Quantitative study on the isocyanate-cellulose reacted resultants

• 1、Northeast Forestry University

Abstract：The reactions that isocyanate reacted to cellulose and water in cellulose to form the urethane (cellulose carbamates) and urea are basic knowledge for the adhesion of isocyanate-terminated polyurethane resins to wood, and for the modification of cellulose and cellulose derivatives with isocyanate. It has significant meaning to understand that different quantity of urethane and urea affect the strength of adhesive bond and modifying result. Based on the nitrogen content analysis by Kjeldahl, the paper proposed and confirmed a method, which was available to adequately separate and analyze of resultants of isocyanate reacted with cellulose. It regards phenyl isocyanates (BMI) as isocyanate model, and studies the variety rules of total isocyanates attending the reaction and the output of urea and urethane under different conditions (taking cellulose moisture content (MC)、reaction time、reaction temperature into account). FT-IR analysis conformed that the reactants of urethane and urea could be well separated by the method proposed in the study which allowed to be further quantitatively analyzed. The quantitative analysis indicated that phenyl isocyanate (PI) reacted with only a few hydroxyl groups (-OH) on the surface layer of cellulose powder to form urethane because of highly crystallization and poor solubility of cellulose, and the content of urethane formed under different conditions was almost constant, averaged 0.116mmol/g. It also revealed that most isocyanate groups consumed, 80.4-86.0%, reacted with water to form urea, and the mole ratios of PI reacted with water and with cellulose were ranged from 4.10 to 5.33.

Keywords： isocyanate cellulose urea urethane quantitative study