Odor and Constituent Odorants of HDPE–Lignin Blends of Different Lignin Origin

Lok, Bianca; Mueller, Gunnar; Ganster, Johannes; Erdmann, Jens; Buettner, Andrea; Denk, Philipp

doi:10.3390/polym14010206

Cited by 8 publications

(21 citation statements)

References 46 publications

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“…However, a high thermal load during the production of such blends leads to additional odor development, potentially even worse with shear-force during extrusion [27,28]. This has already been demonstrated via the detection of additionally formed odorants during extrusion [20]. Likewise, preceding treatment of technical lignin powder led to odor-reduced material, which, however, showed the same level of off-odor after injection molding compared to the untreated lignin [26].…”

Section: Introductionmentioning

confidence: 93%

“…Besides commercial HDPE for applications in injection molding, also a HDPE-based compatibilizer was also used for the production of the HDPE-lignin blends. For comparison, two different technical lignins were chosen, which had previously proved to be significantly different in odor specifications [20]. One of the chosen lignins resulted from kraft processed softwood, whereas the other lignin was a product of soda processed wheat straw and grass.…”

Section: Raw Materialsmentioning

confidence: 99%

“…Due to the high odor intensity of the samples, 1 g (±0.1 g) of each blend was sufficient for the determination of sensory characteristics. According to Lok et al [20], single sensory characteristics were discussed and chosen by the panel in consensus. In this way determined attributes were subsequently rated individually by the panelists on a scale from 0 (no perception) to 10 (strong perception).…”

Section: Sensory Analysesmentioning

confidence: 99%

“…For gas chromatographic analyses, 2 g (±0.1 g) of each HDPE-lignin blend was extracted with 50 mL of dichloromethane (DCM) for 30 min. Filtration, isolation by means of solvent-assisted flavor evaporation (SAFE; [30]) and subsequent concentration via Vigreux and micro distillation [31] were performed with identical work-up as described in Lok et al [20].…”

Section: Gc-o and Oedamentioning

confidence: 99%

“…Due to their dominance in volatile organic compound (VOC) profiles, several phenolic and sulfur compounds were frequently associated with the malodor [5,15,[17][18][19]. However, as recently revealed, the olfactory impression of technical lignin and lignin blends comprised a multitude of odor-active substances, partly trace compounds with low odor thresholds [20]. Accordingly, the elucidation of causal odorants at trace level requires the combination of advanced analytics with sensory evaluation.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2022

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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.

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Section: Introductionmentioning

confidence: 93%

Section: Raw Materialsmentioning

confidence: 99%

Section: Sensory Analysesmentioning

confidence: 99%

Section: Gc-o and Oedamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2022

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The Smell of Progress in the Circular Plastics Economy – Odor Characterization and Reduction in Polymer Recyclates and HDPE‐Lignin Blends

Lok,

Buettner,

Böker

2024

Lebensmittelchemie

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With respect to the general resource scarcity but the at the same time still rising need for plastic material, the sustainability of future applications and developments in the plastics sector becomes increasingly important. Encouraging the bioeconomic thinking, possible solution approaches which tackle the 'plastic problem' of the modern society include the promotion of plastic recycling or the replacement with natural substances and materials. Both approaches address the conservation of resources via reducing the need for fossil feedstocks. However, they feature associated obstacles, such as off-odors which are especially pronounced in recyclates and natural substance-containing polymers.The detailed elucidation of the causative odor-active substances is addressed in this thesis, and aims to build the knowledge base for subsequent investigations on odor reduction techniques. By combining and correlating human sensory evaluations with multi-dimensional gas chromatographic and mass spectrometric measurements, the odors of post-consumer recyclates and HDPE-lignin blends were characterized. Likewise, efficiencies of diverse odor reduction techniques were assessed.In detail, odorous contaminants detected in post-consumer recycled polypropylene (PP) were

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