Constructing fully carbon-based fillers with a hierarchical structure to fabricate highly thermally conductive polyimide nanocomposites

摘要

A novel kind of fully carbon-based filler (f-MWCNT-g-rGO) is constructed by a reaction between melted urea functionalized multi-walled carbon nanotubes (f-MWCNTs) and graphene oxide (GO) followed by chemical reduction. The corresponding highly thermally conductive polyimide (f-MWCNT-g-rGO/PI) nanocomposites are then fabricated through the combined method of in situ polymerization, electrospinning and hot pressing. An improved thermal conduction model is also proposed and established considering the filler/matrix interfaces, filler dispersion and alignment, etc. The f-MWCNT-g-rGO fillers have a hierarchical "line-plane" structure. The fabricated f-MWCNT-g-rGO/PI nanocomposites possess an outstanding thermal conductivity coefficient (lambda), and excellent thermal stabilities and mechanical properties. Specifically, the f-MWCNT-g-rGO/PI nanocomposites reach the maximum lambda of 1.60 W m(-1) K-1 at a relatively low loading of f-MWCNT-g-rGO fillers (10 wt%, the mass ratio of rGO to f-MWCNT is 2 : 1). In addition, the theoretical lambda value calculated by our established thermal conduction model is more in line with the experimental lambda values compared with other traditional models. Owing to the high thermal conductivities while preserving good mechanical properties and thermal stabilities at a relatively low loading of f-MWCNT-g-rGO filler, the f-MWCNT-g-rGO/PI nanocomposites are expected to be used as thermal pads in light emitting diode (LED) substrates and liquid crystal displays.