Résumé
Mechanochemistry is a promising green solvent-free process that can be applied to change the properties of plant materials. Intense comminution of lignocellulosic biomass leads to the disruption of the crystalline structure of cellulose and the breakage of covalent bonds linking constitutive macromolecules. Thus, it generates free radicals that can recombine with other molecules, modifying the chemical composition and reactivity of the plant mate-rials. Previous work demonstrated that such modifications allow the chemical grafting of a pH-sensitive fluorophore onto flax shives. Those can then be incorporated into a pol-ymer matrix to create specific sensors using 3D printing processes. In this work, we explore the possibility of mechanically exploiting the free radical formation during the ul-trafine milling step to graft fluorescein onto a fine powder of hemp core. The milling was carried out in a vibratory ball mill, with a single ball operating at different frequencies. The specific impact energy (i.e. the energy delivered per gram of powder per impact) and the total milling energy were determinated based on the modelling of the milling device and they were related to the efficency of the grafting based on chemical analysis (fluoresence analysis, FTIR, Solid Stade NMR) of the grafted powder. Our results indicated that the efficiency of the grafting is linearly correlated to the total milling energy and that a similar grafting rate than those obtained by chemical grafting can be achieved. In addition, a high-er total milling energy associated with a lower impact milling energy allow to obtain the higher rate of grafting, while improving the properties of the grafted powders by reducing the agglomeration.