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Gelation on Heating of Supercooled Gelatin Solutions
Author(s) -
Guigo Nathanaël,
Sbirrazzuoli Nicolas,
Vyazovkin Sergey
Publication year - 2012
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.201100748
Subject(s) - supercooling , differential scanning calorimetry , gelatin , exothermic reaction , materials science , thermodynamics , aqueous solution , activation energy , calorimetry , kinetic energy , heat flow , analytical chemistry (journal) , chemistry , thermal , chromatography , organic chemistry , physics , quantum mechanics
Diluted (1.0–1.5 wt%) aqueous gelatin solutions have been cooled to –10 °C at a cooling rate 20 °C min −1 without freezing and detectable gelation. When heated at a constant heating rate (0.5 –2 °C min −1 ), the obtained supercooled solutions demonstrate an atypical process of gelation that has been characterized by regular and stochastically modulated differential scanning calorimetry (DSC) as well as by isoconversional kinetic analysis. The process is detectable as an exothermic peak in the total heat flow of regular DSC and in the nonreversing heat flow of stochastically modulated DSC. Isoconversional kinetic analysis applied to DSC data reveals that the effective activation energy of the process increases from approximately 75 to 200 kJ mol −1 as a supercooled solution transforms to gel on continuous h eating.