Preparation And Properties Of Shape-stabilized Peg-based Composite Phase Change Materials

In the field of thermal energy storage,organic solid-liquid phase change materials?PCMs?have attracted more and more attention due to their suitable phase transition temperature and high energy storage density.However,it's very important to improve the thermal conductivity,solve liquid leakage during phase transition and endow energy conversion function for composite PCMs.In order to solve these problems,the composite PCMs were prepared by in-situ doping with inorganic supporting materials?SiO₂,Ti₃C₂T_x,GO?based on organic-inorganic composites.In these phase change systems,polyethylene glycol?PEG?was used as organic phase change component,and these composites exhibited high enthalpy,enhanced thermal conductivity and shape-stabilized property.The Fe₃O₄/PEG/SiO₂ shape-stabilized PCMs were prepared by sol-gel method while in-situ doping nano Fe₃O₄.The Fe₃O₄ nanoparticles were uniformly distributed in the phase change material system.The mass fraction of PEG in the PCM system is up to 80 wt%.The melting enthalpy of the composites is about 110J/g,and the composites possessed good shape-stabilized property during phase transition.In addition,it is found that the composites have higher thermal conductivity and excellent magnetothermal conversion and thermal energy storage ability due to the good thermal conductivity and magneto-thermal conversion effect of superparamagnetic nano Fe₃O₄.PEG/Ti₃C₂T_x shape-stabilized composite PCMs were prepared by using organic-inorganic composite method through the ultrasonic-assisted.In this PCM system,the inorganic two-dimensional material Ti₃C₂T_x was used as the supporting material.PEG was uniformly filled among the layer space of Ti₃C₂T_x nanosheets,and mass fraction of PEG in the PCM system is up to 85 wt%.The melting enthalpies of the composites were more than 150 J/g.Due to the supporting action,thermal conductivity enhancement and photothermal conversion function of Ti₃C₂T_x nanomaterials,the composites have higher thermal conductivity and shape-stabilied property,as well as excellent photon capture and photothermal conversion ability.The composite exhibited the outstanding efficiency of photothermal conversion and thermal energy storage?up to 95%?.The PEG/GO composite PCMs were prepared by in-situ combination of PEG and GO while preparing GO gel by Ca²⁺cross-linked method.PEG was filled into the three-dimensional pores of Ca²⁺cross-linked GO,and the mass fraction of PEG is up to 99 wt%.Prepared PEG/GO composites had excellent crystallization properties.The melting enthalpy of the PEG?99%?/GO composite is close to that of pure PEG under the condition that ensuring shape stability,which is about 218 J/g.In addition,the composite PCMs also have higher thermal conductivity.