To liquid absorption and liquid – paper interaction

We present a method which provides detailed insights to the dynamics of the water absorption process and waterpaper interaction, based on transmittance measurements of ultrasonic beams. We found that the water absorption process of an uncoated papersheet comprises two consecutive time regimes. The underlying mechanism that governs the regimes’ shift is the combination of bre surface modi cation by water and the recreation of the bres lumen after wetting. In the rst regime, water advances along the dry pore surface, which is hydro neutral, and the water forms a solid column inside the capillary (pore), while in the second regime, moving along the primed (wetted) surface of the capillary is a more favourable path as the surface becomes hydrophilic when wetted. Consequently, the water may not necessarily ll the entire capillary when the capillary expands in volume due to hydroexpansion and hence forms a hollow water column. We propose a model that enables us to determine/predict the depth of water absorption by the dry pore structure of the paperwhich is often the case for inkpaper interaction during printing. The results of our studies suggest that the depth of water penetration along the dry pore surfaces can very well be described by the Bosanquet model. 25770.indb 585 15/08/2013 12:41 Preferred citation: L. Yang, J. Liu and L. Gu. Detailed insights to liquid absorption and liquid-paper interaction. In Advances in Pulp and Paper Research, Cambridge 2013, Trans. of the XVth Fund. Res. Symp. Cambridge, 2013, (S.J. I’Anson, ed.), pp 585–598, FRC, Manchester, 2018. DOI: 10.15376/frc.2013.2.585. Li Yang, Jianghao Liu, and Lingya Gu 586 Session 5: Micro uidics