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Nylon hydrolase degrades various aliphatic nylons, including nylon-6 and nylon-66. We synthesized a nylon-66 copolymer (M_w=22,900, M_n=7,400), in which a part of an adipoyl unit (32 % molar ratio) of nylon-66 was replaced with a ...
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Nylon hydrolase degrades various aliphatic nylons, including nylon-6 and nylon-66. We synthesized a nylon-66 copolymer (M_w=22,900, M_n=7,400), in which a part of an adipoyl unit (32 % molar ratio) of nylon-66 was replaced with a succinyl unit by interfacial polymerization. To quantify the reaction rate of the enzymatic hydrolysis of nylons at the surface of solid polymers, we prepared a thin layer of nylons on the bottom surface of each well in a polystyrene-based micro-assay plate. The thickness of the nylon layer was monitored by imaging analysis of the photographic data. More than 99 % of the copolymer with thicknesses of 260 nm (approximately 600 layers of polymer strands) were converted to water-soluble oligomers by nylon hydrolase (3 mg enzyme ml~(-1)) at 30 °C within 60 h. These results were further confirmed by TLC analysis of the reaction products and by assay of liberated amino groups in the soluble fractions. The degradation rate of the thin-layered nylon-6 was similarly analyzed. We demonstrate that this assay enables a quantitative evaluation of the reaction rate of hydrolysis at the interface between the solid and aqueous phases and a quantitative comparison of the degradability for various polyamides.
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A series of end-capped oligomers 17, 21, 25 and 28 related to nylon 4 6, and 39, 43, 47 and 50 related to nylon 6 6 have been prepared starting from adipic acid monoethyl ester 6, the #alpha#,#omega#-di-secondary diamines 8 and 29...
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A series of end-capped oligomers 17, 21, 25 and 28 related to nylon 4 6, and 39, 43, 47 and 50 related to nylon 6 6 have been prepared starting from adipic acid monoethyl ester 6, the #alpha#,#omega#-di-secondary diamines 8 and 29 and their mono end-protected derivatives 7 and 30, respectively, using the reactions of polypeptide chemistry. The formation of N-protected secondary amide bonds bearing the N-p-methoxybenzyl group ensured the solubility of all intermediates in common organic solvents and enabled purification by chromatography; boiling trifluoroacetic acid removed the protecting group in the final stage of the synthesis.
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End-capped oligomers 16, 24 and 8 of nylon 6 (having 10, 12 and 33 amide bonds, respectively), 32 and 38 of nylon 4 6 (having 9 and 13 amide bonds, respectively), and 43 of nylon 6 6 having 3 amide bonds, have been synthesised usi...
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End-capped oligomers 16, 24 and 8 of nylon 6 (having 10, 12 and 33 amide bonds, respectively), 32 and 38 of nylon 4 6 (having 9 and 13 amide bonds, respectively), and 43 of nylon 6 6 having 3 amide bonds, have been synthesised using N-protected secondary amides and the reactions of polypeptide chemistry. (C) 2000 Elsevier Science Ltd. All rights reserved. [References: 3]
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Nylon 6 and 6,6 literature data are collected over a wide range of water concentrations and temperatures (0 <= [W](0) <= 40.8 wt%, 200 <= T <= 300 degrees C) and used to fit parameters in an updated batch reactor model. The result...
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Nylon 6 and 6,6 literature data are collected over a wide range of water concentrations and temperatures (0 <= [W](0) <= 40.8 wt%, 200 <= T <= 300 degrees C) and used to fit parameters in an updated batch reactor model. The resulting copolymerization model uses side reactions to account for the complex influence of water on kinetics and reaction equilibria. The proposed parameter estimates result in a significant improvement in the fit to the data, corresponding to a 73% reduction in the weighted-least-squares objective function compared to when the parameters of Arai et al. are used. Copolymerization simulations are conducted at industrially relevant conditions, shedding light on the complex influence of water and on the potential to include waste nylon 6 cyclic dimer in the feedstock. The model and parameter estimates will be helpful in future models of nylon 6/6,6 copolymerization in continuous reactor systems.
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A comparative study of the crystal structure of lamellar crystals of the isomeric nylons 46 and 5 was carried out. A lattice made of hydrogen-bonded sheets with chains in fully extended conformation and hydrogen bonds in the norma...
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A comparative study of the crystal structure of lamellar crystals of the isomeric nylons 46 and 5 was carried out. A lattice made of hydrogen-bonded sheets with chains in fully extended conformation and hydrogen bonds in the normal scheme was proposed for the two nylons according to the great similarities in morphology and diffraction data observed for their solution grown crystals. Energy calculations and modeling simulations showed that a model consisting of a statistical arrangement of progressive and alternating intersheet shearing is the most appropriate and consistent to describe the structure of both nylons. A preliminary investigation on the possibility of cocrystallizing nylon 46 and nylon 5 was undertaken. First experimental results were found to be compatible with the occurrence of cocrystallization. Molecular mechanics calculations indicated that insertion of one nylon in the crystal lattice of the other is energetically disfavored. However, cocrystals would be acceptable if they were made of homogeneous blocks of each nylon comprised of about 10 or more hydrogen-bonded sheets. (C) 2000 Published by Elsevier Science Ltd. [References: 16]
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The elastomer toughening of PA66/PA6 nanocomposites prepared from the organic modified montmorillonite (OMMT) was examined as a means of balancing stiffness/strength versus toughness/ductility. Several different formulations varyi...
