Nylon 66 polyamidation amidation

Molecular-Weight Distribution of Condensation Polymers Kinetics and Mechanism of Nylon 66 Polyamidation Amidation... 

Melamine formaldehyde Melamine phenolic Nitrile resins Phenolics Polyamides Nylon 6 Nylon 6/6 Nylon 6/9 Nylon 6/12 Nylon 11 Nylon 12 Aromatic nylons Poly(amide-imide)... 

Polymide polymers contain amide group NH CO in the main chain. The most important are linear aliphatic Polyamides. These are known as nylons. Polyamides are also used as adhesives, coatings and in engineering applications. 

The occurrence of the amide group in important technical polymers (e.g. polyacrylamides, nylon polyamide), in drugs (e.g. lactam antibiotics), in peptides and proteins has stimulated research leading to safe, simple, and in the case of a-asymmetric ca xylic acids nearly racemization-free, condensation methods. 

Amide Polypeptides and polyamides such as nylon Peptide amide bond cleavage, N-alkylation of the amide bonds, imidoester reaction [165,182]... 

Polyamides (PA), Nylon Polyamides represent a family of polymers based on the amide group... 

Fraser and MacRae have reported important absorption bands for natural product proteins and nylon polyamide at 4870 cm- (2188 nm) resulting from a combination of the peptide absorptions at 3305 cm- (3026 nm) and 1540 cm- (6494 nm). For feather shafts, the authors report absorption bands at 4970 cm- (2012 nm) and 5040 cm (1984 nm). A shoulder at 5040 cm (1984 nm) was reported as resulting from side chain amide groups. For beta-keratin, the paper reports important absorption bands at 4600 cm- (2174 nm), 4850 cm- (2062 tun), and 4970 cm (2012 nm). The authors were interested in studying the amorphous components of naturally occurring protein structures. 

The leader of DuPont s effort was Wallace H Carothers who reasoned that he could reproduce the properties of silk by constructing a polymer chain held together as is silk by amide bonds The neces sary amide bonds were formed by heating a dicar boxylic acid with a diamine Hexanedioic acid adipic acid) and 1 6 hexanediamme hexamethylenedi-amine) react to give a salt that when heated gives a polyamide called nylon 66 The amide bonds form by a condensation reaction and nylon 66 is an example of a condensation polymer... 

Polyamide (Section 20 17) A polymer in which individual structural units are joined by amide bonds Nylon is a syn thetic polyamide proteins are naturally occurring polyamides... 

As with polyesters, the amidation reaction of acid chlorides may be carried out in solution because of the enhanced reactivity of acid chlorides compared with carboxylic acids. A technique known as interfacial polymerization has been employed for the formation of polyamides and other step-growth polymers, including polyesters, polyurethanes, and polycarbonates. In this method the polymerization is carried out at the interface between two immiscible solutions, one of which contains one of the dissolved reactants, while the second monomer is dissolved in the other. Figure 5.7 shows a polyamide film forming at the interface between an aqueous solution of a diamine layered on a solution of a diacid chloride in an organic solvent. In this form interfacial polymerization is part of the standard repertoire of chemical demonstrations. It is sometimes called the nylon rope trick because of the filament of nylon produced by withdrawing the collapsed film. 

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). 

Polyamides, often also lefeiied to as nylons, are liigli polymers which contain the amide repeat linkage in the polymer backbone. They are generally characterized as tough, translucent, semicrystalline polymers that ate moderately low cost and easily manipulated commercially by melt processing. 

The nomenclature (qv) of polyamides is fraught with a variety of systematic, semisystematic, and common naming systems used variously by different sources. In North America the common practice is to call type AB or type AABB polyamides nylon-x or nylon-respectively, where x refers to the number of carbon atoms between the amide nitrogens. For type AABB polyamides, the number of carbon atoms in the diamine is indicated first, followed by the number of carbon atoms in the diacid. For example, the polyamide formed from 6-aminohexanoic acid [60-32-2] is named nylon-6 [25038-54-4], that formed from 1,6-hexanediamine [124-09-4] or hexamethylenediamine and dodecanedioic acid [693-23-2] is called nylon-6,12 [24936-74-1]. In Europe, the common practice is to use the designation "polyamide," often abbreviated PA, instead of "nylon" in the name. Thus, the two examples above become PA-6 and PA-6,12, respectively. PA is the International Union of Pure and AppHed Chemistry (lUPAC) accepted abbreviation for polyamides. 

Because the rules for organic nomenclature determine the priority of naming different carbon chains from their relative lengths, the systematic names for type AABB polyamides depend on the relative length of the carbon chains between the amide nitrogens and the two carbonyl functions of the polymer for aUphatic nylon-Ayy, when x < the lUPAC name is poly[imino-R imino(l2y-dioxo-R )]. When x > then the name is... 

Fig. 3. Alignment of amide dipoles in polyamide crystals (a) for a two-dimensional array of an odd nylon, nylon-7, (b) for a one-dimensional array of an odd—odd nylon, nylon-5,7 (c) for one-dimensional arrays of polyamides containing even segments an even nylon, nylon-6 an even—even nylon, nylon-6,6 ...

Nylon-6,6 and nylon-6 have competed successfully ia the marketplace siace their respective commercial iatroductioas ia 1939 and 1941, and ia the 1990s share, about equally, 90% of the total polyamide market. Their chemical and physical properties are almost identical, as the similarity of their chemical stmcture might suggest the amide functions are oriented ia the same directioa aloag the polymer chain for ayloa-6, but are altematiag ia directioa for ayloa-6,6. 

The amide linkage characterizes nylons. In the first commercial nylon, nylon-6,6, R = (CH2 )g and R = (CH2 )4. Nylon-6,6 is familiar as a textile fiber (nylon stockings) and a molded plastic (see Polyamides). 

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