Studies On The Preparation Of Phase Change Composite Materials And Its Properties

With the rapid development of the global economy,the global energy shortage problem has become increasingly prominent,and the energy situation has become increasingly severe.The use of latent heat of phase change in phase change materials to achieve energy storage and utilization contributes to energy efficiency and has become an important research content in the fields of energy science and materials science in recent years.The use of various composite means or techniques to prepare new phase change composite materials is an effective way to solve the problem of easy leakage of phase change materials,improve phase change energy storage and expand its application range.Microcapsule method and sol-gel method are two important methods of preparing composite materials.This topic combines the research of predecessors to continue to study the preparation method of Phase change composite materials in order to make some innovations.?1?The effect of complex coacervation pH,emulsification speed,core-shell ratio,crosslinking agent dosage and re-agglomeration reaction time on product coverage and coating efficiency was investigated by single factor experiment.The significant effect of various factors on the coverage of microcapsules was investigated by orthogonal experiment.The order of influence of each factor is:dosage of crosslinking agent>pH>speed>core-shell ratio.The optimal combination of preparing microcapsules is pH=4.0,rotation speed 1200r/min,core-shell ratio 1:1,cross-linking agent dosage 6mL,and re-agglomeration reaction time 30min.There is no chemical reaction between paraffin and peach/chitosan,and microcapsules are the physical combination between the two.The microcapsules prepared under the optimal process conditions are spherical and have a particle size of between 20 and 30?m.The phase transition point and phase change enthalpy of microcapsules were 55.7 ? and 173.4 J/g,respectively.The coverage and coating efficiency reached 85.9%and 85.7%,respectively.The microcapsules had good heat storage performance and thermal stability.?2?Using the sol-gel method,the preferential process conditions for the preparation of microcapsules were determined by single factor test,which were emulsifier dosage 3.0g,pH=2.0,core-shell ratio 1.5:1,rotation speed 1000pm,TNBT/none.The ratio of water to ethanol is 1:2.FT-IR and XRD analysis indicated that the microcapsules were the product of physical binding of paraffin to TiO₂.DSC analysis showed that the melting point of the microcapsules was 61.8 ? and the melting enthalpy was 90.37 J/g.The coverage of microcapsules reached 69.36%,and the coating efficiency reached 71.69%.TGA analysis showed that the microcapsules have good thermal stability.SEM can be seen that the microcapsules are ellipsoidal or spherical,with a rough surface and a particle size of between 80 and 90?m.?3?SiO₂ coated CaCl₂·2H₂O phase change nanocomposites were prepared by sol-gel method.According to XRD,EDS,SEM and TEM results,the obtained sample is proved to be a phase change nanocomposites.The phase transition point of the phase change nano composites is 75.8 ?,and the latent heat of phase change reaches 52.89 J/g,which has good heat storage?exothermic?performance and thermal stability.Thermal cycling test results show good thermal cycling properties of phase change nanocomposites.