界面活性劑及酸洗處理對 EVA/奈米碳管─聚吡咯複合材料EMI遮蔽性質之研究

Effects of Surfactant Contents and Acid Treatment on EMI Shielding Effectiveness of EVA/CNT-PPy Composites

謝智閔(Chih-Min Hsieh)

指導教授 ： 黃繼遠

大同大學/工程學院/材料工程學系所/碩士(2010年)

摘要

本研究中，在不同含量之界面活性劑氯化十六烷基三甲基銨(cetyltrimethylammonium chloride, CTAC)下，以化學氧化聚合法將導電高分子吡咯(pyrrole)於CTAC-氯化鐵(FeCl3)溶液中聚合並披覆於奈米碳管(CNT)表面，合成複合導電CNT-PPy (PolyPyrrole, 聚吡咯)。將複合導電CNT-PPy與高分子基材乙烯-醋酸乙烯酯共聚合物(ethylene-vinyl acetate, EVA)混煉，使CNT-PPy分散於基材，形成導電通路，使其複材有電磁波遮蔽效果(EMI SE)。在CNT-PPy合成過程中，針對奈米碳管、CTAC含量之影響，使用Raman、SEM分析CNT-PPy結構及PPy於CNT表面之披覆形貌。酸洗處理(Acid Treatment)對於CNT的影響，則使用四點探針、EDS，量測電阻及組成成份的變化。將酸洗碳管(CNTAT)與吡咯合成之複合導電CNTAT – PPy。如同於CNT-PPy，使用Raman、SEM分析並且使用FE –SEM，與CNT-PPy來比較差異。
本研究中，碳管含量會影響與聚吡咯之附著性，大量的碳管對提升電磁波遮蔽效果有限，僅2~3 dB。因此，本研究以界面活性劑CTAC改善聚吡咯於碳管之分散性。在未添加CTAC時，大量的碳管在CNT–PPy中會發生自身叢聚現象，與聚吡咯形成不均勻的導電填充物，其複材之電磁波遮蔽值無法達到5dB。當碳管含量為2g時，CTAC添加至0.01莫耳，可使聚吡咯分散至碳管，形成較均勻的導電填充物，其複材有較佳的電磁波遮蔽值(10~15dB)。另外，本研究發現碳管經酸洗處理後，可增加自身導電性與表面積，使聚吡咯容易附著在碳管上，再搭配界面活性劑CTAC的添加，可增加CNTAT-PPy於EVA中之導電通路，明顯提升複材之電磁波遮蔽值。在相同的碳管含量(2g)下，CNTAT-PPy與添加0.015莫耳CTAC所形成之複材，電磁波遮蔽值可達27~30dB。

關鍵字

界面活性劑 ； 聚吡咯 ； 複合材料

並列摘要

In this investigation, in various content of cetyltrimethylammonium chloride (CTAC) ─ferric chloride (FeCl3), the composited conductive carbon nanotubes (CNT) -PolyPyrrole (PPy) was synthesized by chemical oxidative polymerization from pyrrole monomers polymerized in the CTAC-ferric chloride (FeCl3) covering the surface of CNT.. The composited conductive CNT-PPy was compounded with the polymeric substrate; ethylene-vinyl acetate (EVA) into the composites achieved the electromagnetic interference shielding effectiveness (EMI SE) by CNT-PPy dispersing in the substrate to form conductive networks. In the systemization process of CNT–PPy, the influence of CNT and CTAC contents was analyzed by Raman and SEM to observe variations of structure, and covering conditions of PPy on the surface of CNT. The effect of acid treatment of CNT was using 4-point-probes and EDS to research the variations of resistance and compositions. The conductive CNTAT-PPy that CNT after acid treatment synthesized with PPy was analyzed as CNT-PPy by Raman and SEM; furthermore, the differences of structure between CNT-PPy and CNTAT-PPy were compared by using FE-SEM.
In results of investigation, the contents of CNT would affect the attaching of PPy but the large amount of CNT just increased EMI SE in 2~3 dB. Therefore, this investigation used CTAC to improve the dispersing of PPy in CNT. When the CNT-PPy contained a large amount of CNT would result a self-aggregated phenomenon and formed not uniform conductive filler without CTAC. The EMI SE of composites could not achieve 5 dB. However, the EMI SE of the composites could raise to 10~15dB when the CNT content was 2g, and added 0.01mole CTAC in the synthesizing process of CNT-PPy. Besides, this investigation found the acid treatment of CNT would increase the conductivity and surface areas of CNT and made PPy easily attached on the surface of CNT. If added CTAC in CNTAT-PPy, and the EMI SE of CNTAT-PPy composites were substantially improved. In the same CNT content (2g), the EMI SE of composites obviously raised to 27~30dB when CNTAT-PPy adding 0.015mole CTAC.

並列關鍵字

composite ； polypyrrole ； surfactant

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