- 19/01/2024
GÖTTFERT – Extensional rheometer
An extensional rheometer stresses a continuously flowing strand from a rheometer and thus measures the extensional viscosity of the material.
In the world of plastics processing, the elongation of the material is becoming increasingly important in view of the constantly increasing productivity requirements.

Task definition
The stretch properties of the liquid polymer play an important role in film production, blow moulding, thermoforming, calendering/coating and fibre spinning. These processes not only involve forming in shear and expansion flows in extruders and moulds during the extrusion and injection moulding process, but also drawing out the melt.
In order to precisely describe the complex processing methods, it is essential to precisely determine the elastic properties of the melt. The conventional determination of viscosity or melt flow index is not sufficient in any case. The requirements for the test methods used are diverse and require careful selection.
The test method should enable a short test time in order to meet the requirements of modern production environments. At the same time, it should be easy to operate to ensure efficient use in the industry. The strain rates of the test should be similar to the actual process conditions in order to achieve realistic results. In addition, the method should be suitable for both product development and quality control in order to cover the entire life cycle of plastic products.
In this field of tension between increasing productivity and complex processing requirements, the precise characterisation of melt properties is a key component. By taking these aspects into account, plastics processors can develop innovative products while maintaining quality standards in the industry.
Test equipment
GÖTTFERT has developed four devices, each of which has its own specific target group of plastics processors.
- The RHEOTENS is a technological tensile testing system for determining the elastic properties of polymer melts.
- The HAUL-OFF system is used to measure the ductility of melts by pulling the strand at a constant speed or under linear or exponential acceleration.
- The SLR Spin Line Rheometer is a measuring system that characterises the spinning properties of plastic melts. The vertically extruded plastic thread is drawn off at up to 7000 m/min and the force in the strand is measured at the same time. The system enables large draw ratios in order to simulate the synthetic fibre spinning process on a laboratory scale.
The complete system consists of an extruder, a deflection head and an extensional rheometer. Optionally, an online rheometer can also be used as a melt pump instead of the deflection head. The actual measuring head is an extensional rheometer in the Haul-Off design. - The D-MELT makes it possible to determine the melt flow index and extensional viscosity in one measurement. This combination is particularly interesting as a rapid test in the incoming goods inspection for processing polymers.
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Rheological testing equipment since 1962
GÖTTFERT Werkstoff-Prüfmaschinen GmbH was founded in 1962 by Prof. Dr. Otto Göttfert. In the second generation, his son Dr Axel Göttfert took over as sole managing director.
On the world market, the medium-sized company is known as one of the leading companies in the niche area of rheological testing equipment. The innovative rheological systems are used worldwide in laboratories as well as in production.
To be closer to many customers, a subsidiary was opened in Rock Hill, South Carolina, USA, in 1989. In 2011, GOETTFERT (China) Limited was founded with headquarters in Beijing and Shanghai.
Advantages at a glance
Precision and customer service make all the difference. GÖTTFERT and TeMeCo provide instruments and services on site.
High precision
No compromises when it comes to precision.
Intuitive handling
Modern equipment and intuitive handling.
Highest efficiency
Automated systems for less variability in results and less time spent by the operator.
After-Sale-Unterstützung
Fast response time and best support for questions and problems.