The power density of electronic devices has been progressively increased in the last years, thus raising the urgent demand for the efcient systems of electrical conductivity. In a sense a promising strategy to increase the electrical conductivity of polymer composites is to construct interconnected three-dimensional graphene nanoplatelets networks. Due to the variety commercialized graphene nanoplatelets, some researchers have reported the need to incorporate higher concentrations. This research aims to develop nanocomposites with electrical conductivity potential, based on high concentrations of graphene nanoplatelets (i.e., 12.5 and 25 wt%) and conventional polymers (i.e., polystyrene (PS) and acrylonitrile butadiene styrene (ABS)). Moreover, it will investigate the efects of the high concentrations of graphene nanoplatelets on the mechanical, rheological and morphological properties of the nanocomposites. The results showed that the graphene nanoplatelets directly interfere in the complex viscosity and in the dynamic–mechanical properties of the polymers matrices. A signifcant increase in volume electrical conductivity was verifed in both polymeric matrices when graphene nanoplatelets were added. While polymeric matrices acted as insulating materials, the nanocomposites containing 25 wt% of graphene nanoplatelets acted as semiconductors, for both matrices (PS and ABS). However, the mechanical properties of the tensile strength and impact were strongly reduced, due to the increased stifness of the nanocomposites. These results indicated a potential application of these nanocomposites with high contents of graphene nanoplatelets in the electronics feld, possibly as an alternative to conventional semiconductor materials, provided that the required mechanical properties are of low performance.
Along with the technological development in 5G, big data, artifcial intelligence, etc., the power density of electronic devices has been progressively increased, thus raising the urgent demand for efcient systems with electrical and thermal conductivity to ensure the efciency, reliability, safety, durability, and stability [1, 2]. In this sense, recent research works emphasized the use of metallic ions as candidate materials to improve the performance of supercapacitors and batteries. [3–5].
At the same time, searching for non-metallic materials that conduct electricity well has become essential for diferent applications . In this scenario, polymers have attracted great attentions owing to their impressive properties, such as light weight, low cost, high fexibility and excellent processibility . Although, traditional polymers are generally considered insulating materials, since they promote resistance to the fow of electrons because of the low number of subatomic particles, making electrical charges difcult to transit.
The primary methods for preparing graphene/polymer composites is based on simple physical mixing of very low concentration of graphene with polymer. An outstanding electrically conductive graphene/polymer composite is expected to have higher electrical conductivity at a lower graphene loading. However, due to the distinct properties of the graphene nanoplatelets, when compared to graphene, it is necessary to add higher concentrations of this nanofller. Wherefore, in this research work, nanocomposites were produced from diferent polymer matrices (PS and ABS) and high concentrations of graphene nanoplatelets. By DMA results, it was observed that, for both polymer matrices, the addition of graphene nanoplatelets gradually increased the storage modulus, loss modulus and Tg values associated with the formation of cross-links in the polymeric chain of the matrices, forming stifer composites. Due to the addition of NPGs, the complex viscosity decreased in the PS nanocomposites, due to the lubricating efect of the graphene nanoplatelets. On the other hand, in the ABS nanocomposites, the complex viscosity increased, probably due to the molecular confguration of ABS, the lateral presence of acrylonitrile and longer chains, hindering the fow of graphene sheets between the polymer chains. The mechanical properties of tensile strength and impact strength were strongly reduced with the addition of NPGs, due to the increased stifness of the nanocomposites. Fortunately, an expressive enhancement in volume electrical conductivity was obtained for the nanocomposites with 25 wt% of NPG, for both matrices (PS and ABS). It was found a surprising increase up to 10 orders of magnitude, increasing from 10–14 S/m for pure polymer matrices to 10–4 S/m for nanocomposites containing 25 wt% NPG. Therefore, the sharp transition from insulating materials to semiconducting materials was confrmed. The results presented shed light on the potential applications of the developed nanocomposites, since they exhibited good electrical performance (i.e., semiconductor behavior) becoming a promising candidate in future electronics applications. However, it is worth mentioning that the addition of high concentrations of NPG in these polymeric matrices decreased their mechanical properties, limiting their applications in systems with high mechanical performance.