Kinetic analyses of crystallization and devitrification: Comparison of activation energies in aqueous solutions of glycerol and dimethyl sulphoxide

Abstract

Crystal growth rates in glass forming 50 w/w% glycerol and 45 w/w% dimethyl sulphoxide (DMSO) aqueous solutions were found to follow Arrhenius behaviour over a broad range of temperatures. Activation energies for ice crystal growth in these solutions were determined from Arrhenius plots of the isothermal crystal growth rate data. The values for the activation energy of crystal growth were found to be the same for each solution, suggesting that the activation energy barrier to transport of water molecules across the ice/solution interface is the same in both solutions. The activation energies were compared to activation energy of crystallization values given by several non-isothermal DSC kinetic analysis techniques. It was found for 45 w/w% DMSO that the activation energy for growth was equal to the activation energy for the whole crystallization process. This was not the case for 50 w/w% glycerol solutions, an observation which highlights the inapplicability of the standard analysis techniques under conditions of continued nucleation.