Acta Phys. -Chim. Sin. ›› 2004, Vol. 20 ›› Issue (02): 123-128.doi: 10.3866/PKU.WHXB20040203

• ARTICLE • Previous Articles     Next Articles

Freezing Properties of EG and Glycerol Aqueous Solutions Studied by DSC

Gao Cai;Zhou Guo-Yan;Xu Yi;Hua Ze-Zhao   

  1. Institute of Cryomedicine and Food Freezing, Shanghai University for Science and Technology, Shanghai 200093
  • Received:2003-06-18 Revised:2003-09-15 Published:2004-02-15
  • Contact: Hua Ze-Zhao

Abstract: In order to examine possible relationship between freezing properties and the number of hydroxyl group in solute molecules, a differential scanning calorimeter(Pyris-Diamond DSC)was employed to study the thermal behaviors(supercooling degree of heterogeneous nucleating temperature, hydration properties, glass transition and devitrification) of ethylene glycol and glycerol aqueous solutions. Experiments were conducted on 12 groups (24 in total) aqueous solutions with different concentrations. At the same concentrations (mass fraction, w), the supercooling behaviors of these two polyols aqueous solutions followed similar rules of change. At concentration of 0~5%(w), supercooling degrees decreased first and then increased with increasing concentration. But at concentration of 5%~25%(w), experimental results showed that supercooling behaviors became disorder. At concentrations >25%, supercooling degrees enhanced monotonically with the increasing solutes contents. Hydration experiments showed that the unfreezable water content in aqueous solutions of these two polyols solutions had no significant difference(ratios of unfreezable water contents are 1.04~1.15 ) with the same mass percentage. However, the temperature of glass transition and devitrification exhibited distinct difference. It can be concluded that “hydroxyl-group concentration” of this two polyols aqueous solutions could predict supercooling behaviors and hydration capabilities. Neither mass percentage nor molality of these two polyols solutions could characterize glass transition and devitrification temperature.

Key words: Ethylene glycol(EG), Glycerol, Differential scanning calorimetry(DSC),  Supercooling degree, Hydration, Glass transition and devitrification