| Summary: | 碩士 === 中原大學 === 化學工程研究所 === 90 ===
Aromatic polyimides have been widely used in microelectronic and space industries due to their excellent thermal stability, good electronic properties and easy preparation. In this study two aromatic diamins containing either linear alkyl side chain or alkylene side group were successfully synthesized and characterized by NMR and FTIR methods. These new monomer were then reacted with benzophnenetetracrboxylic dianhydride (BTDA) or hexafluoroisopropylidene bis(phthalic anhydride) (6FDA) to prepare novel side-chain-containing polyimides.
The influence of alkyl group and alkyene group substitutes on the thermal properties of polyimides was investigated by differential scanning calorimetry, thermomechanical analyzer, and thermogravimetric analyses techniques. Experimental results indicate that the incorporation of alkyl moieties leads to a moderate increase in the coefficient of thermal expansion and a slight decrease in glass transition temperature and thermal stability, but all polymers still posses a decomposition temperature higher than 450℃. Furthermore, the dielectric constant also shows greatly dependent on the length of alkyl chain and the chemical composition.
Morover, experimental results also indicate that the incorporation of alkylene moieties results in a moderate decrease in the coefficient of thermal expansion and a slight increase in glass transition temperature and thermal stability. More importantly, the presence of alkylene side-chain effectively decrease the dielectric constant of polyimide. The dielectric constant of 6FDA-BEDA was found to be 3.0.
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