Hexamethylene diamine polyamide monomer

Chemical depolymerization of polyamides is mainly carried out by hydrolysis. Acid hydrolysis of nylon-6 allows the starting monomer, e-caprolactam, to be recovered. Likewise, basic hydrolysis of nylon-6,6 leads to hexamethylene diamine and adipic acid. Degradation of polyamides by ammonolysis has also been reported as an interesting alternative for the chemical recycling of nylon-6 and nylon-6,6 mixtures. 

The diamine (AA) monomer used for the PA610 AABB polyamide is hexamethylene diamine (HMDA), which is produced petrochemically from butadiene. 

Both monomers for the production of Nylon 6-6 (one of the earliest polyamides) may be synthesized from benzene adipic acid and hexamethylene diamine. 

Hexamethylene diamine can be produced by various processes (see also Chapter 24), and is industrially mostly produced from adipic acid, butadiene, or acrylonitrile. Sebacic acid is obtained from castor oil. Because of the uncertain supply situation, the sebacic acid for such polyamides is being increasingly replaced by dodecane diacid, which is obtained by the oxidation of cyclododecatriene, the cyclic trimer of butadiene. The monomers for polyamide 13,13 are derived from erucic acid (see also Chapter 24). 

Polyamides of this type are called nylon ( , m 2), where n is the number of carbons in the diamine monomer and m - - 2 is the number of carbons in the diacid. Nylon 6,6, the most commercially important aliphatic polyamide with this structure, is produced from hexamethylene diamine (HMD) ( = 6) and adipic acid (m- -2 = 6). Nylon 4,6, nylon 6,10 and nylon 6,12 are also produced commercially [1]. 

When one unit A is followed by one unit B, followed by one unit A, etc., the copolymer is alternate and named poly( A-alt-B), but it can also be named poly (A-B). Polyamide 6-6 (Nylon 6-6) is an example of a completely alternate copolymer the monomer unit resulting from reaction of hexamethylene diamine is followed by the monomer unit resulting from the dicarboxylic acid containing six carbon atoms. 

Renewable polyamides (PA) can also be prepared taking advantage of the synthesis of thiol-ene monomers. Meier and co-workers [30] studied the thiol-ene addition of cysteamine hydrochloride to the double bonds of methyl 10-undecenoate, methyl oleate, and methyl erucate (Scheme 6.8), which yielded heterodifunctional monomers at good yields. Ensuing monomers were homopolymerised, copolymerised with each other, as well as copolymerised with adipic acid and 1,6-hexamethylene diamine to yield copolyamides with TBD as the catalyst. The produced PA were obtained with Mn values of 4-19 kDa. 

Polyamide is a polymer formed from condensation of dicarbonic acids and diamines or from condensation of amino acids and lactames. In publications, in English, polyamids are called nylon. To distingmsh them from one another a number is added that represents the number of C-atoms of the monomer or monomers. Nylon type 6.6 (polyamide 6.6) is the most common commercial grade of nylon. It consists of hexamethylene diamine and adipinic acid. 

A mixture of a diacid and a diamine was the starting material for the first commercial, high molecular weight, polyamide. Hexamethylene diamine or HMDA (1,6 diaminohexane) and adipic acid (1,6 hexanedloic acid) yield nylon 66, so named because each monomer contains six carbon... 

Amorphous Nylons n (l)When unsymmetrical monomers are use to synthesize polyamides (Nylons), the normal ability of the chains to crystallize can be disrupted and amorphous (often transparent) polymers are formed. (2) Transparent aromatic polyamide thermoplastics. Produced by condensation of hexamethylene diamine, isophthalic and terephthalic acid (Sepe MP (1998) Dynamic mechanical analysis. Plastics Design Library, Norwich, New York). 

The numeric suffix after nyion defines the type of nylon being used. For example, nylon-6,6 indicates that this polyamide is a reaction product from a diamine monomer containing six carbon atoms (hexamethylene diamine) that has reacted with a diacid possessing six carbons as well (adipic acid). 

Salt dehydration is a convenient reaction which can be used to produce the polyamide nylon 6.6 which is used widely as a textile fibre. The monomers used are hexamethylene diamine and adipic acid, but a normal condensation reaction is not employed. Instead the stoichiometric balance is ensured by utilizing the tendency for the two monomer molecules to form a 1 1 salt which can be crystallized from solution helping to purify the... 

There are examples in which monomers have been polymerized in situ within a cyclodextrin complex. Ogata et al. [30] prepared hexamethylene diamine complexes of P-CD. Polyamides were obtained by condensation of dibasic acid chlorides with inclusion complexes of diamines. Maciejewski reported [31] the polymerization and copolymerization of vinylidene chlorides as adducts with P-CD. There are some reports that suggest interactions... 

Polyamides are formed by the polymerization of a diamine and a dicar-boxyhc acid and are commonly known as nylons. Among the various nylons, nylon 66 and nylon 6 are commercially important polymers. It is shown here that in these cases the application of the equal reactivity hypothesis is no more than an approximation. Nylon 66 is prepared in two stages. In the first stage, the monomers hexamethylene diamine [NH2—(CH2)g—NH2] and adipic acid [COOH—(CH2)—COOH)] are reacted to form hexamethylene adipamide (sometimes called nylon 66 salt). It is known that the amino and carboxylic groups ionise in the molten state and the ionised species do not participate in the step-growth polymerization [7,31-33]. In other words, the polymerization can be... 

Special terminology based on trade names has been employed for some polymers. Although trade names should be avoided, one must be familiar with those that are firmly established and commonly used. An example of trade-name nomenclature is the use of the name nylon for the polyamides from unsubstituted, nonbranched aliphatic monomers. Two numbers are added onto the word nylon with the first number indicating the number of methylene groups in the diamine portion of the polyamide and the second number the number of carbon atoms in the diacyl portion. Thus poly(hexamethylene adipamide) and polyfhexamethylene sebacamide) are nylon 6,6 and nylon 6,10, respectively. Variants of these names are frequently employed. The literature contains such variations of nylon 6,6 as nylon 66, 66 nylon, nylon 6/6, 6,6 nylon, and 6-6 nylon. Polyamides from single monomers are denoted by a single number to denote the number of carbon atoms in the repeating unit. Poly(e-caprolactam) or poly(6-aminocaproic acid) is nylon 6. 

Other polyamides of commercial importance are nylons that are higher analogs of the more common types nylons 11 12 6,10 and 6,12. The numerals in the trivial names refer to the number of carbon atoms in the monomer(s). In designating A-A/B-B nylons, the first number refers to the number of carbon atoms in the diamine while the second number refers to the total number of carbon atoms in the acid. For example, nylon 6,10 is poly(hexamethylene sebacamide) (Equation 2.35). 

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