Effect of graphite nanoplatelets percentage on the in plane thermal diffusivity of ultra-thin graphene based (nanostructured) composite

The increasing demand for high-performance materials in thermal management has focussed the attention on new materials like graphene/graphite paper. These materials offer a unique combination of properties, such as: high electrical and thermal conductivity, high thermal diffusivity, they are flexible, lightweight, good mechanical properties and, sometimes, cost-effective. However, compared to traditional materials, their thermal characterization is more complex. Consequently, it is important to develop and assess both low-cost techniques for GNP composite paper production, as well as procedures to measure their thermal properties. In the present work, graphite nanoplatelets composite (GNPs composite) with different GNP content (in the range 70–100%) were adopted for the production of thin foils (50–70 µm in thickness) by solvent impregnation techniques, followed by hot plate curing. Spatially Resolved Method (SRM) technique was adopted to measure the in-plane thermal diffusivity of the composites. Tests were carried out adopting a diode laser as a heat generator and an IR camera to acquire the temperature distribution after heating. Two different procedures were adopted: in the first, the samples were coated by a radiation absorbent paint, with a known emissivity. The second one involves the use of the “as-received” samples and their actual emission coefficient. ANalysis Of VAriance was adopted to discriminate the effect of the radiation absorbent coating and the GNP content. From the results, the SRM technique is an effective method for the measurement of in-plane thermal diffusivity of ultra-thin GNP composites. The latter varies in the range 33–87 mm2/s, according to the GNP content.