A new fluorocarbon adhesive: Inhibiting agglomeration during combustion of propellant via efficient F–Al₂O₃ preignition reaction

Inhibiting the agglomeration of molten aluminum particles packed in the binder network is a promising scheme to achieve efficient combustion of solid propellants. In this investigation, the hydroxyl-terminated structured fluorinated alcohol compound (PFD) was introduced to modify the traditional polyethylene glycol/polytetrahydrofuran block copolymerization (HTPE) binder; that is, a unique fluorinated polyether (FTPE) binder was synthesized by embedding fluorinated organic segments into the HTPE binder via crosslinking curing. The FTPE was applied in aluminum-based propellants for the first time. Due to the complete release of fluorinated organic active segments in the range of 300°C to 400°C, the burning rate of FTPE-based propellant increased from 4.07 (0% PFD) to 6.36 mm/s (5% PFD), increased by 56.27% under 1 MPa. The reaction heat of FTPE propellants increased from 5.95 (0% PFD) to 7.18 MJ/kg (5% PFD) under 3.0 MPa, indicating that HTPE binder modified with PFD would be conducive to inhibiting the D₉₀ of condensed combustion products (CCPs) dropped by 81.84% from 75.46 (0% PFD) to 13.71 μm (5% PFD) under 3.0 MPa, in consistent with the significant reduction of aluminum agglomerates observed on the quenched burning surface of the propellants. Those results demonstrated that a novel FTPE binder with PFD can release fluorinated organic active segments, which motivate preignition reaction with the alumina shell in the early stage of aluminum combustion, and then enhance the melting diffusion effect of aluminum to inhibit the agglomeration.