氨基甲酸酯基团及氨基甲酸酯——脲基团在聚氨酯结构中称之为硬段，而由多元醇构成的链段称之为软段。
聚氨酯的塑料性质和强度等性能主要由其硬段性质决定，而其橡胶性质和弹性等性能主要由其软段性质决定。因此可通过改变不同原料化学结构、规格指标、品种、配方比例制造出具有各种性能和用途的变化多端的制品，被誉为继聚乙烯、聚氯乙稀、聚丙烯、聚苯乙烯之后的“第五大塑料”。此外，聚氨酯材料是在目前所有高分子材料中唯一一种在塑料、橡胶、泡沫、纤维、涂料、胶粘剂和功能高分子七大领域均有应用价值的合成高分子材料
The carbamate group and carbamate - urea group are called hard segments in the polyurethane structure, while the chain segments composed of polyols are called soft segments.
The plastic properties and strength of polyurethane are mainly determined by its hard segment properties, while its rubber properties and elasticity are mainly determined by its soft segment properties. Therefore, by changing the chemical structure, specification index, variety and formula proportion of different raw materials, we can produce a variety of products with various properties and uses. It is known as the "fifth largest plastic" after polyethylene, polyvinyl chloride, polypropylene and polystyrene. In addition, polyurethane is the only synthetic polymer material with application value in seven fields of plastic, rubber, foam, fiber, coating, adhesive and functional polymer