Study on the variation of the optical properties of PMMA polymer irradiated by gamma

Poly (methyl methacrylate) (PMMA) is an inexpensive polymer widely used in different applications such as the fabrication of optical tools, sensors, and microfluidic medical devices. In the present study, the effect of emitted radiations from a Cobalt-60 gamma source with emission doses between 10-30 kGy on the optical properties of this polymer is investigated. The effect of gamma radiation on optical transmission and absorption, bandgap energy, Urbach energy, dispersive energies, and refractive index of this polymer is investigated, and the obtained results are presented. The results indicate that the absorption coefficient, the refractive index, and the optical conductivity of the PMMA polymer increase within this range of gamma radiation doses. The wavelength-dependent magnitudes of these quantities are measured and represented as graphs. Within this irradiation dose range, the bandgap energy of the polymer gradually decreases, which is in agreement with the optical conductivity increase of the samples. The results indicate the reduction of the bandgap energy of polymer from 4.461 eV to 3.482 eV by 30 kGy gamma irradiation dose. Increment of the refractive index and the absorption coefficient and the enhancement of the optical conductivity with the represented data in this work can be used to fabricate new tools with improved capabilities.