[en] Polymers have their own importance in the field of Solid state nuclear track detector (SSNTD) and in other allied science field. Among the several types of these detectors, polycarbonate detector such as Lexan detector is used for recording fission fragment tracks. Lexan polycarbonate (Lexan) is a promising polymer having lot of desirable properties for different application. When polymer is irradiated by electron, it induces modification in the physical and chemical properties of the polymer. The physical changes include microstructure, glass transition temperature, optical band gap, electrical conductivity etc. and the chemical changes include gas evolution, main chain scission, radical-radical combination etc. In amorphous polymer characterization, the free volume determination plays an important role. The better technique to get information about free volume is positron annihilation lifetime spectroscopy (PALS). In the present work, the modification in Lexan induced by 8 MeV electrons has been studied using PALS technique

[en] The diffused interface widths in an immiscible and a partially miscible polymer blend namely Polyvinyl chloride/Ethylene vinyl acetate (PVC/EVA) and Polystyrene/Polymethylmethacrylate (PS/PMMA) are experimentally measured and reported here. A new empirical relation found between hydrodynamic interaction parameter α derived from free volume data and the Flory-Huggins interaction parameter χ is used to construct density profile across the interface to derive the interface width in above two binary blends.

[en] A new method based on positron lifetime spectroscopy is developed to characterize individual interfaces in ternary polymer blends and hence determine the composition dependent miscibility level. The method owes its origin to the Kirkwood-Risemann-Zimm (KRZ) model for the evaluation of the hydrodynamic interaction parameters (α_ij) which was used successfully for a binary blend with a single interface. The model was revised for the present work for ternary polymer blends to account for three interfaces. The efficacy of this method is shown for two ternary blends namely poly(styrene-co-acrylonitrile)/poly (ethylene-co-vinylacetate)/poly(vinyl chloride) (SAN/EVA/PVC) and polycaprolactone /poly(styrene-co-acrylonitrile)/poly(vinyl chloride) (PCL/SAN/PVC) at different compositions. An effective hydrodynamic interaction parameter, α_eff, was introduced to predict the overall miscibility of ternary blends.

[en] The in situ gamma ray-assisted diffusion of gold nanoparticles in a polycarbonate film modified the nano-structural and surface properties to enable control of functional use with decreases in the free volume nano-hole size and in the fractional free volume measured using positron annihilation lifetime spectroscopic techniques. Coincidenace Doppler broadened spectra showed the identifiable spreading of the gold broadened region of the intensity ratio relative to the pristine polycarbonate film. These results were further corroborated by x-ray photoelectron spectroscopy and Transmission electron microscopy which showed the diffused gold nanoparticles had an average size of about 8 nm, and also showed the bonding of gold nanoparticles with the oxygen functional groups of polycarbonate film. (paper)