Polymers with urethane bonds call Polyurethane (PU) in general. Urethane bond is formed though an addition reaction between an isocyanate group and a compound of an active hydrogen such as
hydroxyl group. Isocyanate groups are highly reactive, that’s why it doesn’t need high temperature to improve reaction (reaction be accomplished in ambient temperature). the most important property of this group of polymers is that it creates a stable structure after the reaction. Polyurethane can be manufactured in different shapes such as foam products, films, elastomers, powders, liquid and emulsions.