Extensional viscosity from entrance pressure drop measurements

1997 ◽  
Vol 36 (2) ◽  
pp. 144-151 ◽  
Author(s):  
Mahesh Padmanabhan ◽  
Christopher W. Macosko ◽  
M. Padmanabhan
Keyword(s):  
Pressure Drop ◽  
Extensional Viscosity ◽  
Entrance Pressure

Extensional viscosity from entrance pressure drop measurements

1997 ◽  
Vol 36 (2) ◽  
pp. 144-151
Author(s):  
Mahesh Padmanabhan *, † , Christopher
Keyword(s):  
Pressure Drop ◽  
Extensional Viscosity ◽  
Entrance Pressure

Elongational Viscosity Measurements Using a Semi-Hyperbolic Die

2006 ◽  
Vol 16 (6) ◽  
pp. 312-320 ◽  
Author(s):  
D. G. Baird ◽  
J. Huang
Keyword(s):  
Pressure Drop ◽  
Laminar Flow ◽  
Extensional Flow ◽  
Elongational Viscosity ◽  
Extensional Viscosity ◽  
Viscosity Data ◽  
Low Density ◽  
Lubrication Approximation ◽  
Type Device ◽  
Shear Effects

Abstract The lubricated semi-hyperbolic die has been proposed as a technique for generating uni-axial extensional flow and, hence, as a device for measuring elongational viscosity. Two methods for extracting extensional viscosity data for polymer melts in laminar flow from this device have been proposed and are evaluated here. Following the approach proposed by Collier and coworkers, values of the transient extensional viscosity, ηe+, obtained from a non-lubricated semi-hyperbolic (SHPB) die for several polyethylene (PE) melts were found to be considerably higher than values obtained by means of the Münstedt-type device. Furthermore, the values of ηe+ obtained from the SHPB die were considerably higher than the strain averaged values of ηe+ which Everage and Ballman proposed would be obtained from a lubricated SHPB. The pressure drop across a SHPB die was estimated assuming resistance was all due to wall shear (using the lubrication approximation) for two PE resins. In the case of low density PE (LDPE) the values agreed to within 20% of the measured values suggesting that shear effects at the die wall were dominating the pressure drop and not extensional stresses. An analysis was carried out which showed that in the presence of lubrication the conditions for which the values of ηe+ obtained from the SHPB would be relatively accurate (Hencky strains > 5.0).

An annular rotating-die technique in extrusion process: effect of mandrel rotating speed on entrance pressure drop and flow properties of molten HDPE

2014 ◽  
Vol 18 (2) ◽  
pp. 241-251 ◽  
Author(s):  
Naret Intawong ◽  
Alongkot Darajang ◽  
Sittichai Udomsom ◽  
Thitipong Yoochooshai ◽  
Chatchawan Kantala
Keyword(s):  
Pressure Drop ◽  
Extrusion Process ◽  
Flow Properties ◽  
Rotating Speed ◽  
Entrance Pressure
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