Graphene nanoplatelets thickness and lateral size influence on the morphology and behavior of epoxy composites

Graphene nanoplatelets/epoxy nanocomposites were prepared using a high shear toroidal mixer as dispersion technique. Suitable dispersions were obtained. Several graphene nanoplatelets, with different thickness and lateral dimensions, were added in order to analyze the influence of these parameters in the final properties. An important nanofiller concentration gradient was found from the top to the bottom in nanocomposites reinforced with large nanoplatelets due to a natural deposition by gravity. This phenomenon is not appreciable when the nanoplatelets size decreased. However, the small nanoplatelets have a greater tendency to agglomerate in packages of several parallel particles. In general, graphene nanoplatelets addition caused an increment in glass transition temperature, stiffness and thermal stability compared to the epoxy resin. However, it was also found that graphene nanoplatelets dimensions significantly affect to these enhancements. Nanocomposites reinforced with larger and thicker nanoplatelets presented lower glass transition temperature, higher modulus and higher decomposition temperature.