Polymer-polymer interactions in dextran systems using thermal analysis

For pure dextrans, Tg increased with Mw up to a critical Mw approximately between 23,000 and 30,000; reaching a plateau at higher Mw. The physical blend of dextrans in powder form resulted in dual Tg even after melting of the blends, indicating immiscibility; whereas for dextrans that were dissolved in water and mixed, only one Tg was observed, indicating miscibility. Tg of miscible systems was better related to the number-average molecular weight than weight-average molecular weight.