A hopper for feeding previously-mixed virgin and crushed plastic materials into the throat of a barrel of an injection unit of a plastic injection molding machine, the hopper comprising a rotating auger extending longitudinally preferably in the center of the hopper from an upper area to a lower area within the hopper. The rotating auger rotates in the same direction as the flights of the auger such that the auger's flights continuously lift up the materials from the bottommost area of the hopper to an upper area of the hopper, thereby minimizing the coagulation of the materials in the lower areas of the hopper.