Effect of ultrasonic dispersion methods on thermal and mechanical properties of organoclay epoxy nanocomposites

This report highlights the importance of nanocomposite formation and dispersion upon improvements in properties for high performance epoxy based layered silicate nanocomposites. This is achieved through the preparation of epoxy nanocomposites with varying clay concentrations using ultrasonic and solvent based fabrication and standard shear mixing procedures. Ultrasonication (combined with a solvent), in comparison to shear mixing methods, produces superior nanoscale dispersion according to SEM and TEM. As a result of the improvements in nanoscale dispersion, the corresponding improvements in fracture toughness, strength, strain to failure (compressive and flexural) and char stability are presented. TGA shows that while the initial thermal decomposition process is not affected, the stability of the char layer formed during decomposition increases with improved nanoscale dispersion as well as increasing concentration. The effect of moisture upon the dynamic mechanical thermal analysis of the epoxy nanocomposites displays some dependence upon the clay dispersion with a modest increase in plasticisation for the sonicated samples. Overall, this work shows that for a high performance epoxy anhydride resin system, significant improvements in key properties can be achieved at low levels of addition if appropriate sonicated dispersion methods can be utilised.