Matrix effects on tubule distribution and dielectrics properties of tubule-based dielectrics

The dielectric properties of composites containing copper‐coated tubules in epoxy and polyurethane were characterized and interpreted in terms of contact angle and interfacial tension between the filler and the polymer matrix. The polyurethane samples had larger permittivity values than the epoxy samples over the entire tubule concentration range. The results suggested the tubules in polyurethane were more aggregated than those in epoxy and, consequently, the polyurethane samples were closer to percolation. This was inconsistent with the contact angle and interfacial tension data, because epoxy had larger contact angles and interfacial tension than polyurethane. Therefore, the contact angle and interfacial tension data could not be used to predict tubule distribution in composites. Also, the De Loor model provided a good fit to the permittivity data. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 53–57, 2005