Situ FT-IR spectroscopic technique is used to study the chemical kinetics of glycidyl azide polymer (GAP) and hydroxyl terminated poly butadiene (HTPB) with isophorone diisocyanate (IPDI) at various temperatures. The reaction was followed by monitoring the change in intensity of the absorption band of NCO stretching at 2257cm-1and CO stretching at 1731cm-1. The polyurethane reaction has been found to be second order and the rate constant seems to be different between GAP/IPDI and HTPB/IPDI due to reactivity difference of OH groups. Dibutyl tin dilurate (DBTDL) was used as curing catalyst. By using Arrhenius and Eyring equations, the activation parameters were obtained at different temperatures (60, 70, 80 and 90°C). The apparent activation energy for the two systems GAP/IPDI and HTPB/IPDI were found to be 63.51 kJ mol-1and 41.06 kJ mol-1while the enthalpy and entropy of activation were found to be 62.35 kJ mol-1and-36.24 kJ.mol-1K-1, 39.08 J mol-1and-98.84 J mol-1K-1respectively.Key words: In-Situ FT-IR; glycidyl azide polymer (GAP); hydroxyl terminated poly butadiene (HTPB); chemical kinetics; polyurethane; dibutyl tin dilurate (DBTDL).
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