Preparation and properties of epoxy nanocomposites. Part 2. The effect of dispersion and intercalation/exfoliation of organoclay on mechanical properties

The effect of the dispersion and intercalation/exfoliation of organoclay on the mechanical properties of epoxy nanocomposites was studied. The epoxy resin was EPON\u2122 828 and the hardener was an amine-terminated polyoxypropylene diol, namely Jeffamine\uae D-230. The organoclay Cloisite 30B (montmorillonite treated with a quaternary ammonium intercalant) was used. Nanocomposites were prepared by different mixing devices that can generate different shear forces, such as a mechanical stirrer, a microfluidizer, and a homogenizer. The epoxy resin and its nanocomposites were cured at 120\ub0C for 2 hours, with subsequent post cure at 140\ub0C for 2 hours. The tensile and compressive properties of the epoxy resin and its epoxy nanocomposites (ENCs) were determined. The effects of nanoclay on the mechanical properties of the EPON828-D230 system were also investigated by dynamic mechanic analysis (DMA). The results indicate that the modulus increases almost linearly with the clay loading and also is improved with the quality of micro-dispersion, although the latter plays a less important role. On the other hand the strength is very sensitive to the dispersion and only good dispersion can improve the strength, while poor dispersion results in loss of strength. Unlike the modulus, the strength levels off above 4 wt% organoclay loading. It can be concluded that finer and more uniform dispersion increases the clay surface area available for interaction with the matrix and reduces stress concentration in the large aggregates that initiate the failure under stress. It is also observed that the presence of nanoclay C30B does not significantly affect the Tg of the epoxy systems regardless of the level of clay dispersion and clay loading. DMA results also show the positive effect of dispersion and intercalation/exfoliation on the storage modulus of ENCs.Peer reviewed: NoNRC publication: Ye