Crystallization behavior and physical properties of polyamide46/graphene oxide and polyamide612/graphene oxide composites

本實驗利用化學改質法來製備出氧化石墨，並經由FT-IR及XRD結果分析氧化石墨有鍵結上氧化官能基的吸收峰存在，使層間距增大 ; 另外由Raman及TGA結果分析顯示氧化後造成ID/IG比值上升，並得知鍵結氧化官能基之比例為25%，再藉由超音波震盪成功得到分散性良好之氧化石墨烯。 本研究以溶液混合法分別將1wt%、3wt%及5wt%氧化石墨烯(graphene oxide，GO)添加入聚醯胺46 (polyamide 46，PA46)與聚醯胺612 (polyamide 612，PA612)中，製備成PA46/GO複合材料與PA612/GO複合材料，來探討添加不同含量GO對高分子的分散性、結構、結晶行為與物理性質所造成之影響。 首先將添加不同含量GO之PA46及PA612複合材料以TEM進行分散性分析，由結果可觀察到GO良好分散於高分子基材中。在XRD結果中發現添加入GO並不會造成高分子基材結構上的改變。 以DSC進行PA46/GO複合材料等溫結晶研究方面，當添加入5wt% GO後，誘發了異質成核效應，因此加速高分子結晶，使得結晶速率常數隨GO含量增加而增加，半結晶時間也有縮短的趨勢，所以5wt% GO/PA46複合材料具有最快之結晶速率。觀察等溫結晶活化能，隨著加入5wt% GO至PA46基材，使活化能由742.8 kJ/mol 下降至588.0 kJ/mol。PA46基材平衡熔點隨添加5wt% GO由335.7℃下降至323.9℃，是由於添加GO造成晶體結構較不完美所致。由POM觀察添加入GO之PA46球晶型態，發現隨著GO添加量增加，球晶變小，數量變多，表示加入GO誘發異質成核效應，增加成核密度所致。PA46基材之表面折疊能隨添加5wt% GO由3.71E+03 erg2/cm4下降至2.08E+03 erg2/cm4。並由DMA觀察複合材料之機械性質，顯示添加入5wt% GO後使PA46之儲存模數由8.9E+08 Pa上升至1.8E+09 Pa，推測是由於高分子鏈被限制於GO薄片中限制其運動所導致。並且也可以觀察到添加5 wt% GO使PA46基材之結晶度由46.7%提升至54.1%，表示加入GO誘發異質成核效應，提升了高分子之結晶度。 以DSC進行PA612/GO複合材料等溫結晶研究方面，當添加入3wt% GO，因異質成核效應，使得結晶速率常數增加，也縮短了半結晶時間，加入5 wt% GO結晶速率常數下降，半結晶時間增加了，顯示GO形成立體空間障礙，阻礙分子鏈移動所致，因此添加入3wt% GO之PA612具有最快之結晶速率。在等溫結晶活化能方面，加入3wt% GO之PA612基材因誘發異質成核，活化能由391.6 kJ/mol 下降至308.3 kJ/mol，當添加5wt% GO使PA612複合材料的活化能上升至331.2 kJ/mol，表示GO已阻礙分子鏈運動。PA612基材在加入5wt% GO之平衡熔點由222.6℃下降至214.7℃，是由於添加GO造成晶體結構較不完美所致。由POM結果顯示添加GO至PA612基材， 使成核密度增加，和球晶尺寸變小。添加入3wt% GO之PA612基材表面折疊能由1.71E+02 erg2/cm4下降至7.32E+01 erg2/cm4，然而添加入5wt% GO之PA612複合材料表面折疊能上升至9.24E+01 erg2/cm4，表示GO阻礙了分子鏈運動。DMA結果顯示，加入5wt% GO之PA612儲存模數由1.03E+09 Pa上升至1.57E+09 Pa，推測是由於高分子鏈被限制於GO薄片中限制其運動所導致。添加3wt% GO 使PA612基材之結晶度由30.4%提升至32.0%，表示加入GO誘發異質成核效應，當添加入5wt% GO之PA612結晶度下降，推測是由於GO已經阻礙到分子鏈排列成晶體。The chemically modified graphite oxide was characterized using FTIR and XRD method. Both results indicate that the presence of oxidation functional groups on the surface of graphite oxide might enlarge the interlayer spacing of graphite. The ratio of ID/IG for graphite oxide determined using Raman spectrometer was increased, which could be well dispersed into graphene oxide through ultrasonication process. Therefore, polyamide 46 (PA46)/graphene oxide (GO) and polyamide 612 (PA612)/graphene oxide nanocomposits were successfully fabricated in this study by solution mixing PA46 and PA612 into chemically modified graphite oxide through ultrasonication process. The effect of GO on the microstructure, crystallization behavior and physical properties were investigated. Both TEM and XRD results show the graphene oxide was well distributed into polyamide matrix. The crystallize structure of polyamide did not change with the incorporation of GO. The crystallization behavior of PA46/GO nanocomposite were investigated using DSC. The addition of 5wt% GO into PA46 matrix could induce hetergeneous nucleation and enhance the crystalline growth rate of PA46 crystalline. The incorporation of 5wt% GO into PA46 matrix could reduce the activation energy from 742.8 kJ/mol for PA46 into 588.0 kJ/mol. The equilibrium melting temperature of 5wt% PA46/GO nanocomposite is reduced from 335.7℃ for neat PA46 matrix into 323.9℃, suggesting that the crystalline structures of PA46/GO nanocomposites was less perfect than that of the PA46 matrix. The POM data of nanocomposite revealed that the addition of GO into PA46 matrix could increase the nucleation density and reduce the spherulitic size. The folding energy of PA46/GO nanocomposites decreased from 3.71×103 erg2/cm4 for PA46 into 2.08×102 erg2/cm4 for 5wt% PA46/GO nanocomposites. The storage modulus of nanocomposites