Preparation and performance optimization of CA-SA@SiO2 microencapsulated phase change materials for construction
In order to solve the problems that the phase change temperature of fatty acid is higher than the build-ing application requirements,and the existing fatty acid microencapsulated phase change materials have low en-capsulation rate and low latent heat,the binary phase change material capric acid-stearic acid was first prepared in this paper.The thermal properties results show that the phase change temperature and latent heat of phase change of capric acid-stearic acid are 24.28 ℃ and 178.21 J/g,which meet the building application requirements.On this basis,CA-SA@SiO2 MPCM(microencapsulated phase change materials)with different core wall mass ratio were prepared by sol-gel method of capric acid-stearic acid with silica as the outer wall material.Micro morphology,particle size,thermal properties,chemical stability and anti-seepage performance of the MPCM were characterized.The results show that core wall mass ratio directly affects the properties of the MPCM.The optimal core wall mass ratio is 50:50.The MPCM is spherical,smooth and dense,the particle size ranges from 2 to 500 μm,and the mainly concentrated below 50 μm.The wall material covers the core material only by physical action,and the thermal stability of phase change core material can be improved after microencapsula-tion.Moreover,the thermal decomposition temperature is significantly higher than the use environment of the wall material.The equilibrium leakage rate is only 4.53％,and the phase change temperature is 24.63 ℃,which is within the comfort range of human body.The latent heat of phase change and encapsulation rate is 138.16 J/g and 77％,respectively.It effectively solves the problems of high phase change temperature,low encapsulation rate and low latent heat of phase change,and provides a new material compatible with suitable temperature zone,high energy efficiency density and high stability for phase change energy storage building envelopes.
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