Nature and relative contribution of luminescent species in the photodegradation of polyolefins

Luminescent species observed in the polyolefins were mainly foreign impurities, i.e., polynuclear aromatics (PNA) adsorbed from an ambient atmosphere. The luminescent species adsorbed under normal atmospheric conditions and an equivalent amount of PNA did not affect the photodegradation of high‐density polyethylene (HDPE). On the other hand, the extracted precipitates from HDPE accelerated the photodegradation of the polymer and, also, 3‐octanone slightly accelerated it, but little effect was observed in 1‐icosene. Therefore, the activity of impurities on the photodegradation of HDPE can be expressed in the following order: Extracted precipitates >> C=sO > PNA ∞ ‐CH=CH2