Capillary Rheometry
Capillary Rheometry measures apparent viscosity (resistance to flow) over a broad range of shear rates and at varied temperatures, which are comparable to the conditions encountered in molding, calendaring, extrusion, etc. The data is commonly used to determine processing parameters, for lot-to-lot quality control, to measure processing degradation, which could reduce physical properties, and to study thermal stability.
Test Procedure:
According to customer specifications, temperature, shear rate and other parameters are selected. In a Shear Sweep melted plastic is extruded through a capillary and the force at varied shear rates is determined. To determine Thermal Stability, melted plastic is extruded through a capillary after varied periods of residence time in the barrel of the extruder.
Specimen size:
At least 30g of material are required.
Data:
In a Shear Sweep, shear stress and shear rate are calculated and plotted.
For Thermal Stability, apparent melt viscosity is calculated and plotted versus residence time.
Equipment used at Plastics Technology Laboratories, Inc.:
Kayeness capillary rheometer
**Please note that this test description is intentionally generic in nature and aimed at providing a descriptive summary to enhance test understanding. For detailed procedures please contact a PTLI Technical Representative at ptli@ptli.com or obtain full and most recent revisions of the specific standard.
Plastics Technology Laboratories, Inc., 50 Pearl Street, Pittsfield, MA 01201. Tel: 413-499-0983; Fax: 413-499-2339.