Electrically conductive epoxy nanocomposites as Joule adhesives for out-of-autoclave Carbon Fibre Reinforced Polymer (CFRPs) joining

Abstract

This thesis investigates the potential of electrically conductive epoxy nanocomposites filled with carbon nanomaterials, specifically graphene nanoplatelets (GNPs) and carbon nanotubes (CNTs), as effective Joule adhesives for out-of-autoclave (OoA) carbon fibre-reinforced polymer (CFRP) repair and bonding, as well as for efficient Joule debonding to enable the recovery and reuse of CFRPs components. This study demonstrates that Joule heating these electrically conductive nanocomposites spread on the bonding area between two CFRPs adherends provides a uniform thermal distribution throughout the bonding line, enabling an effective bonding of CFRPs adherends, also allowing for easy debonding. Single lap shear tests of the joints Joule bonded with these conductive adhesives revealed that their mechanical strengths were comparable to those bonded via the traditional oven curing method, evidencing this as a promising alternative for bond or repair CFRPs components. Additionally, dynamic fatigue testing revealed superior fatigue resistance in GNPs-reinforced adhesives compared to both neat epoxy and the CNTs-reinforced adhesives, indicating enhanced crack propagation resistance of the bonded joints and longer lifespans under high stress. This research also highlights the potential of these conductive adhesives for an effective deconstruction of the bonded joint when they are Joule heated up to their Tg through thermally induced softening, leading to an easy debonding without having to apply much external force. These findings suggest that electrically conductive nanocomposites emerge as promising Joule structural adhesives, offering an efficient and environmentally friendly strategy for joining CFRPs components, opening new pathways for effective management of the increasing CFRPs waste, which is currently raising serious environmental concerns.

Date of Award	1 Aug 2025
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Ian Kinloch (Supervisor) & Cristina Valles (Supervisor)