Abstract
In order to enhance the application performance of glycidyl azide polymer (GAP) in solid propellant, an energetic copolyurethane binder, (poly[3,3-bis(2,2,2-trifluoro-ethoxymethyl)oxetane] glycol-block-glycidylazide polymer (PBFMO-b-GAP) was synthesized using poly[3,3-bis(2,2,2-trifluoro-ethoxymethyl)oxetane] glycol (PBFMO), which was prepared from cationic polymerization with GAP as the raw material and toluene diisocyanate (TDI) as the coupling agent via a prepolymer process. The molecular structure of copolyurethanes was confirmed by attenuated total reflectance-Fourier transform-infrared spectroscopy (ATR–FTIR), nuclear magnetic resonance spectrometry (NMR), and gel permeation chromatography (GPC). The impact sensitivity, mechanical performance, and thermal behavior of PBFMO-b-GAP were studied by drop weight test, X-ray photoelectron spectroscopic (XPS), tensile test, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA), respectively. The results demonstrated that the introduction of fluoropolymers could evidently reduce the sensitivity of GAP-based polyurethane and enhance its mechanical behavior (the tensile strength up to 5.75 MPa with a breaking elongation of 1660%). Besides, PBFMO-b-GAP exhibited excellent resistance to thermal decomposition up to 200 °C and good compatibility with Al and cyclotetramethylene tetranitramine (HMX). The thermal performance of the PBFMO-b-GAP/Al complex was investigated by a cook-off test, and the results indicated that the complex has specific reaction energy. Therefore, PBFMO-b-GAP may serve as a promising energetic binder for future propellant formulations.
Highlights
MaterialsGAP with molecular weight of 3500 g mol−1 and hydroxy value of 0.9% was provided from the Liming Chemical Engineering Research and Design Institute (Luoyang, China)
Introduction published maps and institutional affilA recent trend in the field of energetic material formulations is to replace inert binders (viz., hydroxy terminated poly butadiene (HTPB), carboxyl terminated polybutadiene (CTPB), and hydroxyl terminated polyether (HTPE), etc.) by energetic binders, which contain energetic groups such as –N3, nitro
differential scanning calorimetry (DSC) equipped with a TA instruments DSC Q1000 and thermal gravimetric analysis (TGA) measurements of samples were performed in a nitrogen atmosphere using a SDT Q600 TGA instrument in the temperature range from 25 to 500 ◦ C with heating rate of 10 K min−1
Summary
GAP with molecular weight of 3500 g mol−1 and hydroxy value of 0.9% was provided from the Liming Chemical Engineering Research and Design Institute (Luoyang, China). Butane diol (BDO), BF3 -etherate and dibutyltindilaurate (DBTDL) were purchased from. Toluene diisocyanate (TDI), N,N-dimethylformamide (DMF), dichloromethane (DCM), and ethanol were supplied by Sinopharm Chemical. BDO and BF3 -dimethyl ether were distilled under reduced pressure prior to use. All other solvents for the reactions were of analytical grade and distilled before use
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