Modeling of interfacial modification effects on thermal conductivity of carbon nanotube composites

Abstract

ABSTRACT:The effect of functionalization of carbon nanotubes on the thermal conductivity of nanocomposites has been studied using a multi-scale modeling approach. These results predict that grafting linear hydrocarbon chains to the surface of a single wall carbon nanotube with covalent chemical bonds should result in a significant increase in the thermal conductivity of these nanocomposites. This is due to the decrease in the interfacial thermal (Kapitza) resistance between the single wall carbon nanotube and the surrounding polymer matrix upon chemical functionalization. The nanocomposites studied here consist of single wall carbon nanotubes in a bulk poly(ethylene vinyl acetate) matrix. The nanotubes are functionalized by end-grafting linear hydrocarbon chains of varying length to the surface of the nanotube. The effect which this functionalization has on the interfacial thermal resistance is studied by molecular dynamics simulation. Interfacial thermal resistance values are calculated for a range of chemical grafting densities and with several chain lengths. These results are subsequently used in an analytical model to predict the resulting effect on the bulk thermal conductivity of the nanocomposite.

Multiscale modeling of thermal conductivity of polymer/carbon nanocomposites

“…interfacial resistances by 1/3 to 1/2, the effect on the thermal conductivity of the composite is not large. This result contrasts with the conductivity predictions for carbon nanotube composites in [8], which easily rose an order of magnitude above the base polymer. Both the thermal conductivity of the particle itself and the assumed aspect ratio were higher for the CNT.…”

“…Error bars shown are standard deviations among runs for all 3 independent configurations. Although the effect of ester-linked EVA on R K is substantial, it is noticeably less than the effect seen with directly grafted linear hydrocarbon chains [8]. Thus as might have been expected, the coupling of SWCNT vibrations to the polymeric matrix [5] is seen to be sensitive to the chemical bond topology adjacent to the tube.…”

“…This functionalization architecture is different from the end-grafting of linear chains that was modeled in ref. [8].…”

“…In a previous paper [8], functionalization of single-walled carbon nanotubes (SWCNT) by covalent grafting of alkane chains to the tube walls was studied. It was shown using molecular dynamics (MD) simulations that functionalization could reduce the interfacial thermal resistance with a vinyl polymer by an order of magnitude.…”

Graphite-high density polyethylene laminated composites with high thermal conductivity made by filament winding

“…The problem is that as polymers are typically amorphous in nature [1] they have low thermal conductivity, typically on the order of 0.1 W·m -1 ·K -1 . The two primary approaches pursued to increase the thermal conductivity of the polymers are: 1) adding high thermal conductivity materials to polymer matrices to form composites [2][3][4] and 2) mechanically stretching the native polymer itself to increase its own thermal conductivity [5][6][7][8][9][10][11]. With regards to the addition of high thermal conductivity filler materials to form composites, the concept is based on the idea of effective medium theory [12,13].…”