Design And Preparation Of A New Polymer-Based Composite Phase Change Material And Their Thermal Properties

In response to the growing energy shortage,the development and rational storage of existing energy sources is currently a key research priority for human development.As one of the most promising technologies for thermal energy storage,phase change materials have great potential for the practical application of thermal energy storage.However,the development and promotion of conventional organic phase change materials in the field of energy storage is severely restricted by the disadvantages of easy leakage and low thermal conductivity.New composite phase change materials have the advantages of small phase change volume change,high thermal stability and high latent heat and thermal conductivity,which can compensate and solve the inherent obstacles of conventional phase change materials.Therefore,in this paper,a series of high-performance polymer-based composite phase change materials were synthesized through the optimization of molecular structure assembly,where PEG with polyethylene glycol as the phase change functional unit with the help of design ability of polymer material chain structure.This research provides new ideas for the structural design of new composite phase change materials and expanding the application fields of phase change materials.The specific research content is as follows.（1）Boron nitride（BNNSs）/single-walled carbon nanotubes（SWNTs）synergistically enhanced composite phase change materials:In this study,polyethylene glycol（PEG 8000）was used as the phase change functional unit,one-dimensional SWNTs and two-dimensional BNNSs were used as reinforcing materials.The three-dimensional thermal network structure of the SWNTs and BNNSs maintain the solid-state structure and good thermal storage properties during the phase change process,enhancing the overall thermal performance of the PEG 8000.The thermal conductivity of the composite phase change material was improved to 0.95 W/（m·K）,which was increased of 178.8%compared to PEG,and its light-thermal conversion efficiency was increased to 97.15%.（2）The construction and thermal storage properties of titanium dioxide（TiO₂）/graphene oxide（GO）mutually synergistic reinforced composite phase change materials:In this study,TiO₂/GO reinforced PEG-based composite phase change materials were prepared by self-assembly using the excellent light-thermal conversion properties of TiO₂and the unique molecular structure of GO,to solved high temperature leakage of phase change materials and improved the comprehensive thermal properties.The three-dimensional continuous thermal conductivity network constructed by TiO₂and GO provides a good thermal conductivity pathway for the composite phase change material,increasing its thermal conductivity to 0.7 W/（m·K）and significantly increasing its thermal response rate.The composite phase change material demonstrates an absorbance of94.43%and a light-thermal conversion efficiency of 93.5%.（3）Construction and comprehensive thermal performance of silver nanoparticles（AgNPs）composite shaped phase change materials:In this study,AgNPs-reinforced composite shaped phase change materials with high thermal conductivity,high thermal storage density and antibacterial properties were prepared using PEG 8000 as the phase change functional chain segment and in situ reduction and polymerization reactions.Based on the spatial barrier effect of the polymer’s macromolecular structure,the problem of AgNPs’tendency to agglomerate is solved and the AgNPs are uniformly dispersed.The complexation of AgNPs with oxygen-containing functional groups in the molecular chain gives the composite phase change material excellent thermal conductivity and antibacterial properties The results show,the silver ions were transformed into silver nanoparticles during the reduction process and uniformly dispersed in the composite phase change material.The composite shaped phase change material maintained excellent thermal storage properties.And it achieving a thermal conductivity of 0.87 W/（m·K）,which was163.6%higher than that of the pure PEG 8000.