Study On Phase Change Materials Microcapsule For Building Energy Saving

The Microcapsulation of phase change materials (microPCMs) were prepared by using in-suit polymerization with prepolymer of melamine-formaldehyde (MF) and urea-improved melamine-formaldehyde. The properties such as shape, diameter distribution, thermal prosperities, strength, shell thickness and penetration property were charactized During the polymerization course, the above properties of microPCMs were studied by changing emulsifying speed and mole ratio of reactive monomers.When the emulsifying speed reached 2500rpm, microPCMs have homogeneous diameter distribution, smooth and compact shell. Also the enthalpy of microPCMs was the highest at this emulsifying speed. The enthalpy of microPCMs with different emulsifying speed was not regular with increasing thermal cycles.For microPCMs with urea-improved melamine-formaldehyde, the mole ratio of three reactive monomers had a little influence on thermal prosperity. And after increasing thermal cycles from -10℃to 50℃, the enthalpy of microPCMs were obvious decreasing, and the surface of shell was very rough. All these results showed, microPCMs with urea-improved melamine-formaldehyde had a bad compactibility .The content of formaldehyde in microPCMs with melamine-formaldehyde and urea-improved melamine-formaldehyde were detected by acetylacetone method. As a result, the content of formaldehyde in microPCMs with melamine-formaldehyde was much more than that with urea-improved melamine-formaldehyde. However, for microPCMs with urea-improved melamine-formaldehyde , the content of formaldehyde was decrease as the mole ratio of urea increasing, but the content of formaldehyde in these two microPCMs didn't reach national standard.