Thermoplastic polyurethanes (TPUs) are formed by linear polymeric chains of segmented structure. They are prepared by the addition reaction of difunctional isocyanates, chain extenders and long-chain polyols. Most conventional TPUs are based on either polyester or polyether polyols, 4,4'-diphenylmethane diisocyanate (MDI) as the isocyanate component and 1,4-butanediol (BDO) as a chain extender [2].
Hydroxyl-terminated polybutadiene diols are now available that can be employed to prepare novel soft TPUs. These hydrophobic elastomers are suitable for adhesive and sealant applications requiring excellent hydrolytic stability, low-temperature flexibility, and outstanding resistance to aqueous acids and bases.
Development of soft grades of TPUs (having hardness ranging from 70-85 Shore A) has been reported among the latest trends in the TPU market. The main interest of researchers is focused on the polyol component [3].
Polyurethanes based on polybutadiene polyols could fall into this category.