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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/3927

    Title: 以溶膠-凝膠法製備有機無機混成相轉移材料微膠囊;Preparation of Phase Change Materials Microcapsules by Using PMMA Network-Silica Hybrid Shell via Sol-Gel Process
    Authors: 張智中;Chih-Chung Chang
    Contributors: 化學工程與材料工程研究所
    Keywords: 相轉移材料;溶膠-凝膠法;微膠囊;microcapsule;phase change material;sol-gel process
    Date: 2006-05-24
    Issue Date: 2009-09-21 12:26:12 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 本研究探討以熔點28℃之正十八烷相轉移材料為核物質,PMMA架橋體-二氧化矽混成材料為殼層之微膠囊的製備方法與條件。首先探討三種合成方式製備PMMA架橋體之微膠囊。之後再將預聚合液與TEOS經過事先的混合後作為油相,以懸浮聚合法為基礎製備出相轉移材料微膠囊。TEOS在酸性環境之下與分散相中的水行溶膠凝膠法反應。所得之微膠囊潛熱值與正十八烷之含量以DSC量測,微膠囊中二氧化矽殘餘量及其熱性質以TGA分析,微膠囊之粒徑大小與表面結構則由SEM觀察。 實驗結果顯示,單獨使用PMMA預聚合液才可成功製備出相轉移材料微膠囊。當預聚物添加TEOS時,產物之潛熱值為151 J/g,比未加TEOS時之微膠囊潛熱值88.3 J/g要來得高出許多。此微膠囊之平均粒徑約在10μm。「熟成」指的是在反應過後將產物於某個溫度下靜置不同的天數,此一步驟能增加Si-O-Si之鍵結與改變產物之表面結構。隨著熟成時間與溫度之不同,所得微膠囊之二氧化矽殘餘量、正十八烷之含量與潛熱值皆會有所不同。TEOS的增加對於微膠囊之包覆量與潛熱值並無明顯的幫助,最高的潛熱值178.9 J/g出現在無機含量為5 wt%時。帶有不同官能基之矽偶合劑對於微膠囊之包覆量也無明顯幫助,當添加不同矽偶合劑時,微膠囊之潛熱值反而會從180.5 J/g分別下降至135.9 ~ 165.7 J/g,而正十八烷之含量則從原本的74%分別下降至55.7 ~ 67.9%。為縮小微膠囊之粒徑,添加不同濃度之界面活性劑Tween 60,隨著界面活性劑之添加,雖然能有效降低微膠囊之粒徑,但微膠囊之潛熱值與包覆量亦隨之降低。 Encapsulation of phase change materials (PCMs) by using poly(methyl methacrylate) (PMMA) network-silica hybrid as the shell material has been developed. n-Octadecane melted at 28℃ was used as PCMs. First three kinds of methods, preparation of PCMs microcapsules by using PMMA network as the shell material, were discussed. Then PCMs microcapsules were prepared based on suspension by mixing and reacting of ethylene glycol dimethacrylate (EGDMA) and precopolymer solution with tetraethoxysilane (TEOS). TEOS was reacted with water supplied by disperse phase in acid condition to obtain PMMA-Silica hybrid via the sol-gel process. Latent heat and n-octadecane content of PCMs microcapsules were characterized by differential scanning calorimeter (DSC). Residual silica content and the thermal properties of microcapsules were characterized by thermogravimetric analysis (TGA). Particle size and microcapsules morphology were analyzed by scanning electron microscope (SEM). The results showed that PCMs was able to be successfully encapsulated by using PMMA prepolymer solution. The microcapsules prepared by this precopolymer solution with adding TEOS had higher latent heat (ΔH=151 J/g) than those without adding TEOS (ΔH=88.3 J/g). The average size of PCMs microcapsules is about 10μm. After encapsulation, the ageing process, placed the products at the certain temperature for certain days, was able to increase Si-O-Si bonding and change surface structure of microcapsules. With increasing ageing time and ageing temperature of the ageing process, silica content, n-octadecane content and latent heat of microcapsules were changed. The highest amount of latent heat (ΔH=178.9 J/g) and n-octadecane content (73.3%) of microcapsule was obtained when the inorganic content of the microcapsule was 5 wt%. It is not effective in increasing n-octadecane content (74% to 55.7 ~ 67.9%) and latent heat (180.5 J/g to 135.9 ~ 165.7 J/g) of microcapsules by introducing different functional groups of silanes.
    Appears in Collections:[化學工程與材料工程研究所] 博碩士論文

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