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- Title
Online optical monitoring of polymer melting in a twin‐screw extruder.
- Authors
Bicalho, Luciana Assumpção; Covas, José António; Canevarolo, Sebastião Vicente
- Abstract
An experimental setup containing a sliding online optical device is used to monitor in real‐time the melting process of a commercial polypropylene in a corotating intermeshing twin‐screw extruder. Turbidity and birefringence are measured at several axial locations upstream and along the first restrictive zone of the screw, where melting develops. The experiments are performed using different set barrel temperatures, extruder feed rates, and screw speeds, to generate distinct flow histories and, accordingly, changes in the onset and rate of melting of the polymer. The local flow conditions are characterized in terms of residence time distribution and data equivalent to axial pressure profiles. Turbidity and birefringence are sensitive to changes in the operating conditions providing a coherent description of melting. The onset of melting seems to take place in partially filled conveying elements, and then melting develops quickly as the latter become fully filled, and is completed well before flow through the kneading block. The melting process of polypropylene inside a twin‐screw extruder at several axial locations upstream and along the first restrictive zone of the screw was measured and shown in a diagram. The onset of melting takes place in partially filled conveying elements, then melting develops quickly as the latter become fully filled, and is completed well before flow through the kneading block. Turbidity and birefringence are sensitive to the unmolten PP solid content and so were used to take the quantitative measurements.
- Subjects
POLYMER melting; OPTICAL devices; TURBIDITY; ATMOSPHERIC turbidity; BIREFRINGENCE; DATA distribution; POLYPROPYLENE
- Publication
Polymer Engineering & Science, 2020, Vol 60, Issue 9, p2163
- ISSN
0032-3888
- Publication type
Article
- DOI
10.1002/pen.25460