Preparation And Characterization Of Clay-graphene Aerogel Composite Phase Change Material

Phase change material(PCM),which is based on latent heat storage technology,presents a good prospective in the field of thermal energy storage,owing to their high energy storage density and the phase change process occurs at a constant temperature.However,single PCM has some defects,such as large supercooling degree,low thermal conductivity and easy leakage and so on.Importantly,some composite phase change material(CPCM)have the same problem as well.Therefore,it is of great significance to develop new CPCM to improve the situation.Based on the raw materials of graphene oxide(GO),clay,stearic acid(SA)and hexadecanol(HD),a series of carrier and its CPCM were prepared using hydrothermal method.The aim of this study is to obtain CPCM with high performance and thermal conductivity,and explore the effect of clay content and clay species on the structure and properties of the carrier and CPCM.Using SA as the PCM,GO and attapulgite(ATP)as raw materials,a series of attapulgite-graphene aerogel composite carrier and stearic acid/attapulgite-graphene aerogel CPCM were prepared by hydrothermal method to study the effect of attapulgite content on the structure and properties of attapulgite-graphene aerogel carrier and stearic acid/attapulgite-graphene aerogel CPCM.The result shows that attapulgite-graphene aerogel carrier has a three-dimensional(3D)porous structure.Besides,with the increase of ATP content,the surface of the attapulgite-graphene aerogel carrier becomes rougher,and the cluster-like structure of the stearic acid/attapulgite-graphene aerogel CPCM becomes more obvious,the melting and solidification latent heat values of the stearic acid/attapulgite-graphene aerogel CPCM decrease firstly and then increase.The 100 times colding-heating cycling experiments show that the change of ATP content has no influence on the structure stability and the thermal storage stability of stearic acid/attapulgite-graphene aerogel CPCM.But when the quality percentage of ATP are 33%and 50%respectively,the weightlessness rate of stearic acid/attapulgite-graphene aerogel CPCM are reduced by 0.8%and 0.2%after 100 times colding-heating cycling,respectively,compared with before 100 times colding-heating cycling.As the content of attapulgite increase,stearic acid/attapulgite-graphene aerogel CPCM exhibits better thermal stability.Firstly,attapulgite was organic modified by cetyl trimethyl ammonium bromide(CTAB),sodium dodecyl sulfate(SDS)and triamopropyl trimethoxysilane(APTS).Then based on the raw materials of HD,GO and organic modified attapulgite,a series of modifier-attapulgite-graphene aerogel carrier and hexadecanol/modifier-attapulgite-graphene aerogel CPCM were prepared by hydrothermal method.That is aim to investigate the effect of modifier species and organic modified attapulgite(OATP)content on the structure and performance of modifier-attapulgite-graphene aerogel carrier and hexadecanol/modifier-attapulgite-graphene aerogel CPCM.The research results show that the surface of hexadecanol/sodium dodecyl sulfate-attapulgite-graphene aerogel CPCM is all covered by white substance.Besides,the thermal energy storage stability of hexadecanol/triamopropyl trimethoxy silane-attapulgite-graphene aerogel CPCM is poor,but the hexadecanol/cetyl trimethyl ammonium bromide-attapulgite-graphene aerogel CPCM exhibits good thermal stability.DSC analysis shows that with the increase of cetyl trimethyl ammonium bromide-attapulgite content,the melting latent heat values of hexadecanol/cetyl trimethyl ammonium bromide-attapulgite-graphene aerogel CPCM present a gradually decreasing trend.100 times colding-heating cycling experiments show that hexadecanol/cetyl trimethyl ammonium bromide-attapulgite-graphene aerogel CPCM has good structure stability,thermal stability and heat storage stability.A series of organic montmorillonite(OMMT)-graphene aerogel carrier and stearic acid/organic montmorillonite-graphene aerogel CPCM were prepared by hydrothermal method.The results show that the organic montmorillonite-graphene aerogel carrier has 3D porous structure.Importanly,with the increase of OMMT content,the surface of organic montmorillonite-graphene aerogel carrier becomes rougher,and the 3D porous structure of stearic acid/organic montmorillonite-graphene aerogel CPCM becomes more obvious.The melting latent heat values of stearic acid/organic montmorillonite-graphene aerogel CPCM increase firstly and then decrease.After 100 times colding-heating cycling,the change of the content of OMMT has no influence on the structure stability and thermal storage stability of the stearic acid/organic montmorillonite-graphene aerogel CPCM.However,when the OMMT content increase to 50wt%,with the increase of the content of OMMT,the thermal stability of stearic acid/organic montmorillonite-graphene aerogel CPCM becomes worse.