Thermal characterization of polyethylene glycol 600 in liquid and solid phase and across the phase transition

The polyethylene glycol (PEG) is characterized by experimental means in both solid and liquid phase. Main thermal properties inherent to the phase transition are also provided. More specifically, we focus on PEG 600, whose average molar mass is 600 g mol-1 and melting temperature transition is around 283???298 K. The phase change does not occur at a given temperature but rather over a range of temperature, highlighting the complexity of the material. Several methodologies have been developed and calibrated in order to obtain, in both phases, the density and the thermal conductivity. A temperature dependence fit is proposed for the density in liquid phase. The relative density variation from the liquid to solid phase is significant as it can reach about 35%, meaning a quite large volume shrinkage. Differential Scanning Calorimetry (DSC) has been used for measuring the heat capacity of solid and liquid phase and the effective heat capacity at the transition states. The latent heat of fusion and solidification converge to a value of around 128 kJ kg -1. Undercooling effects are mitigated by performing DSC with slow temperature variation rates. Lastly, we have also observed several exothermic peaks during the solidification process that are related to structural reorganizations of the material. Superscript/Subscript Available

Automated summary

This study characterizes polyethylene glycol (PEG) in both solid and liquid phases experimentally, providing thermal properties and density information. Differential Scanning Calorimetry (DSC) is used to measure heat capacity, latent heat, and observe structural reorganizations during solidification.