Effects of Additives, Photodegradation, and Water-tree Degradation on the Photoluminescence in Polyethylene and Polypropylene

Toshihide Ito, Norikazu Fuse, Yoshimichi Ohki

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Photoluminescence (PL) spectra induced by irradiation of ultraviolet photons are compared among low-density polyethylene (LDPE), crosslinked polyethylene (XLPE), and polypropylene (PP). Three PL bands appear around 4.2, 3.6, and 3.1 eV in LDPE and XLPE, while similar three PL bands are observed at similar energies in PP. The PL spectra and their decay profiles are independent of the presence of additives and are also independent of whether the samples were crosslinked or not. These results indicate that neither the additives nor the crosslinking has any significant effects on the respective three PLs in PE and PP. When the sample was pre-irradiated by the ultraviolet photons under different atmospheres (air, O2, and vacuum), all the PL intensities decrease with the progress of the pre-irradiation regardless of whether the sample is PE or PP. Therefore, all the PLs are considered to result from impurities. In all the pre-irradiated samples, a new PL band appears at 2.9 eV, of which intensity is stronger when the oxygen partial pressure during the pre-irradiation was lower. This PL is considered to be due to photo-induced conjugated double bonds. It has also been confirmed that water-tree degradation in LDPE or in XLPE does not contribute to PL.

Original languageEnglish
Pages (from-to)624-630
Number of pages7
JournalThe transactions of the Institute of Electrical Engineers of Japan.A
Volume124
Issue number7
DOIs
Publication statusPublished - 2004 Jan 1

Keywords

  • additive
  • photodegradation
  • photoluminescence
  • polyethylene
  • polypropylene
  • water tree

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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