Thermal Conductivity of Graphene Laminate: Making Plastic Thermally Conductive

TL;DR

This study measures the thermal conductivity of graphene laminate films on plastic substrates, revealing that flake size and alignment significantly influence heat conduction, with potential for substantial enhancement of plastic thermal properties.

Contribution

It demonstrates that flake size and alignment are key factors in thermal conductivity, and shows how compression improves heat conduction in graphene laminates.

Findings

Thermal conductivity ranges from 40 to 90 W/mK at room temperature.

Flake size and alignment are more influential than mass density.

Compression improves flake alignment and thermal conductivity.

Abstract

We have investigated thermal conductivity of graphene laminate films deposited on polyethylene terephthalate substrates. Two types of graphene laminate were studied - as deposited and compressed - in order to determine the physical parameters affecting the heat conduction the most. The measurements were performed using the optothermal Raman technique and a set of suspended samples with the graphene laminate thickness from 9 to 44 micrometers. The thermal conductivity of graphene laminate was found to be in the range from 40 W/mK to 90 W/mK at room temperature. It was found unexpectedly that the average size and the alignment of graphene flakes are more important parameters defining the heat conduction than the mass density of the graphene laminate. The thermal conductivity scales up linearly with the average graphene flake size in both uncompressed and compressed laminates. The compressed laminates have higher thermal conductivity for the same average flake size owing to better flake alignment. The possibility of up to 600X enhancement of the thermal conductivity of plastic materials by coating them with the thin graphene laminate films has important practical implications.