Structure and electrical conductivity of polymer based graphene-carbon nanotubes composite

The enhancement of electrical conductivity of silicone rubber polymer has been reported when graphene and carbon nanotubes (CNTs) are added as separate carbon nanofillers into a polymer matrix. The concept of synergy through combining various types of carbon nanofillers is seen as one of the successful approaches to obtain desired properties of new materials. However, the electrical conductivity properties of graphene and CNTs combination as a single carbon nanofillers into polymer matrix are still unknown and has not been reported elsewhere. This study aims to synthesize polymer composites and compare their electrical conductivity and physical properties. The solution mixing technique was used to synthesize these polymer composites. The nanofillers’ weight percentage (wt%) were varied, and the electrical conductivity test was performed using the Two-Point Probe system. Three sets of samples were prepared; (i) graphene-polymer composites, (ii) CNTs-polymer composites and (iii) graphene-CNTs-polymer composites. The highest electrical conductivity value recorded was 1.94 × 10-1 S/m when an applied voltage of 10 V was subjected to the 2 wt% of graphene mixed with 25 wt% of CNTs in the polymer matrix. The increment of electrical conductivity recorded by the Two-Point Probe system was supported by the field emission scanning electron microscope and high resolution transmission electron microscope structural images. The microstructural observation on the prepared conductive polymer composites samples indicated that graphene and CNTs were distributed homogeneously in the polymer matrix. The results also showed that graphene and CNTs created a conductive network in a polymer matrix, which greatly increased the electrical conductivity of polymer composites. Thermogravimetric analysis revealed that the thermal stability of graphene-CNTs-polymer composites was higher than the other prepared polymer composites and elastomer. At 400 °C, only 3.39% of weight loss for graphene-CNTs-polymer composites compared to elastomer where their weight loss was approximately 3.97%. This result shows that incorporation of graphene and CNTs in a polymer matrix enhanced the thermal properties of polymer composites