Rheological Behavior and Morphology of Polyamide Nanocomposites

Polymeric nanocomposites (NC) are materials that contain dispersed nanometer – size particles in a single or multi – component polymeric matrix . The nano-particle can be lamellar ,fibrillar, tubular , shelllike , spherical ,etc . The most commonly used nanoparticle is the smectite group mineral such as montmorillonite (MMT) , which belongs to the general family of 2:1 Layered Silicates. To ascertain good dispersion in a hydrophobic melt , they are usually reacted with organic compounds , such as alkylammonium ions via an ion-exchange reaction to render the hydrophilic layered silicate organophilic and forming organoclay . The majority of commercial NC contain 2-10 wt % of organoclay . Nanocomposites have been prepared with virtually all commodity and engineering , thermoplastic and thermoset resins . However , from the long list , the historically first and commercially the most important are nanocomposites based on polyamides , especially on poly – є – caprolactam (PA-6) . In this article, the nanocomposites of injection grade polyamide 6 with organically modified nanoclay were prepared via melt compounding in a twin-screw extruder. The rheological behavior, orphology and mechanical properties of nanocomposites have been studied using capillary rheometer, X-ray diffraction (XRD) and tapping-mode atomic force microscopy (AFM) . XRD patterns and AFM images indicate that organically modified layered silicate is well dispersed in polyamide 6 matrix. The rheological studies show that the prepared nanocomposites have shear thinning behavior, obeying the power law equation. ddition of organoclay increase the shear stress and shear viscosity. At high rate of shear deformation the viscosity of nanocomposites are comparable to those of the pure polyamides. The activation energy of flow decreases with increasing nanoclay content, while for most of nanocomposites the activation energy values increase with increasing shear rate.

کلیدواژه ها:

Polymer ، Nanocomposite ، Rheology ، AFM