Oligomers nylon

I Plot DI H aiwlag out FIGURE 13.29 Nylon oligomer separation. 

Estimation of Molecular Weight Distribution of Polyamide Blocks. The molecular weight distribution of the polyamide blocks was estimated by gel permeation chromatography (GPC) using two instruments, model HLC-802R (Toyo Soda Industry Co., Ltd.) and model GPC-2i U (Waters Associates, Inc.). Polystyrene and nylon oligomer were used as standards. 

CPAEs 1-6, as estimated by end-group assay, were 3750, 1030, 2870, 850, 830, and U80, respectively. Nylon oligomers with low molecular weight are expected to be biodegradable. 

Negoro S, Ohki T, Shibata N et al (2007) Nylon-oligomer degrading enzyme/substrate complex catalytic mechanism of 6-aminohexanoate-dimer hydrolase. J Mol Biol 370 142-156... 

Negoro S (2000) Biodegradation of nylon oligomers. Appl Microbiol Biotechnol 54 461 66... 

Usually polymer has its own configuration in die complex formation. The fact that the polymer complex gives a unique polymer radical is shown (164-169). Nylon oligomer gives a polymer radical in carbon tetrachloride and it polymerizes vinyl compounds. This initiation reaction of the polymerization reaction was considered as an intramolecular cooperative reaction. The following scheme was presented... 

Kakudo, S., Negoro, S., Urabe, I., and Okada, H. (2000) Nylon oligomer degradation gene, nylC, on plasmid pOAD2 from a Flavobacterium strain encodes endo-type 6-aminohexanoate oligomer. Appl. Environ. Microbiol., 59 (11), 3978-3980. 

Negoro, S., Ohki, T Shibata, N Sasa, K Hayashi, H., Nakano, H Yasuhira, K Kato, D.I., Takeo, M and Higuchi, Y. (2007) Nylon-oligomer degrading enzyme/substrate complex catalytic mechanism of 6-aminohexanoate-dimer hydrolase./. Mol. Biol, 370 (1), 142-156. 

Negoro, S., Taniguchi, T., Kanaoka, M., Kimura, H. and Okada, H. (1983) Plasmid-determined enzymatic degradation of nylon oligomers. Journal of Bacteriology, 155, 22. 

Cu(II)-polymer complexes initiate radical polymerization and often show higher activity than the corresponding monomeric analogues. The systems of Cu(II) ion with nylon [97], a-aminocaproic acid [96], nylon oligomers [96], polyethylene-polyamine [98,99], pt)ly(vinylamine-co-vinyl alcohol) [100], and cellulose have been made by Imoto and Takemoto as initiation systems for free radical polymerization of vinyl monomers, such as methyl methacrylate (MMA). Inaki et al. reported that Cu(II)-polyvinylamine complexes in the presence of CCI4 in an aqueous solution showed higher activity as an initiator than Cu(II)-diaminopropane complex for the radical polymerization of methyl methacrylate, acrylonitrile, and styrene [101]. The pH dependence for activity indicates that the free amine groups on the poly(vinylamine) chain are involved in the catalysis. The initiation mechanism is proposed as follows [Eqs. (78-80)] ... 

As a final example of column durability and solvent resistance in small pore gels we were able to resolve nylon 6 oligomers using a methanol mobile phase and 205-nm UV detection as shown in Figure 13.29. In fact, polar solvents such as acetone, acetonitrile, methanol, and 2-propanol, are used routinely as needed with no ill effects. 

In order to establish die feasibility of alkaline hydrolysis with respect to recycling of nylon-4,6, it was necessary to determine whether die recovered oligomers could be repolymerized to form nylon-4,6. For diis purpose, solid-state polymerization was performed on nylon-4,6 oligomers formed via alkaline hydrolysis with 50 wt% NaOH at 165°C for 24 h. The solid-state polymerization process... 

In order to isolate adipic acid, nylon-6,6 fibers were depolymerized under reflux with a 50% NaOH solution in the presence of catalytic amounts of benzyltrimethylammonium bromide. The oligomers formed in successive steps were depolymerized under similar conditions. The yields in steps 1, 2, and 3 were... 

The mixture of oligomers was heated in a flask to 200°C in a mineral bath (the DSC peak melting temperature of the oligomers was 230°C) while stirring and removing water formed with a vacuum pump to form high-molecular-weight nylon-6,6. 

Nylon-6,6 fibers (6.0 g) were depolymerized under reflux with 200 mL of 50% NaOH solution in the presence of 0.20 g BTEMB to form 0.55 g of adipic acid (after acidification) and 4.52 g of oligomer. In a second step, the oligomer... 

Oligomers (2.0 g) obtained from the alkahne hydrolysis of nylon-4,6 were charged to a round-bottom flask. The flask containing the oligomers was heated in a mineral bath at 210°C for 16 h under vacuum. 

A method for the depolymerisation of PETP fibres using quarternary ammonium salt phase transfer catalysts in saponification processes at atmospheric pressure and temperatures as low as room temperature is reported. Terephthalic acid was produced in yields as high as 93%. Also reported are similar processes for the depolymerisation of nylon 66 and nylon 46 fibres. Nylon 46 oligomers produced were repolymerised using solid-state polymerisation to produce high molecular weight nylon 46. Nylon 66 was depolymerised to produce oligomers and adipic acid in reasonable yields. 11 refs. USA... 

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