Dehybridisation of fibre-metal laminates via blowing agents in the thermosetting adhesive layer

The experiments conducted in this study examine Debonding on Demand strategies for fibre–metal laminates by using blowing agents embedded in the epoxy adhesive layer, with motivation rooted in recycling and efficient end-of-life separation of material compounds. Four blowing agents—two chemical (OBSH and ADC based) and two physical (thermally expandable microspheres) are tested through thermal analysis, mass/volume changes and microscopic evaluation focusing on their interaction with an epoxy matrix and their separation mechanisms after thermal activation. The experimental results demonstrated that the utilised chemical blowing agents induce pronounced cracking and enable targeted weakening of the adhesive interface, while the physical agents used in this study primarily lead to volumetric expansion and changes in colour after activation without sufficient macroscopic damage. Edge shear testing of manufactured fibre–metal laminates confirmed that ADC-based chemical blowing agent exhibited nearly complete delamination after activation, while the utilised physical blowing agent showed a significant but insufficient reduction of 29.0% in shear strength. The systematic analysis of thermal behaviour, interfacial shear strength, and mechanical degradation mechanisms demonstrates the feasibility of tailoring FML architectures for separation via targeted weakening of the adhesive interface, supporting improved recycling and material reuse. • Introduces Debonding on Demand for laminates using thermally activatable adhesives. • Comparison of chemical and physical blowing agents for end-of-life separation. • Physical microspheres cause volume expansion but insufficient interface failure. • Utilised chemical blowing agents form pronounced crack networks after activation.