Optical properties of modified grafted polypropylene

The optical properties of PP thin films of radiation-graft copolymerization of N-vinyl-2-pyrrlidone and the modification of grafted polymer by a, beta-unsaturated nitrile are investigated in the UV-visible region. The absorption coefficient (a) is calculated as a function of the degree of grafting and modification copolymerization. The values of the optical band gap (E-g) have been obtained from the indirect allowed transitions in k-space. The width of the tails of localized states in the band gap (E-u) was evaluated from Urbach edges. Both the parameters (E-g) and (E-u) vary with the degree of grafting and the modification of grafting copolymers for irradiated and unirradiated samples.