Technical and market substitutability of recycled materials: Calculating the environmental benefits of mechanical and chemical recycling of plastic packaging waste.

Most plastics are today mechanically recycled (MR), whereas chemical recycling (CR) is an emerging technology. Substitutability of virgin material is vital for their environmental performance assessed through life cycle assessment (LCA). MR faces the reduction in the material's technical quality but also the potential market because legal safety requirements currently eliminate applications such as food packaging. This study presents a data-driven method for quantifying the overall substitutability (OS), composed of technical (TS) and market substitutability (MS). First, this is illustrated for six non-food contact material (non-FCM) applications and three hypothetical future FCM applications from mechanical recyclates, using mechanical property and market data. Then, OS results are used in a comparative LCA of MR and thermochemical recycling (TCR) of several plastic waste fractions in Belgium. For mechanical recyclates, TS results for the studied non-FCM and FCM applications were comparable, but OS results varied between 0.35 and 0.79 for non-FCM applications and between 0.78 and 1 for FCM applications, reflecting the lower MS results for the current situation. Out of nine application scenarios, MR obtained a worse resource consumption and terrestrial acidification impact than CR in six scenarios. MR maintained the lowest global warming impact for all scenarios. This study contributes to an improved understanding of the environmental benefits of MR and TCR. Inclusion of other criteria (e.g. processability, colour, odour) in the quantification of the overall substitutability for MR products should be further investigated, as well as the environmental performance of TCR at industrial scale.

Excimer laser radiation for endarterectomy of experimental atheromas.

Open laser endarterectomy produces a smooth arterial surface with welded distal end points. This report evaluates 308-nm excimer laser radiation for the laser endarterectomy operation. Arteriosclerotic New Zealand white rabbits (N = 15) were studied. A thoraco-abdominal exploration was performed, the aorta was isolated, heparin was administered, and multiple endarterectomies were performed in each rabbit. A line of laser craters was created at the proximal and distal ends of an atheroma. Laser radiation was used to connect the craters to form the proximal and distal end points. The atheromas were dissected from the aorta with laser light and the end points were fused. The aortas were removed for light and electron microscopy and the animals were sacrificed. Excimer radiation was delivered by a 600-microns fiber at 50 mJ/pulse, 120-ns pulses and either 15- or 20-Hz frequency. At 15 Hz excimer laser endarterectomies showed no perforations along the surface or at the end points. The surfaces were smooth but the end points were not welded in place. At 20 Hz, perforations were seen along 7/11 surfaces and at 5/11 end points. Excimer laser endarterectomy is best performed at 15 Hz. The end points, however, cannot be welded with excimer laser radiation.