Effect of Freeze-drying Factors on Collapse Temperature

Abstract:

Freeze-drying microscopy was used to investigate the effect of freezing rate, pressure and mass fraction on the collapse temperature (Tc) during freeze-drying of aqueous solutions, and differential scanning calorimetry was used to investigate the glass transition temperature (T′g) of the maximally freeze concentrated solution. The experimental results showed that for 10% sucrose/water binary solution, the freezing rate had little effect on Tc although it could affect the size of ice crystals. For 10% tertiary butyl alcohol/10% sucrose/water ternary solution, both T′g and Tc decreased with the increase of freezing rate. Few variations in collapse temperatures could be expected when varying the pressure. For sucrose aqueous solutions at different mass fractions (5%～25%), the variation of collapse temperature was less than 1℃