A polymer processing system includes a mixer. The mixer includes at least one side wall and a bottom wall that cooperate to define a chamber. At least one side wall also defines a bore. The mixer also includes a pair of rotors that are disposed in the chamber and are rotatably received by the at least one side wall for mixing polymers. The mixer also includes at least one injector that at least partially extends through the bore of the at least one side wall. The polymer processing system also includes a ram that is movably connected to the mixer. The polymer processing system also includes a compressed air supply that is fluidly connected to the at least one injector to supply compressed air to the chamber through the at least one injector.

A rubber composition manufacturing method comprises an operation in which at least rubber, silica, and silane coupling agent are kneaded in an internal kneader at not less than a temperature lower limit for a coupling reaction between the silica and the silane coupling agent to proceed. For at least a portion of time during which that operation is being carried out, a compressed gas is delivered to the kneading chamber while the ram is in a nonpressing state.