Preparation And Properties Of Polyethylene Glycol-based Thermally Conductive Double Skeleton Shape-stabilized Phase Change Materials

Phase change materials（PCMs）have been widely used in energy-saving buildings,hot water systems,solar power generation,battery thermal management and other fields as a thermostatic latent heat energy storage material.As an organic PCMs with suitable phase transition temperature and latent heat,polyethylene glycol（PEG）has been further limited in various fields due to its low thermal conductivity,easy leakage during phase transition and excessive rigidity.To address the problems of PEGs in applications,this paper first shaped and encapsulated them in porous materials,which can enhance their impermeability and thermal conductivity,and then compounded them with a polymer matrix,which can improve their rigidity and further reduce their leakage rate.The main contents of this paper are as follows:（1）A dense amine foam（MF）/graphene aerogel（GA）double skeleton with excellent mechanical properties was self-assembled in situ,and then MF/GA@PEG shape-stabilized phase change materials（SSPCMs）were prepared by vacuum-assisted impregnation,and the effects of different graphene oxide（GO）concentrations on the morphology and properties of MF/GA double skeleton and MF/GA@PEG SSPCMs were investigated.The results showed that the compressive strength of MF/GA₄ could reach 101 k Pa at 80%compression level,which is 405%higher than that of pure MF.Compared with pure PEG,the thermal conductivity of MF/GA₄@PEG SSPCMs was increased by 161%and the photothermal conversion efficiency was increased by 186%.Due to the excellent mechanical properties of MF/GA,the MF/GA@PEG SSPCMs have good shape stability and shape recovery ability under heat.（2）The carbonized double skeleton（cMF/GA）was prepared by high-temperature carbonization of MF/GA,and then the cMF/GA@PEG thermally conductive shape-stabilized phase change materials（TSPCMs）were prepared by vacuum impregnation.The effects of different carbonization temperatures on the morphology and properties of the carbonized double skeleton of cMF/GA and cMF/GA@PEG TSPCMs were investigated.The results show that high temperature treatment can substantially eliminate the structural defects and oxygen-containing groups of cMF/GA and enhance its graphitization.Under 50%compression,cMF/GA₈₀₀ exhibited a relatively high compressive strength of 63.4 KPa.The thermal conductivity of cMF/GA₁₆₀₀@PEG is 0.91 W·m^-1·K^-1,which is 387%higher compared to PEG.High temperature treatment effectively enhances the solar/electricity-thermal energy conversion capability of cMF/GA@PEG.PEG@CMGA₁₆₀₀ has a solar-to-thermal energy conversion efficiency of 91.7%and an electric-to-thermal energy conversion efficiency of87.3%.（3）The（cMF/GA@PEG）/GNPs/PU thermally conductive phase change films were prepared by blending granulated cMF/GA@PEG with polyurethane（PU）by solution blending method and adding thermally conductive filler graphene nanosheets（GNPs）,and the effect of the percentage of cMF/GA@PEG and GNPs on their phase change films was investigated.The results show that the content of GNPs is proportional to the tensile strength and thermal conductivity of（cMF/GA@PEG）/GNPs/PU thermally conductive phase change films.When the percentage of GNPs reaches 10 phr,the thermal conductivity of（cMF/GA@PEG）/GNPs/PU thermally conductive phase change films is 1.77 W·m^-1·K^-1,the tensile strength can reach 8.9 MPa,the melt enthalpy is 98.2 J/g,and the energy storage efficiency can reach 95.6%.The（cMF/GA@PEG）/GNPs/PU thermally conductive phase change films exhibit excellent impermeability with a leakage rate of less than 0.8%.