Ignition and combustion analysis of direct write fabricated aluminum/metal oxide/PVDF films

Metallized energetic composite films incorporating high mass loadings of aluminum nanoparticle fuels and metal oxide oxidizers (thermite) within a polyvinylidene fluoride (PVDF) polymer matrix were constructed via repeatable direct write additive manufacturing (3-D Printing). High speed videography, Temperature-Jump/Time of Flight Mass Spectrometry (T-Jump/TOFMS), and 2D spaciotemporal temperature mapping were used to analyze the role of composition and particle loading with respect to ignition behavior and combustion performance. This study reveals that, while the ignition temperatures of films are relatively unvaried in pressurized environments, ignition temperatures in vacuum are strongly dependent on the inclusion of thermite material and the specific type of thermite utilized. Increasing thermite mass loading results in a reduction in film flame speed and mechanical integrity but increases flame temperature. Coupled time of flight mass spectrometry reinforces and elaborates on previous findings regarding the Al/PVDF reaction mechanism as it pertains to the coupled behavior of incorporating increasing amounts of metal oxides. TOFMS highlights carbon dioxide generation from the metal oxide interaction with PVDF, leading to unintended stoichiometric considerations and distinct changes in steady burn behavior which contribute adverse factors towards flame propagation.