Acid–base properties of fibers. Part II. A polyelectrolyte theory of the combination of fibers with acids and bases

A. R. Mathieson; C. S. Whewell

摘要

AbstractA. 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 pK0′ 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, V̄Hthe partial molar volume of the hydrogen ion, and Δμ Hothe 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, pK0′ is independent of salt concentration but varies linearly with degree of dissociation, indicating that two pK's are operating, pKq= 3.585for paired groups and pKp= 4.855for 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 pK0′ = 4.0. For nylon, the value of pK0′ is, to a first approximation, independent of degree of dissociation and salt concentration, in agr

Acid–base properties of fibers. Part II. A polyelectrolyte theory of the combination of fibers with acids and bases

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