Polyurethane
Introduction Polyurethane are a discovery and development of O.Bayer and his chemist in Germany beginning about 1937. The reaction of an isocyanate and an alcohol results in the formation of a urethane. By the same reaction polyhydroxy materials will react with poly isocyanate and give polyurethane. The raw materials used for the polyurethane elastomers are 1.polyols 2.Diisocyanates 3.Chain extenders 1.Polyols The polyol components of polyurethane elastomers is usually ba macro glycol of molecular weight about 500 to 4000. 2. Diisocyanate The diisocyante components may be any of a multitude of relatively small molecules. 3. Chain extenders Chain extenders or crosslinkersvof polyurethane elastomers is relatively small usually di functional molecule chain extenders or glycols or diamines. Polyurethane can be processed by a. Castable PU b. Millable PU c. TPE based PU Simple reactions between the glycol/diamines and diisocyante give the product with u
