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Aspects of vapor pressure osmometry
Author(s) -
Morris C. E. M.
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.1977.070210210
Subject(s) - osmometer , vapor pressure osmometry , vapor pressure , toluene , solvent , polystyrene , chemistry , virial coefficient , chloroform , drop (telecommunication) , volatility (finance) , analytical chemistry (journal) , calibration , thermodynamics , chromatography , organic chemistry , polymer , telecommunications , physics , statistics , mathematics , computer science , financial economics , economics
Three aspects of vapor pressure osmometry were examined: drop size, solute volatility, and the constancy of the calibration factor. It was shown that there is a drop size effect which is dependent on the solute concentration. Solutes having vapor pressures as low as 0.3 mm Hg under the operating conditions were found to give unsatisfactory results. The calibration factor was determined using eight compounds in the molecular weight range of 128 to 883 in chloroform, toluene, and methyl ethyl ketone at several temperatures; a small but significant dependence of the calibration factor on molecular weight was demonstrated. The results fitted, with a high degree of accuracy, the relation log M̄ n = a + b log (Δ V / C ) C = 0 , where a and b are constants for a given solvent/temperature combination. However, measurements with standard polystyrene samples, using extrapolations of this relationship to higher molecular weights, revealed considerable discrepancies in results for the one compound under different solvent/temperature combinations.