Measurement of fibre-fibre contact in three-dimensional images of fibrous materials obtained from X-ray synchrotron microtomography

A series of wood-fibre mats was investigated using high-resolution phase-contrast microtomography at the beamline ID 19 of the European Synchrotron Radiation Facility in Grenoble, France. A method for data reduction to quantify the degree of fibre-fibre contact has been derived. The degree of fibre-fibre contact and bonding plays a fundamental role in the mechanical properties of cellulose-fibre mats, paper materials and cellulose-fibre composites. The proposed computerised automated method consists of two parts. First, fibre lumens are segmented using a watershed based method. This information is then used to identify fibre-fibre contacts in projections along the z-axis of the material. The method is tested on microtomographic images of mats made of wood pulp fibres, and is shown to successfully detect differences in the amount of fibre-fibre contact between samples. The degree of fibre-fibre contact correlates well with measured out-of-plane strength of the fibrous material.