Fibres surface macromolecular rearrangement for biocomposites production

Plastics are today fulfilling structural and mechanical functions in cross-disciplinary domains. In a context of reducing the environmental issues, decreasing the amount of plastic is a global concern. One solution to reduce the use of pure and unsustainable material is biocomposites. These materials are composed of natural fibres and polymer matrices, and possess hybrid properties of the initial components. These natural fibres are cellulose-rich which confer them a high mechanical resistance comparable to glass fibres which have been for years incorporated in composites at the industrial scale. Here, natural bast flax fibres were modified to modulate their properties. A treatment able to enhance the aesthetical and physico-chemical fibres properties was developed. The treatment lead to unexpected hydrophobic behaviour and an enhance crystallinity. Such results suggested that the fibres surface composition was modified. For industrial application, such as biocomposites, interfaces play a crucial role in the final material properties. Recombinant proteins were used to characterize the fibres surface. These fluorescent tagged proteins are detecting specifically polysaccharides such as cellulose, xylan and mannan. The amount of polysaccharides detected at the fibres surface clearly increased after the treatment. Noteworthy, this macromolecular modification of the fibres surface is correlated to the apparition of the unexpected fibres properties. Side beneficial effect are also detected after treatment and are completely independent to the variation of the fibres surface composition.