Investigation of critical concentrations of poly(vinyl pyrrolidone) in N, N-dimethylformamide by a viscosity technique

The viscosity of solutions of poly(vinyl pyrrolidone) (PVP) in N,N-dimethylformamide over a wide range of concentrations and at different temperatures was measured. The polymer solutions exhibited a critical concentration c**, separating dilute solutions into extremely dilute solutions and dilute so...

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Bibliographic Details
Published in:Physics and chemistry of liquids 2015-01, Vol.53 (1), p.75-83
Main Authors: Cherif, Emna, Zoghlami, Ons, Othman, Tahar
Format: Article
Language:English
Subjects:
Behavior
Constants
Dilution
intrinsic viscosity
Liquids
Mathematical analysis
poly(vinylpyrrolidone)
polymer solution
Surface chemistry
Thermodynamics
Viscosity
Viscosity measurement
viscosity-temperature
Walls
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Summary:The viscosity of solutions of poly(vinyl pyrrolidone) (PVP) in N,N-dimethylformamide over a wide range of concentrations and at different temperatures was measured. The polymer solutions exhibited a critical concentration c**, separating dilute solutions into extremely dilute solutions and dilute solutions. The viscosity-temperature dependence is discussed on the basis of a formula of the correlation between the true and the experimental relative viscosity. The results revealed that an abnormal viscosity of neutral PVP solutions in the dilute solution region (c › c**) and extremely dilute solutions (c ‹ c**) can be ascribed to interface effects. The polymeric solutes were readily adsorbed on the wall surface of the cone-plate rheometer, which greatly influenced the viscosity measurements of the PVP solutions and resulted in the apparent abnormal viscosity behaviour. The intrinsic viscosity [η] and the Huggins constant k H , were calculated. The solute adsorption behaviours and structural information of the polymer were discussed in depth.
ISSN:0031-9104
1029-0451
DOI:10.1080/00319104.2014.937864