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Influence of gamma-ray irradiation on optical and thermal degradation of poly (ethyl-methacrylate) (PEMA) polymer

S.Fares

Polymer based on (polyethyl- methacrylate) (PEMA) were exposed to different doses of gamma radiation up to 100 kGy and the physical properties have been studied. The effects of gamma irradiation on the optical spectrumof PEMAfilms have been investigated using spectrophotometric measurements of reflectance and transmittance in the wavelength range 200- 1100 nm. The structure of the sample is analyzed byX-ray diffraction technique and is found to be amorphous and partially crystalline. TGA studies revealed that the thermal stability of polyethyl methacrylate, improved after irradiation doses up to 100 kGy. On other hand driving absorption coefficient  () , consequently the band tail width Ee and optical band gap estimated. This behavior is believed to be associated with the generation of excess of electronic localized states. Also, Optical constants such as refractive index (n), extinction coefficient (K) have been determined using Swanepole method. Optical dispersion parameters and the dispersion parameters, such as Eo (single–oscillator energy), Ed (dispersive energy) are discussed in terms of the single-oscillatorWemple- DiDomenico model.