單壁奈米碳管/酚醛樹脂複合材料之機電及熱性質研究

Mechanical, Electrical and Thermal Properties of SWNTs/Phenolic Composites

彭泰豪(Tai-Hao Peng)

指導教授 ： 葉孟考 ； 戴念華

國立清華大學/工學院/動力機械工程學系/碩士(2006年)

摘要

奈米碳管質輕、尺寸小、高強度、高韌性、導熱佳及具有優秀之電氣性質，為極佳之補強材。高分子材料為常使用之基材，其機械性質不佳，需加入補強材加以改善。奈米碳管與高分子材料混合，可提升高分子材料之性質，本研究以化學氣相沉積法生成之單壁奈米碳管補強熱固性高分子材料酚醛樹脂，探討不同碳管重量百分比對其機械、電氣及熱性質之影響。結果顯示，加入單壁奈米碳管可提升材料之機械性質，隨著碳管含量增加有飽和效應出現。另外以修正型Halpin-Tsai方程式可嵌合實驗數據。電性量測結果顯示，加入單壁奈米碳管可提升材料之導電度以降低電阻，當碳管含量達1.0wt％時可降低表面電阻率約10個數量級，導電門檻的閥值(Percolation threshold) 約為碳管含量0.5~1.0wt％。差式掃描熱量計(DSC)測試結果顯示，加入碳管可提升材料內部之交聯程度(Crosslink)並提高試片之玻璃轉換溫度(Glass transition temperature)。最後以掃描式電子顯微鏡觀察試片破壞面微結構，發現單壁奈米碳管於裂縫產生時之架橋現象(Crack-bridging)及碳管含量會影響複合材料內基材與補強材間之包覆及交聯情況。

關鍵字

單壁奈米碳管 ； 複合材料 ； 機械性質 ； 熱性質 ； 電性 ； 酚醛樹脂

並列摘要

The carbon nanotubes are known as good reinforcements because of the light weight, small size, high strength, high toughness, good thermal property and electrical conductivity. Polymers require reinforcements to improve their mechanical properties. Therefore, fabricating composites with carbon nanotubes can effectively improve the properties of polymers. In this thesis, single walled carbon nanotubes (SWNTs) synthesized using the floating catalyst method through the chemical vapor deposition (CVD) process were used to reinforce the phenolic resin. The effects of SWNTs content on the mechanical, electrical and thermal properties of the composites were investigated. The modified Halpin–Tsai equation was used to fit the experimental data of mechanical properties of SWNTs/phenolic composites. In addition, using SWNTs to reinforce phenolic resin can enhance the electrical conductivity and decrease the resistivity. The surface resistivity decreased about 10 orders of magnitude when the SWNTs content reached 1.0wt%. The percolation threshold of conductivity is between 0.5 and 1.0wt% of SWNTs in matrix. In the differential scanning calorimetry test (DSC), the composites have higher glass transition temperature than phenolic resin due to a better crosslink between the matrix and the reinforcement. The tensile fracture surfaces of SWNTs/phenolic composites were examined using field emission scanning electron microscope to investigate the failure morphologies of the SWNTs/phenolic composites. It is found that the crack-bridging in the cracks and the SWNTs content would indeed affect the crosslink and wetting between the matrix and the reinforcement.

並列關鍵字

single wall carbon nanotube ； composite ； mechanical property ； thermal property ； electrical property ； phenolic

參考文獻

2. S. Iijima, “Helical microtubules of graphitic carbon,” Nature, Vol. 354, pp. 56-58, 1991.

4. E.T. Thostenson, Z. Ren and T.W. Chou, “Advences in the science and technology of carbon nanotubes and their composites：a review,” Composites Science and Technology, Vol. 61, pp. 1899-1912, 2001.

5. F. Li, H.M. Cheng, S. Bai and G. Su, “Tensile strength of single-walled carbon nanotubes directly measured from their macroscopic ropes,” Applied Physics Letters, Vol. 77, No. 20, pp. 3161-3163, 2000.

6. Y. Li, K. Wang, J. Wei, Z. Gu, Z. Wang, J. Luo and D. Wu, “Tensile properties of long aligned double-walled carbon nanotube strands,” Carbon, Vol. 43, pp. 31-35, 2005.

7. M.F. Yu, O. Lourie, M.J. Dyer, K. Moloni, T.F. Kelly, and R.S. Ruoff, “Strength and Breaking Mechanism of Multiwalled Carbon Nanotubes Under Tensile Load,” Science, Vol. 287, pp. 637-640, 2000.