High-resolution calorimetry on thermal behavior of glycerol (I): Glass transition, crystallization and melting, and discovery of a solid–solid transition

We determined temperature scanning thermograms of glycerol, with the same scanning rate for cooling and warming cycles by using an ultra-sensitive calorimeter at the scanning rate β from 0.05 to 4 mK/s. Four peaks were observed during the warming process starting from below the glass transition temperature T g ′ ; glass transition, crystallization, solid–solid phase transition, and melting. T g ′ and the crystallization temperature Tp depends on β with Arrhenius relation. A broad melting behavior was obtained in a temperature range larger than 10 K, which suggests that structural distribution exists in the crystal. The solid–solid phase transition at 229.1 K was discovered.