Demethylation of Wheat Straw Alkali Lignin for Application in Phenol Formaldehyde Adhesives

Song, Yan; Wang, Zhixin; Yan, Ning; Zhang, Rong; Li, Jinchun

doi:10.3390/polym8060209

Cited by 74 publications

(53 citation statements)

References 36 publications

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“…The presence of severe steric hindrance can extremely diminish the reactivity of lignin. As compared to commercial resins, lignin-modified thermosetting resins such as lignin-phenol-formaldehyde resins and lignin-urea-formaldehyde resins require a higher temperature or more time to achieve the curing [25,26]. Therefore, it is attractive but still challenging to use lignin as fillers in UF resins to effectively improve the reactivity of lignins.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Lignin-Based Polyacid Catalyst and Its Utilization to Improve Water Resistance of Urea–formaldehyde Resins

et al. 2020

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In this study, a lignin-based polyacid catalyst was synthesized via two steps to enhance water resistance of urea–formaldehyde (UF) resins. The first steps involved a hydroxymethylation reaction to increase the hydroxyl content in lignin. Then, hydroxymethylated lignins were reacted with maleic anhydride to form maleated lignin-based polyacids. The acid groups were expected to function as acid catalysts to catalyze the curing process of UF resin. In order to elucidate the structural variation, 3-methoxy-4-hydroxyphenylpropane as a typical guaiacol lignin structural unit was used as a model compound to observe the hydroxymethylation and the reaction with maleic anhydride analyzed by 1H and 13C NMR. After the structural analysis of synthesized lignin-based polyacid by FTIR and 13C NMR, it was used to produce UF resin as an adhesive in plywood and medium density fiberboard (MDF) production, respectively. The results showed that when the addition of lignin-based polyacid was 5% in plywood, it could effectively improve the water resistance of UF resins as compared to commercial additive NH4Cl. It also exhibited a lower formaldehyde emission. Like plywood, lignin-based catalysts used in medium density fiberboard production could not only maintain the mechanical properties, but also inhibit the water adsorption of fiberboards.

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Section: Introductionmentioning

confidence: 99%

Synthesis of Lignin-Based Polyacid Catalyst and Its Utilization to Improve Water Resistance of Urea–formaldehyde Resins

et al. 2020

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“…PU foams synthesized from the modified Kraft lignins showed a higher compressive strength than conventional ones [36,37]. Song et al used the same method for white straw alkali lignin, with results that showed a significant increase in the total hydroxy content of demethylated lignin [38] when samples were explored for the synthesis of bio-based PF resins by demethylations with sulfur-containing compounds (sulfur, n-dodecyl mercaptan, sodium hydrogen sulfide and sodium sulfite). Here, soda lignin was heated with the reagent for 1 h at 90 • C. This research aimed to provide a cost-effective and efficient method for the chemical demethylation of lignin.…”

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confidence: 99%

Antimicrobial Activity of Lignin-Derived Polyurethane Coatings Prepared from Unmodified and Demethylated Lignins

