Polyamides solubility

In order to keep polyamides soluble in relatively apolar solvents, the use of flexible (macro)monomers such as a, co-(diaminopropyl)polydimethylsiloxane [52] or oligoethyleneglycol-based diamines [53, 54] has been proven to be a successful approach (Fig. 10). Poly condensations of dimethyl adipate with a variety of diamines were successful in bulk and at moderate temperatures between 60 and 100 °C (reaction A in Fig. 10). The low temperatures (60-100 °C) that suffice in these polymerizations also allow the use of monomers that are thermally instable, such as diethyl fumarate [53]. Moreover, multifunctional amines could be regioselectively polymerized up to molecular weights of 9 kDa, making lipase catalysts a valuable tool for the preparation of well-defined polyamides that can be further functionalized with active groups. 

Photopolymerize polymers bound by polyamides are applied to printing plates. They are mixed with polyamides soluble to alcohol... 

Polyimides for use ia molded products and high temperature films can be produced by the reaction of pyromelHtic dianhydride [89-32-7] and 4,4 -diaminodiphenyl ether [13174-32-8] ia DMAC to form a polyamide that can be converted iato a polyimide (13). DMAC can also be used as a spinning solvent for polyimides. AdditionaUy, polymers containing over 50% vinyHdene chloride are soluble up to 20% at elevated temperatures ia DMAC. Such solutions are useful ia preparing fibers (14). 

Amidation. Heating of the diammonium salt or reaction of the dimethyl ester with concentrated ammonium hydroxide gives adipamide [628-94-4] mp 228°C, which is relatively insoluble in cold water. Substituted amides are readily formed when amines are used. The most industrially significant reaction of adipic acid is its reaction with diamines, specifically 1,6-hexanediamine. A water-soluble polymeric salt is formed initially upon mixing solutions of the two materials then hea ting with removal of water produces the polyamide, nylon-6,6. This reaction has been studied extensively, and the hterature contains hundreds of references to it and to polyamide product properties (31). 

These polymers possess enhanced solubility compared to the aromatic polyamides with no deterioration in thermal stability. Their Ts vary from... 

The polyamides are soluble in high strength sulfuric acid or in mixtures of hexamethylphosphoramide, /V, /V- dim ethyl acetam i de and LiCl. In the latter, compHcated relationships exist between solvent composition and the temperature at which the Hquid crystal phase forms. The polyamide solutions show an abmpt decrease in viscosity which is characteristic of mesophase formation when a critical volume fraction of polymer ( ) is exceeded. The viscosity may decrease, however, in the Hquid crystal phase if the molecular ordering allows the rod-shaped entities to gHde past one another more easily despite the higher concentration. The Hquid crystal phase is optically anisotropic and the texture is nematic. The nematic texture can be transformed to a chiral nematic texture by adding chiral species as a dopant or incorporating a chiral unit in the main chain as a copolymer (30). 

TrimeUitic anhydride is converted to PVC plasticizers, polyesters, water-soluble alkyd coatings, and polyamide—imide resias. The trimellitate plasticizers have a lower volatility than those derived from phthaUc anhydride (see Plasticizers). 

The derivatives used in corrosion inhibitor formulations for down-hole use constitute a significant industrial appHcation for polyamines. Again, mono- and bisarnidoamines, imidazolines, and polyamides made from the higher polyamines are the popular choices. The products made from DETA and fatty acids have been widely used (308). A wide variety of other polyamine-based, corrosion inhibiting derivatives have been developed, generally incorporating some form of oil-soluble or od-dispersible residue. Sulfur and its derivatives are also used in these polyamine-based corrosion inhibitors on... 

Hydrophobic fibers are difficult to dye with ionic (hydrophilic) dyes. The dyes prefer to remain in the dyebath where they have a lower chemical potential. Therefore nonionic, hydrophobic dyes are used for these fibers. The exceptions to the rule are polyamide and modified polyacrylonitriles and modified polyester where the presence of a limited number of ionic groups in the polymer, or at the end of polymer chains, makes these fibers capable of being dyed by water-soluble dyes. 

