導熱相變化複合材料之製備

Preparation of conductive filler / phase change material composites

黃郁雯(Yu-Wen Huang)

指導教授 ： 石燕鳳

朝陽科技大學/理工學院/應用化學系/碩士(2013年)

摘要

本研究以石蠟和十八烷醇混合作為相變基材，並加入不同比例之氮化硼(BN)、石墨(EG)與多壁奈米碳管(MWCNT)，成為具高導熱、高潛熱值及高電阻之相變化複合材料。其中石墨與多壁奈米碳管並經有機改質(C18-E及C18-C)以增進其與相變化基材(石蠟及十八烷醇)之相容性。並對於此複合材料之熱傳導、電阻性、型態學及儲熱與放熱進行探討。經有機表面改質之導熱材料添加於相變基材後，熱傳導係數由0.308W/m．K提升至6.328W/m．K，顯示熱傳導路徑及網絡形成，有助於提升複合材料的散熱功能，且電阻可達3.83×106Ω/□。由掃描式電子顯微鏡(SEM)觀察，複合材料之基材與導熱材料表面相容性很好。由微差掃描熱分析(DSC)顯示，複合材料的相變溫度都與相變基材相似，其相變焓與複合材料中相變基材含量成正比。複合材料其儲熱時間比相變基材縮短了47.7%；而放熱時間也大幅縮短77.9%。以上結果顯示，添加表面改質及混合之導熱材料所製成的相變化複合材料，可提升整體相變材料的熱傳導性、儲熱與放熱速率且同時可具有高電阻。

關鍵字

儲熱與放熱 ； 電阻值 ； 熱傳導 ； 多壁奈米碳管 ； 石墨 ； 氮化硼 ； 石蠟 ； 十八烷醇

並列摘要

As a phase change material (PCM), paraffin or octadecanol has high latent heat, but low thermal conductivity. In this study, different proportion of boron nitride (BN), expanded graphite (EG) and multi-walled carbon nanotubes (MWCNT) were added into paraffin and octadecanol to form a high thermal conductivity composite material with high latent heat value, as well as a high electrical resistance. Moreover, the EG and MWCNT were organo-modified (C18-E and C18-C) to improve their compatibility with matrix (paraffin and octadecanol). The thermal conductivity, electrical resistance, morphology and thermal storage and heat release of the composite materials were investigated. Thermal conductivity of paraffin (0.308 W/m．K) was increased to 6.328 W/m．K, indicating the formation of conducting path and network, and the electrical resistance can reach to 3.83×106 Ω/□. The results of scanning electron microscope (SEM) reveal that good compatibility was observed between the matrix and the thermally conductive materials. Differential scanning thermal analysis (DSC) shows that the phase transition temperature of the composite material was similar to that of the matrix, and the phase change enthalpy of the composite was proportional to the content of the matrix in the composite.
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Moreover, the thermal storage time of composite was shorter than the matrix by 47.7%; exothermic time was also significantly reduced by 77.9%. On the basis of all results, it revealed that the use of modified and mixed conductive additives can be considered an effective method to enhance the thermal conductivity, and thermal storage and exothermic rates of PCM, as well as a high electrical resistance.

並列關鍵字

heat storage and heat release ； Resistance ； Thermal conductivity ； multi-walled carbon nanotubes ； graphite ； Boron nitride ； Octadecanol ； Paraffin

參考文獻

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