In situ dispersion of lignin in polypropylene via supercritical CO₂ extrusion foaming: effects of lignin on cell nucleation and foam compression properties

Supercritical CO2 (scCO2) extrusion foamed high-melt-strength (HMS) polypropylene (PP) often suffers from low cell density, large cell sizes, and poor cell structure uniformity due to the poor nucleation rates of CO2 in the PP. To remedy this, various inorganic fillers have been used as heterogeneou...

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Main Authors: Ho, Keen Hoe, Lu, Xuehong, Lau, Soo Khim
Other Authors: School of Materials Science and Engineering
Format: Article
Language:English
Published: 2023
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Online Access:https://hdl.handle.net/10356/169240
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Institution: Nanyang Technological University
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spelling sg-ntu-dr.10356-1692402023-07-14T15:45:00Z In situ dispersion of lignin in polypropylene via supercritical CO₂ extrusion foaming: effects of lignin on cell nucleation and foam compression properties Ho, Keen Hoe Lu, Xuehong Lau, Soo Khim School of Materials Science and Engineering Singapore Institute of Manufacturing Technology, A*STAR Engineering::Materials Polypropylene Lignin Supercritical CO2 (scCO2) extrusion foamed high-melt-strength (HMS) polypropylene (PP) often suffers from low cell density, large cell sizes, and poor cell structure uniformity due to the poor nucleation rates of CO2 in the PP. To remedy this, various inorganic fillers have been used as heterogeneous nucleation agents. Although their efficient nucleation effects have been demonstrated, the preparation of these fillers causes some adverse effects on the environment/human health or involves relatively expensive processes or non-eco-friendly chemicals. In this work, biomass-based lignin is studied as a sustainable, lightweight, and cost-effective nucleating agent. It is found that scCO2 could assist in situ dispersion of lignin in the PP in the foaming process, leading to significantly increased cell density, smaller cells, and improved cell uniformity. The Expansion Ratio is also simultaneously improved due to reduced diffusive gas loss. The PP/lignin foams with low lignin loadings exhibit higher compression moduli and plateau strengths than the PP foams with the same densities owing to the improved cell uniformity and probably also the reinforcing effect of the small lignin particles in cell walls. Moreover, the energy absorption capability of the PP/lignin foam with 1 wt% lignin could match the PP foam with similar compression plateau strengths; even the density of the former is 28% lower than the latter. Therefore, this work provides a promising approach to a cleaner and more sustainable production of HMS PP foams. Published version 2023-07-10T04:32:30Z 2023-07-10T04:32:30Z 2023 Journal Article Ho, K. H., Lu, X. & Lau, S. K. (2023). In situ dispersion of lignin in polypropylene via supercritical CO₂ extrusion foaming: effects of lignin on cell nucleation and foam compression properties. Polymers, 15(8), 1813-. https://dx.doi.org/10.3390/polym15081813 2073-4360 https://hdl.handle.net/10356/169240 10.3390/polym15081813 37111960 2-s2.0-85154070319 8 15 1813 en Polymers © 2023 by the authors. 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/). application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Engineering::Materials
Polypropylene
Lignin
spellingShingle Engineering::Materials
Polypropylene
Lignin
Ho, Keen Hoe
Lu, Xuehong
Lau, Soo Khim
In situ dispersion of lignin in polypropylene via supercritical CO₂ extrusion foaming: effects of lignin on cell nucleation and foam compression properties
description Supercritical CO2 (scCO2) extrusion foamed high-melt-strength (HMS) polypropylene (PP) often suffers from low cell density, large cell sizes, and poor cell structure uniformity due to the poor nucleation rates of CO2 in the PP. To remedy this, various inorganic fillers have been used as heterogeneous nucleation agents. Although their efficient nucleation effects have been demonstrated, the preparation of these fillers causes some adverse effects on the environment/human health or involves relatively expensive processes or non-eco-friendly chemicals. In this work, biomass-based lignin is studied as a sustainable, lightweight, and cost-effective nucleating agent. It is found that scCO2 could assist in situ dispersion of lignin in the PP in the foaming process, leading to significantly increased cell density, smaller cells, and improved cell uniformity. The Expansion Ratio is also simultaneously improved due to reduced diffusive gas loss. The PP/lignin foams with low lignin loadings exhibit higher compression moduli and plateau strengths than the PP foams with the same densities owing to the improved cell uniformity and probably also the reinforcing effect of the small lignin particles in cell walls. Moreover, the energy absorption capability of the PP/lignin foam with 1 wt% lignin could match the PP foam with similar compression plateau strengths; even the density of the former is 28% lower than the latter. Therefore, this work provides a promising approach to a cleaner and more sustainable production of HMS PP foams.
author2 School of Materials Science and Engineering
author_facet School of Materials Science and Engineering
Ho, Keen Hoe
Lu, Xuehong
Lau, Soo Khim
format Article
author Ho, Keen Hoe
Lu, Xuehong
Lau, Soo Khim
author_sort Ho, Keen Hoe
title In situ dispersion of lignin in polypropylene via supercritical CO₂ extrusion foaming: effects of lignin on cell nucleation and foam compression properties
title_short In situ dispersion of lignin in polypropylene via supercritical CO₂ extrusion foaming: effects of lignin on cell nucleation and foam compression properties
title_full In situ dispersion of lignin in polypropylene via supercritical CO₂ extrusion foaming: effects of lignin on cell nucleation and foam compression properties
title_fullStr In situ dispersion of lignin in polypropylene via supercritical CO₂ extrusion foaming: effects of lignin on cell nucleation and foam compression properties
title_full_unstemmed In situ dispersion of lignin in polypropylene via supercritical CO₂ extrusion foaming: effects of lignin on cell nucleation and foam compression properties
title_sort in situ dispersion of lignin in polypropylene via supercritical co₂ extrusion foaming: effects of lignin on cell nucleation and foam compression properties
publishDate 2023
url https://hdl.handle.net/10356/169240
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