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Polyamide, aromatic reaction

The reverse reaction is an intramolecular acidolysis of amide group by the o-carboxyhc acid to reform anhydride and amine. This unique feature is the result of an ortho neighboring effect. In contrast, the acylation of an amine with ben2oic anhydride is an irreversible reaction under the same reaction conditions. The poly(amic acid) stmcture (8) can be considered as a class of polyamides. Aromatic polyamides that lack ortho carboxylic groups are very... [Pg.398]

In 1974, Higashi et aL described a novel procedure to prepare aromatic polyamides. This reaction involved the complex 1 of an add with triphenylphos-phite in NMP and pyridine [8] (Scheme 2). CaQ2 and LiQ were used along with NMP to improve the molecular weight of the polymer obtained in the synthesis of para wholly aromatic polyamides. [Pg.181]

H. W. Hill, Jr., L. S. Kwolek, and W. P. Morgan. Polyamides from reaction of aromatic diacid halide dissolved in cyclic nonaromatic oxygenated organic solvent and an aromatic diamine. US Patent 3 006 899, assigned to Du Pont, October 31,1961. [Pg.442]

Carboxyhc acids react with aryl isocyanates, at elevated temperatures to yield anhydrides. The anhydrides subsequently evolve carbon dioxide to yield amines at elevated temperatures (70—72). The aromatic amines are further converted into amides by reaction with excess anhydride. Ortho diacids, such as phthahc acid [88-99-3J, react with aryl isocyanates to yield the corresponding A/-aryl phthalimides (73). Reactions with carboxyhc acids are irreversible and commercially used to prepare polyamides and polyimides, two classes of high performance polymers for high temperature appHcations where chemical resistance is important. Base catalysis is recommended to reduce the formation of substituted urea by-products (74). [Pg.452]

Other Preparative Reactions. Polyamidation has been an active area of research for many years, and numerous methods have been developed for polyamide formation. The synthesis of polyamides has been extensively reviewed (54). In addition, many of the methods used to prepare simple amides are appHcable to polyamides (55,56). Polyamides of aromatic diamines and aUphatic diacids can also be made by the reaction of the corresponding aromatic diisocyanate and diacids (57). [Pg.224]

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. [Pg.333]

The two-step poly(amic acid) process is the most commonly practiced procedure. In this process, a dianhydride and a diamine react at ambient temperature in a dipolar aprotic solvent such as /V,/V-dimethy1 acetamide [127-19-5] (DMAc) or /V-methy1pyrro1idinone [872-50-4] (NMP) to form apoly(amic acid), which is then cycHzed into the polyimide product. The reaction of pyromeUitic dianhydride [26265-89-4] (PMDA) and 4,4 -oxydiani1ine [101-80-4] (ODA) proceeds rapidly at room temperature to form a viscous solution of poly(amic acid) (5), which is an ortho-carboxylated aromatic polyamide. [Pg.396]

In 1973 Du Pont commenced production of another aromatic polytunide fibre, a poly-(p-phenyleneterephthalamide) marketed as Kevlar. It is produced by the fourth method of polyamide production listed in the introductory section of this chapter, namely the reaction of a diamine with a diacid chloride. Specifically, p-phenylenediamine is treated with terephthalyl chloride in a mixture of hexamethylphosphoramide and V-methylpyrrolidone (2 1) at -10°C Figure 18.32). [Pg.514]

It is also possible to prepare them from amino acids by the self-condensation reaction (3.12). The PAs (AABB) can be prepared from diamines and diacids by hydrolytic polymerization [see (3.12)]. The polyamides can also be prepared from other starting materials, such as esters, acid chlorides, isocyanates, silylated amines, and nitrils. The reactive acid chlorides are employed in the synthesis of wholly aromatic polyamides, such as poly(p-phenyleneterephthalamide) in (3.4). The molecular weight distribution (Mw/Mn) of these polymers follows the classical theory of molecular weight distribution and is nearly always in the region of 2. In some cases, such as PA-6,6, chain branching can take place and then the Mw/Mn ratio is higher. [Pg.150]

Para-quinone methide intermediates, 403 Para-quinone methides, 404 para-Trishydroxybenzylamine, reaction with 2,4-xylenol, 397 Partial aromatic polyamides, 136, 143, 180-184... [Pg.591]

