Effect of compatibilising agents on the morphological, thermal and rheological properties of high density polyethylene/carbon nano fiber composites

High-density polyethylene filled with low-volume fractions of carbon nanofibers (CNFs) were prepared by melt-compounding. Two types of maleic anhydride (MAH) grafted polymers such as polypropylene-grafted-maleic anhydride (PPgMAH) and polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene-graft-maleic anhydride (PSgMAH) were selected as compatibilizing agents for the nanocomposites. The combined effects of these agents along with carbon nanofiber on the morphological and thermal properties were examined. All the composites mainly displayed a strong XRD reflection peak at 21.6 degrees followed by a less intensive peak at 24.0 degrees, correspond to the unit cell structure of (110) and (200) reflection planes. Scherrer analyses of XRD data showed no significant changes in the crystalline nature of nanocomposites with respect to the neat PE. Microscopic examinations revealed that the dispersion of CNFs in the nanocomposite matrices was well dispersed within the matrix without leaving any voids. DSC analysis showed clear miscibility of CNF in the HDPE matrix and showed almost same melting temperature. TGA results showed that PE/CNF samples blended with PSgMAH exhibited higher thermal stability. The melt rheological analysis of HDPE/CNF composites was performed using an oscillatory rheometer. From flow curve, it could be understood that processing of these kinds of polymer nanocomposites is quite easy at moderate high shear rate. The oscillatory rheological analysis showed the shear-thinning behavior for the prepared composites. An improvement in the viscoelastic modulus was observed as the nanofiber concentration increases. The progress in the modulus values was attributed to the structural rigidity imparted by the high aspect ratio CNF.