Enhancing the mechanical properties of an epoxy resin using polyhedral oligomeric silsesquioxane (POSS) as nano-reinforcement

This paper reports on the mechanical and failure properties of epoxy reinforced by polyhedral oligomeric silsesquioxane (POSS), a hybrid organic-inorganic nanofiller. The unique properties of POSS-reinforced epoxy resin are exploited to overcome processing issues. POSS molecules with different organic substituents (methacryl, glycidyl, and trisilanol phenyl) were added to the epoxy resin by direct mixing at loadings between 0.5 and 8 wt%. It was observed that the addition of POSS significantly increases the fracture toughness and work of fracture of epoxy resin by an average of 130% and 400%, respectively, while no significant change was observed in the flexural modulus and strength. Scanning electron microscopy (SEM) was done on fractured surfaces to investigate evidence of extrinsic toughening mechanisms due to POSS inclusion. The chemical interaction of POSS with the epoxy resin was investigated using Fourier transform infrared (FTIR). Finally, differential scanning calorimetry (DSC) was used to measure the change in glass transition temperature (Tg) resulting from inclusion of POSS.