Interface-tuned epoxy/clay nanocomposites

Though interface has been known for playing a critical role in determining the properties of conventional composites, its role in polymer nanocomposites is still fragmented and in its infancy. This study synthesized a series of epoxy/clay nanocomposites with different interface strength by using three types of modifiers: ethanolamine (denoted ETH), Jeffamine® M2070 (M27) and Jeffamine® XTJ502 (XTJ). XTJ created a strong interface between clay layers and matrix because it bridged the layers with matrix by a chemical reaction which was proved by Fourier transform infrared spectroscopy; M27 produced an intermediate interface due to the entanglement between grafted M27 molecules and matrix molecules; the interface made by ETH was weak because neither chemical bridging nor physical entanglement was involved. The studies of mechanical & thermal properties and morphology at both low and high magnification show that high interface strength promoted the exfoliation and dispersion of clay clays, and improved the Young’s modulus, fracture toughness and glass transition temperature (Tg) of matrix. With ~1.3 wt% clay, the critical strain energy release rate G1c of neat epoxy improved from 188.6 to 405.3 kJ/m, 115% improvement and Tg enhanced from 93.7 to 99.7 C, 6.4 % improvement