| 摘要 |
A high temperature resistant fiber, especially a polyimide fiber, having a dielectric constant less than 3 is prepared by first reacting 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane with 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride in an aprotic solvent to form a polyamic acid resin solution. The polyamic acid resin solution is then extruded into a coagulation medium to form polyamic acid fibers, which are thermally cured to their polyimide form. Alternatively, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane with 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride to form a polyamic acid, and the polyamic acid is chemically converted to its polyimide form. The polyimide is then dissolved in a solvent to form a polyimide resin solution, and the polyimide resin is extruded into a coagulation medium to form a polyimide wet gel filament. In order to obtain polyimide fibers of increased tensile properties, the polyimide wet gel filaments are stretched at elevated temperatures. Tensile properties of the fibers were measured and found to be in the range of standard textile fibers. Polyimide fibers obtained by either method will have a dielectric constant similar to that of the corresponding polymer, viz., less than 3 at 10 GHz.
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