Polymer nanocomposites are known to exhibit superior insulation performance. As a reason for this, interactions at the filler/polymer interfaces are widely believed. To obtain information on this, the glass transition temperature (T g), complex permittivity (ε*), and conductivity (σ) were measured in various epoxy resin nanocomposites. As a result, all the parameters (T g , ε*, and σ) decrease when the filler is MgO, whereas T g decreases and ε* and σ increase when the filler is TiO 2. This fact clearly indicates that the filler exerts significant influences on various properties such as molecular motions in the host epoxy resin, and that these influences differ profoundly depending on the filler material.

Optical absorption spectra in a frequency range from 0.5 to 5.0 THz were measured in several epoxy resin nanocomposites with and without co-addition of micro-sized fillers, aiming at obtaining important information on intermolecular interactions between filler and polymer. As a result, significantly large absorption appears when both micro-sized MgO and nano-sized SiO2 fillers were added in epoxy resin. Similar but smaller absorption is also found in an epoxy resin composite with nano-sized TiO2 fillers.

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In this report, the bowing behavior and the state of stress in PI film during tenter heating process were predicted by a finite element method (FEM). In the FEM analysis, the authors focused especially on the first zone of tenter heating where the shrinking stress and changes in film hardness arise resulting from removal of residual solvents and chemical reaction (imidation). The analysis was carried out under the assumption that the PI film in the tenter heating was linearelastic. From the orientation measurements of PI film, which underwent the heating at the tenter 1 st zone, the angle of orientation axis at the film edges tilted approximately 45 degrees from the machine direction (MD) and became level with the transverse direction (TD) at film center. These results comparatively agreed with the direction of the maximum principal stress calculated by FEM. Moreover the FEM results revealed reverse bowing around the entrance of tenter.

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