Fluoroelastomer pyrotechnic time delay compositions

Abstract

The feasibility of aluminium or magnalium filled fluoropolymer Viton B as an open-burn time delay was investigated. Film samples with a thickness of 245  21 m. were prepared via a slurry casting process. Fuel filler content was varied from 20 to 60 wt.%. The films retained the elastic properties of the parent polymer except that the elongation at break decreased rapidly with increasing filler content.Sensitivity tests showed that the films were insensitive to ignition by friction and impact. EKVI thermodynamic simulations showed that, for both systems, the maximum energy output is ca. 8.3 MJ kg 1 . Energy measurements indicated that the maximum energy output occurred in the range 30 to 40 wt.%. Maximum burn rates of 82 mm s 1 and 40 mm s 1 were achieved using a magnalium and flake aluminium as fuels respectively.

Extrudable Gassy Pyrotechnic Time Delay Compositions

“…The measured burning rate results, listed in Table 1, were comparable to results obtained in other studies [12,16]. Filaments extruded for 3D printable compositions based on PVDF, with 20 wt.% aluminium as fuel, exhibited burning rates of up to 18.7 ±1.3 mm•s −1 [12].…”

“…Filaments extruded for 3D printable compositions based on PVDF, with 20 wt.% aluminium as fuel, exhibited burning rates of up to 18.7 ±1.3 mm•s −1 [12]. Potgieter et al [16] measured the burning rates of energetic films based on Viton B fluoropolymer as oxidant with 50 wt.% metal fuel. Their films had a thickness of 245 ± 21 µm and they were prepared via a slurry casting process.…”

Review of Gasless Pyrotechnic Time Delays

“…Upon ignition the black powder core will burn at a steady rate, transferring the flame front to the detonator. Alternatively, it has been suggested that fluoropolymer-based systems could be used in a similar fashion [8]. The production of the fuse can be simplified by extruding a fluoropolymer filled with a suitable fuel, e. g. aluminum, since it will only consist of a single part.…”

“…The calculation and analysis using the differential equation (8), as well as other relevant energy and mass continuity equations, are simplified by converting them into dimensionless form. This automatically leads to characteristic dimensionless parameters that are included in the list of dimensionless groups or numbers enumerated in Table 1 [57a].…”

“…The reaction kinetics were assumed second order in conversion. The differential equation (8), in its dimensionless form, was solved numerically subject to the boundary conditions stated in equation (9). A parametric analysis was then performed to determine the ignition criteria for gasless selfpropagating reactions through an ignition temperature analysis.…”