Epoxy composites using functionalized alumina platelets as reinforcements

Epoxy composites with 200 nm thick alumina platelets as reinforcements were prepared and the effect of platelet volume fraction and functionalization of the platelets on the mechanical and fracture properties of the composites was investigated. The use of as-received platelets resulted in an increase in elastic modulus and fracture toughness; however, there was considerable reduction in the tensile strength of the composite at higher volume fraction. Subsequently composites were prepared using platelets functionalized with 3-glycidoxypropyltrimethoxysilane (GPS). It was observed that GPS coating of platelets improved the tensile strength of epoxy while retaining the improvements in elastic modulus and fracture toughness. Chemical changes due to GPS coating at the platelet-epoxy interface were investigated using Fourier Transform Infra-Red (FTIR) spectroscopy. The FTIR investigation clearly indicated the formation of Si–O–Al bonds. The fracture surface was studied using scanning electron microscope to understand the mechanisms responsible for the improvement in fracture toughness.