A kneading apparatus for a thermoplastic resin, includes: a plasticizing cylinder which has a high pressure kneading zone and a pressure reduction zone; a screw in the plasticizing cylinder; a downstream side seal mechanism which shuts off communication between the high pressure kneading zone and the pressure reduction zone; and a pressure reduction zone pressure adjusting mechanism which is connected to the pressure reduction zone and which controls a pressure of the pressure reduction zone so that the pressure is not less than an atmospheric pressure and the pressure is not more than a maximum pressure of the high pressure kneading zone that is achieved when kneading a molten resin with a pressurized fluid, when the downstream side seal mechanism shuts off the communication between the high pressure kneading zone and the pressure reduction zone.

A plasticizing unit and/or injection unit for a molding machine with an injection cylinder for plasticized material, at least one degassing opening, and a degassing device in flow connection with the at least one degassing opening for releasing and discharging undesired gases from the plasticized material. The degassing device has a flow element, in flow connection with the at least one degassing opening, which is formed to generate a negative pressure by the Venturi effect at the degassing opening, and/or the degassing device has a filter device, in flow connection with the at least one degassing opening, for filtering gases being released.