Polyamides 1,2-form

Polyamides from diamines and dibasic acids. The polyamides formed from abphatic diamines (ethylene- to decamethylene-diamine) and abphatic dibasic acids (oxabc to sebacic acid) possess the unusual property of forming strong fibres. By suitable treatment, the fibres may be obtained quite elastic and tough, and retain a high wet strength. These prpperties render them important from the commercial point of view polyamides of this type are cabed nylons The Nylon of commerce (a 66 Nylon, named after number of carbon atoms in the two components) is prepared by heating adipic acid and hexamethylenediamine in an autoclave ... 

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. 

Nylon-6 is the polyamide formed by the ring-opening polymerization of S-caprolactam. The polymerization of S-caprolactam can be initiated by acids, bases, or water. Hydrolytic polymerization initiated by water is often used in industry. The polymerization is carried out commercially in both batch and continuous processes by heating the monomer in the presence of 5—10% water to temperatures of 250—280°C for periods of 12 to more than 24 h. The chemistry of the polymerization is shown by the following reaction sequence. 

Other polyamides produced experimentally include polymers with active lateral groups (hydroxy, keto groups etc.), polymers with heteroatoms (sulphur and oxygen) in the polyamide-forming intermediates, polymers with tertiary amino groups in the main chain and polymers with unsaturation in the main chain. There does not, however, appear to have been any serious attempt to develop unsaturated polyamide analogues to the polyester laminating resins. 

Proteins are polyamides formed by the polymerization, through amide linkages, of a-amino acids. Three of the 25-30 important natural a-amino acids are shown in Figure 18-13. Each acid has an amine group, —NHj, attached to the a-carbon, the carbon atom immediately adjacent to the carboxylic acid group. 

Proteins are linear polyamides formed from a-amino acids. An a-amino acid is one in which carboxylic acid and the amino group reside on the same carbon atom (1.7). 

A major challenge in using interactive chromatography for polyamides is to find a suitable mobile phase (Mengerink et al., 2001, 2002 Weidner et al., 2004). Polyamides form semicrystalline morphologies that limit the solubility in organic solvents. Besides hot phenol, formic acid, and trifluoroethanol (TFE) (Mori and Barth, 1999), 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) represents a suitable solvent for polyamides (Chen et al., 2002). These solvents are mainly used to analyze the molar mass distribution of polyamides by SEC. 

Indeed, in the world of tomorrow we can expect new aspects of polymer solids to extend the conventional and successful structure ideas of this century. These, of course, were the recognition as molecular identities of the chains of repeating chemical monomers. The circumstances of those entities have resulted in interesting concepts of solubilities, viscosity, and other mechanics, and especially thermodynamic limitations m mutual solubility or comparability of polymer mixtures. But we have known for decades that even homogeneous regular chain polymers such as Carothers polyesters and polyamides formed solids with manifold imperfections and irregularities, such as order-disorder crystal configurations.(22,23)... 

The PA-300 membrane was commercially developed by Riley and coworkers (15), and is similar to the NS-101 membrane in structure and fabrication method. The principal difference is the substitution of a polyetheramlne, the adduct of polyepichlorohydrin with 1,2-ethanediamine, in place of polyethylenlmine. Use of the polyetheramlne was significant improvement in that considerably higher membrane fluxes were possible at salt rejections equivalent to the NS-lOO membrane system. The actual barrier layer in the PA-300 membrane is a polyamide formed by Interfaclal reaction of Isophthaloyl chloride with the polyetheramlne. 

Polymers were originally classified by Carothers [1929] into condensation and addition polymers on the basis of the compositional difference between the polymer and the monomer(s) from which it was synthesized. Condensation polymers were those polymers that were formed from polyfunctional monomers by the various condensation reactions of organic chemistry with the elimination of some small molecule such as water. An example of such a condensation polymer is the polyamides formed from diamines and diacids with the elimination of water according to... 

The first product that DuPont commercialized was polyamide, to which they gave the trademark Nylon. These polymers can be made from a diamine and a diacid or from an amino acid (the silk spider). (Remember that proteins are just polypeptides, which are polyamides formed from atnino acids so the DuPont scientists were only adapting and scaling up nature s process.)... 

Proteins are polyamids formed from amino acids having the formula H2N —CHR —COOH therefore different R groups occur along the polymer backbone according to the amino acid sequence in the protein. Write structural formulas for the R groups in the following amino acids ... 

The nylon filter currently sold as l- xm pore size Nylasorb (Gelman Sciences), probably the most widely used filter for HN03 sampling in the United States, was initially marketed by Ghia Corporation. Until 1985, these filters were fabricated from nylon 6, a polyamide formed from the homopolymerization of e-caprolactam. More recently, Gelman, Sartorius, and other vendors have supplied filters fabricated from nylon 6,6, made by polymerization of adipic acid and hexamethylenediamine. 

All proteins are polyamides formed by joining amino acids together. 

Nylons are polyamides formed by step-growth polymerization. In Section 22.16A, we learned that nylon 6,6 can be prepared by the reaction of a diacid chloride and a diamine. Nylon 6,6 can also be prepared by heating adipic acid and 1,6-diaminohexane. A Br0nsted-Lowry acid-base reaction forms a diammonium salt, which loses H2O at high temperature. In both methods, each starting material has two identical functional groups. 

The third principal type of fibrous materials comprises the synthetic polymers. Unlike natural fibers, which apparently are always H bonded, some synthetic fibers are not H bonded. The polyamides form the best example of man-made H bonded polymers. These include nylons or polyamides, polyamino acids, polythioamides, polyurethanes, and some less well known polymers of substituted urea, hydrazide, aminotriazole, sulfonamide, or others. Specialized reference books are available (954). 

One of the most important condensation polymers is nylon, a name so ingrained into our language that it has lost trademark status. It was developed by Wallace Carothers, director of organic chemicals research at DuPont, and was the outgrowth of his fundamental research into polymer chemistry. Introduced in 1938, it was the first totally synthetic fiber. The most common form of nylon is the polyamide formed by the condensation of hexamethylene diamine and adipic acid ... 

The repeating units (i.e. cyclic imides) could result either from dehydration of the polyamide formed in a ring opening polymerization... 

Methylvinylpolysiloxane Polyamide formed by reacting a Cye dicarboxylic acid with l,3-di-4-piperdyl-propane and piperidine in the respective mole ratios of 1.00 0.90 0.20 5is (2-ethylhexyl) sebacate polyester Phenyldiethanolamine succinate polyester Sorbitol... 

Major results. Carbon black has a better affinity to polyamide than polypropylene. Even if carbon black was added to polypropylene, it was preferentially transferred to the polyamide phase during mixing. " In a polymer blend of two polymers, polyamide formed the minor phase and, due to preferential location of carbon black in its phase, the carbon black concentration in the polyamide phase was much higher than expected Irom the amount of carbon black added. This high concentration of carbon black in the minor phase resulted in substantially increased conductivity of the blend. ... 

The functional thin coating in composite membranes for water desalination is often a polyamide formed in-situ on the porous substrate by interfacial polymerization. Interfacial polymerization of polyamides is a polymerization technique that was pioneered by Du Pont (20). 

An aromatic polyamide formed between 1,4-diaminobenzene and isophthalic acid (Scheme 1)... 

Nylon 66 is an example of a step-growth polymer formed by two different bifunctional monomers adipic acid and 1,6-hexanediamine. It is called nylon 66 because it is a polyamide formed from a six-carbon diacid and a six-carbon diamine. 

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