Structure elucidation of photoluminescent degradation products from polyolefins and evaluation of stabilizer formulations

In the present work, we focused on the aging behavior of stabilized and unstabilized polyolefins using the solvent squalane as a polypropylene-mimicking model. It was found that squalane as well as polypropylene show aging-induced photoluminescence emissions at elevated temperatures. To separate and identify the photoluminescent species from other aging-induced degradation products, a high performance liquid chromatography method using photoluminescence detection (λEx = 375 nm, λEm = 410 nm) was developed. Comparison of the integrated photoluminescence intensities allowed performing a stabilizer efficacy rating of different squalane-antioxidant formulations. For characterization and structure elucidation of the photoluminescent degradation products, the liquid chromatogaphic method was adapted for coupling to a high resolution Orbitrap mass spectrometer. It was possible to assign the observed masses to (multiple) unsaturated carbonyl compounds, which is in accordance to previous investigations.