*2.4. Dielectric Loss (tan δ)*

Dielectric loss is represented by the dissipation factor (tan *δ*) which is the amount of dissipated energy or electrical loss by insulating material when a voltage is applied to the material [40]. The dielectric loss of a material is directly related to the electrical conductivity of the corresponding matrix. Usually, from the graph of dielectric loss, it always decreases as the frequencies are increased. This is attributed to the time lagging associated with the orientation of dipoles within the polymer matrix. Ramesan and Santhi also studied dielectric loss in their conducting polymer composite of polypyrrole (PPy) with different silver doped nickel oxide (Ag–NiO) content nanocomposite system and found that the tan *δ* of composites was higher than that of PPy alone. This was similar to their findings in the dielectric constant. Furthermore, when they increased the nanoparticle content, the tan *δ* value of the composite also increased. This may be due to the high surface area, surface domain polarization, and the quality of the electrical network formation. With further loading of nanocomposites (>10 wt%), the tan *δ* value was seen to decrease. This might be caused by the formation of clusters or discrete aggregates in the PPy matrix, which then prevented the migration of charge carriers through the polymer [40]. Besides that, Ramesan and co-workers also worked on different types of nanocomposite and polymer matrices. They studied poly (vinyl cinnamate) (PVCin) with different ratios of zinc oxide (ZnO). Their results showed a similar pattern to the other studies [43].
