Mechanical properties of epoxy-based composites using nanoclays

Various percentages of nanoclay added into the epoxy resin were mixed by mechanical stirring and then mould forming to a dog-bone shape samples. The mechanical properties of the composites were characterized in terms of tensile tests and Vickers' hardness tests. Moreover, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to investigate the quantity and the distribution of nanoclay inside the composites. From the XRD patterns, the height of the diffraction peaks of nanoclay in the nanoclay-epoxy samples increased linearly with the weight percentage of nanoclay added. It was found that the composition at 5 wt% nanoclay gave the higher ultimate tensile strength, when compared with pure epoxy sample by an increment of about 5%. Furthermore, it gave the largest Vickers hardness value amongst all the compositions. However, the ductility decreased drastically and the sample was abruptly torn apart right after showing the peak of ultimate tensile strength. Furthermore, from the SEM images, the more the addition of nanoclay inside the epoxy, the smaller the fracture pieces in the cleavage surface. Therefore, it can be concluded that the ribbon-like nanoclay as shown in the SEM image hindered the linking up of epoxy chains network in decreasing the ductility, but it did make the nanoclay-epoxy samples stronger and harder in a certain extent. (C) 2006 Elsevier Ltd. All rights reserved.