Rheological Characterization & Analysis

Rheological Characterization & Analysis

Polymer melt rheology is a complex subject that requires careful experiment design in order to obtain the information needed to meet an investigator’s requirements. AAPPI’s Rheology Laboratory is well-equipped to satisfy the rheological testing needs of research and development. Among the instruments present in the lab are a TA Instruments ARES-LS strain-controlled rheometer, a TA Instruments AR 2000 stress-controlled rheometer, a Malvern RH10 Advanced Capillary Rheometer, a Brabender torque rheometer, and a 100-ton, 18" x 18" Wabash-MPI compression molding press.

These instruments provide the necessary support for sample preparation, and linear and non-linear shear rheological analyses of fluids ranging from aqueous solutions to highly viscous polymer melts. Extensional viscosity measurements can be provided using the TA Instruments ARES-LS in conjunction with the planetary gear extensional viscometer fixture.

Rotational Rheometers

These instruments normally require a small specimen of the material to be tested in the form of disk, typically 25mm diameter and 1mm thick. The sample is placed between a pair of parallel plates or upper cone and lower plate whose temperature can be maintained by an oven.

Rotational rheometers use a number of test types to characterize a material over a range of temperatures and flow rates. Examples of the types of the types of tests available are:

•   Flow curves
•   Creep tests
•   Stress relaxation tests
•   Small amplitude sinusoidal oscillatory testing

Capillary Rheometers

Capillary rheometers are comprised of a temperature-controlled barrel incorporating one or more precision bores fitted with capillary dies at the exit. Pressure transducers are mounted immediately above the dies to record the pressure drop as the material being tested is extruded through the dies at a set volumetric flow rates.

Capillary rheometry is a technique whereby a sample is extruded through a die of defined dimensions and the shear pressure drop across the die recorded at set volumetric flow rates.

What materials can be tested using a capillary rheometer?

Polymer and rubber testing are historically the main areas for capillary rheometry use. However, applications for capillary rheometers cover a wide range of industries:

Capillary Rheometer
Malvern RH10


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Advanced & Applied Polymer Processing Institute

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