Effect of sonication and high shear mixing parameters on nanoclay dispersion in epoxy

In this study we have investigated the effects of mixing parameters on the extent and structural morphology of the nanoclay dispersion and distribution in the epoxy matrix. Two mixing methods namely, sonication mixing and high shear mixing were used to disperse organically modified Nanomer I.30E nanoclay within Diglycidyl ether of Bisphenol A (DGEBA) epoxy resin. Mixing by sonication was performed for periods ranging from 5 to 60 minutes, whereas high shear mixing (HSM) was performed at mixing speeds ranging from 500 to 8000 rpm and mixing durations of 15 to 90 minutes. Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) techniques were employed to examine the effects of sonication time and HSM speed and time on the extent of dispersion and structural morphology of the nanocomposite. The results show that under the same optimal curing conditions, the mixing parameters play a significant role in determining the degree and structural morphology of clay dispersion in the epoxy matrix. Increasing sonication time enhanced the clay dispersion and the highest d-spacing was observed for nanocomposite sonicated for 30 minutes. The optimum structural morphologies resulted from HSM at 6000 rpm for 60 minutes. Both techniques predominantly produced intercalated morphologies and the d-spacing of nanocomposites fabricated by HSM is higher than that of sample prepared by sonication which indicated that HSM is more effective than sonication in nanoclay dispersion.