Rational analysis of dispersion and solubility of Kraft lignin in polyols for polyurethanes

Haridevan, Hima; Evans, David A. C.; Martin, Darren J.; Annamalai, Pratheep K.

doi:10.1016/j.indcrop.2022.115129

Cited by 11 publications

(7 citation statements)

References 56 publications

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“…The modification of lignin served a clear purpose; to compatibilize lignin with the F5000 linker. F5000 is composed of a polypropylene glycol backbone which is incompatible with unmodified Kraft lignin, as indicated in several studies . As a result, using Kraft lignin as a filler in the DA formulation would only be relevant for very small lignin concentrations, as increasing amounts of lignin would have a direct negative impact on the mechanical properties.…”

Section: Resultsmentioning

confidence: 99%

Bioaromatic-Associated Multifunctionality in Lignin-Containing Reversible Elastomers

Thys

Kaya

Soetemans

et al. 2023

ACS Appl. Polym. Mater.

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The unique molecular structure of lignin, intrinsically rich in bioaromatic groups (phenolic hydroxyls), gives it, e.g., antioxidant, antistatic, antimicrobial, UV-blocking, hydrophobic, or even flame-retardant properties, which are highly interesting. An attractive strategy to use lignin as a macro-monomer for the design of functional materials that retain certain of these lignin-specific properties is to partially preserve some phenolic groups during the synthesis. In this work, we explore the properties of reversible elastomers containing a lignin fraction whose phenolic groups have only been partially modified. To do so, Kraft lignin was first fractionated and partially (89%) modified with furan groups, allowing its homogeneous incorporation in Diels–Alder formulations. The effect of the residual phenolic groups embedded in the polymer matrix was then systematically studied, focusing on the specific material properties associated with lignin. The obtained lignin-containing networks notably showed increased radical scavenging activity (which directly resulted in improved antistatic and antioxidant properties), displayed improved UV absorbance due to the presence of multiple lignin chromophores, and were even able to inhibit the growth of bacteria. This article demonstrates that tailored and partially modified lignin fractions could be used as multi-functional building blocks for the design of complex (and reversible) polymer architectures, mimicking some of the unique lignin functionalities found in nature, and this without the need to add specific additives.

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Section: Resultsmentioning

confidence: 99%

Bioaromatic-Associated Multifunctionality in Lignin-Containing Reversible Elastomers

Thys

Kaya

Soetemans

et al. 2023

ACS Appl. Polym. Mater.

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“…Since kraft lignin is the most commonly produced technical lignin, most of the studies are focused on this type of lignin. For example, Haridevan et al [ 112 ] recently evaluated the dispersion and solubility of kraft lignin in different types of polyols at room temperature for the production of polyurethanes based on microscopic, gravimetric, and rheological analyses. This study demonstrated that kraft lignin has different degrees of dispersion in various polyols, depending on the structural characteristics such as solubility parameter, molecular weight, and monomeric unit type.…”

Section: Lignin As a Building Block To Synthesize Polyurethanesmentioning

confidence: 99%

Lignin as a Renewable Building Block for Sustainable Polyurethanes

et al. 2022

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Currently, the pulp and paper industry generates around 50–70 million tons of lignin annually, which is mainly burned for energy recovery. Lignin, being a natural aromatic polymer rich in functional hydroxyl groups, has been drawing the interest of academia and industry for its valorization, especially for the development of polymeric materials. Among the different types of polymers that can be derived from lignin, polyurethanes (PUs) are amid the most important ones, especially due to their wide range of applications. This review encompasses available technologies to isolate lignin from pulping processes, the main approaches to convert solid lignin into a liquid polyol to produce bio-based polyurethanes, the challenges involving its characterization, and the current technology assessment. Despite the fact that PUs derived from bio-based polyols, such as lignin, are important in contributing to the circular economy, the use of isocyanate is a major environmental hot spot. Therefore, the main strategies that have been used to replace isocyanates to produce non-isocyanate polyurethanes (NIPUs) derived from lignin are also discussed.

