A Study of SHI and Gamma Ray Induced Modification of Some Polymers and their Characterization

Abstract

Radiation induced modifications in various physico-chemical properties of the polymeric materials in the recent times has become one of the most sought after technique. Since polymers are radiation sensitive materials so their properties can be effectively modified through irradiation by heavy ions (heavier than helium), gamma radiation, light ions (such as electrons, protons, etc.) among other ions at different energies and fluences. The energetic heavy ions also called swift heavy ions (Sill) are high LET radiation i.e. they transfer huge amount of energy to the material through which they pass, in comparison to light ions as well as gamma radiation which are low LET radiation. This energy deposited by the radiation while passing through the material results in the ionisation and excitation of atoms and molecules of the material along their path and induces permanent changes in the polymeric material. The extent of damages done to the material depends on the parameters such as charge, mass, energy and fluence of the impinging ions and the nature and structure of the polymeric material. The major part of the energy lost by the Sills is in the form of electronic energy loss i.e. by inelastic collisions of ions with the electrons of the material which produces intermediate species such as free radicals, anions, cations. etc. These intermediate species induce cross-linking or scission of various polymeric chains and produces conjugated bonds with the evolution of gaseous products and thus modify the properties of the polymers. Radiation induced modifications in the polymers find applications in almost all fields, be it the commercial or domestic or medical or scientific or any other field. In commercial applications the irradiated polymers find uses in packaging, labelling, textiles, various electrical and electronic gadgets, automobiles, outer space environments, nuclear establishments, etc. Track etched polymer membranes find uses in radiation detection, blood separation, laboratory filtration, storage, etc...