Preparation and properties of epoxy-organically modified layered silicate nanocomposites

Abstract

Epoxy-silicate nanocomposites were prepared by dispersing synthetic layered silicates modified with alkylammonium ions. In the dispersing process, the organically modified layered silicates were mixed in epoxy resin with shearing, and aggregations of the silicates were removed by centrifugal separation after mixing epoxy resin and silicates. Micrographs taken by transmission electron microscopy (TEM) indicate that the nanocomposites have a mixed morphology including both parallel silicate layers (0.1-0.5 /spl mu/m, 5-15 layers) and exfoliated silicate layers (nano-scale dispersion) area. In terms of thermal resistance properties, the glass transition temperature (T/sub g/) of the nanocomposite was shifted to a higher temperature (/spl Delta/20/spl deg/C) than pure epoxy. Furthermore, dispersion of modified silicate prevented relative permittivity (/spl epsiv//sub r/) and dielectric loss (tan/spl delta/) from increasing at a high temperature above the glass transition temperature.