Preparation Of Phase Change Materials Microcapsule For Building Energy Saving

In recent years, much more attention is focused on building energy efficiency .Applying in the field of building energy efficiency, phase change materials (PCMs) can lighten the degree of mismatch between time and speed. Along with the development of polymer technology, PCMs will occur in the form of microcapsule, because of the appropriate shell of microcapsule are obtained, and the produce technology simplify. The objective of this study was to synthesize microcapsules containing phase change materials for application in door wall controlling temperature, which would save energy and make indoors comfortable.A kind of microencapsulated phase change materials (MicroPCMs) was prepared by using melamine-urea-formaldehyde resin as the shell material and a phase change material as the core, of which the melt point and phase change enthalpy are 24℃ and 225.5J/g respectively through in-situ polymerization. The surface morphology, diameter, melting point of the microcapsules were investigated by using FTIR, SEM, DSC. As a result, the encapsulation efficiency increases as the increase of ratio of coating-core, but the encapsulation efficiency fluctuate as the increase of emulsifying speed, when the emulsifying speed reaches the 2500rpm, the encapsulation efficiency reaches the maximum.The core release dynamics model was established, and the penetrability of the microcapsule was characterized by mean of 752 spectrophotometer. As a result, the penetrability of the microcapsule influenced with emulsifying speed , the ratio of coating-core , the amount of dispersant, emulsifying time , and the penetrability increases as the emulsifying speed, the ratio of coating-core.The strength of microcapsule was investigated by altering the weight rate of urea and melamine. The thermal damage mechanism is that the PCMs leak from the microcapsule whenthey are heated, and the breakage of the shell is due to the thermal expansion of the core materials at high temperature. So the damage temperature of the microcapsule shell was determined by TGA. The strength of shell is also evaluated through observing the surface change under pressure by means of SEM. As a result, the encapsulation efficiency increases as the increase of ratio of coating-core, but the encapsulation efficiency fluctuate as the increase of emulsifying speed, when the emulsifying speed reaches the 2500rpm, the encapsulation efficiency reaches the maximum. The thermogravimetic temperature of microcapsule can be further enhanced up to approximately 30℃ while reaction system contained 20wt% urea. The microcapsules do not rupture under a pressure of 6.0MPa.The composite which contain phase change materials were prepared and the effect of control temperature was investigated, found that he melt point of phase change material in shell is not change, the microcapsule could reversibility and the effect of energy storage is obvious. And theenergy efficiency is 68%.