Characterization of oxidized LDPE by solid state fluorescence spectra

Abstract

AbstractThe fluoresence excitation and emission spectra of commercial LDPE and oxidized LDPEs using phase transferred permanganate as oxidant have been examined using solid state fluorescence spectra. The luminescent impurity species present in commercial polyethylene is found to be olefinic dione. LDPE has an emmission spectra at 330–345 nm and excitation spectra at 235 and 300–310 nm. The emission spectra of oxidized LDPEs contain two main peaks, one at 290–300 nm and the other at 330–345 nm. A comparison of the emission spectra of LDPE blends with the reference compounds, viz., stearic acid and stearone, with those of the oxidized LDPEs proves the presence of “saturated” keto groups (carbonyl in the main chain not conjugated with C = C) in oxidized LDPEs. This also enables us to find out quantitatively the amount of the keto groups present. The estimates thus obtained tally with the results of FT‐IR measurements and follow the increasing order of the stability constant of the permanganate ionpair in benzene.