Properties Of Polyurethane And Polyurethane Rubber

Introduction to the properties of polyurethane and polyurethane rubber polyurethane is polymerized by polyester (or polyether) and diisocyanate compounds. It has good wear resistance, followed by good elasticity, high hardness, oil resistance and solvent resistance. Whether polyurethane should be classified as plastic or rubber depends on the actual situation. Taiwan, Hong Kong and other regions generally call plastics plastics, so it is meaningless to strictly distinguish between plastics and rubber. From a theoretical point of view, the distinction between plastics and rubber generally depends on whether the glass transition temperature (TG) of the material is above or below room temperature. Generally, polymer materials with TG less than normal temperature are called plastics (such as polyethylene with Tg of - 78 ℃), while polymer materials with TG higher than normal temperature are called rubber. Polyurethane is a special polymer, which is composed of hard segment and soft segment. The Tg of the hard segment is very low and has the characteristics of plastic. The Tg of the soft segment is much higher than the room temperature and has the characteristics of rubber. In the synthesis process of polyurethane, the proportion of hard segment and soft segment of polymer can be adjusted by controlling the polymerization reaction, so that polyurethane can behave as plastic or rubber. Polyurethane rubber (U) is the product of the reaction of oligomer Polyols (polyether glycol, polyester glycol or polyene glycol and polyether glycol containing phosphorus, chlorine and fluorine), polyisocyanates and chain extenders in the presence of catalysts. Polyurethane rubber can be divided into polyester polyurethane rubber (AU) and polyether polyurethane rubber (EU) according to the different raw materials used. The structural characteristics of polyurethane rubber molecules not only determine its valuable comprehensive physical and mechanical properties, but also adjust its elasticity, cold resistance, modulus, hardness and mechanical strength by changing the composition, relative molecular weight and ester ratio of its raw materials.