Quantitative study on the isocyanate-wood reacted resultants

• 1、Northeast Forestry University

Abstract：The reactions that isocyanate reacted to cellulose, semicellulose, lignin, and water in timber to form the urethane and urea are basic knowledge for the adhesion of isocyanate-terminated polyurethane resins to wood. It has significant meaning to understand that different quantity of urethane and urea affect the strength of adhesive bond. Based on the previous study on the separation and quantitative analyses of resultants of isocyanate reacted to cellulose, the paper regards the wood powder as wood model, and separates and analyses the resultanats of isocyanates reacted to wood powder using the technology of FT-IR and Kjeldahl methods. The FT-IR analysis conformed that the reactants of urethane and urea could be well separated in isocyanate/wood system as well by the separation technique proposed. The study showed that due to the fact that wood is a porous composite from cellulose, lignin and semicellulose, the amount of isocyanate reacted with wood was more than that with cellulose. It also indicated that in isocyanate-wood reactions the temperature and time had significant effects on the contents of urethane formed that increased with increases of temperature and decreases of time. The isocyanate consumed and formed urea accounted for 46.2-60.6%, thereby the mole ratios of isocyanate reacted with hydroxyl groups and with water in wood were ranged from 0.86 to 1.54. And the moisture content (MC) of wood had narrowly minor effect on the contents of urethane formed.

Keywords： isocyanate wood urea urethane Quantitative study