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A study of the stick‐slip phenomenon in single‐screw extrusion of linear polyethylene
Author(s) -
Kay D.,
Carreau P. J.,
Lafleur P. G.,
Robert L.,
Vergnes B.
Publication year - 2003
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.10007
Subject(s) - materials science , linear low density polyethylene , extrusion , plastics extrusion , polyethylene , volumetric flow rate , compressibility , mechanics , mass flow rate , composite material , slip (aerodynamics) , mass flow , flow (mathematics) , thermodynamics , physics
We present results of a study on the stick‐slip phenomenon observed for two linear polyethylenes (HDPE and LLDPE). Experiments were carried out in a single screw extruder using dies of different diameters and L / D ratios. The pressure and the mass flow rate have been measured simultaneously and the instant mass flow rate was determined using laser Doppler velocimetry. Our results clearly confirm the hypothesis that the flow jumps from one stable branch to the other during oscillations as suggested in the literature. The role of the melt compressibility in the reservoir is also established. The effect of the average mass flow rate imposed by the extruder Q IN on the respective compression and decompression phases is in good agreement with effect predicted by the mass balance in the reservoir. We also used different reservoir volumes to confirm that the period of oscillations increases with the compressed melt volume upstream of the die.