Energy Release Rate Characterization of Additively Manufactured Al/PVDF with Varying Infill Densities and Patterns

The additive manufacturing of energetic materials is a novel way to alter the properties of an energetic material without necessarily changing its chemical structure. There are many methods of additive manufacturing which can be applied to energetic material fabrication, each of which have unique advantages and disadvantages. The most well characterized additive manufacturing method is the commercially refined technique of fused filament fabrication (FFF) printing. FFF manufacturing techniques can be applied to additively manufacture thermoplastic energetic materials. The thermoplastic aluminum and polyvinylidene difluoride (Al/PVDF) system is suitable for manufacture with FFF techniques, shapeable into pyrotechnics with custom geometries using commonly available FFF printers. This theoretically allows Al/PVDF systems to be tailored for a wide variety of multifunctional needs, such as reactive structures. Following a literature review describing energetic material additive manufacturing techniques, this thesis focuses on the creation of outwardly identical Al/PVDF samples and the use of a geometric correction factor to control for uneven feedstock diameter. By varying the infill pattern, infill density, and interior geometry, different sample energy densities were obtained and observed during combustion. High speed videography measurements and the mass of individual samples were used to estimate the overall energy release rate. An Ashby plot contrasting the energy density and energy release rate was obtained. While full density printed samples burned similar to cast propellant strands in a linear burn, the energy release rates of additively manufactured Al/PVDF could be increased via convective combustion by varying the infill type and density. These results have significance for the fields of structural energetic materials and for additive manufacturing studies of energetic materials.