Adipic polycondensation with

Nylon-6,6 is made by the polycondensation of hexamethylene diamonium adipate salt with removal of water. 

In an attempt to avoid the polymerization/depolymerization equilibrium that occurs during melt polycondensation, Albertsson and Lundmark (1988) also studied the irreversible reaction of adipic anhydride with ketene. However, they reported very little difference in molecular weights when two ketene syntheses were compared to melt polycondensation and ringopening polymerization using a zinc catalyst (Albertsson and Lundmark, 1988). 

Galbis et al. described a variety of carbohydrate-based linear polyesters 61 of the poly(alkylene dicarboxylate) type that were obtained by polycondensation reactions of the alditols 2,3,4-tri-(9-methyl-L-arabinitol (9) and 2,3,4-tri-O-methyl-xylitol (10), and the aldaric acids 2,3,4-tri-(9-methyl-L-arabinaric acid (26) and 2,3,4-tri-(9-methyl-xylaric acid (27), butanediol, and adipic acid were also used as comonomers [28]. Copolyesters of the poly(aIkylene-c )-arylene dicarboxylate) type were obtained using bisphenols as comonomers (Scheme 1). Chemical polycondensation reactions were conducted in bulk or in solution. Enzymatic polycondensation reactions of adipic acid with the above-mentioned alditols were carried out successfully using Lipozyme and Novozyme 435. The hydrolytic degradations of some of these polyesters were also described. 

Polycondensation reactions were also carried out using a mixture of ethylene-diamine and adipic acid (55). IR techniques again were used to confirm the polymer composition. The results are summarized on Table 9. The chemistry of polyethylene terephthalate) mechanical polycondensation with diamines proceeds as follows ... 

A polycondensation is a series of such reactions, which takes place between bifunctional molecules. For example, the polycondensation of adipic acid with hexamethylene-diamine gives nylon 6-6. In fact, the chemical method of production is not so simple, but we may (naively) write the reaction in the form... 

Nylon-MXD6 is one of the crystalline polyamide resins which is produced through polycondensation of mctu-xylylene diamine (MXDA) with adipic add with Mitsubishi Gas Chemical Company s own technology. It is a unique aliphatic polyamide resin which contains m-xylylene groups in the... 

The cause of deviations at lower yields is not known. Deviations are not observed in the polycondensation of 12-hydroxyl stearic acid (see Figure 17-4), but they are, for example, in the polycondensation of adipic acid with glycol. Since the initial monomers are much more polar in the latter polycondensation, the change in the activity coefficients of the end groups with yield could be the cause of these deviations. 

The monomers used in the production of these materials are adipic acid, hexamethylenediamine and caprolactam. Polymerization is traditionally done via bulk polycondensation. The commercial success of nylon-6 and nylon-6,6 is due to outstanding properties and an economically attractive raw material base. Nylon-6,6 is produced by melt condensation of adipic acid with hexamethylenediamine. Both... 

Together with these, a series of special nylons is also produced. The formation of polymer occurs by polycondensation of diamines with dicarboxylic acids. The necessary equivalence of the functional groups is achieved by first producing the salt from 1 mol each of dicarboxylic acid and diamine, e.g., neutralization to produce the so-called AH salt from adipic acid with hexamethylene diamine. The amidization equilibrium is so favorable that polycondensation can take place in the presence of water, which is therefore used as a heat sink. The polycondensation of nylon 6,6 is typical of commercial syntheses. A 60-80% suspension of the salt is precondensed for 1-2 h at 220-230°C and 13-17 bar (vapor pressure of steam). After an 80-90% yield has been reached, further condensation takes place above the polymer melting point (264 C) at 270-280°C under vacuum. 

The mixture of 2,2,4- and 2,4,4-trimethyl hexamethylene diamine gives a highly transparent, clear, amorphous polyamide after polycondensation with terephthalic acid. To produce the diamine mixture, acetone is tri-merized to isophorone, which subsequently splits into a mixture of 2,2,4-and 2,4,4-trimethyl adipic acid ... 

Another approach of enzymatic synthesis of sugar-containing polyesters was demonstrated (123). Lipase CA-catalyzed reaction of sucrose or trehalose with an excess of divinyl adipate produced 6,6 -diacylated product having vinyl esters at both ends, which was employed as monomer in the enzymatic polycondensation with various glycols, jdelding linear polyesters with Mw up to 2.2x 10. ... 

Recently, various polyesters such as poly(ethylene adipate), poly(tetramethylene adipate), poly(caprolac-tone), and poly(aliphatic carbonate), having terminal hydroxyl groups, were reacted with ACPC to give corresponding macroazoesters and their thermal behaviors were observed by DSC [14]. The block copolymers of these polycondensation polymers with addition polymers such as PSt and PMMA were synthesized [14]. 

Immobilized Mucor miehei lipase (lipase MM) induced the polycondensation of adipic acid and 1,4-butanediol in ether solvents [26]. A horizontal two-chamber reactor was employed to facilitate the use of the molecular sieves. A low disper-sity polyester with DP = 20 was obtained by two-stage polymerization. 

Later, polythioesters were prepared by the polycondensation of dicarboxylic acid diesters with a dithiol [43] (Fig. 12). Initially, various lipases were screened in the polycondensation between diethyl adipate and hexane-1,6-dithiol at 120 °C in the presence of molecular sieves. The use of 70wt% immobilized CALB as catalyst proved to be efficient in these polycondensation reactions with dicarboxylic acid... 

While all previous examples employ enzymatic ROP, there are two reports on block copolymer synthesis employing enzymatic poly condensation. The first one was published by Sharma et al. and describes the synthesis and solid-state properties of polyesteramides with poly(dimethylsiloxane) (PDMS) blocks [21]. The polycondensation was carried out with various ratios of dimethyl adipate. 

Hexamethylenediamine (HMDA) is a colorless solid when pure, but it slowly degrades to colored products when it contacts air. It is commercially available as the anhydrous product or in aqueous solutions. In 2003 it had a global capacity that was approaching 3.0 billion pounds per year, and it was made by only one main route hydrogenation of ADN. Commercially the most important use of HMDA is in a polycondensation reaction with adipic acid to eventually give nylon 6,6274. The chemical formula for HMDA is ... 

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