Department of Materials Engineering, Indian Institute of Science , Bengaluru 560012, Karnataka, India.
Boeing International Corporation India Private Limited , RMZ Infinity, Tower D, 5th Floor, Old Madras Road, Bengaluru 560001, Karnataka, India.
ACS Appl Mater Interfaces. 2017 Apr 26;9(16):14347-14357. doi: 10.1021/acsami.7b01608. Epub 2017 Apr 13.
In the present study, noncovalently functionalized tungsten disulfide (WS) nanosheets were used as a toughening agent for epoxy nanocomposites. WS was modified with branched polyethyleneimine (PEI) to increase the degree of interaction of nanosheets with the epoxy matrix and prevent restacking and agglomeration of the sheets in the epoxy matrix. The functionalization of WS sheets was confirmed through Fourier transform infrared spectroscopy and thermogravimetric analysis. The exfoliation of the bulk WS was confirmed through X-ray diffraction and various microscopic techniques. Epoxy nanocomposites containing up to 1 wt % of WS-PEI nanosheets were fabricated. They showed a remarkable improvement in fracture toughness (K). K increased from 0.94 to 1.72 MPa m for WS-PEI nanosheet loadings as low as 0.25 wt %. Compressive and flexural properties also showed a significant improvement as incorporation of 0.25 wt % of WS-PEI nanosheets resulted in 43 and 65% increase in the compressive and flexural strengths of epoxy nanocomposites, respectively, compared with neat epoxy. Thermal stability and thermomechanical properties of the WS-PEI-modified epoxy also showed a significant improvement. The simultaneous improvement in the mechanical and thermal properties could be attributed to the good dispersion of WS-PEI nanosheets in the matrix, intrinsic high strength and thermal properties of the nanosheets, and improved interaction of the WS nanosheets with the epoxy matrix owing to the presence of PEI molecules on the surface of the WS nanosheets.
在本研究中，非共价功能化的二硫化钨（WS）纳米片被用作环氧树脂纳米复合材料的增韧剂。WS 通过支化聚乙烯亚胺（PEI）进行改性，以增加纳米片与环氧树脂基体的相互作用程度，并防止纳米片在环氧树脂基体中重新堆积和团聚。通过傅里叶变换红外光谱和热重分析证实了 WS 纳米片的功能化。通过 X 射线衍射和各种微观技术证实了块状 WS 的剥离。制备了含有高达 1wt%WS-PEI 纳米片的环氧树脂纳米复合材料。当 WS-PEI 纳米片的负载量低至 0.25wt%时，它们的断裂韧性（K）显著提高。K 从 0.94 增加到 1.72MPa·m，当加入 0.25wt%的 WS-PEI 纳米片时，环氧树脂纳米复合材料的压缩和弯曲性能也分别显著提高，与纯环氧树脂相比，压缩强度和弯曲强度分别提高了 43%和 65%。WS-PEI 改性环氧树脂的热稳定性和热机械性能也得到了显著改善。机械和热性能的同时提高可归因于 WS-PEI 纳米片在基体中的良好分散、纳米片的固有高强度和高热性能，以及由于 WS 纳米片表面存在 PEI 分子而改善的 WS 纳米片与环氧树脂基体的相互作用。
