Synthesis, Characterization, And Performance Of Microencapsulated Phase Change Materials With Photoluminescent Characteristics

Microencapsulated phase change material is a material to avoid leakage and increase the heat transfer efficiency by the new substance packaging technology, which has a typical core-shell structure. It can change the phase at a certain temperature to storage and release energy, and good transfer with the external environment. In this paper the syntheses of microencapsulated phase change materials use n-eicosane and n-dodecane as the phase transition cores, while zirconium oxide and zirconium oxide doped with rare earth elements as the shells. And through the design research, a series of different core-shell ratios of microcapsules have been successfully synthesized. The resulting inorganic microencapsulated phase change materials are not only have good phase change performance and excellent thermal conductivity, but also have a special photoluminescent characteristic. The main works are as follows:(1) A series of inorganic microencapsulated phase change materials with specific properties have been synthesized in non-aqueous formamide solvent. The dual-functional microencapsulated phase change materials are based on n-eicosane core and zirconium oxide shell. It has been clearly proved the successful microcapsules with core-shell structures by scanning electron microscope (SEM) and transmission electron microscopy (TEM). Characterized by fourier infrared spectra (FTIR), X-ray spectrometer (EDX) and X-ray photoelectron spectrometer (XPS), the microencapsulated phase change materials are zirconium oxide coating paraffin. Differential scanning calorimeter (DSC) and thermal gravity analysis (TGA) data show the thermal stability of the packed n-eicosane and shell material. Meanwhile, analyzing without adding NaF and adding NaF of the microencapsulated phase change materials through X-ray diffractometer (XRD), we find that the addition of NaF has the mixing crystals of tetragonal phase and monoclinic phase. The shell materials of zirconia have been characterized by UV-visible and fluorescence spectra. The crystalline and amorphous zirconia have a strong ultraviolet absorption and high emission spectra when excitated at 296 nm. The fluorescence spectra display that amorphous systems have emission in the ultraviolet band and crystalline systems have emission in the ultraviolet and green bands.(2) Based on the first experiment, the microencapsulated phase change materials have been designed by Er3+, Sm3+, Yb3+ doping zirconia as the microcapsule wall and n-docosane as the phase change core. It mainly focus on the optical properties and thermal properties of the rare earth doping microencapsulated phase change materials. In addition to using some of the basic characterizations, such as TEM, SEM, FTIR, EDX, the more important is the optical performance of UV and fluorescence spectra for each doping systems. Increasing the fluorescence microscope, it can show the visual luminescence phenomenon of blue-purple through purple exciting. Of course, the most is phase change performance, mainly characterized by DSC and TGA. The data show that the rare earth doping zirconia microencapsulated phase change materials can effectively decrease the supercooling degree of phase change materials.