Sl. Shamblin et al., THE EFFECTS OF CO-LYOPHILIZED POLYMERIC ADDITIVES ON THE GLASS-TRANSITION TEMPERATURE AND CRYSTALLIZATION OF AMORPHOUS SUCROSE, Journal of thermal analysis, 47(5), 1996, pp. 1567-1579
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 th
e T-g of a sucrose-additive mixture, relative to the T-g of pure sucro
se, and its ability to inhibit crystallization. Differential scanning
calorimetry was used to measure the glass transition temperature, T-g,
the non-isothermal crystallization temperature, T-c, and the inductio
n time for crystallization, Q, of sucrose in the presence of co-lyophi
lized Ficoll or poly(vinylpyrrolidone) (PVP). The effect of these poly
mers on the crystallization of sucrose was significant as demonstrated
by a marked increase in T-c, and in the induction time (Q) in the pre
sence of relatively small amounts (1-10%) of additive. Surprisingly, s
mall amounts of polymeric additive had no effect on the T-g of sucrose
, although at higher concentrations, the T-g increased proportionally.
Thus, it appears that the inhibition of sucrose crystallization by th
e addition of small amounts of a higher-T-g component cannot be attrib
uted solely to changes in molecular mobility associated with an increa
se in T-g.