Emulsion polymerized polystyrene/montmorillonite nanocomposite and its viscoelastic characteristics

A novel polystyrene ( PS)/clay nanocomposite was synthesized using a simple emulsion polymerization method in the presence of sodium ion exchanged montmorillonite ( Na-MMT). Prior to the radical polymerization procedure with potassium persulfate ( KPS) as an initiator, the hydrophobic styrene monomer was intercalated into hydrophilic clay layers using sodium dodecyl sulfate ( SDS) as a surfactant. The FTIR spectra of the products showed the characteristic absorbance peaks of both the synthesized PS and Na-MMT. The x-ray diffraction patterns of the products exhibited an increase in the d(001)-spacing, pointing to the intercalation of the PS chains into the intergalleries of the Na-MMT. The enhancement of the thermal properties of the nanocomposite materials, such as the increase in the glass transition temperature of the PS, was investigated by differential scanning calorimetry ( DSC). Furthermore, based on the viscoelastic properties of the products examined using a rotational rheometer with a parallel plate geometry, the nanocomposites were found to exhibit more rapid shear thinning and increased storage ( G') and loss ( G '') moduli with increasing clay content.