Preparation and Physical Properties of Poly(ethylene terephthalate) / Carbon Nanotube Nanocomposites

本研究目的為將多壁奈米碳管(Multi-walled carbon nanotube, CNT)進行二氧化矽改質後，與聚對苯二甲酸乙二酯(Polyethylene terephthalate, PET)進行熔融混煉得到PET/改質碳管奈米複合材料。將CNT先吸附改質矽烷(Modified Silane, MS)，再利用四乙氧基矽烷(Tetraethylorthosilicate, TEOS)在碳管表面上生成二氧化矽，接著與甲基丙烯氧基丙基三甲氧基矽烷(Methacryl oxypropyl trimethoxy silane, MPS)反應，使二氧化矽表面上帶有C=C官能基。之後以表面聚合法在碳管表面上接枝親油性高分子，並藉由高分子中之環氧基和PET中之羧酸官能基(COOH)反應，期許改質碳管對PET的界面黏著力可以更好。 一開始為先將MS吸附在CNT表面上，得到吸附平衡曲線，得知CNT的酸根含量大約為5.91×10-4 mol/g-CNT。之後將CNT吸附不同倍率之MS(0.038倍、0.05倍和0.5倍)，再經過與TEOS反應後得到二氧化矽改質碳管，以FTIR光譜分析知道有Si-O-Si 拉伸振動峰(二氧化矽)。能量散佈分析(EDS)可以得知Si/C原子比值隨著TEOS含量增加而增加。SEM型態分析發現碳管表面有二氧化矽粒子，表示二氧化矽生成在CNT表面上。與MPS反應後，FTIR分析得知有C=C 拉伸振動峰(MPS)的存在。接著以表面聚合法在碳管表面接枝親油性高分子。以FTIR光譜分析可以發現苯乙烯(styrene)與甲基丙烯酸環氧丙酯(Glycidyl methacrylate, GMA)的特徵峰，表示二氧化矽表面上已接枝高分子。 進一步以熔融混煉法製備PET/改質碳管奈米複合材料，由SEM斷裂面型態分析得知改質碳管對PET的界面黏著力較強。導電度分析中得知改質碳管中降低MS比例，則加入較低含量就可達到降低電阻率的效果。由DSC結果得知碳管皆以異相成核效應提高PET的冷卻結晶溫度。而DMA分析中，得知在改質碳管中降低MS的重量比例，可以有效的提昇PET的儲存模數(E’)，如MS比例為CNT之0.038倍時，且含量為5.0 phr時，複材之E’可提高52 %; 由損失模數中得知改質碳管皆會提高PET的玻璃轉移溫度(Tg)，表示碳管經過二氧化矽與親油性高分子改質後可以阻礙PET分子鍊的移動性。In this study, the multi-walled carbon nanotube (CNT) was modified to prepare PET/CNT nanocomposites by melt blending. The CNT was adsorbed with a modified silane (MS), and then tetraethylorthosilicate (TEOS) was added to form silica on the CNT surface. Then, the reaction of methacryloxypropyltrimethoxysilane (MPS) on the SiO2/CNT was done to bring the active C=C function group. Finally, styrene and glycidyl methacrylate (GMA) were added and polymerized on SiO2/CNT surface. The epoxy functional group of GMA may react with the carboxylic acid group of PET to improve dispersibility. The adsorption isotherm of MS on CNT was studied, and the capacity of carboxyl of acid on CNT was evaluated as 5.19×10-4 mol/g-CNT. Three kinds of MS weight ratio with 0.038-fold, 0.05-fold and 0.5-fold to CNT were added for the preparation of SiO2/CNT. The Si-O-Si stretching from SiO2/CNT is revealed by FTIR. The Si/C atomic ratio of SiO2/CNT increases with the increase of TEOS as measured by Energy Dispersive X-ray Spectroscopy (EDS). SiO2 nanoparticles on the CNT surface were observed by FESEM. The C=C stretching belonging to MPS, grafted on silica, is confirmed by FTIR. For surface modification, styrene and GMA were added to obtain modified CNT. The characteristic peak of styrene and GMA is observed from FTIR. Furthermore, PET / modified CNT nanocomposites were prepared by melt blending. The interfacial interaction between modified CNT and PET is better than virgin CNT observed by FESEM. The percolation threshold decreases when the weight ratio of MS to CNT increases as determined by electrical conductivity measurement. It is obvious that the added CNT or modified CNT can serve as a good nucleating reagent for PET and accelerates the rate of crystallization. When decreasing the weight ratio of MS to CNT, the storage modulus (E') of composites increases based on DMA data. In particular, when the weight ratio of MS to CNT is 0.038, the E' is enhanced by 52% with a 5 phr of modified CNT. Also, adding the modified CNT can increase Tg of PET composites. This is explained by the confinement of dispersed polymer chains by modified CNT and limits their segmental motions.中文摘要 i 英文摘要 ii 謝誌 iii 目錄 iv 表目錄 vi 圖目錄. vii 一、緒論 1 1.1 前言 1 1.2 聚對苯二甲酸乙二酯簡介 2 1.3 奈米碳管簡介 3 1.4 研究方向 3 1.5 研究架構與流程 5 二、文獻回顧 8 2.1 二氧化矽改質碳管相關文獻 8 2.2 聚對苯二甲酸乙二酯/奈米碳管複材相關文獻 12 三、實驗 22 3.1 實驗儀器 22 3.2 實驗藥品 23 3.3 實驗步驟 25 四、結果與討論 28 4.1 二氧化矽改質碳管(SiO2/CNT)之製備與鑑定分析 28 4.1.1 紅外線光譜之官能基分析(FTIR) 30 4.1.2 熱性質分析 31 4.1.3 場發射式電子顯微鏡分析(FESEM) 31 4.1.4 能量散佈光譜分析(EDS) 32 4.2 .MPS接枝SiO2/CNT之製備與鑑定分析 32 4.2.1 紅外線光譜之官能基分析(FTIR) 33 4.2.2 熱性質分析 33 4.3 親油化SiO2/CNT之製備與鑑定分析 33 4.3.1 紅外線光譜之官能基定性分析(FTIR) 34 4.3.2 熱性質分析 34 4.3.3 導電度量測 35 4.4 熔融混煉法製備PET/改質碳管奈米複合材料與鑑定分析 35 4.4.1 紅外線光譜之官能基分析(FTIR) 36 4.4.2 導電度量測 37 4.4.3 熱性質分析 39 4.4.4 動態機械性質分析 42 4.4.5 場發射式電子顯微鏡分析(FESEM) 44 五、結論 47 六、參考文獻 49 附錄(A)、樣品代號說明 91 附錄(B)、Langmuir方程式求取平衡參數 92 附錄(C)、四點碳針直流微歐姆電阻計求取校正因子 9