Polyamides acids

An all aromatic polyetherimide is made by Du Pont from reaction of pyromelUtic dianhydride and 4,4 -oxydianiline and is sold as Kapton. It possesses excellent thermal stabiUty, mechanical characteristics, and electrical properties, as indicated in Table 3. The high heat-deflection temperature of the resin limits its processibiUty. Kapton is available as general-purpose film and used in appHcations such as washers and gaskets. Often the resin is not used directly rather, the more tractable polyamide acid intermediate is appHed in solution to a surface and then is thermally imidi2ed as the solvent evaporates. 

Proton Conducting a. Polyamidic acid sulfamic acids... 

Originality This application provides a method for preparing polyamidic acid... 

Preparation of polyamidic acid sulfamic acid derivatives... 

TABLE 1. Proton Conductivity and Open-Circuit Testing Results for Electrolytic Membranes Consisting of Selected Polyamidic Acid Sulfamic Acid Derivatives Conducted at 150oC ... 

Transient Tms have been observed in other systems (i.e. polyimides) and appear to be due to synthetic conditions coupled with chemical structure. Under the same synthetic conditions, polymers of certain chemical structures form transient crystalline phases whereas others do not For example, when the polyamide acid from the reaction of 3,3, 4,4 -benzophenonetetracarboxylic di-... 

LARC TPI is a linear polyimide prepared with BTDA and 3,3 -diaminobenzo-phenone. The polyamide acid intermediate was used to prepare a semi-IPN with the PMR-15 reactants. After curing the blend exhibited a twofold Tg and an improved value of Glc (Table 8). 

The polyimide is prepared from 1,5 naphthlene diamine (1,5 ND) and 3,3, 4,4 diphenylhexafluoroisopropylidene tetracarboxylic acid dianhydride (6F). A polyamide acid is obtained initially and this is cyclized to give the polyimide. Because polyimides are derivatives of polyamides, polyimides are often included in reviews of aromatic polyamides. Another reason polyimides are included in this paper is that they illustrate the role of Structure Level II on gas transport properties in a straightforward manner. 

The polyamide-acid solution obtained was cast as a film (ca.. 25 mm thick) onto a glass plate and dried for 12 hours at 80°C under vacuum (30 min). The resulting film was subjected to the following cure cycle under nitrogen on a hot plate monitored with a surface thermometer to effect imidization 100°C (2 hours), 150°C (2 hours), 200°C (1.5 hours) and 300°C (1 hour). High Tg films (Tg > 300°C) were optionally cured for an additional 0.5 hours at a temperature of 480°C in an inert atmosphere oven to ensure imidization and removal of volatiles. 

Thus, the Eq. (50) gives the analytical intercommunication of Z) and ATM. The authors [52] estimated the value TA for polyamide acid in case of values ATM=4xlO" and 15x10" g/mole, corresponding to two ranges of values according to the data of Ref [48] and obtained the exact correspondence of the values (or a ), obtained experimentally and calculated... 

Metal-2,9,16,23-tetraaminophthalocyanines have been employed in the synthesis of polyimides and as curing agents for epoxy resins [133-135] Variables such as molar concentrations of the reagents, solvents and temperature were investigated to improve the conditions of the polycondensation. Solutions of the polyamide-acid copolymers can be used to fabricate films or fibers. The polyimide copolymers obtained in the second step of the reactions are insoluble. Excellent thermal stabilities up to 500 °C in air and 600 °C under vacuum were reported. 

Chem. Descrip. Unsaturated polyamide, acid ester salts in solvents (xylene,n-butanol, monopropylene glycol)... 

Acid orange 11. See Cl 45370 D C Orange No. 5 Solvent red 72 Acid orange 19 Synonyms Cl 14690 Empihcai C23Hi8N3NaOeS2 Properties M.w. 519.52 Uses Dye for wool, silk, and polyamide Acid orange 20 CAS 523-44-4... 

Classification Azobenzene Empirical C22HisN4Na04S Properties M.w. 454.44 Toxicology TSCA listed Uses Dye for wool, silk, polyamide, jute Manuf./Distrib. Aldrich http //www.sigma-aldrich.com, Anar Int l. http //www.anarchem.com, Sigma Acid red 179 Synonyms Cl 19351 Classification Chromium complex Uses Dye for wool, silk, polyamide Acid red 183... 

Acid violet 19. See Acid fuchsin Acid violet 41 Synonyms Cl 62020 Empirical C2oHi3N2Na06S Properties M.w. 432.37 Uses Dye for wool, polyamide Acid violet 43... 

Acid black 63 Acid orange 92 FD C Yeiiow No. 5 Tartrazine dye, polyamides Acid green 1 dye, poiyester... 

FIGURE 7 The data ofthe X-ray analysis for organoclay and nanocomposite polyamide acid/ organoclay. 

Table 17-1. Equilibrium Constants of Various Polycondensations. The Examples 6 and 7 Refer to the First Stage of the Polycondensation to Polyamidic Acids Which Proceeds without Water Elimination...

In polyimides (PI) the imide bond is initially subject to thermal conversions. The presence in the chain not only of the imide bond but also of a definite number of amide bonds, the existence of which is caused by the kinetic arrest of the cyclodehydration reaction of polyamide acids in the solid phase, impedes the analysis of PI degradation [18]. Therefore, the role of each type of bond during the pyrolysis of PI should he estimated by thorough analysis of the composition and properties of the decomposition... 

The chemistry of imidization has been reviewed elsewhere [1-5]. It is briefly outlined below in Eq. (8.1). The key elements are reaction of a diamine and a dianhydride to form an amide-acid polymer via ring opening of the anhydride by nucleophilic attack of the diamine. The polyamide acid is then formed into a polyimide by removal of water. These polymerizations are usually conducted in high-boiling polar solvents to dissolve the monomers and keep the polyamide acid in solution. Heating is frequently used to drive off water and form the polyimide. In some cases, other means of dehydration may be used. 

In most cases, the final polyimide is an intractable material that is very hard to shape and form. Traditional polyimides are usually made in solution as the amide-acid precursor to the polyimide. Often the polyamide-acid... 

The solution-based polyamide-acid process limits the type and speed at which articles can be made from these polyimides. This limitation is true of many polyimides that have very rigid backbones. These polyimides, which have very little flexibility in the polymer chain and a high Tg, are very hard to melt process into complex shapes, especially on a commercial scale. Such intractable polymers are processed into articles in the more flexible polyamide-acid form, often with solvent present. The solvent needs to be removed and recovered to form the final polyimide article. This is true of polyimides based on PMDA and BPDA with ODA, as discussed previously. They have only one flexible hnk in the polymer chain— the ether group of the ODA— and can only be melt-formed in the amide-acid stage or by machining from a sohd block of resin. 

BPADA is reacted with a more or less equimolar amount of a diamine, for instance, m-phenylene diamine (MPD), to make the polyamide acid. Water is removed by heating to form the polyetherimide (PEI). In this case, after removal of water and solvent, the added flexibility of the polyimide allows the molten resin to be extruded into strands. Strands of the BPADA-MPD polyetherimide [Eq. (8.5)] are cooled and chopped into pellets, which can subsequently be remelted to form parts or film. PEI powder can be made by grinding pellets or through precipitation methods. Special processes have been developed to make small-particle (15- 0,m) PEI powders. 

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