Influences of dynamic impregnating on morphologies and thermal properties of polyethylene glycol-based composite as shape-stabilized PCMs

Abstract

Polyethylene glycol (PEG)/active carbon granule (ACG) and/or expanded graphite (EG) composite as a shape-stabilized phase change materials (PCMs) were firstly prepared by a melt blending via novel dynamic impregnating method which can be applied to air conditioning system in the middle of the heat medium, radiant cooling systems, etc. Various characterization techniques including X-ray diffraction, scanning electron microscope, differential scanning calorimeter, thermal gravimetry (TG) and thermal conductivity were performed to investigate the crystalline and thermal properties of the PCMs. The results indicated that phase change temperatures and enthalpies were decreased as the mass percentage of PEG was decreased. The crystallinity of PEG in the PCMs decreased with the increase in the ACG and/or EG content. And, the TG and thermal conductivity results showed that the thermal conductivity of PEG-based PCMs could be improved when ACG and/or EG was introduced. Interestingly, compared to PEG/ACG PCMs, the PEG/EG PCMs had higher crystallinity, better thermal conductivity. A reasonable physical model was also established to analyze the packing theory for PEG/ACG and/or PCM/EG PCMs. Notably, this study will provide an novel and efficient fabrication method of shape-stabilized polymer-based PCMs for heat storage application.