Viscometric methods were applied in this work for a comparative study of two binary mixtures, viz., polyvinyl alcohol (PVA)–water and PVA–hexamethylphosphoramide (HMPA). It was established experimentally that the parameter K , which describes the deviation from the linearity of the reduced viscosity versus concentration dependence in concentrated regimes (after crossover concentration), compared with the dilute one, can be used as an effective tool to measure the goodness of solvents. Based on the calculated [?] and ф
m parameters, it was shown that HMPA is a better solvent for PVA from the thermodynamic point of view if compared with water.
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