Optical properties of modified grafted polypropylene

Abstract

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

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“…density of states model, E g decreases as the degree of disorder in the amorphous regions increases. 34 The Urbach empirical rule, 35 which relates both a and E ph at low absorption is given by:…”

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