Characterising fibre alignment in moulded fibre materials across X, Y, and Z axes

Abstract

Abstract Moulded fibre is emerging as a sustainable alternative to single-use plastic items, commonly used for food and non-food packaging. Yet its mechanical properties are often inferior to oriented paper products, due to the limited fibre alignment during forming. This study introduces a method for characterising fibre orientation (FO) within moulded fibre products, enabling analysis of pulp flow patterns and turbulence during the production of moulded fibre items. The fibre alignment is characterised by sheet splitting the samples using an automated sheet splitter, and high-resolution scans of the split layers were analysed using MATLAB Structure Tensor analysis to determine the fibre orientation (FO) in the X and Y directions. The MATLAB analyses provided FO distribution across layers, in the Z-direction and offered insights into X and Y directional alignment. Outputs included visual heatmaps using a block approach and quantitative metrics. This approach enables efficient, detailed FO characterisation throughout the layers of a product, allowing for further improvement of moulded fibre properties. Validation results showed accurate and sensitive results. This method introduces opportunities to understand and control fibre alignment, a key step toward improving the strength properties of moulded fibre packaging.