Company: GÖTTFERT
Extensional rheometer
In the world of plastics processing, the elongation of the material is becoming increasingly important in view of the constantly increasing productivity requirements.
In blow molding, thermoforming, calendering, coating and spin processes, it provides valuable information on the processability of the material.
Application
An extensional rheometer measures the extensional viscosity of a continuously flowing strand from a rheometer. These elongation properties play a crucial role in various manufacturing processes, including film production, blow molding, thermoforming, calendering/coating and fiber spinning.
Forming in extrusion and injection molding processes takes place not only through shear and expansion flows in the tool, but also through the extraction of the melt. The precise determination of the elastic properties of the melt is therefore crucial, and conventional methods such as viscosity or the melt flow index are not sufficient in many cases.
The requirements for the test methods used are diverse and require careful selection. The chosen test method should not only enable a short test time to meet the requirements of modern production environments, but also 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 a field of tension between increasing productivity and complex processing requirements, the precise characterization 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.
The extensional rheometers from GÖTTFERT
RHEOTENS
The extensional rheometer for material characterization in film production
When it comes to the characterisation of polymer materials in film production, i.e. typically in blow moulding, deep drawing, calendering/coating, the RHEOTENS provides valuable information on structural viscosity and molecular weight distribution. Basically, the device is designed like a beam scale. The puller wheels and the drive motor are arranged on a cradle-mounted beam. The liquid polymer strand is pulled downwards by the wheels. In contrast to the HAUL-OFF system, the strand is not deflected at the puller wheel but continues straight downwards. This means that the melt can be pulled out from the zero point of force even at very low expansion rates.
- Pull-off speed: up to 1900 mm/s
- Linear or exponential acceleration
- Measuring range up to 2 N, resolution 0.001 N
Compared to earlier versions of the Rheoten, the current RHEOTENS has the following (retrofittable) features:
- 4 instead of 2 wheels
- Cooling (e.g. for sticky materials)
- Automatic calibration. Pneumatic.
- Different wheel surfaces
- USB connection
HAUL-OFF
The extensional rheometer for spin applications
The HAUL-OFF system also involves measuring the ductility of melts at a constant or increasing pull-off speed. The pull-off force during stretching of the liquid melt strand is measured. This force is used to calculate the apparent elongation rate as well as the elongation viscosity, the elongation ratio and the elongation stress. The design of the HAUL-OFF system makes it particularly attractive for spin applications.
- Pull-off speed: 0-2000 m/min
- Linear or exponential acceleration
- Measuring range up to 1 N, resolution 0.05 mN
D-MELT
The melt flow index / extensional rheometer for spin applications
The D-MELT makes it possible to determine the melt flow index and extensional viscosity in one measurement. It consists of a mi-40 melt index tester and a permanently installed HAUL-OFF extensional rheometer. This combination is particularly suitable as a rapid test for incoming goods inspection.
- Simultaneous measurement of melt flow index and melt elasticity
- Recording of force, speed and time
- Determination of MVR value
- Graphical representation and meaningful characteristic value from the HAUL-OFF measurement
- Pull-off speed: 0-44.8 m/min
- Precise and high-resolution force sensor
- For smaller shear rates, around 50-100, possibly 200
SLR - Spin Line Rheometer
The extruder or rheograph / extensional rheometer for spin applications
This measuring system is specifically designed to investigate the spinnability of plastic melts. A small extruder or rheograph produces a continuously flowing, vertical plastic filament that is quickly drawn off with a HAUL-OFF system at up to 7000 m/min. The force in the strand is measured via a small deflection pulley.
The measuring system is designed for the largest possible haul-off ratios and reproduces the synthetic fiber spinning process on a laboratory scale.
- Pull-off speed: 0-8000 m/min
- Spin distance approx. 1300mm
- Measuring range up to 1N, resolution: 0.05 mN
- PC software RheotensE
Downloads and links
Accessories
GÖTTFERT – Accessories for polymer testing
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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.