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Acid–base properties of fibers. Part II. A polyelectrolyte theory of the combination of fibers with acids and bases
Author(s) -
Mathieson A. R.,
Whewell C. S.
Publication year - 1964
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.1964.070080508
Subject(s) - titration , polyelectrolyte , chemistry , dissociation (chemistry) , dissociation constant , titration curve , acid–base titration , fiber , electrolyte , sulfuric acid , polymer chemistry , inorganic chemistry , analytical chemistry (journal) , chromatography , organic chemistry , polymer , biochemistry , receptor , electrode
A. new theory for the acid–base properties of fibers is presented, resembling those for polyelectrolytes, and based on the normal titration of the charged groups of the fibers and the energy needed to remove the protons from the fiber to the solution, against the electrostatic, osmotic, and affinity differences. The acid titration equation for a poly‐ampholyte fiber is:\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm pH} = {\rm p}K_0 ^\prime - \log [{{\left( {1 - \alpha } \right)} \mathord{\left/ {\vphantom {{\left( {1 - \alpha } \right)} \alpha }} \right. \kern-\nulldelimiterspace} \alpha }] - \left( {{{0.4343} \mathord{\left/ {\vphantom {{0.4343} {RT}}} \right. \kern-\nulldelimiterspace} {RT}}} \right)[\chi F + \tau \bar V_{\rm H} + \Delta \mu _{\rm H}^{\rm o} ] $\end{document} where p K 0 ′ is the intrinsic dissociation constant of the titration groups in the fiber, α is the degree of dissociation, χ is the electrostatic potential of the fiber, τ the osmotic pressure, V̄ H the partial molar volume of the hydrogen ion, and Δμ H othe difference of standard chemical potential in the fiber and the solution. In all cases examined, the osmotic term proved to be negligible. The electrostatic potential was calculated as suming it to be uniform over the fiber. For wool, p K 0 ′ is independent of salt concentration but varies linearly with degree of dissociation, indicating that two p K 's are operating, p K q = 3.58 5 for paired groups and p K p = 4.85 5 for nonpaired groups at 0°C., present in equal proportions. Titrations of wool with sulfuric acid and a wide range of strong monobasic acids also obey the theory, and values of the anion affinities in general agreement with those given by Gilbert and Rideal are found. The acid titration of native ox‐hide collagen gave a constant value of p K 0 ′ = 4.0. For nylon, the value of p K 0 ′ is, to a first approximation, independent of degree of dissociation and salt concentration, in agreement with the theory.