HIGH TEMPERATURE MIXED POLYIMIDES AND COMPOSITES FORMED THEREFROM

摘要

PATENT 13DV-9921 Polyimide intercondensation products are prepared from mixed dianhydrides and aromatic diamines. One of the mixed dianhydrides must be 2,2 -bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride (6FDA) and the other dianhydride may be oxydiphthalic anhydride (ODPA) or biphenyl dianhydride (BPDA) or mixtures thereof. Preferred aromatic diamines are p-phenylenediamine (PPD) and/or m-phenylenediamine (MPD). The polyimide products have increased glass transition temperatures (Tg), frequently higher than 400.degree.C. Composites made from the polyimides have high thermal and oxidative stability and may be used in aircraft engine hardware.