Résumé
Arabinoxylans (AX) and (1 -> 3)(1 -> 4)--d-glucans (BG) are the main components of the cell walls in theendosperm of wheat grain. The relative occurrence of these two polysaccharides and the fine structureof the AX are highly variable within the endosperm. Films of AX and BG were used as models of the cellwall to study the impact of polymer structure on the hydration and mechanical properties of the cellwalls. Effective moisture diffusivities (Deff) of AX and BG films were determined from 0 to 95% relativehumidity (RH) at 20°C. Deffwas influenced by the water content, and the structure of polysaccharides.Higher Deffwas obtained for films made with highly substituted AX compared to values obtained for filmsmade with BG or lowly substituted AX. Proton dipolar second moments M2and water T2relaxation timesmeasured by TD-NMR, indicated that the highly branched AX films exhibited a higher nano-porosity,favoring water motions within films. Results from traction tests showed significant different mechanicalproperties between the AX and BG films. BG films exhibited much higher extensibility than AX films.Strength and extensibility of AX films decreased with increasing arabinose to xylose ratio. Our resultsshow that the water motions and the mechanical properties of AX and BG films can be linked to thepolysaccharide chains interactions that modulate the nanostructure of films.