Properties and Characteristics 
The properties of PU elastomer are between plastic and rubber. 
Among the features of PU elastomer is: 
•    excellent abrasion resistance • outstanding low-temperature performance 
•    excellent mechanical properties, combined with a rubber-like elasticity 
•    high shear strength 
•    high elasticity 
•    high transparency 
•     good oil and grease resistance 

The currently available PU elastomer can be divided mainly in two groups, polyester-based PU and polyether-based PU. 
Polyester-based PU has high mechanical properties, good oil and grease resistance but poor hydrolysis resistance. 
Polyether-based PU has excellent low temperature resistance and hydrolysis resistance. But mechanical properties and oil and grease resistance is not good as Polyester-based PU. 

Main differences between polyester- and polyether-based PU

Property	Polyester-based TPU	Polyether-based TPU
Abrasion resistance	excellent	acceptable
Mechanical properties	excellent	good
Low temperature flexibility	acceptable	excellent
Heat ageing	good	poor
Hydrolysis resistance	very poor	excellent
Chemical resistance	excellent	poor
Microbial resistance	very poor	good
Adhesion strength	good	poor
Injectability	excellent	acceptable

According to process methods, the PU elastomers are divided into Casting Polyurethane (CPUR) and Thermoplastic polyurethane (TPUR). 
Casting Polyurethane (CPUR) is easy to process and has wide applications. 

Thermoplastic polyurethane (TPUR) is any of a class of polyurethane plastics with many useful properties, including elasticity, transparency, and resistance to oil, grease and abrasion. 

TPUR has many applications including automotive instrument panels, caster wheels, power tools, sporting goods, medical devices, drive belts, footwear, inflatable rafts, and a variety of extruded film, sheet and profile applications.