Characterization and optical studies of 90/10 (wt/wt%) PVA/β-chitin blend irradiated with γ-rays

Structural, Thermal and Optical Modifications of Chitosan due to UV-Ozone Irradiation

“…It was clear that the absorption coefficient values decreased with increasing the wavelength and the exposure dose up to 38.75 x 10 -14 J/m 2 . This reduction may be a reason for the modification in molecular structure introduced as a result of the degradation/cross-linked process, as mentioned before and previously reported by many researchers [30][31][32]. Figure 9 shows the dependence of ℓn α on the photon energy (hν) of chitosan powder before and after exposure to UV-ozone for different doses.…”

“…Table 4 a and b represents the values of x r , y r and z r and their percentage changes, respectively, at their peak positions for unexposed and exposed chitosan samples. The observed changes in the x r , y r , and z r values indicate that variations in the molecular structure of chitosan due to the formation of new color centers were produced [31,32]. The CIE color parameters (L*, a*, b*, ∆E*, W, C*, and H) of the unexposed and exposed chitosan samples and their percentage changes were calculated according to the formulae reported in the literature [20,32] and presented in Table 5.…”

“…The observed changes in the x r , y r , and z r values indicate that variations in the molecular structure of chitosan due to the formation of new color centers were produced [31,32]. The CIE color parameters (L*, a*, b*, ∆E*, W, C*, and H) of the unexposed and exposed chitosan samples and their percentage changes were calculated according to the formulae reported in the literature [20,32] and presented in Table 5. The table demarcated that: The lightness (L*) values increased with increasing the exposure doses up to 38.75 x 10 -14 J/m 2 which mean that the colour of chitosan powder became fader.…”

“…Nearly no variations in the chroma (C*) and hue (H) values were observed. The obtained results indicate that variations in colour difference occurred due to the exposure to UV-ozone of chitosan powder which means that changes in the physical bonds as well as in the molecular configuration of chitosan were occurred [30][31][32].…”

Optical properties and colorimetry of gelatine gels prepared in different saline solutions

“…The differences in brightness (ΔL * ), red-green colour (ΔU * ) and yellow-blue (ΔV * ) colour were calculated with respect to the properties of the pure gelatine gel [40] . Table 4 shows that the gelatine gels of the Gel-Ni group became more greenish and more yellowish as the concentration of the gelling solution increased.…”