Thermal and rheological properties of the supersaturated sucrose solution in the presence of different molecular weight fractions and concentrations of dextran.

摘要

In our current research work, we investigated the effects of molecular weight (M_w) and the concentration of dextran presence during cane sugar manufacturing on the rheological and glass transition properties of supersaturated sucrose solution. Three dextrans of various M_w, namely 100,000 g/mol (T₁₀₀), 500,000 g/mol (T₅₀₀) and 2,000,000 g/mol (T₂₀₀₀), were admixed in concentrations between 1,000 and 10,000 ppm with 65 and 75% w/w sucrose solution. The results indicated that both the apparent viscosity and dynamic modulus increased with an increase in dextran concentrations and they demonstrated strong dependence on its M_w. Glass transition temperature (T_g) of the samples was measured by differential scanning calorimetry, and their dependence on dextran M_w and concentration was analyzed by the Fox and expanded Gordon-Taylor mathematical models. It was found that the higher the M_w and concentration of the dextran, the greater the increase in T_g. The expanded Gordon-Taylor equation has proved useful in predicting the T_g of the sucrose solution in the presence of polymer. copyright Springer-Verlag 2012.