On phase transitions in the water-ethylene glycol system at subzero temperatures under non-isothermal conditions

The dynamic phase diagrams of the water-ethylene glycol (EG) system have been plotted at the warming rate of 0.4 degreesC min(-1) after cooling of samples down to -196 degreesC by quenching in liquid nitrogen or slow cooling at the rate of approximately 0.15 degreesC. min(-1). The melting of two stable eutectics at the temperatures of -42.7 degreesC and -48.7 degreesC and the metastable eutectic at -63 degreesC was observed. Hydrates 1:1 crystallized separately from ice during warming both after quenching and after slow cooling. Glass devitrification and EG:3H(2)O hydrate melting took place during warming of the samples after quenching but these thermal features were absent after slow cooling in the EG concentration range of 42.0 - 63.5 weight percent. The notions about two-stage mechanism of ice nucleation in EG aqueous solutions might be critically revised.