| Summary: | The fibrous network of cardboard samples was studied with the aid
of tomographic imaging. For analysing the samples a method of
determing the number of contacts between fibres in a planar
fibrous network was introduced. The model is based on the fact
that deposited paper-like structures tend to have predominantly
planar fibre orientation. With this assumption an expression of
the mean segment length was derived in terms of the average
shortest path along fibres through the sample in the out-of-plane
direction.
The density profiles of cardboard samples were analysed by determing
four quantitative features, the solids content,
standard deviation of the solids content, slope and curvature. All
the samples had a slope in the same direction, i.e., they were denser at the bottom surfaces. Densification seems to
occur at both surfaces, as the curvature was larger for samples
with higher solids content.
Our measurements indicate that contact densities of the cardboards,
i.e., the number of fibre-fibre contacts per unit volume are
proportional to the square of the solids content. This is in
agreement with earlier models for three-dimensional fibre
networks.
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