obtained using DMA increased from 8.9×108 Pa for PA46 into 1.8×109 Pa for 5wt% PA46/GO nanocomposite. The result suggests that the incorporation of GO into polymr matrix could reduce the polymr chain movement within the gallery of GO sheets. The crystallinity of PA46/GO nanocomposite is increased from 46.7% for neat PA46 matrix into 54.1% for 5wt% nanocomposite, suggesting that the addition of GO into PA46 matrix could induce hetergeneous nucleation and thus increased the crystallinity. DSC isothermal results of PA612/GO nanocomposites revealed that the addition of 3wt% GO into PA612 matrix could induce hetergeneous nucleation and enhance the crystalline growth rate of PA612 crystalline. Addition of 5wt% GO into PA612 matrix causes more steric hindrance, thus reduce the transportation ability of polymer chains during crystallization process. The incorporation of 3wt% GO into PA612 matrix could reduce the activation energy from 391.6 kJ/mol for PA612 into 308.3 kJ/mol, and then increase to 331.2 kJ/mol as the loading of 5wt% GO. This result indicates that the addition of 5wt% GO into PA612 matrix reduced the transportation ability of polymer chains during crystallization. The equilibrium melting temperature of 5wt% PA612/GO nanocomposite are reduced from 222.6℃ for neat PA612 matrix into 214.7℃, suggesting that the crystalline structures of PA612/GO nanocomposites was less perfect than that of the PA612 matrix. The POM data of nanocomposite revealed that the addition of GO into PA612 matrix could increase the nucleation density and reduce the spherulitic size. The folding energy of PA612/GO nanocomposites decreased from 1.71×102 erg2/cm4 for PA612 into 7.32×101 erg2/cm4 for 3wt% PA612/GO nanocomposites, and then increase to 9.24×101 erg2/cm4 as the loading of 5wt% GO, thus a reduces the transportation ability of polymer chains. The storage modulus of nanocomposites obtained using DMA increased from 1.03×109 Pa for PA612 into 1.57×109 Pa for 5wt% PA612/GO nanocomposite. The result suggests that the incorporation of GO into polymr matrix could reduce the polymr chain movement within the gallery of GO sheets. The crystallinity of PA612/GO nanocomposite is increased from 30.4% for neat PA612 matrix into 32.0% for 3wt% nanocomposite, suggesting that addition of GO into PA612 matrix could induce hetergeneous nucleation and thus increased the crystallinity. As the loading of 5wt% GO into PA612 matrix could decrease the crystallinity to 30.8%, which might due to the limitation of polymer chain movement for crystallization.摘要 I Abstract III 總目次 V 圖目次 VIII 表目次 XII 第一章 緒論 1 1-1 前言 1 1-2 研究動機與目的 3 1-3 研究方向 4 第二章 文獻回顧 5 2-1 高分子複合材料 5 2-2 聚醯胺 (polyamide) 6 2-3 聚醯胺46 (polyamide 46) 7 2-3-1 聚醯胺 46之結晶行為 8 2-3-2 聚醯胺 46複合材料之性質 10 2-4 聚醯胺 612 13 2-4-1 聚醯胺 612複合材料之性質 13 2-5 石墨烯 16 2-5-1 石墨烯之製備 18 2-5-2 化學法製備石墨烯 22 2-5-3 高分子複合材料之特性 26 2-6 高分子結晶動力學 34 2-6-1 Avrami 方程式 34 2-6-2 平衡熔點(equilibrium melting temperature) 35 2-6-3 Hoffman-Lauritzen理論 36 第三章 實驗方法與步驟 38 3-1 實驗材料 38 3-2 實驗儀器 39 3-3 實驗步驟 40 3-3-1 氧化石墨之製備 40 3-3-2 聚醯胺46薄膜之製備 41 3-3-3 聚醯胺46/氧化石墨烯複合材料之製備 42 3-3-4 聚醯胺612薄膜之製備 43 3-3-5 聚醯胺612/氧化石墨烯複合材料之製備 44 3-4 實驗儀器分析原理 45 3-5 樣品代碼 47 第四章 結果與討論 48 4-1 化學法製備石墨烯 48 4-1-1 氧化石墨性質分析 48 4-2 聚醯胺46/氧化石墨烯複合材料之物化特性分析 53 4-2-1 聚醯胺46/氧化石墨烯複合材料之分散性 53 4-2-2 聚醯胺46/氧化石墨烯複合材料之結構分析 56 4-2-3 聚醯胺46/氧化石墨烯複合材料之熱性質分析 59 4-2-4 聚醯胺46/氧化石墨烯複合材料之等溫結晶行為研究 62 4-3 聚醯胺612/氧化石墨烯複合材料之物化特性分析 78 4-3-1 聚醯胺612/氧化石墨烯複合材料之分散性 78 4-3-2 聚醯胺612/氧化石墨烯複合材料之結構分析 81 4-3-3 聚醯胺612/氧化石墨烯複合材料之熱性質分析 85 4-3-4 聚醯胺612/氧化石墨烯複合材料之等溫結晶行為研究 87 4-4 聚醯胺46/氧化石墨烯與聚醯胺612/氧化石墨烯複合材料之物化特性比較 105 第五章 結論 109 參考文獻 11