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.