Thermoplastic Polyurethane (TPU) - Urethanes were the first major elastomers that could be processed by thermoplastic methods. TPUs do not have quite the heat resistance and compression-set resistance of the thermoset type of polyurethanes but most other properties are similar. Thermoplastic polyurethanes come in a wide range of hardness grades. Among elastomers, urethanes have outstanding abrasion resistance, low temperature flexibility is good, oil resistance is excellent, and urethanes rank among the best for load-bearing capability. Additives can improve dimensional stability and heat resistance, reduce friction, and increase flame retardancy, fungus resistance, and weatherability. Urethanes are a reaction product of a di-isocyanate and long and short chain polyether, polyester, or caprolactone glycols. The polyether types are slightly more expensive and have better hydrolytic stability and low-temperature flexibility than the polyester types. However, mechanical properties of the polyester type are generally higher. The caprolactones offer a good compromise between the ether and ester types.