Characterization of the thermal conductivity and diffusivity of graphene nanoplatelets strips: a low-cost technique

Abstract

This paper proposes a new technique to characterize the thermal conductivity and diffusivity of thin strips made by graphene nanoplatelets. The evaluation of these parameters is essential for a reliable design of thermal and electrothermal applications of graphene and is usually performed by means of assessed but expensive techniques such as those based on Raman effects and laser flash. The technique proposed here is simpler and less demanding in terms of equipment, and combines the results of an experimental characterization of the strip heated by the Joule effect obtained with Infra-Red camera, with those provided by an electro-thermal model. Specifically, the evaluation of the thermal conductivity and diffusivity is the result of the analysis of the transient behavior of the measured and simulated solutions. The methodology is here successfully validated by applying it to commercial graphene strips and benchmarking against the thermal parameters provided by the manufacturers. Then, a complete characterization is provided for commercial strips based on different formulations of graphene nanoplatelets and binders such as polyurethane, epoxy resin, and boron nitride. For these materials, the values of thermal conductivity and diffusivity are found in the ranges (50-450) W/(m·K) and (0.5-3.5)·10-4 m2/s, respectively.

A Capacitive Ice-Sensor Based on Graphene Nano-Platelets Strips

“…Table 1 summarizes the characteristics of the industrial graphene strips analyzed in this paper (Figure 1b). The electro-thermal properties of these GNP strips are analyzed in [29,31]. The electrical resistivity exhibited by these strips is suitable for their use as heater elements based on the Joule effect, as shown in [29].…”

“…The fitting parameters for the GNP strips and for copper are given in Table 2: compared to copper, the GNP strips exhibit a higher conductivity (more than one order of magnitude), but a negative TCR. The thermal properties of the GNP material analyzed in this paper are instead investigated in [31]; Table 3 summarizes the estimated emissivity (ε) and thermal conductivity (k). As expected, the thermal conductivity value of this industrial graphene is lower than the values expected for pure graphene (that can rise by up to thousands of W/mK, e.g., [48]), but is still of interest, being comparable to those exhibited by conducting materials usually adopted for industrial thermal and electro-thermal applications (like copper, as reported in Table 3).…”

“…This would allow the use of such techniques for aircraft applications, where they are not currently used, due to the impact of the conventional heaters, in terms of weight for instance. The authors have investigated the electrothermal properties of graphene strips which may be proposed as heating elements for de-icing systems [ 29 , 30 , 31 ]. Similar results have recently been assessed in the literature [ 32 , 33 ].…”