Effect of γ-radiation on the structure and morphology of polyvinyl alcohol films

ESR and XRD investigation of effects induced by gamma radiation on PVA-TiO2 membranes

“…The connections between two adjacent monomer is realized trough the carbon covalent bonds of the backbone chain. The oxygen and hydrogen atoms are included in OH bending groups and don't participate to the connections between the monomers, but these atoms participate in the hydrogen bonds established between the bending groups OH of two neighboring chains, [21]. A detailed description of the behavior of the hydrogen bonds in the excited state, caused by the interaction of matter with radiation is presented in references [22,23].…”

“…The ions H + and OH − can combine together to create water molecules. The final effect is the breaking of the backbone chain with the creation of double bonds C=C and C=O in the repeat unit and the apparition of water molecules [21]. The possibility also exist of a gamma photon breaking the bond between H and C atoms of H-C-OH group without other rearrangement of the chemical bonds inside the monomer, [24].…”

“…These processes cease when the irradiation is stopped. The OH − and H + ions have the tendency to recombine giving rise to water molecules, so called free water [21]. The free radicals also have a tendency to recombine.…”

“…However in some cases, the peculiarities of the monomer allow the apparition of some ordered formations along the chain itself or between two neighboring chains, known as crystalline domains, [30]. For PVA the apparition of such structures is determined by the hydrogen bonds that may appear between the H and OH bending groups, [21]. These links allow the arrangement of different segments of the same chain in parallel structures, or the arrangement of entire regions of two different chains in parallel domains, [31].…”

Characterization of calcium phosphate coating and zinc incorporation on the porous alumina scaffolds

“…In Figure 2a is presented the FTIR spectrum of calcium phosphate powder used in the suspension deposited on the surface of alumina scaffold, that identified bands corresponding to the vibration modes of PO 4 3-group (565, 599, 960 and 1041 cm -1 ) and to CO 3 2-group (871, 1414 and 1454 cm -1 ), characteristics of the apatites 13 . FTIR spectrum of alumina samples immersed in CaP/PVA suspension followed by zinc incorporation (Figure 2b) showed the same bands as Figure 2a with the addition of vibration bands corresponding to the C-OH at 1336 cm -1 of PVA 14 and bands corresponding to the Al-O bonds 15 in the region below 700 cm -1 . Figure 2c presents the reference FTIR curve obtained from the alumina scaffold used on the production of porous tri-dimensional structure after thermal treatment at temperature of 1550 °C.…”