Polyhedral oligomeric silsesquioxane (POSS) is a suitable nanoscale reinforcement for thermosetting polymers, such as epoxy resin systems in order to modify its mechanical, thermal and chemical properties. The inclusion of POSS the at higher loading (greater than 1 wt.%); however, it introduces ductility during fracture behavior these nanocomposites. Consequently, J-integral used quantify mater...