Tailoring the reactivity of printable Al/PVDF filament

Within the energetic materials and additive manufacturing (AM) communities, a number of aluminum/fluoropolymer (Al/FP) combinations have been identified for their suitability in various techniques. For practical applications, such as case reactive wire or core solid propellant, range selectable reactivity within given Al/FP selection is needed. The purpose this study was to alter aluminum/polyvinylidene fluoride (Al/PVDF) produce consistent burning rates, enabling design printable filament suitable use propellant core, other related applications. Three potential methods tailoring rate Al/PVDF filaments were investigated: (1) selecting different aluminum fuel particles, (2) adjusting stoichiometry material, (3) changing particle size ratio from pure micro- nano-aluminum. Reactive consisting PVDF either mechanically activated aluminum-polytetrafluoroethylene (MA Al-PTFE), nanoscale (nAl), mixtures nano- micro-aluminum (nAl:µAl) tested assess reaction speeds well intra- inter-batch variability. Differential scanning calorimetry, thermogravimetric analysis, drop weight impact testing, friction porosity analysis conducted on select materials. Filaments 20 wt% nAl/PVDF 32.2 MA Al-PTFE/PVDF printed using material extrusion method into strands with dimensions, porosities, rates comparable feedstock. This determined that particles could reliably moderate between 17 40 mm/s. mixed formulations inconsistent mid-range (20–30 mm/s) significant deviation indicating threshold phenomenon potentially shift slower faster mode.