Hydrothermal Carbon-Doped Polyethylene Glycol as Phase-Change Materials with Good Thermal Conductivity and Shape-Stability

Polyethylene glycol (PEG) is limited by the low thermal-conductivity and poor shape-stability in practical applications. In our work, the thermal conductivity and shape-stable phase change Materials (SSPCMs) doped with hydrothermal carbon (HTC) was successfully prepared. HTC with - OH and - COOH groups on the surface was prepared by hydrothermal carbonization of glucose. The hydrogen bonds were formed between functional groups on HTC surface and PEG to obtain the network structure. When the HTC doping ratio is 6 wt%, good shape-stability can be achieved. Besides, the thermal conductivity of the HTC/PEG SSPCMs with the HTC doping ratio of 9 wt% is 0.6121 W/(m.K), which is 134.7% higher than PEG. The DSC results show that the melting enthalpy (Delta H-m) of PEG and HTC/PEG SSPCMs is almost the same, as is the crystallization enthalpy (Delta H-c). It indicates that doping HTC does not substantially affect the heat storage capacity of PEG.