| Summary: | 碩士 === 中原大學 === 化學研究所 === 94 === Clay-dispersed polyimide nanocomposites were synthesized by a in-situ polymerization processes. By using the wide angle X-ray diffraction(WAXRD) and transmission electron microscopy (TEM) technique, polyimide inserted between the interlayer of montmorillonite (MMT) clay was indentified. The thermal and mechanical properties of polyimide-clay nanocomposites were studied by the TGA、DSC and DMA. The reduced moisture absorption of polyimide-clay nanocomposites was found to be related with content of clay. The dielectric properties of polyimide-clay nanocomposites were measured under frequency of 1kHz ~1MHz and temperature of 25℃~ 150℃.
Three major topics were investigated in the present study：First, PI-clay nanocomposites exhibit better intercalation/exfoliation, enhance thermal, mechanical properties and lower dielectric constants when double-swelling agents are used.
Second, PK 802, a clay with negative charge resident in its octahedral polyhedra, results in lower moisture absorption, dielectric constant and loss in PI-clay nanocomposies due to its weak ionic strength to polymer matrix.
Third, it was found that dielectric constant of PI-clay nanocomposites is related to the：(1) dispersion of clay, (2) symmetry of fluorine atom, (3) fluorine content in the PI, and (4) thickness of film specimen. Higher fluorine content in PI matrix results in lower dielectric constant.
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