Rheological and thermal properties of exfoliated graphite nanoplatelets‐filled impact modified polypropylene nanocomposites

The objective of this research was to investigate the influence of exfoliated graphite nanoplatelets (xGnP) particle diameter, filler loading, and the addition of coupling agents on the rheological and thermal properties of xGnP‐filled impact modified polypropylene (IMPP) nanocomposites. xGnP‐filled IMPP composites were manufactured via melt mixing with and without the addition of polypropylene‐graft‐maleic anhydride (PP‐g‐MA). Particle diameter of xGnP had no significant effect on the melting (T_m) and crystallization (T_c) temperatures as well as degradation behavior of the composites. Storage modulus (E′) of the composites increased with increasing xGnP percent at high filler loadings and the incorporation of xGnP did not significantly affect the glass transition temperature, but filler loading does have a significant effect on the magnitude of the tan delta max peak values. The shear storage modulus (G′) of the composites with smaller diameter xGnP particles was lower than those of the composites with big diameter particle xGnP at lower frequencies. The higher the xGnP content of the composite, the higher the shear viscosity and the smaller particle diameter of xGnP results in lower viscosity values. Addition of a coupling agent decreased the melt viscosity of the xGnP‐filled nanocomposites and caused a slight reduction in the shear‐thinning behavior. POLYM. COMPOS., 39:E1512–E1519, 2018. © 2017 Society of Plastics Engineers