Additive manufacturing of multifunctional epoxy adhesives with self-sensing piezoresistive and thermoresistive capabilities

Epoxy resin composites are a class of materials that are widely used in various industries, including automotive, marine, and aerospace. They serve as adhesives to improve the mechanical strength of structures or to replace traditional joining methods. This work evaluates the adhesive performance of a modified epoxy resin, emphasizing its application for bonded joints with piezoresistive and thermoresistive sensing capabilities for real-time structural monitoring. A novel processing method has been developed that utilizes acetone to disperse conductive carbon nanotubes, thereby controlling the viscosity of the solution for screen-printing applications. This method enhances print definition and device design while maintaining the feasibility of large-area applications for industrial scale-up and minimizing waste during the process. The approach demonstrated high adhesion properties and the capability to detect bending deformation and temperature variations in screen-printed adhesive bonded joints, achieving sensitivities up to GF approximate to 30 and S 60- 90 approximate to 0.03 (%.degrees C-1) for piezoresistive and thermoresistive sensing, respectively. Finally, a successful proof-of-concept was developed using glass fiber adherents bonded with the functional adhesive, enabling real-time measurement of bending.