Polyamide imides structure

Effect of polyamide-imide structure on alignment properties... 

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. 

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 ... 

There are also a few common polymers whose accepted names convey relatively little information about the repeating unit structure. The primary examples are polycarbonate, poly(phenylene oxide), polyamide-imides, poly-sulfones, and polyether ketones (see Table 1.3). 

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. 

Polyamide-imides are heterocyclic polymers having an atom of nitrogen in one of the rings of the molecular chain. A typical chemical structure is shown below ... 

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] ... 

Another polyamide-imide is formed through a reaction of trimellitic anhydride, isophthalic acid, and diisocyanate. It has the following structure ... 

Most polyamide-imides are not as heat resistant as are the polyimides discussed in the next section. They are, however, easier to process. The polyester-imides might be considered as upgraded polyesters, though properties vary, depending upon chemical structure. ... 

Cao X, Lu F. Structure/permeability relationships of polyamide—imides. J Appl Polym Sci 1994 54 1965-70. 

Figure P.14 General chemical structure of polyamide-imide.

Fig. 10. (a) The structure of a solvent-soluble polyimide based on DAPI monomer, (b) The structure of a solvent-soluble polyamide-imide. 

A polyamide-imide (PAI) features alternating imide and amide substructure sequences, an example being a pyromellitimide and amide, with a general structure as indicated below, where A1 is an alkyl group. The IR spectrum of a polyamide-imide is similar to that of a polyimide, except that amide grouping provides an additional carbonyl stretching vibration at around 1670 cm ... 

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

Polyamide imides, PAI, were first developed at DuPont in 1955. In the early 1960s they became commercially available from Standard Oil of Indiana (Amoco now Solvay Advanced Polymers) under the Torlon trade name [52]. PAIs are prepared from trimellitic anhydride chloride and various aromatic diamines such as ODA and methylene dianiline, MDA [53]. PAIs are amorphous thermoplastics that offer T s around 275 °C. Structures are shown in Fig. 1.30. PAIs offer long-lasting performance in severe service environments and a distinct combination... 

Regiospecific polyamide-imide (PAI) materials can be structurally represented as ... 

The separation of gas mixtures by polymeric membranes has become a commercially important methodology for a number of different systems (1). Several recent review articles have discussed the interaction between polymer structure and gas permeability properties (2,3). The quantification of the effect of polymer structure on gas transport properties recently has been reported (4,5) and it is now possible to optimize gas transport properties for well defined polymeric materials. For those materials which do not have a well defined data base it is necessary to prepare and measure the gas transport properties. The polyamide-imides (PAI) are a class of polymeric materials which do not have an extensive data base for gas transport properties (6,7). Work by Yamazaki and coworkers (8) demonstrated that PAI materials could be prepared easily and in a manner whereby the amide bond could be prepared from a phosphite activated carboxylic acid and an aromatic amine. Yang and CO workers (9-11) have shown that novel dicarboxyl ic acids could be prepared from trimellitic acid anhydride (TMA) and aromatic diamines and that these dicarboxylic acids could be coupled with a second diamine to form regiospecific PAI materials. Our focus was to examine the effects of a phenylene diamine and its alkylated analogs on the gas transport properties of regiospecific PAI materials and to identify those structures which maximized both permeability and selectivity. 

Figure 7.25 Chemical structures of monomers used to make polyamide-imides.

Figure 7.26 Chemical structure of a typical polyamide-imide.

---