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“…When dispersed at lower loading and/or in compatible polyols, lignin exists as micro-nanoparticles enhancing the nucleation effect thus reducing the cell size of RPUF, whereas at higher loadings and/or in less compatible polyols, lignin tends to form microagglomerates, which can affect the microstructure (cell coalescence and agglomeration in struts) and thus the physical properties. ,, Further, owing to this broad spectrum of dissolution-to-dispersion behavior, it has been postulated that lignin-incorporated polyols might exhibit significant rheological differences, depending on the lignin loading level, and affect the efficient mixing with isocyanates and therefore the microstructure formation during foaming. , However, the changes in the foam microstructure caused by particles with such complex dispersion behavior are not yet defined due to the difficulty in “imaging” of foamed plastics using conventional microscopy techniques. However, for better engineering of the performance of lignin-incorporated RPUF, it is essential to elucidate the influence of the broad spectrum of micro- and nanolignin particles on the microstructure.…”

Section: Introductionmentioning

confidence: 99%

“…Hence, understanding the dispersion behavior of lignin from its incorporation into polyol and subsequent conversion into RPUF is essential. 15,16 When dispersed at lower loading and/or in compatible polyols, lignin exists as micro-nanoparticles enhancing the nucleation effect thus reducing the cell size of RPUF, whereas at higher loadings and/or in less compatible polyols, lignin tends to form microagglomerates, which can affect the microstructure (cell coalescence and agglomeration in struts) and thus the physical properties. 8,13,16 Further, owing to this broad spectrum of dissolution-to-dispersion behavior, it has been postulated that lignin-incorporated polyols might exhibit significant rheological differences, depending on the lignin loading level, and affect the efficient mixing with isocyanates and therefore the microstructure formation during foaming.…”

Section: Introductionmentioning

confidence: 99%

“…However, due to its structural complexity and purity issues, associated with the extraction methods, the valorization of lignin in RPUF is still a challenge. , Also, lignin can be a non-reactive filler and/or exist as micro-nanoparticles ,, and/or reactive additives cross-linking with the available isocyanate (NCO) groups ,, in polyurethanes depending on its size and processing approach. Hence, understanding the dispersion behavior of lignin from its incorporation into polyol and subsequent conversion into RPUF is essential. , …”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

X-ray Tomographic Reconstruction for Understanding Lignin-Induced Changes in the Microstructure and Properties of Polyurethane Insulation Foam

Haridevan

Barkauskas

Sokolowski

et al. 2023

ACS Appl. Polym. Mater.

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Lignin, the most abundant aromatic biopolymer, is explored as a renewable polyol substituent and functional additive in rigid polyurethane foam (RPUF) for structural and insulation applications. The understanding of the complex microstructural changes in the RPUF caused by lignin micro-nanoparticles has been limited by traditional two-dimensional cross-sectional imaging methods (typically limited to the average cell diameters). This study reports the microstructural changes induced by the dispersion of kraft lignin (0−2% w/w) in RPUF as monitored using X-ray computed microtomographic (X-ray μCT) analysis. The reconstruction and quantification analysis provide greater insight into the changes induced by lignin on the microstructure of the RPUF, allowing rationalization of the microstructure with physical properties. In comparison to scanning electron microscopy, the magnitude of differences observed in spatial parameters (cell volume, cell surface area, cell ellipticity, and distribution) and skeletal parameters (thickness, length, and the distribution of cell walls and struts) is significant and the presented methodology can be applied to the in-depth analysis of other cellular plastics.

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Rational analysis of dispersion and solubility of Kraft lignin in polyols for polyurethanes

Cited by 11 publications

References 56 publications

Bioaromatic-Associated Multifunctionality in Lignin-Containing Reversible Elastomers

Bioaromatic-Associated Multifunctionality in Lignin-Containing Reversible Elastomers

Lignin as a Renewable Building Block for Sustainable Polyurethanes

X-ray Tomographic Reconstruction for Understanding Lignin-Induced Changes in the Microstructure and Properties of Polyurethane Insulation Foam

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