The dry‐to‐wet transition of fiber networks—Return to mechanical stability

Abstract

AbstractIn this article, we provide a comprehensive experimental, numerical, and theoretical explanation of the dry‐to‐wet transition of nonbonded fiber networks made of natural fibers. Given that the main functionality of many common products consisting of fluff pulp fiber networks requires absorption of liquids, we focus on understanding the solid volume fraction transition from a dry to a wet state as a crucial component for controlling properties such as permeability and capillary pressure, on which product function eventually depends. From studying the wetting of fluff pulp fiber networks with a distribution of fiber lengths, we show that the change in the solid volume fraction going from dry to wet state is driven by the disappearance of fiber–fiber adhesion. The mechanically stable state to which the network transitions is independent of its prior dry solid volume fraction and predetermined primarily by the fiber aspect ratio.