The Distribution and Polymerization Mechanism of Polyfurfuryl Alcohol (PFA) with Lignin in Furfurylated Wood

There is increasing interest in furfurylated wood, but the polymerization mechanism between its internal polyfurfuryl alcohol (PFA) and lignin is still uncertain. This paper investigated the distribution of PFA and the feasibility of the polymerization of PFA with lignin in furfurylated balsa wood. The wood first immersed in the furfuryl alcohol (FA) solution followed by in situ polymerization and the distribution of PFA was characterized by Raman, fluorescence microscopy, SEM, and CLSM. Then, the mill wood lignin (MWL) of balsa wood and lignin model molecules were catalytically polymerized with PFA, respectively, studying the mechanism of interaction between PFA and lignin. It was concluded that PFA was mainly deposited in cell corner with high lignin concentration, and additionally partly deposited in wood cell cavity due to high concentration of FA and partial delignification. TGA, FTIR, and NMR analysis showed that the cross-linked network structure generated by the substitution of MWL aromatic ring free position by PFA hydroxymethyl enhanced the thermal stability. New chemical shifts were established between PFA and C5/C6 of lignin model A and C2/C6 of model B, respectively. The above results illustrated that lignin-CH2-PFA linkage was created between PFA and lignin in the wood cell wall.