The traditional method for producing curable particulate composites relies on casting the blend of particulate, binder and curing agents together in a mold. Especially on large scales, the casting process has two crucial difficulties that hinder performance. First, as the composite hardens, the particulate phase incites internal stresses in the bulk material. This can result in crack propagation, which may alter the desired performance. Second, mold geometries are limited by availability, which discourages on-demand production of complex geometries. The goal of this work is to apply an extrusion-based 3D printing technique to a hydroxyl-terminated polybutadiene (HTPB) binder infused with metal particulate (i.e. aluminum).<br/>The key challenges lie in printer performance and binder cure rate. At high particulate loadings, the composite slurry exhibits high viscosity. Most off the shelf printers are incapable of delivering continuous flow to these high viscosity slurries. To resolve this, printer modifications were made to control pressure gradients in order to improve flow continuity during the printing process. Additionally, slurry viscosity increases as a function of time. By varying relative concentrations of initiator and surfactant, binder viscosity can be tuned to facilitate various particulate loadings.

3D printing curable particulate composites: Printer design and composite performance

255th National Meeting (2018)

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