Presently disclosed embodiments concern an isocyanate-modified composition which includes A) from about 65 to about 99 weight % (based on the total weight of the isocyanate-modified composition) of a base polymer having either hydroxyl groups or amine groups or mixtures thereof, and B) from about 1 to about 35 weight % (based on the total weight of the isocyanate-modified composition) of a blocked isocyanate. The presently disclosed embodiments also include a golf ball made from the isocyanate-modified composition, and a method of making a golf ball using the isocyanate-modified composition, such as by injection molding.