Nonplanar 3D Printing of Epoxy Using Freeform Reversible Embedding
Neeha Dev Arun, Humphrey Yang, Lining Yao, Adam W. Feinberg
Abstract
Thermally cured thermoset polymers such as epoxies are widely used in industry and manufacturing due to their thermal, chemical, and electrical resistance, and mechanical strength and toughness. However, it can be challenging to 3D print thermally cured thermosets without rheological modification because they tend to flow and not hold their shape when extruded due to cure times of minutes to hours. 3D printing inside a support bath addresses this by allowing the liquid polymer to be held in place until the thermoset is fully cured and expands the structures that can be printed as extrusion is not limited to layer-by-layer. Here we report the use of Freeform Reversible Embedding (FRE) to 3D print off-the-shelf thermoset epoxy into lattice structures using non-planar extrusion. To do this we investigate how extrusion direction in 3D space impacts epoxy filament morphology and fusion at filament intersections. Further, we show the advantages of this approach by using non-planar printing to produce lattice geometries that show ~4 times greater specific modulus compared to lattice structures printed using other materials and printing techniques.