應用於儲存熱能之植物纖維/相變微膠囊 /高密度聚乙烯導熱複合材料之開發

Plant Flour/Micro-encapsulated Phase Change Material/High-density Polyethylene Thermally Conductive Composite used for Thermal Energy Storage

陳佩瑱(Pei-Tian Chen)

指導教授 ： 石燕鳳

朝陽科技大學/理工學院/應用化學系/碩士(2019年)

摘要

本研究以懸浮聚合方式製備微膠囊，其中相變化材料被含有奈米石墨之殼層包覆，以避免其在相變過程產生洩漏及揮發問題，並可加速熱的傳遞。並且利用相變化材料其吸、放熱效應以達到儲能及調節溫度的效果。首先藉由甲基丙烯酸甲酯及三乙氧基乙烯基矽烷共聚成預聚物，而添加三乙氧基乙烯基矽烷，其目的在於提升殼層與石墨導熱材之間的相容性，然後加入到聚乙烯醇與石蠟所配製的溶液中，並藉由乙二醇二甲基丙烯酸酯為架橋劑，隨後添加熱傳導係數高之奈米石墨，製備成殼層含奈米石墨、核心含石蠟之高導熱相變微膠囊。經此改良之相變微膠囊能夠加速相變化材料釋出或吸收熱量，使其能有效達到導熱、散熱、儲能等之功能。從微觀結構分析中，證實微膠囊趨近於球體狀態，粒徑範圍8.64~32 µm。進一步分別將高導熱相變微膠囊及木粉加入高密度聚乙烯中製備一系列的導熱相變化複合材料，機械強度分析顯示其拉伸強度無太大差異，耐衝擊強度則略微提升；熱性質分析中，高密度聚乙烯其熱變形溫度約72.7 ℃，而複合材料皆呈現上升趨勢（94~105 ℃）。另外從微差掃描分析中發現，隨著高導熱相變微膠囊含量提升，複合材料的焓值都有逐漸提升趨勢。熱傳導分析中，高密度聚乙烯的導熱係數（0.46 W/m．K），經由添加高導熱相變微膠囊後提升到0.64 W/m．K，表示添加含石墨導熱材的高導熱相變微膠囊可提升高密度聚乙烯的散熱機制以及加快熱擴散的速度。

關鍵字

微膠囊 ； 相變化材料 ； 奈米石墨 ； 木粉

並列摘要

In this study, microcapsules were prepared by suspension polymerization, in which phase change materials (PCM) were encapsulated by a nano-graphite containing shell to avoid leakage and volatilization during phase transition and accelerate the heat transfer. Moreover, the endothermic and exothermic effects of PCM are applied to achieve energy storage and temperature regulation. First, the vinyl-silane compound was polymerized with the methyl methacrylate (MMA) to form a copolymer. The purpose of adding vinyl-silane compound is to improve the compatibility between shell and nano-graphite. In addition, polyvinyl alcohol was used as a surfactant and mixed with PCM (paraffin) to form a suspension solution. Moreover, ethylene glycol di-methacrylate was used as a crosslinking agent and a thermally conductive nano-graphite was added. And then the PCM microcapsules with paraffin core and the thermally conductive material containing copolymer as the shell is prepared. This obtained microcapsule can accelerate the release or absorption of heat of the phase change material, so that it can effectively achieve the functions of heat conduction, heat dissipation and energy storage. Subsequently, the microcapsule and wood flour were incorporated into high density polyethylene (HDPE) to form a series of thermally conductive PCM composites. Structure analysis shows that the microcapsules approached the sphere state, and the particle size ranged from 8.64 to 32 μm. Mechanical strength analysis shows that tensile strengths of HDPE and its composites were not much different. On the other hand, the impact strength of HDPE was slightly improved and the thermal deformation temperature of HDPE was significantly elevated when the microcapsule and wood flour were added to HDPE. The DSC analysis shows that the enthalpy value gradually increases with the increase of the microcapsule content in the composites. Heat conduction analysis shows that the thermal conductivity of HDPE (0.46 W/m．K) was increased to 0.64 W/m．K after adding microcapsule. It means that the addition of microcapsule can improve heat dissipation mechanism and accelerate the heat diffusion speed.

並列關鍵字

Microcapsules ； Phase change material ； Nano-graphite ； Wood flour

參考文獻

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https://doi.org/10.1016/j.ijheatmasstransfer.2018.09.126

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https://doi.org/10.1016/j.solener.2012.04.008

3 Akanksha Mishra, A. S., Atul Sharma. Latent Heat Storage Through Phase Change Materials. Rajiv Gandhi Institute of Petroleum Technology 532-541 (2015).