Several Experimental Results Indicating Filler/Polymer Interactions in Polymer Nanocomposites

As a reason for superior insulation performance of polymer nanocomposites, interactions at the filler/polymer interfaces are widely believed. However, their evidence has been scarcely reported. In this paper, several experimental results obtained by the authors, which provide evidence of direct influences of the addition of fillers on the properties inherent to host polymers, are presented.

I. Introduction

Recently, many attempts have been carried out to give superior dielectric properties to insulating polymers by making their nanocomposites. This paper reports several results obtained experimentally, which clearly indicates the presence of a strong interaction at the filler/polymer interfaces. First, a dielectric absorption peak appearing in polyamide-6 at around 3.1 THz shifts towards a lower frequency with addition of a small amount of layered nanosilica. Secondly, a significantly large absorption appears when micro-sized magnesia and nano-sized silica were co-added in bisphenol-A epoxy resin. Thirdly, the glass transition temperature of bisphenol-A epoxy resin decreases with an increase in content of nano-sized magnesia, while the conductivity shows a similar decrease. These phenomena indicate strongly that a certain interaction really occurs at interfaces between the polymer and the filler.