Influence of Interface on epoxy/clay Nanocomposites: 2. Mechanical and Thermal Dynamic Properties

The particle interface has been known to play a critical role in conventional composites. Nevertheless, the understanding of the role of interface in mechanical and thermal properties of polymer nanocomposites remains in its infancy. Similar to the previous study, two different designs of interface modification—molecular entanglement and chemical reaction—were adopted by using three variants surfactants, i.e. ethanolamine (denoted eth), Jeffamine M2070 (m27) and Jeffamine XTJ502 (xtj). Epoxy nanocomposites were prepared via solution compounding with 0.46–1.87 vol% of the modified clay. To that end, the interface strength was measured by tensile test, fracture toughness and dynamic mechanical analysis. The results found that a consistent increase in Tgs with increases in clay fractions. With 1.16 vol% layer clays, the critical strain energy release rate G1c of neat epoxy improved from 188.6 to 405.3 kJ/m, 115% improvement and stiffness enhanced from 2.69 to 3.54 GPa, 31% improvement. This result proved that the chemical reaction of amino-groups of xtj-clay with epoxy created a strong interface, thus resulting in a large enhancement of mechanical properties, fracture toughness and thermal dynamic properties.