Fabrication And Application Research Of Microcapsules Of Phase Change Materials

In this research, Spherical Phase Change Microcapsule materials with suitable phase change temperatures were prepared by in-situ polymerization method. And then SiO2nanoparticles were added to increasing the roughness of microcapsules. The hydrophobic surface was fabricated on SiO2-MCPCM followed by treatment with polydimethylsiloxane (PDMS) and KH-570. The as-prepared SiO2-MCPCM not only have phase change properties with nature, but aslo have excellent superhydrophobi-c performance. The changes in the morphology, thermal performance and surface chemical composition of the microcapsules before and after a series of treatment were investigated by Scanning electron microscope (SEM), Fourier transform infrared analysis (FT-IR) and Differential scanning calorimeter (DSC). Meanwhile, the performance of superhydrophobic surface was investigated.Microencapsulated phase change materials (MCPCM) were prepared by in-situ polymerization method, with butyl stearate as the core and melamine resin as the shell. The effect of butyl stearate emulsion preparation process on phase change properties of Microcapsules were studied. The experimental result shows that the optimum emulsifying conditions for preparing butyl stearate emulsion was obtained as follow:the HLB value of composite emulsifier (Span-80and Tween-80) is about11, emulsifying time is20min, emulsifying temperature at70℃, dosage of emulsifier is10%, stirring speed is2000～7000r/min. FT-IR spectra analysis showed that there is no free formaldehyde existed in the pre-polymer and microcapsules. That means butyl stearate was coated with melamine resin form as microcapsules core-shell structure. The phase transition temperature and phase change latent heat of microcapsules were20.4℃and87.81J/g.In order to obtained the organic-inorganic doped material (SiO2-MCPCM) with uniformity of size and morphology, MCPCM were modified with silica sol which was prepared in laboratory. SEM and EDS analysis shows that, SiO2nanoparticles were well distributed on the surface of MCPCM and no aggregated when the addition of silica sol was10wt%. DSC patterns was indicates that the latent heat of modified MCPCM were reduced to58.34J/g. Meanwhile, we aslo discovered a certain amount of silica sol can significant improve the seal properties of microcapsules, resulted in superior compatibility and compactness of composite. The hydrophobic SiO2-MCPCM were fabricated on SiO2-MCPCM followed by treatment with polydimethylsiloxane (PDMS) and KH-570. The surface wettability of the KH-570-treated and PDMS-treated changes from hydrophilic to hydrophobic with an apparent water CA of145.7°and158.5°. The results showed that the hydrophobic effect of PDMS-treated is better than KH-570treated. With the amount of silica sol added, the roughness of SiO2-MCPCM were increased, which led to the better the hydrophobic. Additional, the phase change temperature and latent heat of MCPCM after treated have no change than before, which indicated hydrophobic modification only reduced the surface energy of materials, but not change the chemical structure and original performance of materials.