Mechanical and thermal behavior of clay/epoxy nanocomposites

Clay/epoxy nanocomposites with concentrations of 1-10 wt.% of clay particles were prepared by shear mixing. The mechanical and viscoelastic behavior of nanocomposites was investigated using a servohydraulic testing machine and a dynamic mechanical analyzer, respectively. It was found that the addition of clay particles improved both the elastic modulus and storage modulus of pure epoxy significantly and the higher the clay content, the higher the modulus of the nanocomposite. The elastic modulus of the nanocomposites was also measured at elevated temperatures and was found to decrease gradually with temperature followed by a sudden drop at T_g, which showed a monotonic drop with increasing clay content. However, the effect of thermal exposure above T_g was found not to affect their room temperature elastic modulus. The thermal expansion coefficient (CTE) of both pure epoxy and nanocomposites was measured using a thermomechanical analyzer and it was found that the incorporation of clay particles reduced the CTE of pure epoxy.