Electrothermal free-form additive manufacturing of thermosets

Despite the extensive use of thermosetting resins, additive manufacturing of such materials is limited. Traditional processing requires either (i) long curing schedules to avoid the collapse of an uncured printed part or (ii) changes to the resin chemistry and curing mechanism. This work demonstrates a material-extrusion based setup capable of printing and curing any industry-standard thermoset resin through the use of electric fields and carbon nanomaterial susceptors. A material extrusion printer is used to deposit the liquid ink, composed of uncured epoxy with a carbon nanotube filler. After each layer is deposited, the nanotube-loaded ink is exposed to radio frequency (RF) fields generated by a coaxial applicator suspended over the part. The resulting current generates heat rapidly and volumetrically, thus curing the resin, preventing part collapse, and enabling further printing. This methodology enables rapid additive manufacturing of arbitrarily large structures with low viscosity resins that are otherwise impossible to print.