Electrospun tungsten oxide NPs/PVA nanofibers: A study on the morphology and Kramers–Kronig analysis of infrared reflectance spectra

Preparation and Characterization of Ultrasound Treated Polyvinyl Alcohol/Chitosan/DMC Antimicrobial Films

“…In contrast, the characteristic peaks of the pure PVA film embodied a peak belonging to O-H and stretched vibration at wavenumber 3300 cm −1 , another peak belonging to CHOH stretched vibration at 1258 cm −1 while other noticeable peaks at 1713 and 1142 cm −1 belong to C=O stretching vibration of ester bond and carboxyl C=O groups, respectively. The absorption peak at 2941 cm −1 belongs to the bending vibrations of C-H bonds, agreeing with the literature that was previously reported [37]. There was an interaction between CS and PVA, provided the typical peaks of PVA and CS are viewed with a little shift in their frequencies [38].…”

TiO2-nanoparticles enhances the structure and optical behaviors of PMMA/glass polymeric films: Kramers-Kroning analysis

“…Figure 10 illustrates the values of refractive index (n), which indicates the spectral feature of TiO 2 /PMMA nanocomposites as a function of wavelength, where in general, all the samples have the same trend. The refractive index spectra of the TiO 2 /PMMA thin films display a wide clear peak in the visible wavelength region, and it was at about 650 nm for higher concentration S7, agrees with the reported results in [52]. As the TiO 2 weight concentration increased, the refractive index's maximum value increased and, the position of the refraction peak shifted to the highest wavelength.…”

“…Figure 12 illustrates the relationship between the dielectric constant and the photon energy. It is noticeable that all TiO 2 /PMMA nanocomposites display a peak with a positive dielectric constant then follows with a valley of negative value, which agrees very well with the refractive index's obtained results spectra [52]. For example, for the prepared 50 wt% TiO 2 /PMMA composite thin film (S7), the maximum value of the dielectric constant of +70 was around 1.8 eV of the photon energy, and the minimum value was about −70 at 2.4 eV of the photon energy.…”

“…For example, for the prepared 50 wt% TiO 2 /PMMA composite thin film (S7), the maximum value of the dielectric constant of +70 was around 1.8 eV of the photon energy, and the minimum value was about −70 at 2.4 eV of the photon energy. This is because that the synthesized TiO 2 /PMMA thin films are semiconductors with sizeable dielectric constant [52]. In figure 12, the double peak structure is because of the resonances between electric and magnetic fields, respectively [58].…”

“…At low TiO 2 doping concentrations, the extinction coefficient (k) had low negative values because of the large fraction of voids in S1-S3 samples. Thus, transmittance rises, and absorbance reduces [52]. Regularly, the extinction coefficient (k) is associated with the oscillation damping of the incident light.…”