Dielectric response of modified epoxy/clay nanocomposites

Thermoset polymers are frequently used as matrices for nanocomposite materials because nanofillers, such as clay, can be easily incorporated into liquid polymer precursors. Since in the crystal structure of clay such as Montmorillonite the layers are physically linked by cations, replacing these cations with larger organophilic molecules changes the clay surface into hydrophobic and increases the interlayer space. This improves the compatability between montmorillonite and most of engineering polymers, making it suitable for nanocomposite application. This paper investigates the influence of surface treatment on calorimetric and dielectric properties of a commercially available organoclay with different extent of free surfactant and moisture level, using filled epoxy nanocomposites. The moisture content of the nanocomposites was measured using Thermogravimetric Analysis (TGA). Thermal stability was investigated using Differential Scanning Calorimetry (DSC) with the glass transition temperature chosen as an indicator. Finally, dielectric response of the materials was investigated at room temperature using Broadband Dielectric Spectroscopy (BDS).