Halloysite nanotubes functionalized with epoxy and thiol organosilane groups to improve fracture toughness in nanocomposites
Halloysite nanotubes functionalized with epoxy and thiol organosilane groups to improve fracture toughness in nanocomposites
复制标题
DOI：
10.1007/s42452-020-03909-2
复制
发表时间：
2020-12-02
影响因子：
2.6
通讯作者：
Koricho, Ermias
中科院分区：
文献类型：
--
作者：
Murphy, Zachary;Kent, Malachi;Koricho, Ermias
纳米填料在基体内的表面功能化提供了与环氧树脂的良好界面粘附性，因此，在本研究中，使用纯功能化的高岭土纳米管（HNTs）作为填料来提高SC-15环氧树脂的断裂韧性。通过红外光谱（IR）、扫描电镜（SEM）、x射线能谱（EDS）、粉末x射线衍射（PXRD）和热重分析（TGA）对HNTs进行了表征。由这些填料制成的纳米复合材料进行了致密拉伸（CT）测试，重量从0到2%不等，然后按照ASTM D5045标准进行了制造和测试，以评估断裂韧性。测量了临界应力强度因子（K-IC）和临界应变能释放率（G(IC)），并将试验结果与SEM获得的裂隙面图像模式建立了相关性。实验结果表明，在SC-15环氧树脂中加入HNTs纳米填料可以观察到协同效应。K-IC和G（IC）的最高改进分别是使用2%的HNT-硫醇，其次是2%的纯HNT，和1%的HNT-环氧纳米填料。SEM观察进一步证实，纯官能化的HNT的存在使SC-15环氧树脂基体的韧性机制从光滑、低伪延性转变为多种能量吸收机制，如原纤维、河衬、裂纹桥接、裂纹、微孔和毛刺。
The surface functionalization of nanofillers imbibed within the matrix provides great interfacial adhesion with the epoxy resin and as such, in this study, the pure and functionalized halloysite nanotubes (HNTs) were used as fillers to improve the fracture toughness of an SC-15 epoxy resin. The HNTs were grafted with an organosilane group having terminal epoxy and thiol functional groups as two different crosslinkers and were thoroughly characterized with infrared spectroscopy (IR), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). The nanocomposites resulting from these fillers were used in compact tension (CT) testing with varying weight % from 0 to 2%, which were then fabricated and tested as per ASTM D5045 standard to evaluate the fracture toughness. The critical stress intensity factor (K-IC) and the critical strain energy release rate (G(IC)) were measured, and a correlation was established between the test results and the mode of fractured surface images obtained by the SEM. Experimental results showed that the synergistic effect was observed with the addition of HNTs nanofillers into the SC-15 epoxy. The highest improved K-IC and G(IC) were achieved using 2% HNT-thiol, followed by 2% pure HNT, and 1% HNT-epoxy nanofillers, respectively. SEM observation further confirmed that the presence of pure and functionalized HNT in the SC-15 epoxy matrix changed the toughness mechanics from smooth and low pseudo-ductile to several energy absorption mechanisms such as fibrils, river liner, crack bridging, crazing, microvoids, and hackles.