Modeling Fibre-Fibre Joints with Cellulose Nanofibril Filaments

The mechanical properties of fibre composites are largely dependent on the strength of individual fibre-fibre joints. Whereas bulk material properties are easily measured, the heterogeneity and small size of pulp fibres makes it challenging to create and measure individual joints. In this work we seek to model fibre joints through the use of uniform cellulose nanofibril (CNF) based filaments and to provide insight into the interfacial interactions that occur in fibre composites.

Using a novel co-axial spinning technique, we are able to produce CNF filaments with dimensions and morphology similar to that of pulp fibres. These filaments retain Cellulose I crystal structure, are readily handleable and can be surface modified to reproducibly form individual joints for tensile testing. Specifically, we investigate how layer-by-layer assembly of oppositely charged polyelectrolytes can be used to increase fibre-fibre joint strength, and ultimately improve bulk mechanical properties of fibre composites.