A quantitative assessment of variability in impact polypropylene mechanical recycling
Henda MRABTI, Gaël COLOMINES, Sophie QUILLARD, Yves BÉREAUX
Abstract. Plastic recycling has become an environmental and economic necessity. Mechanical recycling by extrusion and injection molding is the preferred method for thermoplastics recycling, owing to its energy efficiency and capacity to process large quantities of plastic solid waste at an industrial scale. For a sustainable plastics economy, it is crucial that mechanical recycling produces high-performance products, even from waste of variable quality. In this context we evaluated the performance of a recycled Impact copolymer polypropylene (PPc), considering a wide range of properties such as dimensions, chemical composition, morphology, melt viscosity, and appearance like color, and mass, as well as mechanical properties such as flexural strength and Charpy Impact resistance. This study highlights that reprocessing leads to changes in color, including a gradual shift from white to light yellow with successive injection molding cycles. A reduction in bulk density is also observed during the transition from pellets to reground flakes. Furthermore, significant chain scission in PP becomes evident from the first reprocessing cycle, reflected in increasing melt flow index (MFI) values. However, the recycling process does not alter the weight of the specimens molded.
Keywords
Mechanical Recycling, Polymer Recycling, Material Degradation, Injection Molding, Polypropylene Copolymer Impact
Published online 5/7/2025, 10 pages
Copyright © 2025 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA
Citation: Henda MRABTI, Gaël COLOMINES, Sophie QUILLARD, Yves BÉREAUX, A quantitative assessment of variability in impact polypropylene mechanical recycling, Materials Research Proceedings, Vol. 54, pp 2399-2408, 2025
DOI: https://doi.org/10.21741/9781644903599-259
The article was published as article 259 of the book Material Forming
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
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