Preparation And Modification Of Microencapsulated Paraffin

Phase change material has a particular potential in the field of energy-saving and environmental protection field, and it is getting more and more widely attention and research on the improvement. At present, However, this kind of material is restricted in its application. This thesis aims to develop phase change microcapsules applied in green building in the environment of which the temperature is relatively high to broaden the scope of application of this kind of material.Phase change microcapsules (PCMs) were synthesized by in-situ polymerization using ammonium chloride as curing agent and urea-formaldehyde resin as shell material while liquid/solid paraffin at room temperature as core material. The formation of the microcapsules during acidating process was observed using polarized microscopy (POM). Chemical structures of the microcapsule composition were analyzed by fourier transform infrared spectroscopy (FTIR). The ability of heat storage of the microcapsules was studied through differential scanning calorimetry (DSC). The surface morphology and the microscopic state were characterized using scanning electron microscopy (SEM). The thermal stability of microcapsule was evaluated by thermo-gravimetric analyzer (TGA).Silicane coupling agent was used to modify the SiO2-sol during surface modification of the microcapsules by sol-gel method. The chemical structures, ability of heat storage, surface morphology and microscopic state before and after modification of the microcapsule composition were analyzed by the methods of fourier transform infrared spectroscopy, differential scanning calorimetry and scanning electron microscopy respectively. In addition, the hydrophilicity of the microcapsule composition was investigated by means of height method.The microcapsules were then added to building materials such as cements and coating materials to form construction composite material for application. Chemical structures of the microcapsule building composition were analyzed by means of fourier transform infrared spectroscopy. The heat storage ability, surface morphology and the microscopic state of the microcapsules were studied through differential scanning calorimetry and scanning electron microscopy.The results show that:(1) Urea-formaldehyde resin can effectively capsulize an organic material of paraffin and form a regular morphology of the microcapsules. During the phase change of the paraffin, the microcapsules can store and release energy and has thermal stability. Various factors such as the core/wall ratio, emulsifier types and dosage, acidification conditions, oil/water ratio and the concentration of ammonium chloride were considered as they can affect the performance of microcapsule a lot. (2) The hydrophilicity, abio-compatibility, compactness and dispersion of the microcapsules were promoted by sol-gel method along with the silicane coupling agent, they can be used to design and develop new types of environmental friendly construction material.(3) The microcapsules can interface well with building materials. The construction composite material has an effective thermal energy capacity and could be widely used in the energy saving field.