R. Gendron et al., RESIDENCE TIME DISTRIBUTION IN EXTRUDERS DETERMINED BY IN-LINE ULTRASONIC MEASUREMENTS, Advances in polymer technology, 15(2), 1996, pp. 111-125
The knowledge of residence time distribution (RTD) in industrial extru
ders is critical, notably when dealing with easily degradable polymers
or when using extruders as chemical reactors. Many methods have been
proposed for RTD determination but there are some drawbacks associated
with each; they are expensive, hazardous, time consuming, or lacking
sensitivity. A novel ultrasonic technique, sensitive to the filler con
centration of polymer suspensions, is proposed. Ultrasonic properties
(ultrasonic velocity and attenuation) were evaluated with regard to pa
rameters such as linearity of the response, resolution of the measurem
ent, and especially robustness to pressure and temperature variations.
The attenuation, chosen for RTD evaluation along with a specific grad
e of calcium carbonate filler as the tracer, was then monitored to yie
ld the RTD of the material in a twin-screw extruder, for different exp
erimental conditions where quantity of filler utilized, as well as the
method used to feed it, were changed in order to optimize the techniq
ue. (C) 1996 John Wiley & Sons, Inc.