Slit-die Rheometry and its Potential in Polymer Melt Rheology

Description

Slit die rheometry is known since the early 70th of the last century aiming at improving pressure drop measurement, widening the shear rate range to be covered and offering new possibilities to characterize compounds with complex rheological behavior such as wall slipping PVC and rubber compounds. Adapting slit die systems to processing machines in injection molding and extrusion offers new possibilities in rheological characterization at conditions close to processing. In this contribution the application of slit-die rheometers for thermoplastics and uncurable rubbers compounds will be discussed in detail from first systems up to special machine rheometers such as by-pass extrusion rheometers and injection molding machine rheometers. Advantages and disadvantages as well as new possibilities in characterizing pressure dependency of viscosity will be pointed out. Rheological measurements will be presented for polypropylene, wall slipping PVC, wood plastic compounds and rubber compounds containing no curatives. A special injection mold for slit die rheometry offers the possibility to widen the shear rate range up to 106 s-1 and to measure the pressure dependency of viscosity up to pressure levels of approx. 600 bars. The rheological evaluation of measured values and the approximation of true viscosity curves take into account temperature rise due to shearing according to a method of Aggassant.

Period	24 Mar 2015
Event type	Guest talk
Location	AustriaShow on map