(764a) Direct ink write 3D printing of high solids loading bimodal distributions of particles

As additive manufacturing expands as a processing technology for structurally customizable

materials, there is increasing interest in printing with high particle contents. For suspensions with particle contents of over 50 vol% there are significant formulation and processing challenges due to increased interparticle friction and suspension complexity. We focus on suspensions with bimodal particle distributions and two common binder systems, a high molecular weight polymer in a solvent that solidifies via solvent evaporation and a monomer mixture that cures via UV irradiation. We examine the interplay between formulation and processing and show that the formulation effects are particularly important at optimal printing parameters, but that they are overcome by processing-related defects at sub-optimal parameters. By understanding the processing and formulation effects specific to direct ink write additive manufacturing of high solids suspensions, new customized inks can be designed for a wide range of applications, including construction, energetics and ceramics.