Product molecular structure：
Polyurethanes were first produced and investigated by Dr. Otto Bayer in 1937. Polyurethane is a polymer in which the repeating unit contains a urethane moiety. Urethanes are derivatives of carbamic acids that exist only in the form of their esters. The major advantage of PU is that the chain is not composed exclusively of carbon atoms but rather of heteroatoms, oxygen, carbon and nitrogen. For industrial applications, a polyhydroxyl compound can be used. Similarly, poly-functional nitrogen compounds can be used at the amide linkages. By changing and varying the polyhydroxyl and polyfunctional nitrogen compounds, different PUs can be synthesized. Polyester or polyether resins containing hydroxyl groups are used to produce polyesteror polyether-PU, respectively. Variations in the number of substitutions and the spacing between and within branch chains produce PUs ranging from linear to branched and 9exible to rigid. Linear PUs is used for the manufacture of fibers and molding. Flexible PUs is used in the production of binding agents and coatings. Flexible and rigid foamed plastics, which make up the majority of PUs produced, can be found in various forms in industry. Using low molecular mass prepolymers, various block copolymers can be produced. The terminal hydroxyl group allows for alternating blocks, called segments, to be inserted into the PU chain. Variation in these segments results in varying degrees of tensile strength and elasticity. Blocks providing rigid crystalline phase and containing the chain extender are referred to as hard segments. Those yielding an amorphous rubbery phase and containing the polyester/polyether are called soft segments. Commercially, these block polymers are known as segmented Pus
Flexible polyurethane is mainly a linear structure with thermoplasticity, which has better stability, chemical resistance, resilience and mechanical properties than PVC foam, with less compression variability. It has good thermal insulation, sound insulation, shock resistance and anti-toxic properties. Therefore, it is used as packaging, sound insulation and filtering materials. Rigid polyurethane plastic is light, sound insulation, superior thermal insulation, chemical resistance, good electrical properties, easy processing, and low water absorption. It is mainly used as structural material for construction, automobile, aviation industry, heat insulation and thermal insulation. Polyurethane elastomer performance between plastic and rubber, oil resistance, wear resistance, low temperature resistance, aging resistance, high hardness, elasticity. It is mainly used in the shoe industry and medical industry. Polyurethane can also be made into adhesives, coatings, synthetic leather, etc.