Effects of the degree of saponification and concentration on the thermal and rheological properties of poly(vinyl alcohol)-dimethyl sulfoxide-water gels

Abstract

Differential scanning calorimetry (DSC) and dynamic viscoelasticity measurements were carried out in order to clarify the relation between structure and gel properties of poly(vinyl alcohol) (PVA)-dimethyl sulfoxide (DMSO)-water systems. The gel-to-sol transition temperature Tm, endothermic enthalpy ΔH and elastic coefficient E of gels showed maximum at about 0.277 mf DMSO as a function of DMSO concentration. Tm, ΔH, and E of gels increased with increasing degree of saponification (DS) and concentration of the polymer. It was suggested that the number and structures of junction zones and the conformation of flexible chain molecules connecting junction zones are optimized to give maxima of E, Tm, and ΔH at a concentration of 0.277 mf DMSO. The gel containing 0.277 mf DMSO showed no endothermic DSC peak when heated from −100°C. © 1989 The Society of Polymer Science, Japan.