University of Cambridge > Talks.cam > Seminars for the Centre for Environmental and Industrial Flows > Clare Rees-Zimmerman - Diffusiophoresis of latex in silica and Mohammed Al-Sharabi - Investigating the liquid transport kinetics of ceramic powder compacts using terahertz pulsed imaging

Clare Rees-Zimmerman - Diffusiophoresis of latex in silica and Mohammed Al-Sharabi - Investigating the liquid transport kinetics of ceramic powder compacts using terahertz pulsed imaging

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Clare Rees-Zimmerman – Diffusiophoresis of latex in silica

Analogous to diffusion, diffusiophoresis is the motion of particles along the concentration gradient of a different particle type. One mechanism that can cause diffusiophoresis is an excluded volume effect, occurring where there is a mixture of particle sizes. In this talk, a Hele-Shaw experiment investigating evidence for diffusiophoresis in particles of different size ratios will be presented.

Mohammed Al-Sharabi – Investigating the liquid transport kinetics of ceramic powder compacts using terahertz pulsed imaging

The liquid penetration into ceramic powder compacts is an important phenomenon in many processes, such as tablet disintegration in the pharmaceutical field as well as impregnation in the catalysis field. This study aims at providing a better understanding of the effect of the preparation conditions and type of solvent on the liquid transport kinetics of ceramic powder compacts to enhance their design and performance. Terahertz pulsed imaging (TPI) was used to investigate the impact of the heating rate during sintering (firing) on the water penetration into α-alumina powder compacts that were prepared at different compaction forces. The TPI method was also used for the first time to study the transport of a less polar solvent, i.e. 1-octanol, into a range of α-alumina compacts and compare the transport results to those of water. For 1-octanol, it is possible to study the imbibition process as well as any changes in the sample structure behind the liquid front, such as the change in the effective refractive index of the sample and the fill fraction of solvent in the sample. The TPI results reveal that the alumina samples fired at the largest heating rate of 200 °C h-1 have the largest water penetration rate compared to the heating rates of 100 °C h-1 and 150 °C h-1. The results confirm that both the microstructure characteristics, particularly porosity, as well as the surface properties, i.e. wettability, influence the liquid transport kinetics. It was also found that the effective refractive index of the sample, obtained through the analysis of the peak behind the liquid front, increases as a function of time upon the transport of 1-octanol into the sample due to the increase in the fill fraction of the solvent in the sample. The results demonstrate the usefulness of the TPI method to quantitatively investigate the transport of solvents with different polarities into ceramic powder compacts that are prepared at different manufacturing conditions for better quality control and optimised design and performance of such materials.

This talk is part of the Seminars for the Centre for Environmental and Industrial Flows series.

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