STRUCTURE OF JUNCTION ZONES IN POLY (VINYL ALCOHOL) GELS BY RHEOLOGICAL AND THERMAL STUDIES

Differential scanning calorimetry (DSC) and dynamic viscoelastic measu rements were carried out far poly(vinyl alcohol) (PVA) gels with diffe rent molecular weights and various concentrations prepared by a freeze -thaw process. The temperature dependence and the concentration depend ence of the elastic modulus of PVA gels were interpreted by a reel-cha in model and a cascade treatment respectively. Structural parameter; f or junction zones of PVA gels were determined by a modified Eldridge-F erry plot for DSC data as follows: junction zone consists of 2 similar to 3 ordered chains with about 24 similar to 120 segments.