Content area
Full text
ABSTRACT
The values of coefficients of permeability of organic solvents through polyurethane membrane Vibrathane B-600 can be generalized by means of multiparameter linear equations. Polarity of solvents increases their permeability whereas increase in molar volume of solvents, their self-association and ability to electrophilic solvation of amide structures of membrane reduce it.
(ProQuest: ... denotes formulae omitted.)
INTRODUCTION
Numerous researches are devoted to investigation of polymer swelling in organic liquids and determining of the proper diffusion coefficients [1-3]. However the problem of determining of liquid permeability through polymeric films has taken on special significance recently due to a wide distribution of membrane technologies. Nevertheless dependence of this index on physical and chemical characteristics of diffusing solvents is considered still only at qualitative level.
In the last decade a number of T.M. Aminabhavi's and coauthors' works have been published [4], where the values of permeability coefficients P of organic liquids through a number of polymeric membranes of different nature are presented. These coefficients were determined in accordance with [5] as a product of the proper diffusion coefficients D (cm2/s) on the value of maximal swelling Smax (an amount of solvent (in grams), absorbed by 1 gram of polymer); accordingly, it has dimension cm2/s:
P = D × Smax . (1)
The coefficients D were determined, in turn, on the basis of experimental data using the dependence of solvent adsorption on time τ [5]:
D = π (h×Ø/4Smax)2 , (2)
where h is a thickness of the sample, Sh is the slope of the straight part of the dependence S -τ1/2.
However, the attempts of authors of review [4] to establish quantitative relation between the values of P and some physical and chemical properties of penetrant failed. In particular, at plotting dependences lg P vs molar volume of penetrant Vm relative straight part (with numerous exceptions) is observed only within the limits of separate groups of solvents - alkanes, esters, cyclic compounds. At the same time it is known, that at usual consideration of the processes of polymer swelling (including coals), on the basis of the theory of regular solutions, obtained dependences of values of Smax for different solvents on their solubility parameter δ or squared parameter δ2 are curvilinear, bell-shaped. A number of the data deviate...