High temperature mixed polyimides and composites formed therefrom
AssigneeGeneral Electric Company
InventorsRichard N. Griffin, Robert A. Gray
Life of this patent
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Abstract
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.
Claims39
A polyimide having improved glass transition temperature consisting essentially of the product of reaction of:
- (a) mixed dianhydrides wherein one of the mixed dianhydrides is a biphenyl dianhydride or derivatives thereof, or an oxydiphthalic anhydride or derivatives thereof, or a mixture thereof and the other dianhydride is 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride or derivatives thereof, and
- (b) aromatic diamines
A method of increasing the glass transition temperature of polyimide resins derived from a reaction mixture of aromatic diamines and mixed dianhydrides wherein one of the mixed dianhydrides is a biphenyl dianhydride or derivatives thereof, or an oxydiphthalic anhydride or derivatives thereof, or a mixture thereof, consisting essentially of adding 2,2-bis(3,4- dicarboxyphenyl)hexafluoropropane dianhydride or derivatives thereof as the other mixed dianhydride to the reaction mixture whereby a polyimide is formed by the intercondensation of aromatic diamines and the mixed dianhydrides.
A polyimide, having improved glass transition temperature consisting essentially of structural units of the formula (I):
- ##STR4## and structural units of the formula:
- ##STR5## or mixtures of formulas (II) and (III), where a and b represent any ratio from about 1:9 to about 9:1, and R is a divalent aromatic hydrocarbon radical having from 6 to about 20 carbon atoms and halogenated derivatives thereof.
Dependencies are inferred from the claim text.