Aliphatic iodine derivatives, 14 376 Aliphatic ketones, 14 563, 571, 581-585 reactions of, 16 331-332 Aliphatic monothiopolyesters, 23 739 Aliphatic nitration, 12 187 Aliphatic peroxyacids, 13 464 Aliphatic peroxycarboxylic acids, 18 463 Aliphatic phosphines, 19 60 Aliphatic polyamides (PA), 10 207-210 19 713, 739. See also Aromatic polyamides PA entries producers of, 10 210 properties of, 10 208, 209t Aliphatic polycarbonates, 24 703 preparation of, 19 798 Aliphatic polyketones (PK), 10 197 costs of, 10 222 properties of, 10 198t Aliphatic poly(monosulfide)s, 23 702-704 Aliphatic polyphosphonate dyes, 9 480 Aliphatic poly(polysulfide)s, 23 711 Aliphatic polysulfides, 23 734 Aliphatic polysulfoxides, 23 733 miscibility of, 23 735 Aliphatic polyurea preparation, carbonyl sulfide in, 23 625... [Pg.28]

The PET polymer structure can also be generated from the reaction of ethylene glycol and dimethyl terephthalate, with methyl alcohol as the byproduct. A few producers still use this route. The aromatic rings coupled with short aliphatic chains are responsible for a relatively stiff polymer molecule, as compared with more aliphatic structures such as polyolefin or polyamide. The lack of segment mobility in the polymer chains results in relatively high thermal stability, as will be discussed later. [Pg.404]

The use of HMF or the corresponding dialdehyde precursors obviously applies to the synthesis of monomers for polycondensation reactions as shown by the examples given in Scheme 2. ITiese difimctional structures again mimic the corresponding well-known aliphatic and aromatic counterparts used in the preparation of polyesters, polyamides, polyurethanes, etc. [Pg.196]

The most extensive research on furanic polyamides is recent (33) and deals essentially with furanic-aromatic structures, although an important effort was also devoted to all-fiiranic compositions. The reaction of the diacid 11a with various aromatic diamines leads to high-molecular weight polymers with good thermal stability and ciystallinity. Structure 23, obtained with p-phenylenediamine, exhibited features resembling closely those of polyaramides ... [Pg.204]

Fully aromatic polyamides are synthesized by interfacial polycondensation of diamines and dicarboxylic acid dichlorides or by solution condensation at low temperature. For the synthesis of poly(p-benzamide)s the low-temperature polycondensation of 4-aminobenzoyl chloride hydrochloride is applicable in a mixture of N-methylpyrrolidone and calcium chloride as solvent. The rate of the reaction and molecular weight are influenced by many factors, like the purity of monomers and solvents, the mode of monomer addition, temperature, stirring velocity, and chain terminators. Also, the type and amount of the neutralization agents which react with the hydrochloric acid from the condensation reaction, play an important role. Suitable are, e.g., calcium hydroxide or calcium oxide. [Pg.288]

During the synthesis of aromatic polyamides special attention must be paid to the purity of the monomers and an exact control of the reaction conditions. [Pg.294]

The routes give, using well-known condensation and radical reactions, bakelites (I), polyazophenylenes (II), polyimides (III), polyurethanes (IV), nitro compounds and polyamides (V), aromatic polyethers and polyesters (VI), polychalcones (VII), polyphenylene sulfides (IX), ammonia lignin (X), carbon fibers (XI), silicones (XII), and phosphorus esters (XIII). In addition, radiation and chemical grafting can be used to obtain polymers of theoretical interest and practical use. Although the literature on the above subject is very large, there are comprehensive summaries available (1,28,69). [Pg.202]

The liquid polymer is converted to the rubbery state by reagents that react with mercaptan (-SH) and side groups of the polymer segments by oxidation, addition or condensation to effect sulfide (-S-S-) bond formation. The oxidation reactions are exothermic and accelerated by an alkaline environment. The most commonly employed oxidizing agents which are suitable for curing liquid polymers are cobalt or manganese or lead octoate, p-quinonedioxime and di- or tri-nitrobenzene. Epoxy resin also reacts with liquid polysulfide polymers by addition in the presence of an aliphatic or aromatic amine and polyamide activator as shown in Equation 5.8 ... [Pg.352]


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See also in sourсe #XX -- [ Pg.829 ]




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