本研究利用懸浮聚合法與無乳化劑乳化聚合法以正十八烷製備相轉移材料微膠囊。微膠囊之殼物質為甲基丙烯酸甲酯(MMA)與苯乙烯(St)單體以及乙二醇二甲基丙烯酸酯(EGDMA)架橋單體之共聚物，以低溫微差掃描熱分析儀(DSC)、掃描式電子顯微鏡(SEM)、熱重損失分析儀(TGA)、傅立葉轉換紅外線光譜儀(FTIR)來探討製備條件對所生成之微膠囊的潛熱值、產率、包覆效率、外觀、粒徑和熱穩定的影響。 懸浮聚合法即將單體、交聯劑、相轉移材料及油性起始劑分散在含有聚乙烯醇(PVA)穩定劑之水溶液後，以乳化均質機攪拌再行聚合反應。由實驗結果顯示，MMA與St需同時存在且添加交聯劑的情況下，才可製備出152.3 J/g高潛熱值之相轉移材料微膠囊，其相轉移材料含量為60%，所製備出微膠囊之平均粒徑為148 nm，由TGA測試結果可知，相轉移材料微膠囊的熱重損失曲線比正十八烷的熱重損失曲線往高溫移動，由此可知微膠囊化後，可提高耐熱性質。 無乳化劑乳化聚合法即在St與EGDMA存在下，並以沸騰狀態先行聚合反應，且在適當反應時間下添加St、MMA、EGDMA與正十八烷，並再行聚合反應。實驗結果顯示，兩階段皆需添加交聯劑，且在兩階段之間暫停加熱下，可成功製備潛熱值為94.4 J/g之相轉移材料微膠囊，相轉移材料含量為37.2%，平均粒徑為179 nm。由TGA測試結果可知，相轉移材料微膠囊的熱重損失曲線比正十八烷的熱重損失曲線往高溫移動，由此可知微膠囊化後，可提高耐熱性質。另外，利用此方法製備相轉移材料微膠囊可縮短聚合反應時間至2小時。 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.
