Shape-stabilized phase change materials based on polyethylene glycol/porous carbon composite: The influence of the pore structure of the carbon materials

The phase change behaviors of polyethylene glycol (PEG)/porous carbon composites are extensively studied. Three types of shape-stabilized PCMs were prepared using expanded graphite (EG), active carbon (AC) and ordered mesoporous carbon (CMK-5) as supporting materials with various pore structures. They have distinct influences on the phase change behaviors of PEG/porous carbon composites. The highest stabilized PEG content is 70 wt% for AC and 90% for both EG and CMK-5. The phase change enthalpy and the PEG crystallinity increases in the order AC<CMK-5<EG at the same PEG content in the composite. The study suggests that pores with micrometer size exhibit the same level of shape stabilization ability as the pores with nanometer size, while being able to minimize the enthalpy loss due to the interactions between the pores and the PEG chains. This study will provide insights into the design of composite PCMs through tailoring the pore structures.