探討有機黏土在玻璃纖維/環氧樹脂奈米複合材料上對於機械性質所造成的影響

Abstract

本研究致力於探討有機黏土對於玻璃纖維/環氧樹脂複合材料在機械特性上的影響。 拉伸機械特性、彎曲機械特性以及層間破壞行為都在本文討論範圍之內。 為了證明有機黏土所帶來的影響，三種不同比重含量分別為2.5wt%、5wt%及7.5wt%的有機黏土，先經由機械攪拌後輔以超音波強力震盪使其均勻散布在環氧樹脂當中，利用手工積層步驟將混合好的基材塗佈於同向性的玻璃纖維布上，形成玻璃纖維/環氧樹脂奈米複合材料板材以供實驗測試。 大型萬能拉伸試驗機將用於在試片的纖維方向以及側向纖維方向施力進行拉伸測試。 而三點式彎曲試驗則可獲得複合材料的彎曲機械特性。 另外，雙懸臂梁試片將用於得到纖維複合材料的破壞行為。 從拉伸實驗中發現，當有機黏土添加的比例增高時會造成纖維方向拉伸強度的下降； 但在側向纖維方向上之拉伸強度則有明顯的提升，在側向纖維方向的材料模數上亦有相同的效果。 在側向纖維方向的試片斷裂面上利用電子掃描式顯微鏡做細部觀察，可以得知整體材料機械特性的提升，是因為有機黏土增強了玻璃纖維與環氧樹脂界面的黏著性所造成。 在側向纖維方向的材料彎曲強度也可發現相同的趨勢。 模態一的破壞試驗可測得有機黏土的比重增加時，複合材料的韌性會有明顯的下降。 不同於之前的同向性板材，擬均態複合板材試片將製作完成且進行拉伸試驗，實驗結果顯示有機黏土的添加對於此類型複合材料板材並沒有明顯的影響。

This research is aimed to investigate the organoclay effect on mechanical behaviors of the fiber/epoxy/organoclay nanocomposites. Tensile, flexure and fracture behaviors were considered in this study. To demonstrate the organoclay effect, three different loadings, 2.5, 5 and 7.5 wt% of organoclay were dispersed in the epoxy resin using mechanical mixer followed by sonication. The corresponding glass/epoxy nanocomposites were prepared by impregnating the organoclay epoxy mixture into the dry glass fiber through a vacuum hand lay-up process. For the tensile behaviors, the coupon specimens were tested in MTS machine in both longitudinal and transverse directions. The flexural properties were characterized using three point bending tests. In addition, the fracture behaviors of the fiber composites were determined from the double cantilever beam specimens. From the tensile tests, it was revealed that the longitudinal tensile strength decrease as the organoclay loading increases, on the other hand, the transverse tensile strength as well as the transverse tensile modulus increases with the increase of the organoclay. SEM observation on the transverse failure specimens indicates that the enhanced mechanism is due to the interfacial bonding between the fibers and the surrounding matrix modified by organoclay. The similar tendency was also found in the transverse flexural strength of the composites. From the mode I fracture tests It was indicated that with the increase of the organoclay, the corresponding fracture toughness of the composites decreases appreciably. In addition to the unidirectional lamina, the quasi-isotropic laminates with organoclay were prepared and tested in tension. Experimental results depict that the strength of the laminates is not affected appreciably by the organoclay.