Dielectric behavior of aqueous solutions of sodium polyphosphates of low degree of polymerization

Abstract

The dielectric relaxation behavior of three sodium polyphosphates with different but low degrees of polymerization in aqueous solution (without salt) has been investigated between 8 kHz and 100 MHz. The highest molecular weight sample (DP 338) exhibits two dispersion regions as is generally observed with synthetic polyelectrolytes at higher degrees of polymerization and is interpreted, according to the theory of van der Touw and Mandel, by attributing a certain flexibility to the polymer chain. The experimentally determined relaxation time of the high‐frequency dispersion is in fair agreement with the theoretically calculated value. For the lowest molecular weight sample (DP 112) the experimental results can best be described by a single dispersion curve pointing to a rigid, more or less stretched, conformation of the polyion in agreement with theoretical predictions. For the sample of intermediate molecular weight (DP 198) the situation is borderline as it is possible to describe the relaxation behavior by either one or two dispersion regions; it is, however, concluded from an analysis of the dielectric results that the average conformation is rather extended, but not completely rigid.

Dielectric Properties of Polyelectrolyte Solutions

“…At room temperature, for degrees of polymerization not too low (DP> 300) and for sufficiently high charge densities (for weak polyacids 0.3 < aD < 1, with aD the degree of dissociation), the measured relative permittivity exceeds the value of the pure solvent for frequencies below 100 MHz. Near 100 MHz, in practically all cases investigated, the dielectric increment with respect to the solvent becomes negligible, indicating that at this frequency no significant contribution of the charged macromolecule to the polarization of the system persists, nor is the polarization of the solvent affected by the polyions (59)(60)(61)(62)(63). Below 100 MHz the dielectric increment increases with decreasing frequency, generally exhibiting two dispersion regions that are more or less well separated (53,(58)(59)(60)(62)(63)(64)(65).…”

Anisotropic counterion polarizations and their dynamics in aqueous polyelectrolytes as studied by frequency-domain electric birefringence relaxation spectroscopy

“…(tl)'1 = (3rR/2)_1 + (r3)_1 (17) The value of r3 calculated by using eq 17 from the observed values of rL and rR is listed in Table III, which shows that tl =* r3; i.e., rL is mostly determined by r3.…”

Electrical properties of polymers

“…In a survey, Williams (96) shows the type of information which can be obtained from microwave measurements of permittivity and loss in amorphous polymers and viscous liquids. Dielectric behavior of various solutions described (97)(98)(99)(100)(101)(102)(103)(104). The effects of a dielectric transition is observed (105) above T in Dioxane solution of poly-(vinyl chloride) and pOlyfp.…”