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Polyvinylalcohol/graphite nanocomposites with graphite nanosheets have been prepared by a mechanical method based on grinding of graphite powder, under low energy pure shearing milling, using water or KOH as lubricant. The use of different lubricant concurs to obtain graphite sheets that differently disperse in hydrophilic polymeric matrix. An improvement of water vapor permeability (up to 12%), compared with homopolymer, has been observed.

MgH2/Nb2O5 composite is one of the most promising candidates for the hydrogen delivery. The performances of these materials are usually improved by mechanical milling because a finer distribution of the catalyst and the induction of defects on the particles accelerate the hydrogen sorption kinetic of the powders. Aiming at elucidating the factors responsible for this improvement, the effect on the reaction kinetics induced by nanometric and micrometric Nb2O5 powders has been investigated by a Sievert type apparatus. Nanometric additive imparts excellent performances in comparison to the micrometric one. The activation of the sample by sorption cycling has been investigated. In order to elucidate the role of the catalyst, a metallographic study of partially desorbed MgH2/Nb2O5 composite has been applied for the first time. The powders have been also characterized by X-ray diffraction and thermal gravimetric analysis.