Cohesive‐energy‐densities of high polymers. Part. III. Estimation of C. E. D. by viscosity measurements
ABSTRACT The intrinsic viscosities and the slopes of ηsp/C against C were estimated for natural rubber, polystyrene, and polyisobutene in hydrocarbon and high mol.wt. alkyl ester solvents. Whereas no correlation could be established between slopes and c.e.d. (cohesive energy-densities) balance of the systems, the plot of [η] versus δ, the solubility parameters of the solvents, yielded smooth curves similar to those obtained by plotting swelling coefficients against δ. GEE's method of estimating δp from swelling coefficients, was therefore extended to estimate δp from viscosity measurements. The present values of δp are in good agreement with those obtained by swelling measurements.Die STAUDINGER-Indices (Intrinsic-Viskositten) und die Neigungen der Kurven der Funktion ηsp/c = f(c) von natürlichem Kautschuk, Polystyrol und Polyisobutylen in Kohlenwasserstoffen und höhermolekularen Alkylestern als Lösungsmittel wurden bestimmt. Falls keine Beziehung zwischen den Neigungen und dem Kohsionsenergiedichte-Gleichgewicht der Systeme gefunden wurde, gab die Auftragung von [η] gegen δ, den Löslichkeitsparametern der Lösungsmittel, glatte Kurven. Diese sind hnlich jenen, die man beim Auftragen der Quellungskoeffizienten gegen δ erhlt. Deshalb wurde GEEs Methode der Bestimmung von δp aus den Quellungskoeffizienten zur Bestimmung von δp aus Viskosittsmessungen erweitert. Die gefundenen Werte von δp stimmen gut mit jenen aus Quellungsmessungen erhaltenen überein.
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ABSTRACT: Geometrical dependence of viscosity of polymethylmethacrylate (PMMA) and high density polyethylene (HDPE) are studied by means of a twin-bore capillary rheometer based on power-law model. Contrary geometrical dependences of shear viscosity are observed for PMMA between 210 and 255°C, but similar geometrical dependences are revealed for HDPE between 190 and 260°C. The fact that wall slip can not successfully explain the irregular geometrical dependence of PMMA viscosity is found in this work. Then, pressure effect and dependence of fraction of free volume (FFV) on both pressure and temperature are proposed to be responsible for the geometrical dependence of capillary viscosity of polymers. The dependence of shear viscosity on applied pressure is first investigated based on the Barus equation. By introducing a shift factor, shear viscosity curves of PMMA measured under different pressures can be shifted onto a set of parallel plots by correcting the pressure effect and the less shear-thinning then disappears, especially at high pressure. Meanwhile, the FFV and combining strength among molecular chains are evaluated for both samples based on molecular dynamics simulation, which implies that the irregular geometrical dependence of PMMA viscosity can not be attributed to the wall slip behavior. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 39982.Journal of Applied Polymer Science 03/2014; 131(6). DOI:10.1002/app.39982 · 1.64 Impact Factor
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ABSTRACT: The Hildebrand solubility parameter (δ), which predicts the miscibility of materials, was determined for the compounds that are involved in the oxidation of p-xylene to terephthalic acid. The δ values were determined from the measured intrinsic viscosity [η] of the compounds. The following compounds (namely, methyl benzoate, p-tolualdehyde, 4-hydroxymethyltoluene, terephthalaldehyde, benzoic acid, p-toluic acid, 4-hydroxymethylbenzoic acid, phthalic acid, trimellitic acid, 4-carboxybenzaldehyde, and isophthalic acid, including p-xylene as the reactant and terephthalic acid as the main product) were studied. The predicted δ values were obtained using the group contribution method, which helped in selecting the solvents to be used for viscosity measurements. Mixtures of solvents were used to obtain δ values for phthalic acid, isophthalic acid, terephthalic acid, and trimellitic acid. It was observed that δ is apparently related to the melting points of the compounds. Three-dimensional Hansen solubility parameters were also determined for important p-xylene oxidation products for a better understanding of their solubility behavior.Industrial & Engineering Chemistry Research 01/2011; 50(4). DOI:10.1021/ie101623c · 2.24 Impact Factor
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ABSTRACT: The behavior of bovine serum albumin (BSA) in water is scarcely studied, and the thermodynamic properties arising from the experimental measurements have not been reported. Intrinsic viscosity measurements are very useful in assessing the interaction between the solute and solvent. This work discussed in a simple determination of the enthalpy of BSA in aqueous solution when the concentration ranges from 0.2 to 36.71% wt. and the temperature from 35 to C. The relationship between the concentration and intrinsic viscosity is determined according to the method of Huggins. The temperature increase reduces the ratio between inherent viscosity and concentration (). This is reflected in the Van't Hoff curve. Furthermore, this work proposes hydrodynamic cohesion value as an indicator of the degree of affinity of protein with water and thermodynamic implications in conformational changes.Advances in Physical Chemistry 05/2013; 2013. DOI:10.1155/2013/360239