Effect of Gamma Irradiation on the Ultrasonic and Optical Properties of PMMA

Polymethylmethacrylate (PMMA) sample of 10 mm thickness and 15 mm diameter were prepared form a half a meter rod and exposed to ϒ-ray dose of different duration in an irradiation chamber with Ir-192 source. The polymer has been subjected to gamma radiation from 45 to 177 mGy dosages. Characterization by Ultrasonics, Fourier transform infra-red spectroscopy (FTIR) and ultraviolet-visible (UV-Vis) was done before and after irradiation. Precise ultrasonic measurements were made in the irradiated sample using 2 MHz longitudinal ultrasonic wave contact type transducer. Ultrasonic velocity measurements have been employed to investigate the microstructural changes in the irradiated sample. It was found that there is a decrease in velocity as the exposed dose is increased. FTIR study for the irradiated samples shows the enhanced CH stretching vibration. The UV-Vis studies for the irradiated samples indicate the shift in wavelength of absorption bands with the increasing irradiation dose was recorded. The result shows the variation in structural and optical properties of PMMA which is helpful for its stability under mild dose irradiations.