Resistance Welding of Carbon Fiber Reinforced Vitrimer Composites

The welding behavior of prototype vitrimer composites with respect to adjustable parameters and protocols is investigated, and a method for resistance welding of vitrimer composites directly adapted from the welding of thermoplastic composites is described. Adherend laminates are positioned on either side of a matrix-saturated carbon fiber heating element, through which current is driven, and resistance heating welds the adherends and heating element together, forming a single lap joint. Weld strengths matched or exceeded the strength of composite parts produced using the manufacturer-recommended consolidation method (12.0 ± 2.6 MPa vs. 8.4 ± 0.6 MPa). Furthermore, repeating the welding process yielded greater shear strength, withstanding up to five weld–break–reweld cycles with an average increase of 4.6 ± 1.5 MPa or 65% compared to the first weld. The findings from resistance weld experiments highlight the suitability of vitrimer matrix composites for repair. Finally, a process for reversing a welded joint was shown, demonstrating the potential for vitrimers for temporary joining and rejoining.