Characterization of Adhesives Modified with Thermally Expandable Microspheres for Reversible Structural Adhesive Bonding

The growing demand for reversible and sustainable bonding possibilities in structural applications has sparked the search for new adhesive bonding systems. The application of thermally expandable microspheres (TEMs) in adhesive systems is explored to enable reversible bonding in structural adhesives. Thermally expandable particles, whose thermal expansion on heat stimulation is due to low-boiling-point hydrocarbons encapsulated within polymeric shells, were integrated into epoxy adhesive matrix to investigate their potential for providing controlled debonding of bonds via thermal expansion. The current study involves comprehensive characterization of the modified adhesives by expansion behavior analysis, optical microscopy, and scanning electron microscopy (SEM) for examining the morphology changes provided by thermal activation. Mechanical properties of bonded joints were assessed by lap shear strength tests between TEM-modified and unmodified adhesives under the conditions of before and after heat treatment. The findings indicate that the introduction of TEMs significantly affects microstructure and mechanical properties of adhesive joints, and offers a potential path for reversible bonding system development. This research offers key understanding for the creation of thermally responsive adhesive systems for use in applications where disassembly, recyclability, or repairability is desired, thereby facilitating the development of sustainable adhesive technologies.