Gelation on heating of supercooled gelatin solutions.
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 heating.
Laboratory of Condensed Matter Physics, (L.P.M.C.-UMR 7336), University of Nice-Sophia Antipolis, 06108 Nice Cedex 2, France.
Nathanaël
N
Guigo
Nicolas
N
Sbirrazzuoli
Sergey
S
Vyazovkin
D002152:Calorimetry, Differential Scanning; D003080:Cold Temperature; D005780:Gelatin / Q000737:chemistry*; D007700:Kinetics; D012996:Solutions / Q000737:chemistry*; D013816:Thermodynamics
D012996:Solutions; D005780:Gelatin