Nylon monadic

The term monadic is used to describe nylons such as nylon-6 that have been produced from one reactant. The term dyadic is used to describe nylons such as nylon-6,6 that have been produced from two reactants. 

What is the most widely used monadic nylon ... 

Likewise, the Tm values of aromatic polyamides (aramids) arc higher than those of the corresponding aliphatic polyamides (nylons). The Tm of monadic and dyadic nylons decreases as the number of methylene groups in the chain increases. Thus the Tm values decrease stepwise as the number of... 

Several commercially available monadic nylons have the following re panting unit ... 

The indue of jt is I in nylon 2. which is the lowest member of this series of monadic polyamides. 

Nylon 6 (polycaprolactam, Perlon) is the most widely used monadic nylon. It has a lower melting point (225 C) than nylon 5 (270 0. which is not available commercially. As shown in Table 14.2 the coefficient of linear expansion of nylon 6 is the same as that of nylon 66. However, its heat deflection temperature (80 ) is slightly higher than that of nylon 66 (75 C). Nylon 7 (polyenantholactam) has a slightly higher Tm (227 0. a slightly greater flexibility, and a lower water absorption than nylon 6. 

Aliphatic polyamides, also known under the generic name nylon. Industrial nylons with the general structure [—RNHCO—] , such as PA-6, PA-11, and PA-12, are called monadic those with the general structure [ —NHR1NHCOR2CO —] are called dyadic (PA-4,6, PA-6,6, PA-6,9, PA-6,10, and PA-6,12). 

Nylon-6 which has a heat deflection temperature of 80°C was produced by the ring opening polymerization of caprolactam in Germany in the 1940 s. iZ Molded articles of these polymers may be produced in situ in the RIM process.(A3)Nylon-ll and nylon-12 produced by the anionic polymerization of 11 and 12-amino acids are also characterized by good resistance to moisture and Superior ductility. The structure of the repeating unit in monadic nylons, such as nylon-6 is ... 

NH(CH2)5C0 4 with regular sequences of six carbon atoms between the nitrogen atoms. A nylon with two numbers is termed dyadic indicating that it contains both dibasic acid (or acid chloride) and diamine moieties, in which the first number represents the diamine and the second the diacid used in the synthesis. The monadic nylons have one number, indicating that synthesis involved only one type of monomer. This terminology means that a poly (a-amino acid) would be nylon-2. 

The best known synthetic polyamides are the nylons. The term nylon originally was a trademark for the polyamide based on hexamethylene diamine and adipic acid (Table 17.3). Later on it became a generic term. The numerals following the name designate the number of carbon atoms in the chain between successive amide groups. The dyadic nylons have two numbers the first for the diamine and the second for the diacid. Monadic nylons such as polycaprolactam require only one number. Although they have been studied as protein models, the synthetic nylon 2 polymers have not been commercialized as fibers or plastics. While some new polymers have been introduced over the years (nylon 4, nylon 1,1, nylon 1,2), nylon 6,6 and nylon 6 have been produced for a longer time and dominate the markets for synthetic polyamides, especially as fibers. 

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