Understanding the linear correlation between diffusion coefficient and molecular weight. A model to estimate diffusion coefficients in acetonitrile solutions

2011 ◽  
Vol 13 (2) ◽  
pp. 129-132 ◽  
Author(s):  
Drochss P. Valencia ◽  
Felipe J. González
Keyword(s):  
Molecular Weight ◽  
Diffusion Coefficient ◽  
Linear Correlation ◽  
Diffusion Coefficients ◽  
Acetonitrile Solutions

Bestimmung des Molekulargewichtes der 20-β-Hydroxy-steroid-dehydrogenase

1962 ◽  
Vol 17 (7) ◽  
pp. 432-436 ◽  
Author(s):  
Matatiahu Gehatia
Keyword(s):  
Molecular Weight ◽  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Specific Volume ◽  
Sedimentation Coefficient ◽  
Partial Specific Volume ◽  
Hydroxy Steroid ◽  
Steroid Dehydrogenase

The enzyme 20-β-Hydroxy-steroid-dehydrogenase obtained from the culture of Streptomyces hydrogenans and dissolved in 0.05 M Tris puffer, pH 7.3, has been investigated by means of a ultracentrifuge at 20 °C. The sedimentation- as well as the diffusion-coefficients obtained from various solutions at different concentrations were extrapolated to the concentration c = 0. The resulting zero-value for the sedimentation coefficient is s0 = 6.64 s and for the diffusion coefficient is D0 = 5.51 × 10-7 cm2/sec. Supposing the partial specific volume of the enzyme under consideration analogously to other similar proteins is V+=0.749 ml/g, the molecular weight has been estimated as M = 118 400.

Temperature dependence of tracer diffusion coefficients in polystyrene

1986 ◽  
Vol 1 (1) ◽  
pp. 202-204 ◽  
Author(s):  
Peter F. Green ◽  
Edward J. Kramer
Keyword(s):  
Molecular Weight ◽  
Diffusion Coefficient ◽  
Shear Rate ◽  
Temperature Dependence ◽  
Diffusion Coefficients ◽  
Tracer Diffusion ◽  
Tracer Diffusion Coefficient ◽  
Critical Molecular Weight ◽  
Tracer Diffusion Coefficients ◽  
Monomeric Friction Coefficient

The temperature dependence of the tracer diffusion coefficient D* of long deuterated polystyrene (d-PS) chains of molecular weight M>Mc, where Mc is the critical molecular weight for entanglement, diffusing into highly entangled PS matrices, each of molecular weight P = 2×107, is studied using forward recoil spectrometry. It is found that the temperature dependence of D*/T, reflected primarily in the monomeric friction coefficient, is accurately described by a Vogel equation. The constants that are used to fit these results are independent of M and are the same as those used to fit the temperature dependence of the zero shear rate viscosity of polystyrene.

SO2 diffusion through acetonitrile-saturated perfluorosulfonic acid membranes

1980 ◽  
Vol 58 (21) ◽  
pp. 2225-2229 ◽  
Author(s):  
Frank M. Kimmerle ◽  
Raymond Breault
Keyword(s):  
Diffusion Coefficient ◽  
Ion Exchange ◽  
Diffusion Coefficients ◽  
Isotopic Ratios ◽  
Residual Water ◽  
Open Area ◽  
Effective Surface ◽  
Perfluorosulfonic Acid Membranes ◽  
Acetonitrile Solutions ◽  
Water Saturated

The diffusion coefficient of SO2 and acetonitrile in Nafion perfluorinated ion exchange membranes have been determined from chromatographic measurements of SO2 concentration and the isotopic ratios in acetonitrile solutions. The diffusion coefficients vary with residual water content and attain values about one fifth those reported for water-saturated membranes falling in the range 1–2 × 10−7 cm2 s−1. Values obtained for Teflon reinforced material indicates diffusion takes place over an effective surface more than twice the optically open area.

