Molecular indications of structure property relationships in enhanced nanocomposites

To obtain good dispersion of nanofillers in nanodielectrics, the surface of nanopowders or colloidal particles can be chemically treated to make them more compatible with the matrix. Epoxy nanocomposites that contain surface functionalized nanosilica, either colloidal or powdered, show higher breakdown strengths than the reference epoxy material. For nanodielectric composites containing 2 wt % of nanosilica, a breakdown strength some 25% higher than that of the unfilled epoxy was obtained. Spectroscopic measurements were obtained from all samples and multi variate statistical analysis was applied to enable selected material properties to be regressed allowing molecular associations of these properties to be identified. Electrical breakdown strength was found to be related to the presence of silica and the degree of curing whereas space charge accumulation was found to be related to a reduction in polar ester formation. In contrast we find clear evidence of space charge accumulation being related to more shallow charge trapping centers.