Abstract: Compositions comprising (A) non-branched polybutadiene having terminal hydroxyl functionality less than 2 per molecule by average; and (B) branched polybutadiene having terminal hydroxyl functionality more than 2 per molecule by average; the weight ratio of (A) to (B) being about 99:1 to 1:99. These compositions are reacted with organic polyisocyanates to form prepolymers which are cured by reaction with a chain extender such as a diol to produce cured resins which exhibit unexpectedly improved tear strength properties and themoplasticity with high modulus, and improved tackiness and shelf life for hot melt adhesives. The prepolymers have lower viscosity and better storage stability as compared with those from conventional branched polybutadienes of the (B) type. Alternatively, the compositions can be cured directly in a one-shot reaction with diisocyanates to form a polyurethane with the described combination of properties.

Abstract: Improved amine-terminated polybutadienes (ATPBs) having one or two terminal groups of the formula —CHRNH2 wherein R is C1-C20 alkyl, are prepared by aminating a secondary hydroxyl-terminated polybutadiene having no ether groups. The ATPBs may be hydrogenated or partially hydrogenated, either prior to or after the amination, to saturate or partially saturate the polymers. Preferred ATPBs are of the formula H2NCHR-(polybutadiene)-CHRNH2 wherein R is C1-C20 alkyl.