Morphological and rheological properties of polyamide 6/poly(propylene)/organoclay nanocomposites

Polyamide 6 (PA6)/Poly(propylene) (PP)/organoclay (octadecylamine intercalated montmorillonite) systems with and without compatibilizer (maleated poly(propylene) and ethylene/propylene-based rubber (PPgMA and EPR-MA, respectively)) were produced by extrusion melt blending and the clay dispersion was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The rheological behaviour of the nanocomposites was determined by various methods, viz melt flow index (MFI), capillary and plate/plate rheological measurements. Attempts were made to trace the rheological parameters that reliably reflect the observed changes in the clay dispersion. It was found that some parameters in the viscoelastic range derived from frequency sweep measurements using a plate/plate rheometer are a suitable indicator for changes in the clay dispersion. High initial viscosity with a strong reduction as a function of frequency was attributed to improved clay exfoliation. The latter was also reflected by a high initial shear storage modulus (U) along with its small change with the frequency.