Wet foam is an excellent carrier phase to produce particle or fibre structures. Thus, it is important to know how particles or fibres affect foam properties. We study foams generated by axially agitated mixing with 60-80% air content. The shear rate and resulting capillary number in mixing are very high compared to similar parameters in typical foam rheology studies. Onset of a flow macro-instability is observed at high rotation speeds both with and without cellulose fibres. The air content of the foam is strongly affected by this instability. By describing the effect of the air content on the stability of bubble interfaces, we explain the bubble size for broad ranges of rotation speed and surface tension. Added fibres usually reduce the bubble size for a fixed rotation speed. After the flow macro-instability, not only the air content but also the bubble size increases with reduced surface tension. Beyond the instability, the effect of fibres on foam properties becomes minor.
|Publication status||Published - 2014|
|Event||9th Annual European Rheology Conference, AERC 2014 - Karlsruhe, Germany|
Duration: 8 Apr 2014 → 11 Apr 2014
|Conference||9th Annual European Rheology Conference, AERC 2014|
|Period||8/04/14 → 11/04/14|
- air content
- bubble size
Ketoja, J., Al-Qararah, A., Hjelt, T., Koponen, A., & Harlin, A. (2014). Wet fibre-laden foams in axial mixing with macro-instabilities. Poster session presented at 9th Annual European Rheology Conference, AERC 2014, Karlsruhe, Germany.