- 01/09/2024
GÖTTFERT – PVT measurements in the capillary rheometer
PVT measurements: Precision instruments for the plastics and elastomer industry
The PVT test device from GÖTTFERT enables isobaric and isothermal measurements in accordance with ISO 17744.
PVT measurements: Precision instruments for the plastics and elastomer industry
PVT stands for pressure, volume and temperature – three decisive factors when analysing the thermodynamic behaviour of materials such as plastics, elastomers, thermosets and liquids. PVT measurements can be used to precisely determine the specific volume changes of a material as a function of pressure and temperature, which is essential for numerous industrial applications.
PVT measurements are essential, especially in the field of injection moulding. They enable precise moulded part design and help with the optimal choice of material, even for existing moulds. PVT analyses also play a key role in the extrusion and pressing of moulded parts, as they provide valuable insights into shrinkage and contraction processes. This data is particularly indispensable in the development and simulation of production processes.
Various devices are available for carrying out PVT tests. One solution is the capillary rheometer from Göttfert, which can perform precise PVT analyses in addition to rheological measurements. Alternatively, the stand-alone PVT 500 device offers specific PVT tests in accordance with the ISO 17744 standards (determination of specific volume as a function of temperature and pressure (pVT diagram) – piston device method). The isobaric measuring process in these devices realistically reflects the conditions of the injection moulding process, making the data obtained highly relevant for industrial practice.
The importance of shrinkage behaviour, which is crucial for tool design and quality assurance in production, should be emphasised in particular. Accurate PVT measurement also provides essential information on the cooling behaviour of materials, such as that which occurs during extrusion.
GÖTTFERT enables isobaric and isothermal PVT measurements to be carried out in accordance with ISO 17744 either with the “PVT” capillary rheometer add-on or with the stand-alone PVT 500 device:
PVT isobaric
In isobaric PVT measurements, the volume is measured under constant pressure as a function of temperature. To do this, the material is first filled at melting temperature and then heated to the initial temperature. The desired pressure is then set and kept constant. Cooling begins and a uniform cooling rate is set. During the cooling process, the volume is recorded in relation to the temperature. Automatic heating then takes place and the next pressure value is set. In this way, several isobaric measurements at different pressure levels can be carried out fully automatically with a single material filling.
PVT isothermal
In isothermal PVT measurement, the temperature remains constant while the pressure is varied and the volume is recorded. The material is first filled at melting temperature and then slowly cooled to the first measuring temperature under pressure. As soon as stable temperature conditions have been established, the different pressure levels are set and the respective volumes are measured. This process is then repeated for the different temperature levels from bottom to top.
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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.
