melting of the material to the exit from the screw channel.
The residence time and the temperature profiles of individual polymer particles
differ from each other, hence, it is necessary to determine the maximum value of the
J* criterion. Figure 9.6 shows the shape of the temperature/time curve for two
melt particles, one of which, particle A enters the space in front of the screw at the
beginning of the plasticating cycle, while particle B enters the space in front of the
screw at the end of the plasticating cycle. The shape of this curve depends primarily
on the ratio of the volume of the screw channel and the volume of the shot. For the
sake of simplicity assume that this ratio is 2, in other words, it is assumed that in each
cycle half of the material leaves the screw channel. This means that particle A entered
the screw channel in the previous cycle (cycle I), at the beginning of the plasticating
cycle (point a), while particle B entered the screw channel at the end of the cycle. Let
the initial temperature of particle A be T0, this temperature increases by the end
of the first plasticating cycle, the material particle reaches point b (at time 4).
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