Wood Science and Engineering, Department of Engineering Sciences and Mathematics, Luleå University of Technology, Forskargatan 1, SE-931 87 Skellefteå, Sweden.
Wood Science and Engineering, Department of Engineering Sciences and Mathematics, Luleå University of Technology, Forskargatan 1, SE-931 87 Skellefteå, Sweden.
Int J Biol Macromol. 2024 Sep;276(Pt 1):133734. doi: 10.1016/j.ijbiomac.2024.133734. Epub 2024 Jul 11.
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, C cross-polarisation magic-angle-spinning (MAS) nuclear magnetic resonance (NMR), and direct excitation single-pulse P 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.
在这项研究中，采用磷酸二氢铵（ADP）和尿素对 kraft 木质素进行改性，以实现磷酸化和氨基甲酰化，从而达到保护木材免受生物和火灾攻击的目的。用含有 kraft 木质素、ADP 和尿素的水溶液浸渍欧洲赤松（Pinus sylvestris L.）边材，然后在 150°C 下进行热处理，导致 kraft 木质素和木材基质的性质发生变化。红外光谱、C 交叉极化魔角旋转（MAS）核磁共振（NMR）和直接激发单脉冲 P MAS NMR 分析表明，磷酸酯和氨基甲酸盐基团接枝到 kraft 木质素的羟基上。扫描电子显微镜结合能谱分析表明，凝结的 kraft 木质素填充了腔，并部分穿透了细胞壁。改性 kraft 木质素赋予木材阻燃性和在高温下增加炭残留量，这一点通过极限氧指数、微量燃烧量热法和热重分析得到了证实。改性木材在实验室条件下表现出对霉菌和腐朽真菌攻击的优异抗性。改性木材的弹性模量与未改性木材相似，但断裂模量有所降低。