Diffusion of Curatives. I

1982 ◽  
Vol 55 (5) ◽  
pp. 1482-1498 ◽  
Author(s):  
D. A. Lederer ◽  
K. E. Kear ◽  
G. H. Kuhls
Keyword(s):  
Experimental Data ◽  
Molecular Weight ◽  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Test Procedure ◽  
Mathematical Techniques ◽  
Increasing Temperature ◽  
Storage Temperatures ◽  
Rubber Article ◽  
Diffusion Profiles

Abstract Curatives will readily migrate across a rubber-to-rubber interface following the classical laws of diffusion. The rate of diffusion increases with increasing temperature. The absolute change in curative concentration diminishes with increasing distance from the interface and increases with time. A test procedure using conventional analytical methods can be used to accurately determine the diffusion coefficients of curatives at various storage temperatures in standard rubber formulations. Diffusion profiles and coefficients are dependent on the curative type. There appears to be a general correlation with molecular weight, with the rate of diffusion decreasing with increasing molecular weight. There is a small, rationalizable effect of concentration on the diffusion coefficient. The diffusion of curatives can cause a significant change in the cure system at or near the interface of a plied rubber article. Diffusion profiles for a particular rubber formulation can be predicted from experimental data using relatively simple analytical and mathematical techniques.

Diffusion of some Hydrocarbons in Air: a Regularity in the Diffusion Coefficients of a Homologous Series

1972 ◽  
Vol 50 (1) ◽  
pp. 31-34 ◽  
Author(s):  
Robert W. Elliott ◽  
Harry Watts
Keyword(s):  
Molecular Weight ◽  
Diffusion Coefficient ◽  
Linear Relationship ◽  
Diffusion Coefficients ◽  
Homologous Series ◽  
Prediction Equations

Diffusion coefficients in air at 298.2 °K and 1 atm pressure are reported for ethane, ethene, ethyne, cyclopropane, propene, propadiene, propyne, butane, 1-butene, 2-methylpropene, cis-2-butene, trans-2-butene, 1,3-butadiene, 1-butyne, 2-methylbutane, 2,2-dimethylpropane, cyclopentane, and 1-pentene.A linear relationship, valid for alkanes and alkenes, has been found between the diffusion coefficient and the reduced molecular weight of the members of a homologous series and air.Diffusion coefficients calculated by ten prediction equations were generally lower than those observed.

What use for polysilsesquioxane lithium salts in lithium batteries?

2016 ◽  
Vol 40 (9) ◽  
pp. 7657-7662
Author(s):  
Mathieu Meyer ◽  
Lydie Viau ◽  
Ahmad Mehdi ◽  
Sophie Monge ◽  
Patrick Judeinstein ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Nmr Spectroscopy ◽  
High Molecular Weight ◽  
Lithium Batteries ◽  
Diffusion Coefficients ◽  
Transference Numbers ◽  
Lithium Salts ◽  
Self Diffusion ◽  
Acetonitrile Solutions ◽  
Pfg Nmr

High molecular weight polysilsesquioxane lithium salts were prepared. Ion self-diffusion coefficients and transference numbers in acetonitrile solutions were quantified by PFG NMR spectroscopy.

A simple and exact method for calculating diffusion coefficients from the data of polarization interferometer. Extension to the case of polymers with narrow distribution of molecular weight

1981 ◽  
Vol 46 (12) ◽  
pp. 3018-3026 ◽  
Author(s):  
Bedřich Porsch ◽  
Lars-Olof Sundelöf
Keyword(s):  
Molecular Weight ◽  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Binary Systems ◽  
Sufficient Accuracy ◽  
Average Value ◽  
Polarization Interferometer ◽  
Time Correction ◽  
Broad Molecular Weight Distribution ◽  
Zero Time

The simple equation derived previously for calculating the diffusion coefficient and the zero-time correction from the data of the polarization interferometer is shown to be valid not only in the case of binary systems but also for the diffusion of polymer solutes with moderately broad molecular weight distribution and results in a diffusion coefficient, which is an average value of a well-defined type. In addition, it is shown experimentally that the equation is applicable with sufficient accuracy also to the evaluation of diffusion coefficients of polymers having a polydispersity index as high as Mw/Mn = 2.

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