A thermoplastically processable cured rubber composition comprises a crosslinked or cured urethane polymer dispersed in a matrix made of a thermoplastic polymeric material. In one aspect, the matrix forms a continuous phase and the crosslinked urethane polymer is in the form of particles forming a non-continuous phase. The processable rubber compositions can be made by a process of dynamic vulcanization of a urethane prepolymer material in the presence of the thermoplastic matrix material. The process involves combining a urethane prepolymer, a curing agent capable of reacting with the urethane prepolymer, and a thermoplastic material to form a mixture, and heating the mixture at a temperature and for a time sufficient to effect reaction between the curing agent and the prepolymer. Mechanical energy is supplied to the mixture during the heating step so that the crosslinking or curing of the urethane prepolymer occurs while the prepolymer and thermoplastic are undergoing a mixing.