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Diffusion of radioactively tagged penetrants through rubbery polymers. II. Dependence on molecular length of penetrant
Author(s) -
Rhee ChongKon,
Ferry John D.,
Fetters L. J.
Publication year - 1977
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1977.070210318
Subject(s) - penetrant (biochemical) , oligomer , hexadecane , polymer , materials science , diffusion , polymer chemistry , thermodynamics , polymer science , chemistry , composite material , organic chemistry , physics
The diffusion of radioactively tagged n ‐hexadecane, n ‐dotriacontane, and a polybutadiene oligomer with molecular weight 1600 has been studied in 12 rubbery polymers. Diffusion coefficients were obtained from the theory for the thin smear method: for n ‐hexadecane and for n ‐dotriacontane (with one exception), in the form appropriate for a completely miscible polymer–penetrant pair, and for the oligomer in the form appropriate for slow entry of the penetrant across the penetrant–polymer interface. For the four flexible linear penetrants, n ‐dodecane, n ‐hexadecane, n ‐dotriacontane, and oligomer, the ratios of diffusion coefficients (or translational friction coefficients) are nearly the same in every polymer. It is concluded that these penetrants travel with similar segmentwise motions, although that is not the case with bulkier, more rigid penetrants. For the three normal paraffins, the friction coefficient is approximately proportional to molecular weight, but that for the oligomer is smaller than would be predicted on this basis.