Nano-alumina modified epoxy based film adhesives

Epoxy based film adhesives were developed that contained nano‐sized alumina particles of different size and shape. These nano‐scale materials were incorporated at 5 and 10 weight percent into an adhesive formulation that was filmed on polyester random mat scrim. Films were applied to composite substrates for fracture testing and aluminum substrates for lap shear and peel testing. Scanning electron microscopy was used to characterize the surfaces of both the aluminum and composite specimens. Results from the bonded aluminum samples showed that in almost all cases the additives increased the peel and shear strength of the adhesives. Composite samples yielded results that were less clear, but still demonstrated that nano‐scale additives can increase the fracture toughness of a thermosetting adhesive.