A small-angle scattering study of cellulose whiskers in aqueous suspensions

Fillers with dimensions in the nanometer range are important components of nanocomposites materials. A crucial point for the modeling of the resulting mechanical properties is to determine their average dimensions accurately as is required for the mechanical coupling modeling. In this work, reinforcing particules are cellulose monocrystalline rods with an average length of 1 mu m. They are prepared from marine animals and obtained in the form of stable aqueous suspensions. Their precise shape and lateral dimensions are determined by use of the small-angle scattering technique (neutron and X-rays). The study is achieved in a rather extended range of concentration (from 0.071 to 1.37% w/w) within which all scattering patterns are found isotropic and homothetic. A form-factor analysis demonstrates that the whiskers are long and rigid fibers whose cross-sectional shape is rectangular (88 x 182 Angstrom(2)). The cross-sectional morphology of the rods is consistent with crystallographic data of the cellulose fillers. The suspensions can be considered as homogeneous in this range of concentration since no significant higher aggregation of the whiskers can be detected.