Microstructures and toughening mechanisms of organoclay/polyethersulphone/epoxy hybrid nanocomposites

Hybrid nanocomposites (HNCs) with high fracture toughness were successfully prepared by incorporating polyethersulphone (PES) and organoclay into epoxy resin. Their microstructures were studied. They were composed of homogeneous PES/epoxy matrices and micron-scale organoclay agglomerates. These agglomerates consisted of smaller tactoid-like regions which were comprised of ordered exfoliated nanolayers. The toughening mechanisms of the two tougheners were also studied and then related to their microstructures. For one thing, the PES which was dissolved in the epoxy resin homogeneously improved the ductility of the epoxy resin and made it easier to deform. For another, the organoclay agglomerates induced crack front bowing, crack bridging, crack deflection, crack bifurcation and plastic deformation of the matrices on the micron-scale, respectively. These toughening processes were achieved by the ordered exfoliated nanolayers with various orientations, which debonded from the matrices, bridged the cracks and induced the plastic deformation of the matrices on the nanoscale.