Mechanics of wet fibrous bundles

There are several ways of forming macroscale elastic structures from a fibre suspension: paper sheets are obtained from the dewatering of a cellulosic fibre suspension on a forming grid, and it has been shown recently that soft viscoelastic gels are formed upon extrusion of a microfibre suspension.

Here, we use suspensions of flexible high aspect ratio hydrogel fibres, with radii ranging from tens to hundreds of microns, with a precise control over the characteristics of the fibres. By pulling a few fibres through an interface, we are able to extract continuous cylinders of aggregated fibres (or fibrous bundles). As these bundles are placed in water right after formation, the fibres separate and the bundles redisperse in the solution. We characterize the conditions (fibre geometry, flexibility and suspension density) at which this continuous bundle is formed. We probe the mechanical and structural properties of the bundles and the reversibility of the process. Initially, the bundles are soft gel-like structures filled with water, and we characterize their evolution as water is slowly removed until forming a dry bundle.