The Rheometer: Different Types And Their Applications

When it comes to discovering and measuring the viscosity of various materials, companies turn to 2 different devices. These are the viscometer and the rheometer. Both instruments serve a specific purpose, measuring viscosity of a specific type. While material suppliers of polymer melts have been using rheometers for decades, only more recently have those who utilize plastic compounds begun to use this particular instrument.

Types of Rheometers

Rheometers can fall into one of three major classifications. These are three:

  1. Capillary Rheometers: In use for both extrusion and injection molding, capillary rheometers are used to obtain the right measures of multiple points on the curve. The capillary rheometers track the flow through a narrow space to track the viscosity alterations relative to the rates of shear. Such an approach is perceived to measure absolute or true viscosity. This is in contrast to that measured by torque rheometers.
  2. Torque Rheometers: Torque rheometers these are comparable to are essentially small extruders or mixers. What they measure is the torque on the rotors or mixing screws. By doing this, they will be able to the difficulty level of mixing the materials. In addition, a technician can obtain data on viscosity and melt flow as the compound, plastic or polymer flows through either the capillary or torque rheometer. Because the result is from a comparison method, it is not absolute or “true” viscosity but is viewed as a relative measure of viscosity.
  3. Dynamic Rotational Rheometers: These types of rheometers investigate the viscoelastic properties as well as the molecular structure of the material, which is positioned between two parts: a stationary component and one that rotates back and forth. The speed on these instruments is easily adjusted to meet the parameters of the test. The intent is to discover viscosity but other additional information on how a process will affect a resin proves to be valuable. These are most commonly employed when the material is thermoplastic

One other form of this instrument worth mentioning is the extensional. Technicians use extensional rheometers when the focus is on high viscosity materials and elongational viscosity. These instruments are extremely sensitive to polymer long-chain branching and crystallinity.

Purpose of a Rheometer

Rheometers have become useful in characterizing the viscoelastic characteristics of polymer melts as well as various resins ability to process in both the plastic and polymer industries. They are now in general use as an effective tool by both quality control (QC) and research and development (R &D) departments. It is becoming increasingly important for a company to employ a rheometer is it wants to understand how it can process a resin successfully.

Goettfert has long been a company you can depend upon for delivering high quality products been delivering rheological testing equipment for thermoplastic, thermosetting plastics and rubber.  From the most innovative type of Rheometer to superior melt indexers and high quality capillary rheometers, their trained and expert staff work hard to ensure all their customers receive the excellent devices they require for their success. As a leading manufacturer in this field, they continue to ensure every product that leaves their facility is the best possible. With a motivated and highly trained staff to provide excellent customer service, you can rely on Goettfert to deliver. To learn more, visit

Sharing is caring!