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Helical flow of curing highly viscous liquids
Author(s) -
Jepsen C.,
Mewes D.
Publication year - 1991
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.760310503
Subject(s) - materials science , annulus (botany) , natural rubber , composite material , shear rate , mechanics , plastics extrusion , curing (chemistry) , cylinder , viscosity , geometry , mathematics , physics
For profile extrusion of rubber, a shear head is frequently placed at the outlet of the extruder. In the shear head, the rubber compound is heated to its cure temperature by means of internal friction between two coaxially rotating cylinders (annulus). The aim of this examination is to find suitable operating parameters for all rubber compounds. The highest possible temperatures and an even cure profile are the characteristics of suitable operations. The degree of cure should be as close as possible to the maximum cure permitted. For examination of the processes in the annulus, a coupled system of differential equations is set up and solved numerically. The cure profiles established along the annulus are of special interest. The effects of the geometry, the rotational speed of the inner cylinder, the volumetric flow, the operating temperatures, and the viscosity as a function of the shear rate and the temperature are examined. The results of the calculations show that the viscosity, which increases with increasing cure, has a strong effect on the velocity and dissipation profiles. The results of the experimental investigations on a shear head coincide well with theoretical prediction.