Use of Py-GC/MS and PCFC to characterize the surface modification of flax fibres

Surface modification of flax fibres with a phosphorous agent in a solvent process have been originally evaluated through thermal degradation using Pyrolysis Combustion Flow Calorimeter and Pyrolysis-Gas Chromatography/Mass Spectrometry. It has been highlighted that these techniques are particularly sensitive to the presence of the phosphonated grafting agent on natural fibres. After treatment, octadecylphosphonic acid (ODPA) was found to be covalently grafted on the flax fibres at a rate of almost 5%. For a better comprehension of the interactions between the phosphonic group and flax, the reactivity of the phosphonic acid function of ODPA with the main components of fibres was assessed. The results showed that ODPA reacts strongly with lignin and at a lower degree with xylan (model for hemicellulose) whereas no reaction with cellulose was evidenced.