Comment on: “Dynamic mechanical and optical characterization of PVC/fGO polymer nanocomposites” [Appl. Phys. A 124(9) 600 (2018)]

In a recent paper, Taha and Saleh (Appl Phys A 124(9):600, 2018) studied the effect of functionalized graphene oxide on the structural, dynamic mechanical, and optical properties of polyvinyl chloride (PVC) polymer films. The authors have used a wrong approach to calculate the reflectance spectra. As the result of using a wrong equation to calculate the reflectance, the obtained values of this parameter are incorrect. Consequently, other reported optical parameters in the commented paper that are calculated based on the reflectance such as refractive index, optical and electrical conductivity, optical dielectric constant, average excitation energy (E0), dispersion energy (Ed), static linear refractive index (n0), static optical dielectric constant (e0), dipole strength (f), high-frequency optical dielectric constant ( $$ \varepsilon_\infty $$ ), long-wavelength refractive index ( $$ n_\infty $$ ), and plasma frequency ( $$ \omega_p $$ ) are wrong.