Spherical Agglomerates of Poly(ethylene glycol)/Silica Fume Composites as Phase Change Materials

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题名:	Spherical Agglomerates of Poly(ethylene glycol)/Silica Fume Composites as Phase Change Materials
作者:	王智霖;Wang,Chih-Lin
贡献者:	化學工程與材料工程學系
关键词:	相轉移材料;混掺;聚乙二醇;燻矽;結晶溫度延長;phase change material;blending;polyethylene glycol;silica fume;transition zone broadening
日期:	2016-06-16
上传时间:	2016-10-13 12:38:56 (UTC+8)
出版者:	國立中央大學
摘要:	本篇論文研究的主要目的是找到固-液態轉換上型態穩定的相轉移材料，聚乙二醇/燻矽複合物，以及透過混摻不同比例的聚乙二醇/燻矽複合物來調製出擁有寬廣使用溫度範圍的相轉移材料，使得此材料在相轉移材料方面有更多不同的應用。接著，經由球晶製程的方式將原本做出來不規則狀的聚乙二醇/燻矽複合物製作成球形來改善此材料的流動性。聚乙二醇/燻矽複合物是透過含浸法來製備，以不同重量比例的聚乙二醇負載於燻矽載體上。其中附載較高的複合物PEG75/SF擁有重量百分比為47.9%的聚乙二醇，其熔點範圍約在攝氏55-58度，結晶點約在攝氏18-24度。我們將負載較高的複合物PEG75/SF及負載相對較低的複合物PEG25/SF或是無負載的燻矽混摻在一起，發現比例為重量比1:1時有較為寬廣的使用溫度範圍。在球晶製程方面，透過兩種不同的攪拌速度(400轉與600轉)所做出來的球晶複合物在粒徑分布上有明顯的不同，在轉速為400轉條件下所做成的球晶複合物裡，有高於百分之四十的球晶複合物仍然小於250微米，我們視其為沒有做成球晶。然而在轉速為600轉時所做出的球晶複合物其粒徑分布較均勻且沒有做成球晶的百分比降低不少。不同攪拌速度對於顆粒的斷裂力在粒徑範圍為355-500微米及710-1000微米時沒有顯著的影響，但在粒徑範圍為500-710微米時則稍有差異。在400轉的條件下所做出的球晶複合物，顆粒的斷裂力在粒徑範圍355-500微米及710-1000微米時分別為0.18±0.06及0.52±0.02牛頓，而在600轉的條件下所做出的球晶複合物，則分別為0.16±0.03及0.53±0.04牛頓。不管是經過轉速為400轉或是600轉的球晶製程後所得到的球晶複合物，在不同的粒徑區間其特性皆沒有太大的差異，都有良好的流動性而在熱性質上也有不錯的均質性。 ;The aim of this thesis was to prepare a solid-liquid shape-stabilized phase change materials, polyethylene glycol/silica fume (PEG/SF) composite, and study the blends of different PCM composites to broaden application temperature to suit for more applications of PCM, then through spherical crystallization to conglomerate the PCM composites become spherical agglomerates to improve the flowability. PEG 4000 was embedded in a low-cost SF to form the PEG75/SF composite with a PEG wt% of 47.9 wt%. The melting point and crystallization temperature of the PEG75/SF composite or spherical agglomerates were around 55-58ﾟC and 18-24ﾟC as determined by the temperature cycle of DSC with a heating rate of 10ﾟC/min and a cooling rate of 10ﾟC/min, respectively. Blends of PEG75/SF composites with PEG25/SF composites or with low-cost SF having a ratio of 1:1 could be used as a phase change material that had a broad crystallization temperature range. The spherical agglomerates of SF and PEG75/SF were made by the spherical crystallization process. Two agitation speeds in the spherical crystallization process about 400 and 600 rpm were studied. It was found that the particle size distribution of agglomerates prepared from different agitation speeds could vary significantly. There were more than 40 wt% of fine particles (< 250 μm) PEG75/SF composites did not conglomerate to become spherical agglomerates at 400 rpm. The particle size distribution was more uniform at 600 rpm. However, the morphology of agglomerates produced at 400 rpm was more spherical than those made at 600 rpm. The effect of the agitation speed on the particle fracture force of agglomerates in the range of 355-500 μm and 710-1000 μm was not obvious. The particle fracture force of agglomerates of 355-500 μm, and 710-1000 μm were 0.18±0.06, and 0.52±0.02 N by 400 rpm and 0.16±0.03, and 0.53±0.04 N by 600 rpm, respectively. There were similar properties between different size cuts of spherical agglomerates of PEG75/SF. Spherical agglomerates of PEG75/SF produced at 400 rpm and 600 rpm had good homogeneity in thermal properties and low Carr’s index indicating good flowability.
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