ISSN:
0025-116X
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Viscosity measurements over a wide range of temperature were made on aqueous solutions of poly(ethylene oxide) samples of different molar mass and of low polydispersity. Above ca. 308 K the Mark-Houwink exponent decreases and tends to a value of 0,50 at a lower critical solution temperature of 376 ± 2 K. The same value for this θ-temperature is derived also as that at which the slope of Stockmayer-Fixman plots tends to zero. At 298 K the unperturbed dimensions [〈r2〉0/M]1/2 = 0,089 nm · g-1/2 · mol1/2 and their temperature coefficient d ln 〈r2〉0/dT ≈ - 1,5 (±0,5) · 10-3 K-1. In aq. KOH the intrinsic viscosity [η] is virtually uninfluenced by pH at low-medium pH, but at high pH, [η] falls sharply. Viscosity and phase separation measurements yield θ-conditions in 1,24 M aq. KOH at 298 K. The derived polymer-water interaction parameters χ increase from 0,449 at 276 K to 0,493 at 358 K, but the enthaplic component χH is incapable of yielding a meaningful value for the solubility parameter δ2 of the polymer in such a hydrogen-bonding system. The calculated value of χ2 was 18,9 (kJ · dm-3)1/2.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/macp.1986.021870718
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