# Mechanical and Conductive Behavior of Graphite Filled Polysulfone-Based Composites
## 3 Results and Discussion
### Electrical Conductivity  
The dispersion, shape and orientation of conductive fillers in an insulator base matrix typically influence both the mechanical characteristics and electrical conductivity of composite materials. Since the filler particles are typically micrometer-sized, relatively significant amounts of fillers are typically required to obtain the threshold percolation value. Poor mechanical qualities and superfluous materials can result from a conductive filler concentration that is too high [40]. Graphite is a form of filler made of carbon, and at temperatures as high as those of carbon fibers, it has an electrical conductivity of 10\({}^{4}\) S/cm [41]. The amount of conductive filler in a composite material with a polymeric matrix, the size and shape of its particles and other factors such as the host phase's adhesion to the  
Figure 10: Thermal conductivity asa function of density of PSU-based composite filled with NG (1); AG (2) and EG (3) at 25 \({}^{\circ}\)C.  
matrix, the processing technique and potential interactions between the conductive filler and conductive phase are all related to electrical conductivity. The variation of the electrical conductivity of the PSU composite filled with NG, AG and EG, as a function of filler content is shown in Table 5 and demonstrates that the electrical conductivity increases continuously at any level of loading concentration. The electrical conductivity of NG ranges from 0.0305 S/cm for 30 wt.%, 8 S/cm for 40 wt.%, 37.5 S/cm for 50 wt.%, and 49.6 S/cm for 60 wt.%, to 52.9 S/cm for 70 wt.%, whereas AG and EG only reach 3.8 S/cm and 17 S/cm for 70 wt.%, respectively. This is related to the creation of conducting networks and the well-distributed NG sheets inside the polymer. Therefore, it is obvious that the conductivity depends on elements such as the composite's filler content and how much of it is incorporated into the matrix. In comparison to the small flake filler of AG, the giant graphite flakes in the NG that made up the composite had the lowest resistance at every concentration. Large flake filler composites exhibit better conductivity as expected because it is well known that the size of the grains and crystallites affects the electrical conductivity of carbon composites. When conducting particles come into contact with one another above a specific particle content, an electrical conduction path forms in an insulating polymer matrix. The packing state of the conducting particles in a matrix was found to be linked with an increase in the probability of contact with each conducting particle. As a result, in NG, the graphite sheets were stacked on top of one another and formed good conductive paths, whereas in AG, the small spheres did not form good conductive paths because the particles compacted together and created agglomerations. Although EG has a large surface ratio and interactions similar to NG, its electrical conductivity is still lower than that of NG composites, due to a flaw in EG's structure. For fuel cell applications, [PERSON] et al. [42] investigated the electrical conductivity of highly filled polypropylene (PP)/graphite composites. The findings indicate that the electrical conductivity tends to rise as filler content does. Even samples containing 10 wt.% graphite are electrically percolated and have conductivities of about 0.6 S/cm. The conductivity values start to climb practically linearly at 20 weight percent graphite, reaching a maximum of 15.9 S/cm for PP composites with 80 wt.% graphite. The thermal conductivity was measured perpendicular to the axis of the graphite sheets placed in the matrix, so its values are less than they would be if it was measured along the axis of the graphite sheets as we did in measuring the electrical conductivity, where the electrical conductivity of the current passing through the compound was measured horizontally.