本研究目的在於克服聚醯亞胺(polyimide)與多壁奈米碳管的相容性,因此,以混酸(H2SO4: HNO3 =3:1,vol %)對多壁奈米碳管預先處理做酸化改質,藉由超音波震盪截斷奈米碳管管壁而在表面接上羧酸基,並且使用耦合劑(coupling agent)先與聚醯亞胺之前驅物PAA(Polyamic acid)反應,之後再將含羧酸基之奈米碳管導入以共價鍵結形成Alkoxysilane terminated amic acid/MWNT-COOH之複合材料,再配合旋轉塗佈及階段性熱熟化步驟得到聚醯亞胺-奈米碳管複合薄膜。本研究將奈米碳管導入基材的目的是為了提升聚醯亞胺的導電性與機械性質,並且比較添加未改質及混酸改質四小時與六小時的碳管於聚醯胺酸中的影響。研究中使用傅立葉轉換紅外光譜儀(FTIR)來鑑定其化學結構,熱重損失分析儀(TGA)探討材料的熱穩定性質,萬能試驗機(Universal Test Machine)及鉛筆硬度計(Hardness Pencil Test)觀察其機械性質,掃描式電子顯微鏡(SEM)與穿透式電子顯微鏡(TEM)來觀察材料的表面型態及奈米碳管於基材中的分散性,超絕緣儀(Super Megohmmeter)量測材料的電性。
In this research﹐MWNTs were modified by mix acid(H2SO4:HNO3=3:1,vol%) under sonication for pretreatment to overcome the compatibility between polyimide and carbon nanotubes. The MWNTs were grafted with carboxylic groups on the wall of the tubes. Besides, APrTEOS was introduced as coupling agent. With ethoxysilane group, it can react with precursor of polyimide(PAA), which then combined with modified carbon nantubes(carboxylic group) to form covalent bond. The PI/MWNTs composites were obtained by a spin coating and multi-step thermal curing process. In this study, the MWNTs were introduced into the matrix in order to increase its electrical and mechanical properties. The effect on PI/MWNTs composite with MWNTs unmodified or acid modified in four or six hours were also discussed. The structure of prepared PI-MWNTs was characterized by Fourier transform infrared (FTIR) spectrometr. The thermal properties, mechanical properties of PI-MWNTs nanocomposite were analyzed by Thermogravimetric analysis (TGA), Universal Test Machine and Hardness Pencil Test. The morphology of PI-MWNTs was observed by scanning electron microscopy (SEM). The dispersion of MWNTs in matrix were observed by transmission electron microscopy(TEM). The electrical property of composite were obtained by Super Megohmmeter.