Testing the influence of the temperature, RH and filler type and content on the Universal Power Law for new reduced graphene oxide TPU composites

Abstract

In this paper, 6 different reduced graphene oxide (rGO) were prepared by a modified Hummers method and reduced by thermochemical methods. rGO materials were intentionally prepared to obtain different BET and thickness and oxygen content maintaining constant the lateral size to compare its performance on thermoplastic polyurethane (TPU) matrix. Microstructure and the effect of the incorporation of rGO on the hardness and electrical properties of TPU were investigated. It has been studied the temperature and humidity dependence of the electrical conductivity and the sensitivity and the response time to humidity changes have been determined. Influence of the filler content, temperature and humidity on the Jonschers universal power law (UPL) for ac conductivity vs frequency and its fitting parameters A and n were determined. It has been observed an anomalous behaviour (according to UPL) and a linear correlation between log A and n independently of the filler content, humidity and temperature, however there is an influence of the rGO used for the preparation of the composite. To study the transport mechanisms the experimental results were adjusted to the equation and the maximum adjustment for like other carbon nanocomposites however there is not an unequivocal behaviour.