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Preparation and Infrared Performance of Multi-phase Change Temperature-microcapsule

Author: DingDong
Tutor: HeDaWei
School: Beijing Jiaotong University
Course: Optical Engineering
Keywords: Phase change material microcapsules Phase transition temperature Core-shell structure Alkane paraffin In situ polymerization (Poly ) styrene (Poly ) methacrylic acid
Type: Master's thesis
Year: 2010
Downloads: 132
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Phase change material microcapsules can be applied not only to traditional energy control, heat exchange, temperature control and other fields, can also be used as infrared stealth materials. Phase change material microcapsules single-phase change microcapsules, limiting the application of microcapsules; multi-phase transition point microcapsules in at the same time retain the original advantages of microencapsulated phase change, phase transition temperature range expansion and extend and expand the scope of application of the microencapsulated phase change. In this thesis successfully prepared on the basis of single-phase-change microcapsules, focus on preparation of a multi-phase transition point the microcapsules and analyze the performance of its microscopic morphology, thermal infrared. In situ polymerization of a single-phase variable series microcapsules sample SEM image shows a sample containing microcapsules polymerization ball diameter of approximately 100 nm: DSC curve consistent with the theoretical value of the phase change endothermic peak. Each series of multi-phase change microcapsules the samples were prepared under different conditions were compared morphology and aggregation effect: increase the proportion of raw styrene and methyl methacrylate styrene, styrene and methacrylic acid mixed solution of warm-up , the occurrence of the prepolymerization mixture of AIBN and KPS as an initiator, the polymerization can be obtained effect is more ideal microcapsules. Improved experimental conditions to prepare a multi-phase transition point core-shell microcapsules sample the SEM figure shows the successful polymerization the microcapsules ball, approximately 100 nm in diameter; Fourier transform infrared spectra confirmed that the sample contains the methyl acrylate-modified styrene copolymer substance, and alkanes paraffin, respectively, the microcapsule wall material and core material, excluding styrene and methacrylic acid, a raw material monomer; DSC curve shown in hexadecane, eicosane, octacosane the phase transition temperature of 18 ℃, around 35 ° C, 56 ° C the phase change endothermic peak endothermic enthalpy of 32.8J / g, showed that the microcapsules coated successfully into the phase change paraffin. Thermal infrared image and data analysis within the temperature range of 30-45 ° C, respectively, cover the the microcapsule samples and of polystyrene thin glass surface near the phase transition point temperature difference, and pulled to the maximum at around 36 ℃ temperature difference; room temperature to 80 ° C rapid heating process, microcapsules sample surface temperature is always lower than the the pure polystyrene surface temperature about 10 ° C, and can be maintained for a short period of time, indicating that the preparation of microencapsulated phase change material covered on the surface of the target, you can effectively reduce target heating rate, and to some extent reduce the target infrared radiation.

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