Precision measurements of osmotic pressure in concentrated polymer solutions

✍ Scribed by H. Vink

• Publisher: Elsevier Science
• Year: 1971
• Tongue: English
• Weight: 442 KB
• Volume: 7
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(71)90035-8

✦ Synopsis

Precision measurements of osmotic pressure have been carried out with several polymers (dextran, hydroxyethyl cellulose, polyvinylpyrrolidone and polyethlene oxide) in aqueous solutions. The concentration dependence of the osmotic pressure over a wide range of concentrations (up to 0-2 g/cm 3) was established; the influence of the molecular weight and the molecular weight heterogeneity of the samples was studied. In all cases investigated, it was found that in the virial expansion of the osmotic pressure the fourth and higher virial coefficients were zero within experimental error. The temperature dependence of the osmotic pressure was also investigated and the partial molar heats and entropies of mixing for the solvent were determined. For the solutions investigated, the heats and entropies of mixing were in general closely correlated. The heats of mixing were all negative, whereas the entropy of mixing was positive in dextran solutions and negative in solutions of the other polymers.