| dc.description.abstract | In this study, the microencapsulated n-octadecane phase change materials (microPCMs) were prepared by suspension polymerization or emulsion-free polymerization. Methyl methacrylate and styrene were used as monomers. EGDMA was used as cross-linking agent. The thermal physical properties, surface morphology, thermal stabilities ,and chemical composition of microcapsules were measured by differential scanning calorimetry (DSC), scanning electron microscope (SEM), thermo gravimetric analysis (TGA) ,and fourier transform infrared spectroscopy (FTIR).
In the first part, monomers, cross-linking agent, PCM, and initiator were mixed and added in PVA solution. The suspension polymerization was occurred after homogenlizing the above solution. The results showed that the highest enthalpy (152.3 J/g) and the PCM content (60%) of microPCMs was obtained in the presence of EGDMA. The average diameter of the microPCMs was 148 nm.
In the second part, the microPCMs were prepared by the emulsion-free polymerization at boiling state. Monomers, cross-linking agent were mixed and polymerized at suitable conversion. Then monomers, cross-linking agent ,and PCM were added and ploymerized again. The results showed that the highest enthalpy (94.4 J/g) and the PCM content (37.2%) of microPCMs was obtained by adding EGDMA at both steps. The average diameter of the microPCMs was 179 nm. The polymerization time could reduce to 2 h.
In addition, TGA analysis showed the weight loss curves of microPCMs prepared by both methods were higher than that of n-octadecane. Based on the results, we propose that the microPCMs possess good potential for thermal energy storage.
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