Abstract: A cylindrical apparatus or module to be included in a screw of a plasticating device. The screw has a helical flight disposed within and cooperating with the inner-wall of a heated barrel to form an upstream where material is fed into and a downstream where material exits the device. The cylindrical module has a helical channel traversing in a reverse helical direction compared with the direction of the flight. Input grooves extend in the surface of the module with input groove openings beginning within the helical channel and terminating in a dead end before intersecting the channel upstream. Output grooves, being adjacent to the input grooves, extend in the surface of the module with output groove openings beginning within the helical channel and terminating in a dead end before intersecting the channel downstream. A barrier is between the pair of adjacent input and output grooves to prevent direct communication therebetween.