Application of elastomers in the manufacture of solid-propelled powerplants is discussed. Thermal, ablative, and erosion-resistant properties of elastomeric composite materials are influenced by the composition of the elastomeric binder, the shape and composition of the reinforcing filler, filler loading, and the filler-to-elastomer ratio. The development of high performance motors, operating at higher chamber pressures, higher combustion flame temperatures, and for longer burning durations clearly point to the need for further advances in the insulative motor components for the liner, motor case, slivers, and nozzle if the requirements for improved future rocket designs are to be met.