Studies on PBFMO-b-PNMMO alternative block thermoplastic elastomers as potential binders for solid propellants

Abstract

An energetic polymer, poly[3,3-bis(2,2,2-trifluoro-ethoxymethyl)oxetane]glycol-block-poly(3-nitratomethyl-3-methyloxetane) (PBFMO-b-PNMMO), was synthesized using poly[3,3-bis(2,2,2-trifluoro-ethoxymethyl)oxetane]glycol (PBFMO) and poly(3-nitratomethyl-3-methyloxetane) (PNMMO) as the raw materials and toluene diisocyanate as the coupling agent via a prepolymer process. The structures of the energetic polymers were characterized by Fourier transform infrared spectroscopy (FT-IR), ¹H nuclear magnetic resonance spectrometry (¹H-NMR), and ¹³C nuclear magnetic resonance spectrometry (¹³C-NMR). A universal testing machine, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to investigate the mechanical properties and thermal behavior of PBFMO-b-PNMMO. The PBFMO-b-PNMMO-based elastomers exhibited superior mechanical properties (10.54 MPa, 723%) in comparison with PNMMO (6.18 MPa, 635%) and good compatibility with HMX and Al. The glass transition temperature (T_g) and decomposition temperature (T_d) were found to be −20.4 and 220 °C, respectively. The cook-off results indicated that the PBFMO-b-PNMMO/Al compositions could release significantly more heat than the PNMMO/Al compositions. Therefore, PBFMO-b-PNMMO may serve as a promising energetic binder for future solid propellant formulations.