FAIR-CT98-5057 The chemical composition of non-textile flax fibres

Contacts




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Biocomposites/Boards : Crops for Biocomposites/Boards : FAIR Area 1.2 - Green Chemicals and Polymers Chain : FAIR Marie Curie Research Training Grants

Objectives:

The aim of the project is to:

• characterise the hemicellulose and lignin fraction of flax fibres
• develop a strategy for determining the chemical composition of flax fibres
• investigate the chemical structure of flax fibres depending on variety (linseed/textile) at different harvesting times
• investigate the effect of different pre-processing routes (retting and decorticating) on surface chemistry and chemical composition (key parameters).

Activities and results:

Lignin and hemicellulose characterisation was carried out with lignin isolated from mature fibres by acid hydrolyses and as Bjorkman lignin. It was characterised by elemental analysis, HPLC, UV and IR/FI'IR spectra and compared with lignin in situ and with wood lignin. Non-lignin, aromatic substances were determined by HPLC. The acetyl bromide method for determining true lignin content was adjusted and developed for flax lignin. Hemicelluloses were isolated by a multiple-step sequential extraction. The fractions were analysed for sugar content and uronic acids using HPLC and GLC of the derivatives. The fractions were further analysed using GPC and/or NMR. A strategy for determining hemicellulose content in flax fibres was developed.

Chemical characterisation of fibres at different harvest times included determination of the total chemical composition for the different raw materials, using the techniques developed in the project combined with established methods for wood chemistry analysis of extracts, ash and cellulose.

Key parameters for characterisation of flax fibre chemistry were used to characterise differences in chemical composition due to different processing schemes (combinations of retting degree and mechanical decorticating). Furthermore, the cellulose DP/levelling-off DP was determined to identify excess cellulose degradation. The effect of retting was followed using CEC, NIR and FTIR analysis. The surface chemistry characteristics of fibres were determined using established methods. Surface energy was to be determined using wetting analysis. Microscope FTIR, ESCA and CLSM were also used. An attempt was to be made to relate the different surface chemistry characteristics to the degree of removal of chemical components as a result of different processing routes.

Keywords: flax fibres, retting, decorticating

Contacts

Scientific Supervisor

• Royal Veterinary and Agricultural University Plant Fibre Laboratory / DENMARK