Synthesis of Lignin Based Phenolic Resin and its Utilization in the Exterior Grade Plywood

This paper reports on plywood glued by adhesives based on lignin-phenol-formaldehyde resins. Lignosulfonate was isolated from sodium based spent sulfite liquor, a waste product of the paper mills in Pakistan, where different grasses are being used as raw material for pulping. Lignin was characterized by using ultraviolet and infrared spectroscopy. Resin was synthesized by poly- condensation of lignosulfonate with phenol and formaldehyde in alkali medium under reflux. Various properties of the adhesive measured, indicate that phenol can be replaced by lignosulfonate up to 70 % without affecting the quality of the glue. Plywood made with these resins was tested in the dry and wet states [cold water resistance, warm water resistance, boiling water resistance and mycological].The glue shear load of the plywood, in all states met the requirements imposed by Pak. Std. 871, 1970. Wood failure of plywood was compared with commercial standard (CS) 3545 and the results found were equally good.

TASLEEM AKHTAR ,GHOSIA LUTFULLAH ,RUBINA NAZLI ,