Thermoplastic polyurethane elastomers are classified into two types: polyester and polyether. They are white, irregularly shaped spherical or columnar granules with a density of 1.10~1.25 g/cm³. The relative density of the polyether type is lower than that of the polyester type. The glass transition temperature of the polyether type is 100.6~106.1℃, while that of the polyester type is 108.9~122.8℃. Both polyether and polyester types have brittle temperatures below -62℃, with the polyether type exhibiting better low-temperature resistance than the polyester type.
