Thermoresistive Properties of Graphite Platelet Films Supported by Different Substrates

Large-area graphitic films, produced by an advantageous technique based on spraying a graphite lacquer on glass and low-density polyethylene (LDPE) substrates were studied for their thermoresistive applications. The spray technique uniformly covered the surface of the substrate by graphite platelet (GP) unities, which have a tendency to align parallel to the interfacial plane. Transmission electron microscopy analysis showed that the deposited films were composed of overlapped graphite platelets of dierent thickness, ranging from a few tens to hundreds of graphene layers, and Raman measurements provided evidence for a good graphitic quality of the material. The GP films deposited on glass and LDPE substrates exhibited dierent thermoresistive properties during cooling–heating cycles in the 40 to +40 C range. Indeed, negative values of the temperature coecient of resistance, ranging from 4 104 to 7 104 C1 have been observed on glass substrates, while positive values varying between 4 103 and 8 103 C1 were measured when the films were supported by LDPE. These behaviors were attributed to the dierent thermal expansion coecients of the substrates. The appreciable thermoresistive properties of the graphite platelet films on LDPE could be useful for plastic electronic applications.