Whilst the aliphatic nylons are generally classified as being impact resistant, they are affected by stress concentrators like sharp comers which may lead to brittle failures. Incorporation of mbbers which are not soluble in the nylons and hence form dispersions of rubber droplets in the polyamide matrix but which nevertheless can have some interaction between mbber and polyamide can be most effective. Materials described in the literature include the ethylene-propylene rubbers, ionomers (q.v.), polyurethanes, acrylates and methacrylates, ABS polymers and polyamides from dimer acid. 

Occasionally, water-soluble plastics are required. Poly(vinyl alcohol) is commonly the first to be considered but some cellulose ethers, polyethylene oxides, poly(vinyl pyrrolidone) and A-substituted polyamides are among many possible alternatives. 

Cellulose acetate is a common membrane material, but others include nylon and aromatic polyamides. The mechanism at the membrane surface involves the influent water and impurities attempting to pass through the pressurized side, but only pure water and certain impurities soluble in the membrane emerge from the opposite side. 

Phenothiophosphine ring-containing polyamides and polyesters were also prepared by the polycondensation of 2,8-bischloroformyl-lO-phenylphenothiophos-phine 5,5, 10-trioxide with aromatic diamines such as 4,4 -diaminodiphenyl ether and 4,4 -diaminodiphenyl-methane, and bisphenols such as 4,4 -dihydroxybiphe-nyl and 4,4 -dihydroxydiphenylmethane, respectively [159]. These polymers are soluble in polar aprotic solvents and also exhibit good heat and fire resistance. Phosphorus containing high performance polymers are shown in Table 6. 

Polyamides (nylons) The main types of nylon are oil and petrol resistant, but on the other hand susceptible to high water absorption and to hydrolysis. There are a few solvents such as phenol, cresol and formic acid. Special grades include a water-soluble nylon, amorphous copolymers and low molecular weight grades used in conjunction with epoxide resins. Transparent amorphous polyamides are also now available. 

Polydithiazoles Polyoxadiazoles Polyamidines Pyrolyzed polyacrylonitrile Polyvinyl isocyanate ladder polymer Polyamide-imide Polysulfone Decompose at 525°C (977°F) soluble in concentrated sulfuric acid. Decompose at 450-500°C (842-932°F) can be made into fiber or film. Stable to oxidation up to 500°C (932°F) can make flexible elastomer. Stable above 900°C (1625°F) fiber resists abrasion with low tenacity. Soluble polymer that decomposes at 385°C (725°F) prepolymer melts above 405° C (76l.°F). Service temperatures up to 288° C (550°F) amenable to fabrication. Thermoplastic use temperature —102°C (—152°F) to greater than 150° C (302°F) acid and base resistant. 

Polyvinyl isocyanate ladder polymer Polyamide-imide Soluble polymer that decomposes at 385°C (725°F) prepolymer melts above 405°C (761°F). Service temperatures up to 288°C (550°F) amenable to fabrication. 

In common with all the higher AB polyamides, PA-12 can be made from either die amino acid or the lactam.12 In practice, PA-12 is made from the cheaper 12-laurolactam (12-dodecane lactam or laboratory-scale synthesis it is advisable to start with the amino acid or a combination of amino acid and lactam. 

Diamantane-based polymers are synthesized to take advantage of their stiffness, chemical and thermal stability, high glass transition temperature, improved solubility in organic solvents, and retention of their physical properties at high temperatures. All these special properties result from their diamantane-based molecular structure [90]. Polyamides are high-temperature polymers with a broad range of applications in different scientific and industrial fields. However, their process is very difficult because of poor solubility and lack of adequate thermal stability retention [90]. Incorporation of 1,6- or... 

These opposing tendencies may defeat the purpose of the fractional precipitation process. The fractional precipitation of crystalline polymers such as nitrocellulose, cellulose acetate, high-melting polyamides, and polyvinylidene chloride consequently is notoriously inefficient, unless conditions are so chosen as to avoid the separation of the polymer in semicrystalline form. Intermediate fractions removed in the course of fractional precipitation may even exceed in molecular weight those removed earlier. Separation by fractional extraction should be more appropriate for crystalline polymers inasmuch as both equilibrium solubility and rate of solution favor dissolution of the components of lowest molecular weight remaining in the sample. 

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