Patent ID: 8794818

Claim:
An injection unit, comprising: an inlet having a feed throat for accepting, in use, PET material that has been dried in a pre-treatment chamber; a plasticizing sub-system for plasticizing the PET material into plasticized material; an outlet for outputting the plasticized material; a dosing unit, the dosing unit being operatively coupled to a source of an un-treated agent, the dosing unit being configured to introduce into the feed throat the un-treated agent configured to increase moisture level of the PET material to be plasticized, wherein the dosing unit is configured to introduce the un-treated agent in the form of PET granules having a moisture content that is comparatively higher than that of the PET material fed from the pre-treatment chamber 130 ; a measurement device that is configured to provide an indication of an operational parameter indicative of a current level of acetaldehyde within the material being plasticized; a controller configured to execute a closed loop control routine, wherein the closed loop control routine comprises receiving an indication of the operational parameter indicative of the current level of acetaldehyde and responsive to the operational parameter being indicative of an increased current level of acetaldehyde, the closed loop control routine being configured to execute: (i) triggering execution of introducing into the feed throat an un-treated agent configured to increase moisture level of the PET material to be plasticized; and (ii) during said introducing, controlling an amount of the un-treated agent being added.