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 Jonscher's 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 = 0 exp[-(TMott/T)] and the maximum adjustment for  = 1/4 like other carbon nanocomposites however there is not an unequivocal behaviour.

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Two different reduced graphene oxides (rGOs) with similar concentration of oxygen and defects and differences in exfoliation were prepared to produce the rGO/thermoplastic polyurethane nanocomposites by solution blending (SB) and melt compounding (MC). Morphology, electrical, and dielectric properties were studied. Large agglomerates have been observed for the composites produced by SB and discrete and low agglomerated rGO particles in the case on the composites produced by MC. These morphological differences justify the observations in hardness, electrical conductivity, and even in the dielectric properties. The composites do not follow Jonscher's universal power law (UPL) and a linear trend between UPL factors (Log A vs n) has been observed for composites produced by SB, however, no trend is observed in the composites produced by MC, being the first time observed. Differences in the tunneling effect and breakage of H-bonds within the polymer can be suggested from the dielectric relaxation characterization.

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