Anisothermal stress relaxation test for characterization of elastomers and determination of crosslinking density
The TSSR-Meter can be used to perform conventional isothermal relaxation measurements as well as Temperature Scanning Stress Relaxation (TSSR), an anisothermal stress relaxation measurement method (AISR method).
This method can be used to characterize the mechanical-thermal properties of elastomers. An important factor here is the determination of the cross-linking density.
With the ever increasing demands on materials, the determination of crosslinking density is an important advantage, and therefore the TSSR meter is particularly suitable for material development and quality control during production.
- Reduced testing time and effort (4h TSSR vs. 72h DVR)
- Very good reproducibility
- Fast determination of the cross-linking density
- Information about relaxation behaviour and structure
The comfortable measuring and evaluation software under Windows® enables you to carry out tests automatically. The measurement data of the sample are displayed in real time during the measurement and then automatically evaluated and stored.
In addition, the data can be exported directly from the application to other calculation programs for further evaluation after the measurement.
Two different measurement methods are possible with the TSSR meter: the conventional isothermal relaxation measurement and the application of the TSSR method.
The measurement with the TSSR meter is performed in two steps: After inserting the sample rod, it is strained by a certain amount (>0-100%). During a freely selectable period of time, short-term relaxation processes can decay at a constant temperature.
In a second step, the anisothermally guided measurement follows. Here, the sample is heated to the specified temperature (max. 300°C) at a constant heating rate of >0 - 4 K/min.
In both phases, the TSSR meter records the force curves / tension curves over time or temperature. These form the basis for the evaluation. Essentially, the cross-linking density, the relaxation spectrum and the maximum working temperature can be determined.
From the measured gradient of the force curve at the beginning of the anisothermal measurement, the cross-linking density can be determined reproducibly and accurately after a few minutes of the actual measuring time. This means that the TSSR meter can also be used very well to detect and determine the different effects of crosslinked concentrations and the degree of crosslinking.
During the anisothermal stress relaxation, the area of the curve under the normalized force (F/F0) to temperature is determined and compared to the area of the idealized elastomer material. This ratio is the TSSR index and is a relative measure of the elastomer-like temperature behaviour of the used sample.
Within the relaxation spectrum 3 distinctive temperature limits are defined. The values T10, T50 and T90 indicate the temperatures at which the force has dropped by 10%, 50% or 90% relative to the initial force F0. Each value represents a specific characteristic of the sample. In addition, 3 further freely selectable temperature limits can be set and allows you to evaluate the material used at these specific working temperatures.
The TSSR-Meter can be used in many areas where mechanical-thermal properties have to be measured and verified.
- The determination of the cross-linking density is an advantage in the development of new materials and in quality assurance.
- The residual pressure deformation value can be predicted on the basis of the limit temperature using a linear correlation.
- The areas of application of TPE in comparison to carbon black-filled elastomers can be clearly defined.
- For soot-filled EPDM compounds, additional information can be obtained by anisothermal stress relaxation curves. These characterize the interactions between carbon black and polymers.
- In addition, the TSSR meter can be used to visualize the thermal limits of application of commercially available TPE materials and to characterize various TPE blends with relaxation spectra. .
- Individual materials can be assigned to product groups via the TSSR index determined by the TSSR meter.
The TSSR meter is based on a patented test method developed at the Osnabrück University of Applied Sciences under the direction of Prof. Dr. Vennemann. There is a close cooperation in the fields of further development and application technology.
|Messsystem||Heating / cooling chamber with electric heating and air cooling
Temperature range 20 - 300°C
Heating rate 0 - 4 K/min
Traverse, parallel and without backlash
Strain 0 - 100%
Force load cell 0 - 200 N
Isothermal relaxation time 0 - 1000h
|Test body||Test body Standard rod S2 rod according to DIN 53504
corresponds to test body 5A according to EN ISO 527
|Connections||PC via USB
Compressed air 5 - 6 bar
|Enviormental conditions||Storage temperature -25°C to +55°C
Operation temperature +5°C to +45°C
|Heating rate||2 x 220 W|
|Power supply||1 X 230 V, 50/60 Hz, 16 A + N + PE|
|Dimmensions (W x D x H)||490 * 610 * 450 mm|