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The elastomer toughening of PA66/PA6 nanocomposites prepared from the organic modified montmorillonite (OMMT) was examined as a means of balancing stiffness/strength versus toughness/ductility. Several different formulations varying in OMMT content were made by mixing of PA6 and OMMT as a master-batch and then blending it with PA66 and different elastomers in a twin screw extruder. In this sequence, the OMMT layers were well exfoliated in the nylon alloy matrix. The introduction of silicate layers with PA6 induced the appearance of the gamma crystal phase in the nanocomposites, which is unstable and seldom appears in PA66 at room temperature and it further affected the morphology and dispersion of rubber phase resulting in much smaller rubber particles. The incorporation of POE-g-MA particles toughened the nanocomposites markedly, but the tensile modulus and strength were both reduced. Conversely, the use of OMMT increased the modulus but decreased the fracture toughness. The nanocomposites exhibited balanced stiffness and toughness.
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A detailed electron microscopy study of the structure and morphology of lamellar crystals of nylon 46 obtained by crystallization from solution has been carried out. Electron diffraction of crystals supported by X-ray diffraction ...
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A detailed electron microscopy study of the structure and morphology of lamellar crystals of nylon 46 obtained by crystallization from solution has been carried out. Electron diffraction of crystals supported by X-ray diffraction of their sediments revealed that they consist of a twinned crystal lattice made of hydrogen-bonded sheets separated 0.376 nm and shifted along the #alpha#-axis (H-bond direction)with a shearing angle of 65deg. The interchain distance within the sheets is 0.482 nm. These parameters are similar to those previously described for nylon 46 lamellar crystals grown at lower temperatures. A combined energy calculation and modeling simulation analysis of all possible arrangements for the crystal-packing of nylon 46 chains, in fully extended conformation, was performed. Molecular mechanics calculations showed very small energy differences between #alpha# (alternating intersheet shearing) and #beta# (progressive intersheet shearing) structures with energy minima for successive sheets sheared at approximately 1/6 c and 1/3 c. A mixed lattice composed of a statistical array of #alpha# and #beta# structures with such sheet displacements was found to be fully compatible with experimental data and most appropriate to describe nylon 46 lamellar crystals. Annealing of the crystals at temperatures closely below the Brill transition induced enrichment in #beta# structure and increased chain-folding order.
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The authors have successfully isolated for the first time bacterial strains degrading nylon 12 (N12), nylon 6 (N6) and nylon 66 (N66). Yeast extract was added as a growth factor to the culture medium for N12 degradation. Its conce...
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The authors have successfully isolated for the first time bacterial strains degrading nylon 12 (N12), nylon 6 (N6) and nylon 66 (N66). Yeast extract was added as a growth factor to the culture medium for N12 degradation. Its concentration of 0.1% was the optimum for the cultivation of the strain as well as the degradation of N12. This quantity is much larger than the usually added amount for the microbial degradation of plastics. That is to say, if we would have followed a usual protocol with an ordinary quantity of yeast extract, the degrading strain would not have been found. Our results also suggest that a 0.1% yeast extract is adequate for the degradation of N6 and N66.
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Nylon 6 and nylon 6,6 reaction equilibria depend in a complex way on water concentration and temperature. For example, data sets from six research groups reveal that the apparent equilibrium constant for polycondensation increases...
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Nylon 6 and nylon 6,6 reaction equilibria depend in a complex way on water concentration and temperature. For example, data sets from six research groups reveal that the apparent equilibrium constant for polycondensation increases with water at low water concentrations, reaches a maximum, and then decreases as the water concentration rises further. In this article, semi-empirical expressions are proposed to describe the experimentally observed equilibrium behavior for the five main reactions that occur during nylon 6 and nylon 6,6 polymerization. Nine side reactions involving amidine ends, cyclopentanone ends, and hydrated carboxyl ends are used to develop expressions that account for the influence of both water and temperature on these equilibrium constants. Excellent fit to the data, over the entire range of the available nylon 6 and nylon 6,6 literature data, suggests that the proposed equations will be helpful for modeling reaction equilibria for nylon 6/6,6 copolymerization.
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The nylon 1010/ethylene-vinyl acetate rubber (EVM)/maleated ethylene-vinyl acetate copolymers (EVA-g-MAH) ternary blends were prepared. The effect of EVM/EVA-g-MAH ratio on the toughness of blends was examined. A super tough nylon...
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The nylon 1010/ethylene-vinyl acetate rubber (EVM)/maleated ethylene-vinyl acetate copolymers (EVA-g-MAH) ternary blends were prepared. The effect of EVM/EVA-g-MAH ratio on the toughness of blends was examined. A super tough nylon 1010 blends were obtained by the incorporation of both EVM and EVA-g-MAH. Impact essential work of fracture (EWF) model was used to characterize the fracture behavior of the blends. The nylon/EVM/EVA-g-MAH (80/15/5) blend had the highest total fracture energy at a given ligament length (5 MM) and the highest dissipative energy density among all the studied blends. Scanning electron microscopy images showed the EVM and EVA-g-MAH existed as spherical particles in nylon 1010 matrix and their size decreased gradually with increasing EVA-g-MAH content. Large plastic deformation was observed on the impact fracture surface of the nylon/EVM/EVA-g-MAH (80/15/5) blend and related to its high impact strength. Then with increasing EVA-g-MAH proportion, the matrix shear yielding of nylori/EVM/EVA-g-MAH blends became less obvious. EVM and EVA-g-MAH greatly increased the apparent viscosity of nylon 1010, especially at low shear rates.
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