Preparation And Thermal Properties Of New Composite Phase Change Materials

In this study, we choose N-octadecane as phase change materials (PCMs), which possess high phase change enthalpy (229.5 J/g). Therefore, it has good ability of thermal storage and could be used as new kinds of phase change materials (PCMs), which may have good application in thermal storage in the future.In order to imprvoe the thermal flow behavior of the above PCMs, we have prepared N-octadecane/Attapulgite composites through infiltration method, to increase its stability. While, we also studied the effects of attapulgite material on the thermal performance of phase change materials, and results are particularly summarized as follows:For N-octadecane composite PCMs, they possess excellent thermal energy storage property and environmental temperature stability. The enhanced performance indicates that attapulgite material could improve the thermal conductivity of composite effectively. Furthermore, the samples prepared could maintain the thermal stability and thermal energy storage property of the PCMs.On the consideration of thermal flow behavior of the phase change material, a new double encapsulated microcapsule was prepared in this paper. When the content of N-octadecane in the microcapsules is 61.7%(sample 4), microcapsule has satisfactory high enthalpy (140 J/g) and good thermal stability of DSC cycle. While, it also has good morphology. And there is a substantial increase in thermal diffusion coefficient of the phase change microcapsule material.In this paper, the double encapsulated capsule wall which formed by 2,4- toluene diisocyanate (TDI), DETA and polyethylene glycol 1000 (PEG1000) has little influence on heat storage capacity of microencapsule. But it can effectively improve the stability and the coating efficiency of the material. When the content of N-octadecane in the microcapsules is 61.7%(sample 4), Microcapsule has satisfactory high enthalpy (140 J/g) and also has good thermal stability of DSC cycle, at the same time, it has good morphology. It has applicable prospect.Based on the TG curves analysis of double coated microcapsule, we found that applying a double wall material can increase the decomposition temperature of the sample. And with polyethylene glycol 1000 (PEG1000) materials increased, the decomposition temperature is gradually increasing, can be described to that-polyethylene glycol 1000 (PEG1000) has good heat resistance itself. In addition, the thermal diffusivity of microcapsules also showed increasing trend. This may be due to polyethylene glycol 1000 (PEG1000) with good thermal conductivity (polyethylene glycol can be used as a heat conducting oil below 180℃).