Preparation Of Spherical Organic-Inorganic Cyclodextrin/Urea-Formaldehyde Phase Change Microcapsules For Energy Storage

Phase change materials are new types of energy-regulating materials with great potential in industrial applications. In this article, phase change microcapsules were prepared successfully with modified Urea-Formaldehyde resin as shell material and paraffin as core material by microencapsulation technology. The shell material of the microcapsules was modified by in situ polymerization and surface grafting method. And the barrier performances and the thermal stability of phase change microcapsules were improved significantly. Also, it offered some useful basis data of phase change microcapsules for industrial application.In this paper, β-cyclodextrin/Urea-Formaldehyde paraffin microcapsules were synthesized with Urea-Formaldehyde resin modified by β-cyclodextrin as the shell material and phase change paraffin as the core material using microencapsulation technology. The effects of different types of emulsifier, the dosage of emulsifier and the stirring rate of emulsifier on emulsification were studied. The preparation technologies of β-cyclodextrin/Urea-Formaldehyde paraffin microcapsules were optimized. The parameters affecting the morphology, chemical structure of the microcapsules, such as pH, the mole ratio of Urea and Formaldehyde, the dosage of OP-10, the emulsion speed, the dosage of β-cyclodextrin, the curing reaction temperature, the curing reaction time and so on, were studied in details. The results showed that OP-10had good dispersing effects for paraffin emulsion, the optimum dosage of OP-10was about5%, the optimum stirring rate of OP-10was7500-10000rpm. And the optimum pH for preparing the microcapsules was about3.0-3.5, the mole ratio of Urea and Formaldehyde was1:2, the dosage of the β-cyclodextrin was0.5g, the curing reaction temperature was70℃, and the curing reaction time was3h. And the microcapsules had a phase change enthalpy of161.0J/g with a paraffin content of78.89%.Inorganic nano TiO2was treated by silane coupling agent, and grafted to the surface of P-cyclodextrin/Urea-Formaldehyde microcapsules to prepare the spherical core-shell phase change microcapsules for energy storage. The influences of pH, TiO2and etc on the chemical structure, surface microstructure, thermal storage performance, crystal form and thermal stability were discussed in details. The results showed that the phase change enthalpy of the spherical microcapsules could reach155.0J/g, the atomic percentage of Si element was0.92%, the atomic percentage of Ti elements was0.31%. And the thermal decomposition temperature of the microcapsule increased from128.82℃to222.73℃, and increased by93.91℃. The microcapsules were spherical with good dispersion.Spherical organic-inorganic SiO2/β-cyclodextrin/Urea-Formaldehyde paraffin phase change microcapsules for energy storage were prepared successfully by treating nano SiO2with silane coupling agent. The parameters on preparation of the microcapsules, including pH. the dosage of SiO2and etc, were discussed in detail. The experimental results showed that the optimum pH and the reaction temperature of preparing the microcapsules were about3.5and55℃. And the atomic percentage of Si element was19.53%, the microcapsules had a phase change enthalpy of157.4J/g with a paraffin content of77.12%. The surfaces of spherical SiO2/β-cyclodextrin/Urea-Formaldehyde paraffin microcapsules were almost no adhesion. and the compactness of the microcapsules was improved significantly.