Enhanced thermal conductivity of polyethylene nanocomposites with graphene, granulated graphene, graphene nanoplatelet, and their hybrids

We report enhanced thermal conductivity of of low-density polyethylene (LDPE) with granulated graphene. The morphological analysis of the nanocomposite releveled granulated graphene is dispersed in LDPE and randomly oriented. The melt processing has reduced the filler's lateral size. At 40 wt. % loading of granulated graphene, the nanocomposite thermal conductivioty (κ_c) reached 2.91 W/m.K, corresponding to ~1000% increase overLDPE. This very high enhancement is attributed to the reduction in the polymer/filler's thermal interfacial resistance due to the graphene sheets' broad size distribution. The experimentally measured κ_c was compared theoretically predicted. The theoretical model provided reasonable prediction of κ_c versus the filler loading. Furthermore, hybrid fillers on binary and ternary combinations of graphene, graphene nanoplatelets, and micrographite with granulated graphene were also prepared. The hybrid fillers revealed that fillers with similar shape and different aspect ratios did not display any synergetic κ_c.