Authors:Sheri L. Shamblin, Eva Y. Huang, and G. Zografi
The purpose of this study was to measure the effect of co-lyophilized polymers on the crystallization of amorphous sucrose, and to test for a possible relationship between the ability of an additive to raise theTg of a sucrose-additive mixture, relative to theTg of pure sucrose, and its ability to inhibit crystallization. Differential scanning calorimetry was used to measure the glass transition temperature,Tg, the non-isothermal crystallization temperature,Tc, and the induction time for crystallization,Q, of sucrose in the presence of co-lyophilized Ficoll or poly(vinylpyrrolidone) (PVP). The effect of these polymers on the crystallization of sucrose was significant as demonstrated by a marked increase inTc, and in the induction time (Q) in the presence of relatively small amounts (1–10%) of additive. Surprisingly, small amounts of polymeric additive had no effect on theTg of sucrose, although at higher concentrations, theTg increased proportionally. Thus, it appears that the inhibition of sucrose crystallization by the additition of small amounts of a higher-Tg component cannot be attributed solely to changes in molecular mobility associated with an increase inTg.