On the wall slip phenomenon of elastomers in oscillatory shear measurements using parallel-plate rotational rheometry: II. Influence of experimental conditions

Journal article
(Original article)


Publication Details

Author(s): Walter B, Pelteret JP, Kaschta J, Schubert DW, Steinmann P
Journal: Polymer Testing
Publication year: 2017
Volume: 61
Pages range: 455-463
ISSN: 0142-9418
Language: English


Abstract


The use of parallel-plate rotational rheometry to characterize ex situ pre-prepared samples of rubber-like polymers is motivated by, for example, the investigation of magneto-rheological elastomers. When exceeding a critical excitation amplitude in oscillatory shear experiments, these elastomeric samples are prone to slip at the sample-plate contact interface. This phenomenon, known as wall slip, starts to occur at the sample's outer rim and leads to an imperfect force transfer onto the sample. This results in a systematic error of measured rheological material quantities.



A thorough investigation is presented to reveal how this phenomenon is affected by selected experimental conditions, namely the static axial preload and measuring frequency. For this purpose disc-shaped samples composed of an unfilled silicone rubber are prepared by casting and examined by means +of a controlled stress rotational rheometer equipped with a serrated rotor configuration.



The oscillatory strain sweep experiments suggest that wall slip, exclusively present at the serrated rotor surface, is significantly influenced by the static preload. In contrast, only a slight frequency dependence is observed within the examined experimental conditions.



Further insights into the wall slip mechanism were attained by two novel methodologies. It is shown that it is possible to produce a master curve for the various applied preloads. This demonstrates that the physical mechanism behind wall slip is independent of the axial force. Furthermore, we derive an empirical model for the criterion governing the onset of wall slip. This links the critical stress at which wall slip is initiated to the static friction condition and geometrical aspects of the rotor configuration. From this it is anticipated that the conditions for reliable experiments involving ex situ pre-prepared samples composed of low damping elastomers can, in the future, be estimated a priori.



FAU Authors / FAU Editors

Kaschta, Joachim Dr.-Ing.
Lehrstuhl für Werkstoffwissenschaften (Polymerwerkstoffe)
Pelteret, Jean-Paul
Lehrstuhl für Technische Mechanik
Schubert, Dirk W. Prof. Dr.
Lehrstuhl für Werkstoffwissenschaften (Polymerwerkstoffe)
Steinmann, Paul Prof. Dr.-Ing.
Lehrstuhl für Technische Mechanik
Walter, Bastian
Lehrstuhl für Technische Mechanik


How to cite

APA:
Walter, B., Pelteret, J.-P., Kaschta, J., Schubert, D.W., & Steinmann, P. (2017). On the wall slip phenomenon of elastomers in oscillatory shear measurements using parallel-plate rotational rheometry: II. Influence of experimental conditions. Polymer Testing, 61, 455-463. https://dx.doi.org/10.1016/j.polymertesting.2017.05.036

MLA:
Walter, Bastian, et al. "On the wall slip phenomenon of elastomers in oscillatory shear measurements using parallel-plate rotational rheometry: II. Influence of experimental conditions." Polymer Testing 61 (2017): 455-463.

BibTeX: 

Last updated on 2018-23-12 at 13:50