The Distribution of the Molecular Weight of Nylon as Determined by Fractionation in a Phenol—Water System

Taylor, Guy B.

doi:10.1021/ja01195a051

Cited by 55 publications

(12 citation statements)

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“…The intrinsic viscosity of nylon 6,12 in formic acid solution was determined with a Ubbelohde viscometer as 2.22 dl g À1 (Taylor, 1947). Nylon 6,12 with a density of 1.3 g ml À1 at 298 K, melting temperature at 491 K and melt flow index 10.72 g (10 min) À1 from Sigma-Aldrich was used as received.…”

Section: Materials and Sample Preparationmentioning

confidence: 99%

“…Nylon 6,12 with a density of 1.3 g ml À1 at 298 K, melting temperature at 491 K and melt flow index 10.72 g (10 min) À1 from Sigma-Aldrich was used as received. The intrinsic viscosity of nylon 6,12 in formic acid solution was determined with a Ubbelohde viscometer as 2.22 dl g À1 (Taylor, 1947). The nanorods were fabricated by allowing nylon 6,12 melt to infiltrate 300, 70, 50 and 30 nm AAO templates in a vacuum tube furnace at 493 K for 24 h. In our research, we observed that the phase grew in the nylon 6,12 nanorods in the temperature region 373-433 K. After annealing at T c = 373 K for 24 h, the nanorods were released from the AAO templates with 5% KOH solution for SEM ( Fig.…”

Section: Materials and Sample Preparationmentioning

confidence: 99%

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Hierarchical structure of the triclinic α-phase crystal in nylon 6,12 mediated by two-dimensional confinement

et al. 2020

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It has been recognized that macromolecular chains can self-assemble into a hierarchical structure from lamellae to spherulites in bulk crystallization. However, little account has been taken of crystal symmetry effects on the hierarchical nanostructure in polymers under cylindrical confinement. In this research, a model polymer, nylon 6,12, most commonly occurring in the triclinic phase, was chosen in order to demonstrate the effect of triclinic symmetry on the 2D-constrained polymer nanostructure. The self-arranging unit of nylon 6,12 takes various forms, including stems, unit cells, hydrogen-bonded sheets, lamellae and complex spherulites, which is an essential structural feature for investigating hierarchical nanostructure. The rod nanostructure in confinement was examined by cross-checking electron and X-ray diffraction techniques. It is found that the a* axis of the -phase cell is inclined at about AE6-11 to the rod long axis within the a*b* plane around the c axis (c axis ? rod long axis). The rotation of the a*b* plane most likely results from the impact of the triclinic symmetry on the molecular chain packing under 2D confinement. A mechanism for this a*b* plane tilting is proposed.

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Section: Materials and Sample Preparationmentioning

confidence: 99%

Section: Materials and Sample Preparationmentioning

confidence: 99%

Hierarchical structure of the triclinic α-phase crystal in nylon 6,12 mediated by two-dimensional confinement

et al. 2020

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“…The results are believed accurate to =!=3 groups/106 g. for each determination. 2 Interfacial polycondensation reactions were quenched by addition of sufficient 3-5% aqueous hydrochloric acid to ensure an acidic system. The mixture was stirred for 1 min.…”

Section: Endgroup Determinationsmentioning

confidence: 99%

Interfacial polycondensation. XIII. Viscosity–molecular weight relationship and some molecular characteristics of 6‐10 polyamide

Morgan

Kwolek

1963

J. Polym. Sci. A Gen. Pap.

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Number‐average molecular weights were estimated by determination of endgroups on 6‐10 polyamide samples prepared by stirred and unstirred interfacial polycondensation procedures under varying conditions. Polymers made by melt and interfacial polycondensation methods obeyed the same dilute solution viscosity relationships. However, polymers from interfacial polycondensation reactions deviated in molecular weight distribution from that found for polymers prepared by the melt method. The deviation, which presents the appearance of broader than random distribution, is believed to result to a considerable degree from the presence of an unusually large low molecular weight fraction rather than a continuous distortion of the distribution curve. The interfacially prepared polyamides having the highest viscosity numbers, obtained by adjusting the concentration ratios of the two reactants, showed the least deviation from random distributions. Evidence was found for branching and even network formation in 6‐10 polyamide prepared by interfacial polycondensation as the concentration of the diacid chloride phase was increased. Branching probably occurred through acylation of amide links along the polymer chain to yield imide groups. These groups were cleaved to amide groups in the molten polymer or upon solution in sulfuric acid. Melt‐prepared, unfractionated 6‐10 polyamide followed the relationship [η] = 1.35 × 10−4 M̄n0.96, and a κ′ factor of 0.43 was found in the equation relating solution viscosity to concentration, ηnp/c = [η] + κ′[η]2c, for dilute solution determinations in m‐cresol at 25°C.

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“…A fractionation of saturated polyesters proved the validity of this molecular weight distribution in a number of cases. [16][17][18] Also fractionation results of an unsaturated polyester prepared by condensation of isophtalic acid, maleic anhydride, and propylene glycol shows the "most probable distrib~tion. "'~ In our case, an unsaturated polyester prepared by condensation of maleic anhydride, phtalic anhydride, and ethylene glycol and terminated by cyclohexanol at the final stage of condensation was used for fractionation.…”

Section: Introductionmentioning

confidence: 99%

Molecular weight distribution of an unsaturated polyester

Kaštánek¹,

Zelenka²,

Hájek³

1981

J of Applied Polymer Sci

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SynopsisA precipitation fractionation was carried out by the nonsolvent addition method of 60 g of an unsaturated polyester. The polyester was prepared by the generally known melt condensation of maleic anhydride, phtalic anhydride, ethylene glycol, and cyclohexanol. Number-average molecular weights of fractions were determined by vapor pressure osmometry in acetone a t 36°C. Polydispersities of fractions were evaluated by gelpermeation chromatography (GPC) measurements with tetrahydrofuran as solvent. They seem to be wider for fractions of higher molecular weights. By infrared spectroscopy the fractions were found not to have marked differences in chemical compositions. The obtained molecular weight distribution curve of the unsaturated polyester was found to be in good agreement with that expected from the theory of polycondensation kinetics. The small differences appear only in the low molecular weight range.

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The Distribution of the Molecular Weight of Nylon as Determined by Fractionation in a Phenol—Water System

Cited by 55 publications

References 0 publications

Hierarchical structure of the triclinic α-phase crystal in nylon 6,12 mediated by two-dimensional confinement

Hierarchical structure of the triclinic α-phase crystal in nylon 6,12 mediated by two-dimensional confinement

Interfacial polycondensation. XIII. Viscosity–molecular weight relationship and some molecular characteristics of 6‐10 polyamide

Molecular weight distribution of an unsaturated polyester

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