Study On The Reaction Of Isocyanate With Alcohol And Water In Room Temperature And Isocyanate With Cellulose Containing Different Moisture Content In Higher Temperature

The thesis firstly studies the reaction rules of isocyanate with alcohol in room temperature in which some factors are discussed such as the concentration of alcohol and isocyanate, the mole ratio, acid, alkali, solvent, temperature. Based on the reaction rules and the IR spectroscopy of alcohol solution, the paper puts forward a new mechanism, Alcohol Polymer Reacting Mechanism(APRM), to explain the reaction kinetics of isocyanate with alcohol. That is, the isocyanate mainly react with n polymeric alcohol, then release n-1 polymeric alcohol. The reaction is still second order. With APRM, the phenomena can be well understood that the kinetic parameters, such as the rate constant, activating energy, pre-exponential factor, activating entropy, are increasing when alcohol concentration increases. The APRM will explain the effects of solvents on the reaction. The alcohol concentration, acid, alkali, solvents and temperature have obvious effects on the rate constant. The alkali, sodium hydroxide, has a good catalysis on the reaction, however the essence of catalysis is alcohol sodium.Secondly, the reaction rules of iscocyanate with water are undertaking in room temperature. The theoretical deduction and many experiments discovered that reaction of isocyanate with water is second order in room temperature, and the water and isocyanate are first order to the rate respectively. Water concentration, solvents and temperature greatly affect the rate constant, while the acid, alkali and isocyanate concentration has no effects. Before the critical accelerating water concentration, rate constant increases linearly with water content. The rate will accelerate when part of strong hydrogen-bonding solvent replaced with hydrocarbon solvent or weak hydrogen-bonding solvent.The following study on the competing reaction of isocyanate with alcohol and water indicates that high alcohol concentration or thin water content will improve the reaction of isocyanate with alcohol. If one wants that isocyanate reacted extremely with alcohol, the alcohol content should be greatly more than water for isocyanate reacts with water is quite fast. However, if watev concentration is 2 times as alcohol, more than 90% of consumed isocyanate reacted with water.Finally, the thesis studies the reaction rules of isocyanate with cellulosecontaining different water content by DSC, FTIR and ESCA. It shows that isocyanate distributes mainly on the cellulose surface. When cellulose contain some water, most isocyanate react with water, and the more water the cellulose contains, the more isocyanate consumed by water. When the moisture content of cellulose is up to 9.78%, about 92.98% isocyanate are consumed by water. The phase interface mechanism controls the reaction of isocyanate with dry cellulose, when water exists, the mechanism is very complicated, and some mechanisms coexist.