聚甲醛／石墨烯 高導熱性奈米複合材料之製備及物性

高速馬達軸承在高轉速下，因摩擦生熱，常使得潤滑油變質，或散逸導致零件摩擦毀損，無法正常運作。為減少潤滑油變質的情形，增加零件的導熱速率，成為一重要課題。石墨烯(graphene)為目前導熱係數最高的材料，若與高強度且自潤滑性好的聚甲醛(Polyoxymethylene, POM)結合，製成奈米複合材料，應能有效提升軸承零件的導熱速率。本研究以兩種不同的方法製備石墨烯，鎂粉燃燒法和還原氧化石墨法，並以其製備複合材料，且比較不同配方比例對複合材料物性及導熱係數的影響。我們以傅立葉紅外線(Fourier transform infrared spectroscopy, FT-IR)光譜檢測石墨烯的表面官能基與結構，其中還原氧化法石墨烯(rGO)有較多的含氧官能基殘留於表面。由X-射線繞射分析(X-ray diffraction, XRD)及拉曼(Raman)光譜我們發現本研究用的兩種方法所製備的石墨烯與市售多層石墨烯(15-20層)標準品相比層間距較大、層數較少。兩種不同的石墨烯製備的複合材料，從FT-IR 光譜中並未發現有官能基的改變，表示摻合過程並無化學反應的產生。在XRD及掃瞄式電子顯微鏡(Scanningelectron microscope, SEM)的圖中可以觀察到複合材料的摻合相當均勻，在石墨烯添加為20wt%時，會有較大的分子團出現。熱重分析儀(Thermal gravimetric analysis, TGA)的結果顯示，複合材料的熱裂解溫度(T_d)會因石墨烯的添加比例增加而減少。在微分掃描熱卡計(Differential scanning calorimetry, DSC)的熱分析圖中，我們發現摻合之後，複合材料的熔點(T_m)並未因而改變。在硬度方面，添加石墨烯後，複合材料整體硬度會有所下降，但至少還有4H以上的硬度，在塑膠材料中仍屬相當優異。導熱係數會因石墨烯的添加比例而提升，其中以添加鎂粉燃燒法石墨烯20wt%的樣品G^(Mg)_(20)/POM最高。Graphene/POM複合材料的表面電阻高達1010Ω以上，可以做為抗靜電材料使用。整體而言，本研究中所製備的4個成分不同的Graphene/POM複合材料中，以G^(Mg)_(20)/POM的物性及導熱係數最佳。

關鍵字

導熱係數；奈米複合材料；石墨烯；聚甲醛

並列摘要

Graphene is a material which has high thermal conductivity. In order to enhance the thermal conductivity, we used graphene to prepare nanocomposites with POM. The graphene/POM nanocomposites were prepared by physical blending. In this study, we prepare graphene from two different methods, including the magnesium powder combustion and the reduce graphite oxide method. We discuss the physical properties, including thermal conductivity of nanocomposites with different graphene ratios. The chemical bonding is identified by FT-IR spactra. The thermal resistance, transmittance, surface resistance, and hardness of these nanocomposites are measured by TGA, DSC, UV-Visible, surface resistant meter and hardness tester respectively. Expermimental results show that the transmittance valus of these nanocomposites are lower than 0.05% and the best T_d value is 331℃, the values are decreased with the increase of grapheme contents. The glass transition temperatures are not changed after adding graphene. The surface resistance of graphene/POM nanocomposites are greater than 1010 Ω/cm^2. The hardness of G^(Mg)/POM and rGO/POM are 5H and 4H respectively, the values are greater than PTFE. The morphology structures of Graphene/POM nanocomposites are estimated by SEM. Showing that the graphene are dispersed well in POM matrix, the thermal conductivity values of graphene/POM nanocomposites are measured by guarded hot plate method. The best thermal conductivity value is 1.10 W/mk, it is better than that of pure POM (0.32 W/mk). The thermal conductivity values are increased when graphene ratio increases. For the physical properties, including thermal conductivity G^(Mg)_(20)/POM is the best among four different nanocomposites of graphene/ POM in this study.

並列關鍵字

Thermal conductivity ； nanocomposite ； graphene ； POM

國際替代計量

聚甲醛／石墨烯高導熱性奈米複合材料之製備及物性

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