Tensile Creep Test
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Tensile creep test
General information
The creep tensile test for determining resistance to environmental stress cracking (ESC) is one of the three most important methods for testing the stress crack resistance of plastics, alongside the flexural strip method and the ball or pin indentation method [1].
The standardised test is carried out in accordance with ISO 22088-2 [2], whereby multipurpose test specimens in accordance with ISO 3167 [3] are preferably subjected to a constant tensile force corresponding to a stress below the yield stress, while a defined medium at a selected test temperature is applied.
Tensile Creep test to determine the stress cracking resistance
In contrast to the creep test for determining creep behaviour [4], the measurement arrangements used require a climate or media chamber (Fig. 1), whereby no strain measurement device is necessary due to the required parameters.
| Fig. 1: | Test setup for creep tensile testing in accordance with ISO 22088-2 and measurement of environmental stress cracking |
In this tensile creep test, the time and/or stress at which the test specimen breaks is determined.
Experimental methods and parameters
Three methods are used to evaluate stress crack behaviour:
- Determination of the tensile stress that leads to fracture after 100 h
- Determination of the fracture time at a constant specified stress
- Determination of the dependence of the tensile stress on the fracture time.
This provides the creep tensile strength (fracture stress) σB as a function of the service life (fracture time) tB.
In another variant, the test specimen is deformed as the force increases, i.e. a simple deformation curve is recorded in the aggressive medium.
Further experimental methods and results are described by Brown [5] and Bledzki [6].
See also
References
| [1] | Ramsteiner, F.: Bewertung der Spannungsrissbeständigkeit. In: Grellmann, W., Seidler, S. (Eds.): Kunststoffprüfung. Carl Hanser (2025), 4th Edition, pp. 400/401 (ISBN 978-3-446-44718-9; E-Book: ISBN 978-3-446-48105-3; see AMK-Library under A 23) |
| [2] | ISO 22088-2 (2006-08): Plastics – Determination of Resistance to Environmental Stress Cracking (ESC) ‒ Part 2: Constant Tensile Load Method |
| [3] | DIN EN ISO 3167 (2014-08): Plastics – Multipurpose Test Specimens |
| [4] | ISO 899-1 (2017-09): Plastics – Determination of Creep Behaviour – Part 1: Tensile Creep |
| [5] | Brown, R. P.: Testing Plastics for Resistance to Environmental Stress Cracking. Polymer Testing 1 (1980) 267‒282 |
| [6] | Bledzki, A. K., Barth, C.: Spannungsrissbeständigkeit von Polycarbonat messen. Materialprüfung 40 (1998) 404‒410 |