Influence of ultrasonic dual mode mixing on the morphology, molecular structure and thermo-physical properties of a SiO₂-epoxy nanocomposite adhesive

Silica nanoparticles (~15 nm) were introduced in an epoxy adhesive using an ultrasonic dual mode mixing route at different amplitudes to tune the thermo-physical properties. Processing at higher amplitude resulted in a homogeneous distribution of less clustered nanoparticles. Glass transition temperature, thermal stability, and activation energy of nanocomposites processed at 55% of amplitude showed a significant enhancement for a very low nanoparticle content of 0.5 wt%. Incorporation of a higher nanoparticle content from 2 to 5 wt% declines the properties of the composite possibly due to increasing the number of clusters rather than the cluster size which may adversely affect the cross-linking density of the base polymer.