Rapid Manufacturing via Selective Radio-Frequency Heating and Curing of Thermosetting Resins

A new method for additive manufacturing of thermosetting resins using selective, localized radio-frequency (RF) heating and curing in a thermoset reservoir is demonstrated. The use of a local RF applicator addresses the challenge of selective curing and printing of heat-curable thermosets from a reservoir of resin, without the addition of photocurable acrylates. The filler of interest is multi-walled carbon nanotubes, which heat up rapidly in response to an RF field. A target temperature can be maintained by modulating the RF power. Multilayered structures were 3D printed by moving the RF applicator relative to the resin reservoir, selectively curing the resin exposed to the field; this process was repeated for each layer. Thermal and mechanical properties of RF-printed samples were compared against conventional samples, with both methods showing similar glass transition temperatures and storage moduli; the RF-heated samples showed a more uniform morphology with lesser voids. The 3D printing process (temperature and conversion varying in space and time) is modeled to demonstrate the scope of this method in printing complex structures. This method of multilayered additive manufacturing of thermosetting resins allows for rapid, free-form processing.