Oxidized Polypropylene Wax in Polypropylene Nanocomposites: A Comparative Study on Clay Intercalation

Polypropylene-clay nanocomposites were prepared in solution and followed by a melt mixing process. The nanocomposites were prepared for 5% (by weight) organoclay with varying amounts of two oxidized polypropylene waxes (OPPWs) as compatibilizer. The clay dispersion was analyzed by X-ray diffraction (XRD), transmission electron microscopy and melt rheology technique. The extent of intercalation in clay platelets was quantified by XRD analysis based on interactions between OPPW and clay layers. A maximum of ca. 10% increase in clay basal spacing was observed. It was revealed that the degree of clay intercalation in solution technique varies by the polarity of OPPW. In subsequent melt mixing process, the clay dispersion was evaluated by XRD which correlated well with the variations of storage moduli at low frequency region and displayed a pseudo solid-like behaviour. The rheological measurements also showed higher dispersion of clay platelets in PP matrix in the presence of OPPW. The increase in storage moduli especially at low frequency region implied that there were stronger interactions between Cloisite® 15A organoclays and polymer chains when OPPW is present. The TEM images mainly suggested to com-patibilizing effect of OPPW in clay intercalation. In spite of low mechanical properties of OPPW, the DMTA showed the highest modulus of glassy region in nanocomposites with maximum OPPW content. These findings agreed well with each other in co-intercalation effect of OPPW in PP nanocomposites.