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The Impact of Reprocessing with a Quad Screw Extruder on the Degradation of Polypropylene
During mechanical recycling, polypropylene typically is reprocessed using a single- or twin-screw extruder. The degradation of polypropylene during this reprocessing reduces the polymer’s molecular weight and, consequently, limits the performance of the recycled resin. This work investigated the imp...
Autores principales: | , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2022
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9269424/ https://www.ncbi.nlm.nih.gov/pubmed/35808706 http://dx.doi.org/10.3390/polym14132661 |
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author | Alotaibi, Mansour Aldhafeeri, Thamer Barry, Carol |
author_facet | Alotaibi, Mansour Aldhafeeri, Thamer Barry, Carol |
author_sort | Alotaibi, Mansour |
collection | PubMed |
description | During mechanical recycling, polypropylene typically is reprocessed using a single- or twin-screw extruder. The degradation of polypropylene during this reprocessing reduces the polymer’s molecular weight and, consequently, limits the performance of the recycled resin. This work investigated the impact of a quad screw extruder (QSE), which has greater free volume, on the reprocessing of an impact copolymer polypropylene. To mimic the recycling process, the polypropylene was subjected to three processing cycles using a QSE and a comparable twin-screw extruder (TSE) operated at three screw speeds. The reprocessed materials were characterized for their rheological, morphological, and mechanical properties. For both extruders, increasing the number of reprocessing cycles and the screw speed resulted in higher melt flow indices, decreases in zero-shear viscosity, and shifting of the crossover points for the storage and loss moduli, which indicate reductions in the molecular weight and narrowing of the molecular weight distribution of the polypropylene. The QSE exhibited greater reductions in molecular weight compared to the TSE, probably due to the higher stresses associated with the three intermeshing points along its screws. Reprocessing caused a significant reductions in the Izod impact strength of the reprocessed polypropylene, which correlated with reductions in the particle size and particle size distribution of the dispersed rubbery phase in the polypropylene during reprocessing. |
format | Online Article Text |
id | pubmed-9269424 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2022 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-92694242022-07-09 The Impact of Reprocessing with a Quad Screw Extruder on the Degradation of Polypropylene Alotaibi, Mansour Aldhafeeri, Thamer Barry, Carol Polymers (Basel) Article During mechanical recycling, polypropylene typically is reprocessed using a single- or twin-screw extruder. The degradation of polypropylene during this reprocessing reduces the polymer’s molecular weight and, consequently, limits the performance of the recycled resin. This work investigated the impact of a quad screw extruder (QSE), which has greater free volume, on the reprocessing of an impact copolymer polypropylene. To mimic the recycling process, the polypropylene was subjected to three processing cycles using a QSE and a comparable twin-screw extruder (TSE) operated at three screw speeds. The reprocessed materials were characterized for their rheological, morphological, and mechanical properties. For both extruders, increasing the number of reprocessing cycles and the screw speed resulted in higher melt flow indices, decreases in zero-shear viscosity, and shifting of the crossover points for the storage and loss moduli, which indicate reductions in the molecular weight and narrowing of the molecular weight distribution of the polypropylene. The QSE exhibited greater reductions in molecular weight compared to the TSE, probably due to the higher stresses associated with the three intermeshing points along its screws. Reprocessing caused a significant reductions in the Izod impact strength of the reprocessed polypropylene, which correlated with reductions in the particle size and particle size distribution of the dispersed rubbery phase in the polypropylene during reprocessing. MDPI 2022-06-29 /pmc/articles/PMC9269424/ /pubmed/35808706 http://dx.doi.org/10.3390/polym14132661 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article Alotaibi, Mansour Aldhafeeri, Thamer Barry, Carol The Impact of Reprocessing with a Quad Screw Extruder on the Degradation of Polypropylene |
title | The Impact of Reprocessing with a Quad Screw Extruder on the Degradation of Polypropylene |
title_full | The Impact of Reprocessing with a Quad Screw Extruder on the Degradation of Polypropylene |
title_fullStr | The Impact of Reprocessing with a Quad Screw Extruder on the Degradation of Polypropylene |
title_full_unstemmed | The Impact of Reprocessing with a Quad Screw Extruder on the Degradation of Polypropylene |
title_short | The Impact of Reprocessing with a Quad Screw Extruder on the Degradation of Polypropylene |
title_sort | impact of reprocessing with a quad screw extruder on the degradation of polypropylene |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9269424/ https://www.ncbi.nlm.nih.gov/pubmed/35808706 http://dx.doi.org/10.3390/polym14132661 |
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