Hello dear researchers,
I was wondering if the glass transition temperature of sucrose is dependent on the concentration of the sucrose. In literature I found the value -32°C, but there was no concentration given, so I assumed it is probably 1M. But my next thought was that maybe the glass temperature is not dependent on the concentration, since there is probably freeze concentration occuring during freezing so the sucrose does not freeze with the water anyway but concentrates up, until it becomes a glass at -32°C. I did some DSC measurements which showed that the glass transition temperature of 0,1M sucrose is much higher than that of 1,0M sucrose, but unfortunately the device can`t give me exact numbers because it has a malfunction. That is why I am asking you people, anybody have experience with this?
I saw a paper that indicates Tg decreases from -32 to -40 deg.C as the concentration rises from 20 to 80% w/v
Generally glass transition temperatures depend on composition (entropic effects). Since you have lots of hydroxyl groups in the sugar, they will perform hydrogen bonds with water molecules, resulting in pretty stable solvation shells. If the viscosity (which depends on concentration) and the cooling rate are sufficient, crystallization seed forming becomes supressed, crystal growing becomes too slow and we obtain the glass. Here is a reference with some experimental data:
Article Effect of water content on the glass transition temperature ...
Tg is a phase transformation, according to the TTT time temperature transformation, the scanning speed of testing tool is an isssue we need to pay more attention.
beside Glass Transition Temperature (Tg) the concentration and thickness are also parameters for time temperature transformation of glass
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