Hybrid Layered Silicate/Calcium Carbonate Reinforced High-density Polyethylene Nanocomposites: Systematic Morphological Evaluation through Rheological Properties and Response Surface Method

High-density polyethylene (HDPE) based hybrid nanocomposites comprising varying concentrations of layered nanoclay (NC) and spherical nano calcium carbonate (nCaCO3) were prepared by a two-step melt compounding process in the presence of polyethylene grafted maleic anhydride (PE-g-MA) as the compatibilizer. Regarding multiple material variables (the NC, nCaCO3 and compatibilizer contents) participated in fabrication of the nanocomposites, response surface methodology (RSM) was utilized to find the correlation between the material variables, morphology and viscoelastic responses in the melt state. Intercalation of the layered silicates was investigated by X-ray diffraction (XRD) technique, and morphological characterization of the nanosized calcium carbonates was carried out by scanning electron microscope (SEM). The findings indicated that higher contents of the PE-g-MA facilitated the intercalation process and increased the interlayer distance. Interestingly, incorporation of the second nanoparticle, nano calcium carbonate, resulted in viscosity increment which is an influential factor on applied stresses during the melt mixing and subsequently, dispersion state of the nanoclay layers. The interplay between the designated material parameters was also discussed by means of interaction plots.