Mechanical and physical properties of polymer-based nanocomposites containing different types of clay

Epoxy-clay nanocomposites based on diglycidyl ether of bisphenol A (DGEBA) epoxy reinforced with 2 wt% of four different types of clay were prepared by high shear mixing (HSM) technique. The resultant nanocomposites were investigated to determine the effects of clay addition and clay types on their mechanical, thermal, and physical properties. The XRD and TEM analyses revealed that good dispersions of nanoclay within the epoxy matrix have been achieved especially for the samples prepared with I.30E clay where a combination of disordered intercalated and exfoliated morphology was observed. The structure of samples synthesized with other types of clay was dominated by intercalated morphologies. The tensile results illustrated that the nanocomposite containing I.30E clay has the best mechanical properties as compared to other nanocomposites. This is mainly due to better dispersion of I.30E nanoclay in the epoxy matrix for this nanocomposite. The increase or decrease in the glass transition temperatures of nanocomposites were found to be dependent on the type of clay used. The effect of clay addition on the barrier properties was examined using water exposure test which demonstrated that the addition of 2% of I.30E and C10A clays resulted in 60% reduction in diffusivity. Noticeable reduction in maximum water uptake was also observed for all nanocomposites. The improvement in these physical properties was attributed to the tortuosity effect, where water molecules have to move around clay layers during diffusion in nanocomposites.