Study of γ-ray induced modifications in the pentaerythritoltetrakis (allyl carbonate) polymer (petac) by UV-visible and FTIR spectroscopic techniques

Modifications induced by gamma irradiation in the dose range of 50.0-2000.0 kGy in the Pentaerythritoltetrakis (allyl carbonate) polymer (PETAC) have been studied. For this, thin films (∼ 700 μm thickness) of polymer samples were irradiated with different gamma doses from a ⁶⁰Co-source. The induced modifications were studied by UV-Visible and FTIR spectroscopy technique. The UV-Visible data show an increase in absorbance and shift of absorption edge towards visible region from UV with the increase of gamma dose. A linear curve obtained between gamma dose and the absorbance in the dose range 0-2000.0 kGy indicated the possibility of using this polymer for high gamma dose measurements. Direct and indirect energy band gap were also determined from the UV-Visible spectra as a function of gamma dose. The results showed that both the direct and indirect energies of transitions decrease with the increasing gamma dose. This decrease with gamma dose increase indicates scissioning of the polymer samples due to gamma irradiation. The UV-Visible spectra results were further supported by FTIR studies. (author)