Surface modification of thermally expandable microspheres for enhanced performance of disbondable adhesive

This research successfully improved the compatibility between thermally expandable microspheres (TEMs) and an adhesive system for enhanced performance. TEMs were grafted with poly(glycidyl methacrylate) (PGMA) chains via atom transfer radical polymerisation (ATRP) with activators regenerated by electron transfer (ARGET) or ARGET ATRP technique. The temperature effect on the surface modification of TEMs was investigated for an optimum modification condition. Compared to adhesive incorporating unmodified TEMs, up to 15.8% increase in tensile lap shear strength and 24.0% increase in ultimate tensile strength (UTS) were achieved. Most notably, after environmental conditioning, the UTS of the adhesive system containing modified TEMs was 8.0% higher than the strength of unmodified TEMs before environmental conditioning.