Phosphorylated and carbamylated Kraft lignin for improving fire- and biological-resistance of Scots pine wood

Luleå tekniska universitet, Träteknik Luleå tekniska universitet, Byggkonstruktion och brand Luleå tekniska universitet, Kemiteknik Laboratory of Wood Science and Technology, Department of Forestry, Wood Sciences and Design, University of Thessaly, GR-431 00 Karditsa, Greece 2024

In this study, Kraft lignin was modified by ammonium dihydrogen phosphate (ADP) and urea for achieving phosphorylation and carbamylation, aiming to protect wood against biological and fire attack. Scots pine (Pinus sylvestris L.) sapwood was impregnated with a water solution containing Kraft lignin, ADP, and urea, followed by heat treatment at 150 °C, resulting in changes in the properties of the Kraft lignin as well as the wood matrix. Infrared spectroscopy, 13C cross-polarisation magic-angle-spinning (MAS) nuclear magnetic resonance (NMR), and direct excitation single-pulse 31P MAS NMR analyses suggested the grafting reaction of phosphate and carbamylate groups onto the hydroxyl groups of Kraft lignin. Scanning electron microscopy with energy dispersive X-ray spectroscopy indicated that the condensed Kraft lignin filled the lumen as well as partially penetrating the wood cell wall. The modified Kraft lignin imparted fire-retardancy and increased char residue to the wood at elevated temperature, as confirmed by limiting oxygen index, microscale combustion calorimetry, and thermogravimetric analysis. The modified wood exhibited superior resistance against mold and decay fungi attack under laboratory conditions. The modified wood had a similar modulus of elasticity to the unmodified wood, while experiencing a reduction in the modulus of rupture.
Validerad;2024;Nivå 2;2024-11-11 (joosat);Full text license: CC BY

Lignin valorization; Phosphorylation; Fire-retardancy; Wood Science; Trävetenskap; Organic Chemistry; Organisk kemi; Article in journal; info:eu-repo/semantics/article; text

10.1016.j.ijbiomac.2024.133734

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UPE oai:DiVA.org:ltu-108336
0000-0003-0852-5066
0000-0002-7711-9267
0000-0001-7864-8091
0000-0002-5474-1512
0000-0003-4720-5380
0000-0002-5565-6651
0000-0003-1067-7990
0000-0002-7140-4737
0000-0002-4526-9391
doi:10.1016/j.ijbiomac.2024.133734
PMID 39002903
ISI:001271805000001
Scopus 2-s2.0-85198237946
1512047386

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