Polyurethane and polyurethane rubber are versatile materials with unique properties. They are composed of polyester or polyether and diisocyanate compounds, resulting in excellent wear resistance, good elasticity, high hardness, oil resistance, and solvent resistance. However, whether polyurethane should be classified as plastic or rubber depends on the situation. In Taiwan, Hong Kong, and other regions, plastics are generally referred to as plastics, making a strict distinction between plastics and rubber meaningless. The difference between plastics and rubber is based on the material's glass transition temperature (TG) being above or below room temperature. Typically, polymers with TG lower than normal temperature are considered plastics (such as polyethylene with Tg of - 78 ℃), while those with TG higher than normal temperature are considered rubber. However, polyurethane is a unique polymer composed of a hard segment and a soft segment. The Tg of the hard segment is low, behaving like plastic, while the Tg of the soft segment is higher than room temperature, exhibiting rubber-like characteristics. The proportion of the hard and soft segments can be adjusted during the synthesis process, allowing polyurethane to behave as both plastic and rubber. Polyurethane rubber is produced by reacting oligomer Polyols, polyisocyanates, and chain extenders in the presence of catalysts. Based on the raw materials used, it can be categorized into polyester polyurethane rubber and polyether polyurethane rubber. The structure of polyurethane rubber's molecules determines its physical and mechanical properties, such as elasticity, modulus, hardness, cold resistance, and mechanical strength, and can be adjusted by modifying the makeup and relative molecular weight of raw materials.