Test Climate
Prüfklima | A service provided by |
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Test climate
General information
To ensure reproducibility when determining characteristic values in polymer testing, it is necessary to guarantee a defined production of test specimens, sufficient consistency of the test climate, and the achievement of a state of equilibrium with regard to temperature and humidity in the test specimen [1]. In the case of plastics, even slight variations in test conditions, such as ambient temperature and humidity, can cause significant changes in characteristic value levels. For this reason, so-called “standard atmospheres” or "standard climates" have been defined as test conditions in order to simulate practical conditions.
Standard climate and classes of standard climates
The standard climate according to ISO 291 [2] requires an air temperature of 23 °C and a relative humidity of 50 % . This standard specifies two different classes of standard atmospheres (standard climates) according to the different deviation ranges. Class 1 specifies a permissible deviation from the temperature of ± 1 °C and from the relative humidity of ± 5 %. Class 2 specifies a deviation from the temperature of ± 2 °C and from the relative humidity of ± 10 %.
Types of air conditioning for conditioning and testing
To ensure that the test specimens are in a reproducible condition, either the entire test laboratory must be air-conditioned or the test specimens must be conditioned to the appropriate test climate. While a period of 4 hours is sufficient for temperature stabilization, a longer normalization period is required for humidity stabilization using climate chambers (Fig. 1) [1]. Once the equilibrium conditions have been set, the test specimens must be stored in a desiccator under defined conditions before being tested in the air-conditioned test laboratory.
| Fig. 1: | Climate chamber VIT 280 from Vötsch Industrietechnik GmbH, Bailingen |
Special conditions apply to plastics such as polyamide (abbreviation: PA), which absorb moisture under standard conditions depending on the matrix type and fillers and reinforcing materials.
Further information on special conditioning regimes for achieving equilibrium in test specimens made of various plastics is provided, for example, by Brown in [3].
See also
References
| [1] | Bierögel, C.: Preparation of specimens. In: Grellmann, W., Seidler, S. (Eds.): Polymer Testing. Carl Hanser, Munich (2022) 3rd Edition, pp. 33–36 (ISBN 978-1-56990-806-8; E-Book: ISBN 978-1-56990-807-5; ePub ISBN 978-156990-808-2; see AMK-Library under A 22) |
| [2] | ISO 291 (2008-05): Plastics – Standard Atmospheres for Conditioning and Testing |
| [3] | Brown, R. P. (Ed.): Handbook of Polymer Testing: Physical Methods. Marcel Dekker, New York Basel (1999) (ISBN 0-8247-0171-2; see AMK-Library under C 5) |