Water sorption behavior and gas barrier properties of cellulose whiskers and microfibrils films

Rod-like straight cellulose whiskers and long flexible entangled microfibrillated cellulose (MFC), both extracted from sisal fibers, were used to prepare cellulosic membranes. In view of the promising barrier properties recently reported separately in the literature for these naturally occurring particles it was of interest to investigate the influence of the nature of the nanoparticles (whiskers vs. MFC) on the transport properties of the films. The water vapor and gas (carbon dioxide, nitrogen and oxygen) permeability of films composed of either cellulose nanocrystals or MFC has been reported. It was observed that the diffusion of water is rather controlled by the surface than by the core, probably because of a barrier effect related to the presence of water at the surface during the sorption kinetics. The cellulose whiskers film was found to be much more permeable to gases than MFC. This difference was ascribed to the higher porosity of the former and to the possibility of entanglements of MFC and different surface chemistry.