Radio Frequency Heating of Laser-Induced Graphene on Polymer Surfaces for Rapid Welding

In this report, we investigate the rapid heating ability of laser-induced graphene (LIG) in response to radio frequency (RF) fields. Graphitic structures were produced from various industrially prevalent thermoplastics via laser irradiation of the polymer surface. We find that RF responsive, graphitic structures may be produced from Kapton, polyether imide (PEI), polyether sulfone (PESU), polyether ether ketone (PEEK), and polycarbonate (PC) using a conventional laser cutting machine. The graphitic structures are also electrically conductive in addition to being RF responsive. Exposure of LIG to RF fields resulted in the rapid heating of LIG with remarkable heating rates up to 126 degrees C/s. Finite-element simulations for these systems show similar heating trends. This heating response may be used in advanced manufacturing as a means to rapidly weld polymer- polymer interfaces, as will be demonstrated in this report. Our technique uses RF fields to induce localized heating in contrast to uniform bulk heating from external sources such as ovens or furnaces. The methods detailed in this paper provide a polymer processing pathway that may be used to generate RF responsive filler in situ. Finally, we aim to show that LIG-polymer composites may function in an industrial setting, with particular application to additive manufacturing and functional coatings.