SynopsisA series of thermally-stable, tough, linear polyimides containing amide linkages were prepared. These materials have potential as high temperature films and coatings as well as matrix resins in graphite reinforced structures. The new polyamide-hides were prepared by reacting a group of isomers of diaminobenzanilide (DABA) with 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) to form the polyamide-acid with subsequent thermal conversion to the polyamide-imide (PAI). Four polymers were synthesized from unsubstituted amide diamines and two others from N-substituted amide diamines. The properties of these polyamide-hides were compared to those of the polyimide of benzophenonetetracarboxylic dianhydride/3,3'-diaminobenzophenone (LARC-TPI) because their structures are similar, except for the presence of the more flexible amide linkages. These polymers exhibited high inherent viscosities and glass transition temperatures. They were made into tough, flexible films which showed good thermal stability and good resistance to organic solvents. Mechanical properties of the PA1 films were better than those of LARC-TPI. Films of the 4,4'-isomer polyamide-bide exhibited an exceptionally high modulus and toughness during impact evaluation.
Narrow strips of various fully imidized polyimide films were stretched under constant load either isothermally or during a temperature ramp. The effects of process variables (load and temperature) on modulus, failure strain, and tensile strength of the stretched films were characterized and room temperature moduli of up to 16 GPa were documented. Several materials that undergo strain-induced crystallization were identified as candidates for further property optimization. Polym. Eng. Sci. 44:1360 -1367, 2004
A series of thermally stable, tough, linear polyimides containing amide linkages was prepared. The new polyamide‐imides were synthesized by reacting a group of isomers of diaminobenzanilide (DABA) with various dianhydrides, such as 4,4′‐oxydiphthalic anhydride (ODPA), 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA), and 2,2‐bis(3,4‐dicarboxyphenyl) hexafluoropropane dianhydride (6FDA). The resulting polyamide‐acids were thermally or chemically converted to the polyamide‐imide (PAI). Twelve polyimides were synthesized from unsubstituted and N‐methyl substituted amide diamines and their properties were compared with previously made polyamide‐imides and the polyimide LARC‐TPI. These polyimides exhibited high inherent viscosities and glass transition temperatures. They were made into tough, flexible films of which some showed good thermal stability and resistance to organic solvents. Overall, the mechanical properties of the PAI films were comparable to those of LARC‐TPI with the 4,4′‐systems exhibiting exceptional properties and crystallinity. These materials have potential as high temperature films, coatings and fibers, as well as molding and laminating resins.
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