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The major adhesive resin worldwide used in the manufacture of plywood is phenol formaldehyde resole (PF) resin. The raw material for this kind of adhesive is derived from petroleum oil. Because of rising prices of crude oil and the scarcity of petroleum products, their replacement by natural resource-based raw material has become a necessity. In the present work, the possibility of replacing phenol in PF resin with lignin was explored. The parameters for preparation of bark lignin substituted PF (LPF) adhesive, such as lignin concentration, formaldehyde to phenol molar ratio, catalyst concentration, reaction time, and reaction temperature, were optimized. It was found that up to 50 wt % of phenol can be substituted by lignin to give an LPF adhesive with better bonding strength compared to that of control PF resin. Prepared resins were characterized using IR, DSC, and TGA. IR spectra of LPF adhesive showed structural similarity with that of PF adhesives. Thermal stability of LPF adhesive was found to be lower compared to that of control PF (CPF) adhesive. DSC studies revealed a lower curing temperature for LPF resin than that for CPF resin. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3514 -3523, 2004

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In the present study, the possibility of development of a wood adhesive using coffee bean shell lignin (Cbsl) has been explored. Cbsl-modified phenolic adhesive has been prepared by replacing phenol with lignin at different weight percents. The optimization of weight percent lignin incorporation was carried out with respect to mechanical properties. It was found that up to 50 wt% of phenol could be replaced by Cbsl to give lignin-phenol-formaldehyde adhesive (LPF) with improved bond strength in comparison to control phenol-formaldehyde (CPF). Optimized LPF and CPF adhesives were characterized by IR, DSC and TGA. The IR spectrum of LPF showed structural similarity to CPF. Thermal stability of LPF adhesive was found to be lower as compared to that of CPF. DSC studies revealed a higher rate of curing in the LPF adhesive.