Synthesis and characterization of trifluromethyl-containing polyimides

A new fluorine-containing diamine of 2-trifluoromethyl-4,4'-diaminodiphenyl ether (3FODA) which has good solubility and high reactivity was synthesized. Two calculated molecular weight PMR polyimide resins were synthesized with 3FODA instead of methylene dianiline (MDA) in the first generation PMR polyimide KH-304 and PMR-15. The results showed that the monomer resin solution has high concentration, low viscosity and good stability under room temperature. The imidization process of the resin was investigated by TGA and FTIR, and the molding powder exhibited good processibility. The molded resins possessed high glass transition temperatures (T-g) in the range of 336 similar to 379 degrees C and the decomposition temperature in the range of 536 similar to 566 degrees C .3FODA-PI-15 resin exhibited high glass transition temperatures and low decomposition temperature compared to 3FODA-PI-30 because of its low molecular weight. In addition, both 3FODA-PI-15 and 3FODA-PI-30 resin showed good thermo-oxidative stability at 320 degrees C and 3FODA-PI-15 resin has lower weight loss because of lower content of nadic anhydride. 3FODA-PI resin exhibited excellent electrical properties and low water uptake. The combined properties suggested that this kind of polyimide resins can be used as matrix resin in aviation and space industry.