| Abstract: | The heats of immersion, in water, of corn starch U. S. P. and a directly compressible corn starch were determined as a function of moisture content. This study, in conjunction with an equilibrium vapor phase adsorption study, allowed the thermodynamic parameters characterizing the two systems to be calculated. In both cases, hysteresis was observed in the heat of immersion data. Plots of the differential enthalpies provided evidence that both starches swell in water at room temperature. Average adsorbate-solid hydrogen bond energies were calculated for the two starch-water systems ( - 8.57 Kcal/mole, corn starch U. S. P. -water; - 7.80 Kcal/mole, Starch 1500-water). |
