Analysis of phenolic compounds obtained from bamboo microwave liquefaction for fast-curing phenol-formaldehyde resin preparation

Three wastes originated from outer surface, shallow surface, and inner surface of bamboo during bamboo-mat preparation were liquefied using microwave energy in a binary solvent (glycerol/methanol). The properties (yield, molecular structure, and molecular weight distribution) of the lignin fractions in the obtained phenolic compounds were contrastively analyzed with proto-lignin in the materials. Results showed that >58% of the lignin in the bamboo cell walls could be degraded and moved to the phenolic compounds via the cleavage of β-O-4′ aryl ether bonds during the microwave liquefaction process. Some polysaccharides still connected with the lignin fraction in the phenolic compounds through covalent bonds. The phenolic compounds displayed well solubility in common organic solvents (ethanol/water cosolvent, acetone, tetrahydrofuran, 1,4-dioxane, and dimethyl sulfoxide). A fast-curing phenol-formaldehyde resin was successfully synthesized with the phenolic compounds under the presence of MgO, and a 23.23% curing time reduction was achieved. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46952.