et al. 2019

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Due to global ecological and economic challenges that have been correlated to the transition from fossil-based to renewable resources, fundamental studies are being performed worldwide to replace fossil fuel raw materials in plastic production. One aspect of current research is the development of lignin-derived polyols to substitute expensive fossil-based polyol components for polyurethane and polyester production. This article describes the synthesis of bioactive lignin-based polyurethane coatings using unmodified and demethylated Kraft lignins. Demethylation was performed to enhance the reaction selectivity toward polyurethane formation. The antimicrobial activity was tested according to a slightly modified standard test (JIS Z 2801(JIS Z :2010. Besides effects caused by the lignins themselves, triphenylmethane derivatives (brilliant green and crystal violet) were used as additional antimicrobial substances. Results showed increased antimicrobial capacity against Staphylococcus aureus. Furthermore, the coating color could be varied from dark brown to green and blue, respectively.Coatings 2019, 9, 494 2 of 16 and DNA in cells of mice against oxidation damage [19] have been tested. Gao [20] and Bshena [21] studied the antimicrobial activity of various textiles, using lignin incorporated into polyethylene films and applied in the finishing processes. For textiles, there are special requirements such as non-toxicity to the consumer, namely cytotoxicity, allergy or irritation and sensitization. In other recent studies, lignosulfonic acid is reported to exhibit broad-spectrum anti-HIV (human immunodeficiency virus) and anti-HSV (herpes simplex virus) properties [22,23]. Thus, Qiu investigated the anti-HIV-1 activity-potential of lignosulfonates as a microbicide to prevent HIV-1 sexual transmission [23]. Another recently reported study revealed that the antimicrobial capacity of lignin correlates with the phenolic components, specifically the side chain structure and the nature of further functional groups [24]. Typically, the presence of a double bond in α, β positions of the side chain and a methyl group in the γ position grants the phenolic fragments with the most potency against microorganisms. However, none of the hitherto published studies included the investigation of the antibacterial activity of lignin when included in polymeric matrices.Unmodified lignin is widely studied as a component for polymer production with a focus on phenol-formaldehyde resins and polyurethanes (PUs) [25], where lignin is used as polyol substitute due to the high amount of hydroxyl groups resulting in high crosslinking densities and variable mechanical properties [26][27][28]. In previous studies, lignin-derived polyurethane coatings have been prepared using Kraft lignin isolated at room temperature from aqueous media (black liquor) at different pH values [29]. In addition, their antioxidative activity has been investigated using the Folin-Ciocalteu (FC) assay [30]. Although lignin contains many functionalities, they are often diff...

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“…Lignin, the second richest renewable material next to cellulose, has been utilized for many applications including bio‐based plastics, polyurethane foams, green antioxidant, flame‐retardant additive, and carbon fibers . Many researchers have been reported lignin‐based resins by blending with phenol, polyethylene oxide, and polyvinyl alcohol (PVA) . They enhances adhesion performance, strongly related to high specific surface area and reactivity.…”

Section: Introductionmentioning

confidence: 99%

“…11,12 Many researchers have been reported lignin-based resins by blending with phenol, polyethylene oxide, and polyvinyl alcohol (PVA). [13][14][15][16][17][18][19][20] They enhances adhesion performance, strongly related to high specific surface area and reactivity. Epoxy and phenol are most commonly investigated ways to utilize lignin as resin.…”

Section: Introductionmentioning

confidence: 99%

Esterified PVA‐lignin resin by maleic acid applicable for natural fiber reinforced composites

Kim

et al. 2019

J of Applied Polymer Sci

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This article reports an esterified polyvinyl alcohol (PVA)‐lignin resin that is applicable for natural fiber reinforced polymer composites. To meet the requirement for the composites, a biopolymer‐based resin is necessary, which should well interact with the natural fiber with good waterproof behavior. By mimicking the relationship between cellulose, lignin and hemicellulose in wood, the esterified PVA‐lignin resin with maleic acid is provided. The preparation and characterization of the environment‐friendly resin are illustrated in this article. 180 °C of esterification reaction temperature and 40% of maleic acid contents are shown to be an optimum condition for the preparation of the resin. The esterified PVA‐lignin resin exhibits 13, 31, and 55% increase of its tensile strength, toughness, and failure strength, respectively. The water contact angle of the esterified PVA‐lignin resin is improved from 0 to 57°. The prepared resin is originally thermoplastic composite and it turned to be a thermoset resin by the esterification reaction at 180 °C, which is beneficial for composite processing. The developed resin is applicable for environment‐friendly and high strength‐natural fiber reinforced polymer composites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48836.

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Demethylation of Wheat Straw Alkali Lignin for Application in Phenol Formaldehyde Adhesives

Cited by 74 publications

References 36 publications

Synthesis of Lignin-Based Polyacid Catalyst and Its Utilization to Improve Water Resistance of Urea–formaldehyde Resins

Synthesis of Lignin-Based Polyacid Catalyst and Its Utilization to Improve Water Resistance of Urea–formaldehyde Resins

Antimicrobial Activity of Lignin-Derived Polyurethane Coatings Prepared from Unmodified and Demethylated Lignins

Esterified PVA‐lignin resin by maleic acid applicable for natural fiber reinforced composites

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