Preparation Characterization And Performance Of Paraffin Microcapsule

The residential housing area is increasing with the advances of living standard of the people, Building energy consμmption amounts to more than one fourths of the terminal energy consμmption of our country. Building energy conservation is getting more and more important. The advantage of phase change materials (PCM) is that it is capable of absorbing or releasing large amounts of energy during phases transformation, and the phases transformation process is isothermal. The fluctua-tion of indoor temperature will be narrowed and the thermal comfort of living will be improved by incorporating PCM into buildings. when the phase transform of PCM from solid state to liquid state take place, It is necessary to enclose PCM because of the possible seepage of PCM.The copolymer of methyl methacrylate (MMA) and methyl acrylic acid (MAA) as shell material, divinylbenzene (DVB) as cross-linking agent, microcapsules with core paraffin wax as PCM (MicroPCM)was obtained by dispersion polymerizati-on. The morphology was observed with scanning electronic microscope (SEM) and optical microscope. The particle size distribution of the microcapsule was determin-ed by laser particle size analyzer. The thermal properties and thermal stability of the MicroPCMs were investigated by differential scanning calorimetry and thermal gravimetric analysis, respectively. The chemical composition of MicroPCMs was characterized by infra-red spectroscopy.Scale-up was conducted successfully after lab scale. the durability of the microcapsule was examined by freezing thawing cycle. The composite PCM material was obtained by incorporating the MicroPCMs into concrete, and the conductive performance of specimen incorporating Micro-PCM into concrete was tested.The following are our conclusions from the research:It is found that prepolymerization of monomers, the mass ratio of MMA to MAA or AA, the mass ratio of core to shell, the amount of the dispersant and cross-linking agent have influence on the fabrication of the MicroPCMs.All MicroPCMs have spherical profiles, but there are many dimples in the su-rface. The particle size ranges from4to5micrometers. The average circularity of the MicroPCMs is0.86. The DSC shows the phase change temperature of Micro-PCMs is29.7℃, and accompanying the highest melting enthalpy106.7J/g. the core content of the MicroPCM is as high as81.8%. Thermal gravimetric analysis shows that the MicroPCMs exhibit good thermal stability.The batch of MicroPCMs is more than one kilogram in scale-up.No thermal performance deterioration of the MicroPCM is observed after1500freezing melting cycles, the life of MicroPCMs exceeds15years when employed in building.The experiments of storage/release heat energy performance demonstrated that6℃of the maximμm temperature difference between the specimen and control specimen was logged, a lag of3hours was detected when the two specimens have the same temperatures during specimens storaging heat energy. when the temperatures of the specimen is the same,2hours was prolonged as a result of heat energy releasing from the specimen.when the mass of MicroPCMs is increased in the specimen, the compressive strength of the specimen is decreased.The copolymer of methyl methacrylate (MMA) and acrylic acid (AA) as shell material, Excess acrylic acid is responsible for the adhension of MicroPCMs.