Synthesis of Phenol-Formaldehyde Resol Resins Using Modified Alkaline Lignin with Laccase
lignin (L)-based phenolic prepolymers with different phenol (P) substitution degrees were synthesized using the modified(M) L with laccase. It was found that the ML showed lower molecular value, polydispersity and higher reactivity compared to unmodified sample, and up to 30% of phenol can be substituted by MF to give LPF wood adhesive having better bonding strength in comparison to a control unmodified lignin phenol formaldehyde wood adhesive. MF was characterized using FTIR and GPC. FTIR showed that after the treatment of laccase, the methoxyl group increased, which was mainly due to the demethylation, and laccase/mediator system made the ether bonds of L cleave to produce more alcohol hydroxyl, as a result, the reactivity of ML was improved.
Zhong Cao, Yinghe He, Lixian Sun and Xueqiang Cao
X. J. Jin et al., "Synthesis of Phenol-Formaldehyde Resol Resins Using Modified Alkaline Lignin with Laccase", Advanced Materials Research, Vols. 236-238, pp. 1410-1414, 2011