Poly bd resins, from Elf Atochem North America Inc., Philadelphia, are liquid, hydroxyl-terminated homopolymers of butadiene. The facile reaction of Poly bd resins with curing agents such as conventional di- and polyisocyanates provides an economical route to the preparation of general-purpose elastomers. The unique structure of these resins provides properties that surpass conventional polyether and polyester urethane systems, as well as conventional, general-purpose rubbers.