# Mechanical and Conductive Behavior of Graphite Filled Polysulfone-Based Composites
## 3 Results and Discussion  
### Dispersion of Filler Particles in the PSU Matrix  
The SEM micrographs can be used to better understand the thermo-electric conductivity and mechanical properties of the PSU/graphite composites. Figure 1 shows that the PSU/Gr 30 wt.% graphite composite has more defined polymeric areas than the PSU/Gr 70 wt.% composite.  
We can see how the filler is well mixed with the matrix by looking at the SEM micrographs. We can clearly detect the natural graphite plates placed in the polymeric matrix that give an excellent heat transmission compared to the dispersion of 30 and 70 wt.% AG and EG in the polysulfone matrix, as shown in Section 3.4. Regarding AG and EG fillers, we see that the filler and polymer combined to form a large agglomeration; this tendency decreases as the filler content is increased. The sheets of natural graphite are seen, seeming to be planted in the polymeric matrix. When these sheets are stacked on top of one another, bridges form between them, which enhances the composite's thermal properties.  
Fakes of natural graphite are inserted into the material perpendicular to the pressing axis. The NG particles overlap with one another (Figure 1a,d), creating substantial contact areas between the particles, which improves the transmission of heat and electricity in this direction. The overlap density rises and the thickness of the polysulfone interlayers decreases as the NG content of the material rises. The number of big pores in the material has greatly decreased as compared to earlier samples [32], and the particle dispersion has improved. With an increase in the filler content, the number of overlaps of polymer interlayers between graphite particles decreases, which should lead to a decrease in the mechanical characteristics of the material. Additional EG particle grinding improved the uniformity of these particles' distribution within the polymer matrix, decreased the number of aggregates, and brought the material's structural makeup closer to that of materials based on NG. This allowed for a significant increase in thermal conductivity and an improvement in mechanical properties.  
The creation of homogenous materials as the filler content is increased is made possible by the employment of spheroidal artificial graphite particles as the agglomeration starts to decrease (Figure 1b,e). However, point interactions between the particles result in lower thermal conductivity values than natural graphite.  
These results may be compared to the findings in previous work [32] where big agglomerations were formed between the matrix and the filler, in addition to pores appearing between the two components, especially for the AG filler. We can see the enhancement in the bonding between the matrix and the filler, with fewer pores and agglomerations. Comparing with the results of the previous study, we can see that using a different type of press mold caused a better mixing between the matrix and the filler, as well as a reduction in the sample's porosity, providing better thermal and mechanical properties.  
In their study on the effects of carbon micro- and nano-fillers on the viscoelastic properties of polyethylene terephthalate (PET), [PERSON] et al. [33] used graphite to prepare composite polymer based on PET. SEM images of graphite/PET at loadings of 2 and 15 wt.% of graphite revealed that the failure of the composite was caused by the development of agglomerations and cracks as the graphite concentration in the matrix increased.