Preparation Of Thermally Conductive Reinforced Polyethylene Glycol-based Phase Change Composites

With the development of economy and social progress,people’s living standard is increasing,but at the same time,the world is facing serious challenges such as population growth,energy shortage and global warming.The key to solve the energy crisis is the development and utilization of renewable energy,and the absorption and release of energy when phase change materials undergo state change can precisely solve the problem of uneven spatial and temporal distribution of renewable energy.The paper uses polyethylene glycol(PEG)as the phase change material,and prepares thermally conductive phase change composites by adding thermal conductivity enhancers such as modified boron nitride KBN and carboxylated multiwalled carbon nanotubes(MWCNTs-COOH),as well as using polyaniline(PANI)as the setting material,to solve the problems of low thermal conductivity and easy leakage of PEG as organic phase change material.The research mainly includes the following aspects:Three series of thermally conductive phase change composites with different percentages of thermally conductive fillers were prepared using PEG as the phase change agent and commercially available hexagonal boron nitride(h-BN)products,ball-milled boron nitride(MBN)and silane coupling agent KH550 chemically modified boron nitride(KBN)as the thermal conductivity additives.The structure and morphology of the resulting three series of thermally conductive phase change composites were characterized by FTIR,XRD,SEM and TG,and the thermal conductivity,phase change latent heat properties and shape stability of the composites were discussed.The results show that the addition of inorganic thermally conductive additives can improve the thermal conductivity of PEG,but the phase change composites still have the problems of poor shape stability and easy leakage at high temperature.A series of KBN-MWCNTs/PEG phase change composites were prepared by amidation reaction of carboxylated multi-walled carbon nanotubes and KBN,using KBN-MWCNTs as thermal conductivity additives and PEG as phase change agent.The results show that the mesh network structure formed between the carboxylated carbon nanotubes can maintain the shape stability of the composites and inhibit the leakage of PEG during temperature rise to a certain extent.effect.In comparison,the thermal conductivity enhancement ability of KBN is higher than that of MWCNTsCOOH,and the thermal conductivity of the composites containing KBN-MWCNTs with thermal conductivity additive increases with the increasing percentage of KBN,but the PEG leakage and shape stability become worse.The best thermal conductivity enhancement was achieved when the content of KBN and MWCNTs-COOH was 1:1,which was due to the synergistic effect of the 2 thermally conductive fillers.To further solve the problems of shape stability and leakage rate of the above phase change composites,KBN-MWCNTs-PANI/PEG composites were prepared by using KBN and MWCNTs-COOH mass ratio of 1:1 as thermal conductivity additives,polyethylene glycol as phase change agent and polyaniline as support material,and changing the proportion of polyaniline.The results of thermal conductivity,latent heat of phase change and shape stability tests were found that the addition of a certain amount of polyaniline does not affect the thermal conductivity of the composites,but the shape stability is significantly improved,and the addition of 3 wt% of PANI can basically solve the problem of leakage of PEG as phase change agent in the molten state,and the resulting phase change composites After 100 cycles of high and low temperature,the energy storage capacity of the samples only showed slight fluctuations and had excellent thermal stability.