Radiation induced nano-scale free volume modifications in amorphous polymeric material: a study using positron annihilation lifetime spectroscopy

Radiation exposure modifies the nano scale free volume of the polymers which has direct correlation to certain properties of polymeric materials. CR-39 (DOP) polycarbonate polymeric films were exposed to gamma radiation at different doses for the study of nano scale free volume as well as structural and optical properties. An overall increase in the number of free volume holes at all doses was observed. UV–visible studies showed an improvement in the optical properties due to decrease in direct band gap energy. X-ray diffraction spectra of the polymer samples showed the increased amorphous nature of the polymer.