Study On Preparation And Characterization Of Self-modulating Temperature MicroPCMs For Building Materials

Phase change material (PCM) has been recently studied and applied for thermal energy storage. As PCM can absorb, store and release large amounts of latent heat over a defined temperature range during itself changes phase, it can be used in many fields. In this study, a kind of PCM is used in architecture field, it can make room comfortable and save energy. Microcapsulation of PCM (microPCMs) offers a measure to solve the super-cool problem and interfacial combine with circumstance materials. Also make the PCM have a long-life. MicroPCMs has been used in functional fiber, solar energy utilize, heat energy transfers, agriculture, and building materials. The objective of this study was to synthesize microcapsules containing a composite phase change materials for application in indoor wall controlling temperature, which would save energy and make comfort indoors. Three microcapsulation methods have been applied to preparation microPCMs.First, the complex coacervation of gelatin-acacia system in microcapsulation process was investigated in this paper. The influence of different technological conditions including pH . mass ratio of gelation, the time of gelation, as well as the hardening time on yields of microcapsulation the efficiency of encapsulation were studied respectively. The microencapsulation condition were also optimized. The means of SEM, DSC and TGA were applied in this study. It was found that the gelation speed of the gelation had a great effect on itsmicrocapsulation process, there was a best fitting gelation time for high yield of the microcapsules and good encapsulation efficiency. The gelation with complete cooling time of 40min had a high yields and encapsulation efficiency, and the process may be contrplled. The microPCMs was stable and its diameter was uniformity. The thermal profile of microcapsule was not affected by the ratio of gelation, but the thermal was not good enough.The microPCMs were prepared by using in-suit polymerization with prepolymer of melamine-formaldehyde (MF) and charactized the properties such as shape, diameter distribution, thermal prosperities, strength, shell thickness and penetration property. Double-shell heat energy storage microcapsule was prepared used the prosperities of microcapsules were investigated. A phase change material as core, which melt point was 24 C and phase transition heat was 225.5J/g .The microcapsules would been used in indoor wall to regulate the temperature and saving energy sources .The surface morphological structure was examined by means of scanning electron microscopy. The strength of shell was evaluated through observing the surface change after pressure by means of scanning electron microscopy. The melting point of the microcapsules was 24.7 C, nearly equaled to the pure phase change material. The DSC results make clearly that the polymer shell of microcapsules do not influence the proprieties of the phase change material. Also founded that the avoiding penetration property of double-shell microcapsules was better than that of single shell. It was necessary to investigate the shell for the thickness would affect the strength and penetration property of the microcapsules. In order to observe the double-shell shell we adapted the methods of in-bed the microcapsules in glutin, and got the SEM images of slices. The average thickness was 0.5-1 m. The thermal test showed the microPCMs had good resisted thermal properties and good absorb thermal property.This article also calculated the microPCms quantities and energy saving effect in theorydesigned the experimental apparatus to measure the energy saving effect, and analyzed the temperature equalization action of the microPCMs by comparing experimnt.Last, polyurea microcapsule containing octadecane as phase change material was successfully synthesized by interfacial polycondensation using TDI and DETA as shell monomers in an emulsion only by reaction of TDI and DETA, but also reaction of TDI and amines which are formed by hydrolysis of TDI at the interface. In this study,...