Mobility of thermal cations in liquids of n-alkanes, n-pentane to n-tetradecane: effect of viscosity and comparison to neutral molecule diffusion

1989 ◽  
Vol 67 (1) ◽  
pp. 27-31 ◽  
Author(s):  
Norman Gee ◽  
Gordon R. Freeman
Keyword(s):  
Free Volume ◽  
Diffusion Coefficients ◽  
Neutral Molecule ◽  
Cation Mobility ◽  
Boiling Points ◽  
Viscosity Effects ◽  
Alkane Solvents ◽  
Best Fit

The cation mobility μ+ was measured in n-pentane at 295 K and in n-C6 to C11 and n-C14 alkanes from ~295 K to their normal boiling points. The dependence on viscosity [Formula: see text] was reexamined and the best fit occurred with p = 1.0. The ratio of diffusion coefficients of neutral molecules to analogous cations was ~3 because of the stronger interaction of ions with the fluid molecules (electrostriction). The dependence of μ+ on free volume is illustrated. Keywords: thermal cation mobility, n-alkane solvents, viscosity effects

scholarly journals Shape and Temperature Expansion of Free Volume Holes in Some Cured Polybutadiene-Polyisoprene Rubber Blends

2021 ◽  
Vol 22 (3) ◽  
pp. 1436
Author(s):  
Giovanni Consolati ◽  
Eros Mossini ◽  
Dario Nichetti ◽  
Fiorenza Quasso ◽  
Giuseppe Maria Viola ◽  
...  
Keyword(s):  
Free Volume ◽  
Radial Direction ◽  
Volume Fraction ◽  
Spherical Shape ◽  
Suitable Model ◽  
Positron Annihilation Lifetime ◽  
Rubber Blends ◽  
Free Volume Fraction ◽  
Hole Model ◽  
Best Fit

The free volume fraction of a macromolecular structure can be assessed theoretically by using a suitable model; however, it can also be evaluated from experimental data obtained from dilatometry and positron annihilation lifetime spectra. In this second case, a regular geometry of the sub-nanometric cavities forming the free volume has to be assumed, although in fact they are irregularly shaped. The most popular approach is to guess spherical holes, which implies an isotropic growth of these last with temperature. In this work, we compared the free volume fraction, as obtained from experiments in a set of polybutadiene and polyisoprene cured rubbers and their blends, with the analogous quantity expected by using the lattice-hole model. The results allowed us to obtain insights on the approximate shape of the holes. Indeed, a cylindrical flattened geometry of the cavities produced a better agreement with the theory than the spherical shape. Furthermore, the best fit was obtained for holes that expanded preferentially in the radial direction, with a consequent decrease of the aspect ratio with temperature.

Cation mobilities in liquid and supercritical C1–C4 hydrocarbons

1980 ◽  
Vol 58 (14) ◽  
pp. 1490-1494 ◽  
Author(s):  
Norman Gee ◽  
Gordon R. Freeman
Keyword(s):  
Free Path ◽  
Ion Mobility ◽  
Diffusion Coefficients ◽  
Critical Region ◽  
Mean Free Path ◽  
Liquid Viscosity ◽  
Boiling Points ◽  
Rough Approximation ◽  
The Relationship ◽  
Lower Liquid

The relationship between ion mobility and liquid viscosity is commonly expressed as μ [Formula: see text] η−m. In hydrocarbons the value of m tends to be near 1.0 at η > 5 mP, m > 1.0 at ~5 < η < 1 mP, and m < 1.0 at η < 0.5 mP. Thus there is a maximum in a plot of μη against η−1 and Walden's rule (m = 1.0) is only a rough approximation. The decrease of μη as the critical region is approached is accompanied by an increase in the ratio of diffusion coefficients Dmolec/Dion. Ion mobilities in the liquids well below their normal boiling points are chiefly controlled by the fluidity. At higher temperatures and concomitant lower liquid densities and viscosities μη first increases, due to an increasing ion mean free path, then decreases as the critical region is approached, due to the increasing liquid compressibility and consequent electrostriction about the ion.

A free volume theory on the chain length dependence of the diffusivity of linear polymers

Soft Matter ◽  
2019 ◽  
Vol 15 (45) ◽  
pp. 9300-9309 ◽  
Author(s):  
Chi Pui Jeremy Wong ◽  
Phillip Choi
Keyword(s):  
Chain Length ◽  
Free Volume ◽  
Diffusion Coefficients ◽  
Linear Polymers ◽  
Free Volume Theory ◽  
Length Dependence

A free volume theory for the crossover in diffusion coefficients of linear polymers from unentangled to entangled regimes is developed.

Temperature Dependence of the Diffusion of 1,2-Dichloroethane, 1,1,1-Trichloroethane, Trichloroethylene, and Tetrachloroethylene in Air

1971 ◽  
Vol 49 (11) ◽  
pp. 1965-1967 ◽  
Author(s):  
Harry Watts
Keyword(s):  
Temperature Dependence ◽  
Diffusion Coefficients ◽  
Room Temperature ◽  
Evaporation Method ◽  
Temperature Range ◽  
Boiling Points ◽  
Rate Of Evaporation

The diffusion coefficients in air of 1,1-dichloroethane, 1,1,1-trichloroethane, trichloroethylene, and tetrachloroethylene have been measured over a temperature range from room temperature to close to their boiling points by a rate of evaporation method.

Prediction of Self-Diffusion Coefficients of Fluids Based on Friction and Free Volume Theories

2015 ◽  
Vol 36 (7) ◽  
pp. 1405-1415 ◽  
Author(s):  
Qiu Zhong ◽  
Liping Yang ◽  
Ye Tao ◽  
Caiyun Luo ◽  
Zijun Xu ◽  
...  
Keyword(s):  
Free Volume ◽  
Diffusion Coefficients ◽  
Self Diffusion
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