Odor-Reduced HDPE-Lignin Blends by Use of Processing Additives

Lok B, Mueller G, Büttner A, Bartel M, Erdmann J (2022)

Publication Type: Journal article

Publication year: 2022

Journal

Polymers MDPI

Book Volume: 14

Article Number: 2660

Journal Issue: 13

DOI: 10.3390/polym14132660

Abstract

The comprehensive use of natural polymers, such as lignin, can accelerate the replacement of mineral oil-based commodities. Promoting the material recovery of the still underutilized technical lignin, polyolefin-lignin blends are a highly promising approach towards sustainable polymeric materials. However, a limiting factor for high-quality applications is the unpleasant odor of technical lignin and resulting blends. The latter, especially, are a target for potential odor reduction, since heat-and shear-force intense processing can intensify the smell. In the present study, the odor optimization of kraft and soda HDPE-lignin blends was implemented by the in-process application of two different processing additives–5% of activated carbon and 0.7% of a stripping agent. Both additives were added directly within the compounding process executed with a twin screw extruder. The odor properties of the produced blends were assessed systematically by a trained human panel performing sensory evaluations of the odor characteristics. Subsequently, causative odor-active molecules were elucidated by means of GC-O and 2D-GC-MS/O while OEDA gave insights into relative odor potencies of single odorants. Out of 70 different odorants detected in the entirety of the sample material, more than 30 sulfur-containing odorants were present in the kraft HDPE-lignin blend, most of them neo-formed due to high melt temperatures during extrusion, leading to strong burnt and sulfurous smells. The addition of activated carbon significantly decreased especially these sulfurous compounds, resulting in 48% of overall odor reduction of the kraft blend (mean intensity ratings of 5.2) in comparison to the untreated blend (10.0). The applied stripping agent, an aqueous solution of polymeric, surface-active substances adsorbed onto a PP carrier, was less powerful in reducing neo-formed sulfur odorants, but led to a decrease in odor of 26% in the case of the soda HDPE-lignin blend (7.4). The identification of single odorants on a molecular level further enabled the elucidation of odor reduction trends within single compound classes. The obtained odor reduction strategies not only promote the deodorization of HDPE-lignin blends, but might be additionally helpful for the odor optimization of other natural-fiber based materials.

Authors with CRIS profile

Bianca Lok Lehrstuhl für Aroma- und Geruchsforschung Andrea Büttner Lehrstuhl für Aroma- und Geruchsforschung

Involved external institutions

Fraunhofer-Institut für Angewandte Polymerforschung (IAP) / Fraunhofer Institute for Applied Polymer Research DE Germany (DE)

How to cite

APA:

Lok, B., Mueller, G., Büttner, A., Bartel, M., & Erdmann, J. (2022). Odor-Reduced HDPE-Lignin Blends by Use of Processing Additives. Polymers, 14(13). https://doi.org/10.3390/polym14132660

MLA:

Lok, Bianca, et al. "Odor-Reduced HDPE-Lignin Blends by Use of Processing Additives." Polymers 14.13 (2022).

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