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 (0.1-0.5cun, 5-15 layers) and exfoliated silicate layers (nano-scale dispersion) area. In terms of thermal resistance properties, the glass transition temperature (T,) of the nanocomposite was shifted to a higher temperature (A20OC) than pure epoxy. Furthermore, dispersion of modified silicate prevented relative permittivity (G) and dielectric loss (tans) from increasing at a high temperature above the glass transition temperature. INTRODU CTl ONRecent rapid progress in nanotechnology has stimulated the research and development efforts focused on new high performance materials. In organic-inorganic hybrid materials, many reports have described high performance resins with layered silicates which are nano-dispersed in a polymer matrix (nanocomposites).Nanocomposites realize many improvements, including mechanical and thermal properties, in comparison with pure resin. Nanocomposites using this approach have attracted much interest, since the Toyota research group developed the nylon-layered silicate nanocomposite [l], which was synthesized by the method in which organically modified layered silicate was dispersed and exfoliated in a nylon matrix (Figure 1). This approach was first extended to epoxy resin systems by Pinnavaia et a1 [2], and various studies have been conducted on epoxy-silicate nanocomposites by many researchers [3-51.Epoxy resin has been widely utilized by various industries not only for its superior properties, but also its low cost. In the electrical power industry, we have taken advantage of epoxy resins as insulating and structural materials. Epoxy resin has its properties enhanced by modifying it with inorganic filler or glass fiber to a level that is indispensable for our products (e.g., spacer and FRP rod for gas insulating apparatus (GCB/GIS)). One of the most interesting features of nanocomposites is that improvements to resin properties can be achieved with the addition of a small weight-percentage silicates, therefore, the performance of nanocomposites enables insulating and shvctural materials to have lower weights and volumes. Figure 1 -Preparation method of nanocomposite. Exfoliation and dispersion of organic modified layered silicate occur upon polymerization.To discuss the properties of nanocomposites as insulating and structural materials, we have prepared epoxy-silicate nanocomposites by dispersing synthetic layered silicates modified with alkylammonium ions. The organically modified silicates have an affinity for polymer matrix and would be expected to disperse easily.The preparation metho...

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Adopting CO 2 as an alternative gas of SF 6 in a gas circuit breaker from the environmental viewpoint, a 72 kV-31.5 kA class CO 2 gas circuit breaker (CO 2-GCB) model, which does not contain SF 6 gas at all, was designed, and produced. In the CO 2-GCB model, some effective technologies for current interruption by CO 2 gas were adopted; namely, puffer pressure enhancing techniques utilizing arc energy during a current interruption and ablation phenomena of a polymer element located in the puffer cylinder. As a result of current interruption and electric insulation tests, the CO 2-GCB model achieved practical levels of performance. Furthermore, it was found by carrying out a life cycle assessment (LCA) that the CO 2-GCB model could reduce the global warming impact by about 40% compared to the latest SF 6 gas circuit breaker in the same rating for 20 years operation including one maintenance opportunity.

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