Loading patent…
AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorsPaul M. Hergenrother, Stephen J. Havens, Mark W. Beltz
Estimating the term…
The semicrystalline polyimide prepared by reaction of 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) and 1,3-bis(4-aminophenoxy-4'-benzoyl)benzene (1,3-BABB) is modified so that it can be more readily processed to form adhesive bonds, moldings and composites. The stoichiometric ratio of the two monomers, BTDA and 1,3-BABB is controlled so that the intermediate polyamide acid is of a calculated molecular weight. A polyamide acid with excess anhydride groups is then reacted with the stoichiometrically required amount of monofunctional aromatic or aliphatic amine required for complete endcapping. A polyamide acid with excess amino groups is reacted with the stoichiometrically required amount of monofunctional aromatic anhydride required for complete endcapping. The stoichiometrically offset, endcapped polyimide is processed at lower temperatures and pressures than the unmodified high molecular weight polyimide with the same repeat unit, and exhibits an improved melt stability.
The polyimide composition having the general structural formula:
The polyamide acid composition having the general structural formula:
The polyimide composition having the general structural formula:
The polyamide acid or polyamide ester composition having the general structural formula:
Dependencies are inferred from the claim text.