Direct fluorination applied to wood flour used as a reinforcement for polymers.

Direct fluorination was applied to wood flour in order to improve its compatibility with polymers and thus enhance the properties of wood-polymer composites. Fourier-transform infrared spectra and (19)F solid-state nuclear magnetic resonance results underlined a successful covalent grafting of fluorine atoms onto the wood chemical structure. No physical damage of the wood particles was observed during scanning electron microscopy analysis. The thermal behaviour of the wood flour was also studied by thermogravimetric analysis. The hydrophilic property changes of wood flour were examined by evaluating the water content and the rate of water uptake of samples under different relative humidity conditions. A decrease in the wood flour water content was noted after fluorination. All these studies tend to prove the efficiency of this treatment on wood hydrophilia.

Direct insights on flax fiber structure by focused ion beam microscopy.

In this article, it is shown that focused ion beam (FIB) systems can be used to study the inner structure of flax fibers, the use of which as a reinforcing material in polymer composites still draws much interest from multiple disciplines. This technique requires none of the specific preparations necessary for scanning electron microscopy or transmission electron microscopy studies. Irradiation experiments performed on FIB prepared cross sections with very low Ga+ ion beam currents revealed the softer material components of fibers. Thus, it confirmed the presence of pectin-rich layers at the interfaces between the fibers of a bundle, but also allowed the precise localization of such layers within the secondary cell wall. Furthermore, it suggested new insights on the transition modes between the sublayers of the secondary cell wall.