The role of nanofiller size and polymer chain configuration on the properties of polypropylene/graphite nanoplates composites

This study aimed to evaluate the impacts of different polypropylene (PP) chain configurations, i.e., linear and branched form, on the rheological, mechanical, and electrical properties of PP-based, graphite nanoplates (GnP)-reinforced nanocomposites. The incorporation of GnP with different particle size gave us constructive information about the influences of filler's dimension on the abovementioned properties. A solid-state shear pulverization (SSSP) technique followed by conventional melt mixing was employed to get GnP-filled samples prepared for better filler dispersion. Due to higher interfacial surface area, the obtained mechanical properties from finer GnP were more satisfying. However, the electrical and rheological percolation thresholds (the formation of conductive pathways) took place at a lower content of larger GnP, which is mainly due to its higher aspect ratio compared to GnP. Replacement of linear PP with branched one did not lead to conspicuous alterations in tensile modulus and strength. Based on rheological evaluations, however, the presence of side branches hindered the development of GnP sound network throughout PP matrix, so that in comparison to linear PP-based sample the augmentation of electrical conductivity of branched PP-based composites against filler loading demonstrated slower rates.