Aromatic polyamide-imides

Polyamide Imide Enamels. Aromatic polyamide imide insulations are made from aromatic acids and aromatic diamines. The polyamide imide polymers are primarily present in the form of polyamic acids in the Af-methyIpyrrolidone solutions. During the enameling process the polyamic acids undergo imidization and become essentially fully imidized. Whereas the polyester and polyester imide enamels contain cresylic acids as the major solvent, the polyamide imide enamels are mainly formulated with A/-methylpyrrolidone as solvent. 

M. Minami and M. Taniguchi. Method of preparing a soluble high molecular weight aromatic polyamide imide composition. US Patent 3 860559, assigned to Toray Industries, Inc. (Tokyo, JA), January 14, 1975. 

The aromatic polyamide-imides are related to the aromatic polyamides described in the previous section. Aliphatic materials of this type were reported originally in 1947. They were formed by reacting tricarboxylic acids with diamines ... 

Three general methcxis are employed to form aromatic polyamide-imides. The first one... 

Discuss the chemistry of aromatic polyamide-imides and aromatic polyester-imides. Give examples. 

Aromatic Polyamide-Imides and Aromatic Polyester-Imides... 

Three general methods are employed to form aromatic polyamide-imides [88]. The first one consists of an initial reaction of a mole of a diacid chloride with two moles of a diamine. The product is then reacted with a dianhydride and after that condensed to an imide ... 

Figure 530. DMA data for samples of an amorphous aromatic polyamid-imide polymer containing various amounts of moisture the data indicate a decrease in Tg of over 100°C with 4.25% moisture sorption. [From Hiltz and Keough (1991) reprinted with permission of the North American Thermal Analysis Society.]...

Polyamide (PA) aromatic polyamide imide 10000 Fligh strengths, resistant because of molecular ring structure... 

Polyamide Imides. Polyamide imides (PAIs) are formed from the condensation of trimellitic anhydride and aromatic diamines (33). The polymer is called amide—imide because the polymer chain comprises amide linkages alternating with imide linkages, with the general chemical stmcture ... 

In addition to the commercial aromatic polyamides described above many others have been prepared but these have not achieved commercial viability. There are, however, a number of other commercial polymers that contain amide groups such as the polyamide-imides. The latter materials are discussed in Section 18.14. 

Potyimides obtained by reacting pyromellitic dianhydride with aromatic amines can have ladder-like structures, and commercial materials are available which may be used to temperatures in excess of 300°C. They are, however, somewhat difficult to process and modified polymers such as the polyamide-imides are slightly more processable, but with some loss of heat resistance. One disadvantage of polyimides is their limited resistance to hydrolysis, and they may crack in aqueous environments above 100°C. 

Figure 5.22 Synthesis of polyamide-imide by catalytic carbonylation of bis-4-chlorophthalimide in presence of aromatic diamine.

Aliphatic-aromatic copoly imides, 268 Aliphatic-aromatic polyesters, 18, 19 Aliphatic degradable polyesters, 41 Aliphatic diacids, polyamide synthesis from, 183-184... 

Polyamide-imides resist most acid and base solutions at low concentrations, alcohols, aldehydes, esters, aliphatic and aromatic hydrocarbons, greases, oils, gasoline, certain chlorinated hydrocarbons, and ketones. 

POLYAMIDE-IMIDE RESINS. An injection-moldable, high-performance engineering thermoplastic, polyamide-imide is the condensation polymer of tnmellitic anhydride and various aromatic diamines with the general structure ... 

In recent years, RO membrane research has proceeded in two diredrions. First, there has been a continuing search for new polymeric membrane materials. Some of the materials with interesting properties that could be cited include other cellulose esters polybenzimidazolea polybenzimidazolone (PBIL), poly-imides and new aromatic polyamides... 

In this paper we use dielectric measurements to calculate the polarizability of absorbed water in a series of aromatic polyimides and polyamide-imides. In the relatively non-polar polyimides, the absorbed water has a dipole moment close to that of free water (/i - 1.88 Debyes). This value drops to less than 0.4/x for polyamide-imides. The decrease may be attributed to hydrogen-bonded water in the very polar polyamide-imides. In addition, the "group" dipole moment for amide is calculated and found to be greater than the dipole moment of free water. 

For polyimides to be useful polymers, they must be processable, which means that they have to be meltable. Melt processability of polyimides can be improved by combining the basic imide structure with more flexible aromatic groups. This can be achieved by the use of diamines that can introduce flexible linkages like aromatic ethers and amides into the backbone. Polyamide-imides (5) are obtained by condensing trimellitio anhydrides and aromatic diamines, while polyetherimides (6) are produced by nitro displacement reaction involving bisphenol A, 4,4 -methylenedianiline, and 3-nitrophthalic anhydride. 

The thermoplastic variety of polyimides with enhanced melt processabihty is obtained by combining the basic imide stmcture with more flexible aromatic groups such as aromatic ethers or amides. Polyamide-imides are produced by condensing trimellitic anhydrides with aromatic diamines, while polyetherimides are made by the reaction between bisphenol A, 4,4 -methylene dianiline, and 3-nitrophthalic anhydride. 

Both polyamide-imide and polyetherimide have high heat distortion temperature, tensile strength, and modulus. Polyamide-imide is useful from cryogenic temperatures up to 260°C. It is virtually unaffected by aliphatic and aromatic chlorinated and fluorinated hydrocarbons and by most acid and alkali solutions. These polymers are used in high-performance electrical and electronic parts, microwave appliances, and under-the-hood automotive parts. Typical automotive applications include timing gears, rocker arms, electrical connectors, switches, and insulators. 

A considerable amount of research has been carried out in recent years into the design of matrix materials for the next generation of supersonic civil transports and much of it has focused on amide, imide and related structures. Among resins studied are the polystyrylpyridine (PSP) family, the polyamide-imides, polyetherimides, polyetherketones, and for very high temperatures, the polyphenylquinoxalines, the polybenzimidazoles and the aromatic polyesters [50,51]. Some generalizations emerge [52] ... 

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