A strategy for prediction of the elastic properties of epoxy-cellulose nanocrystal-reinforced fiber networks

SUMMARY: The reinforcement potential of cellulose nanocrystal (CNC) additions on an idealized 2-dirmensional (2-D) fiber network structure consisting of micron sized fiber elements was investigated. The reinforcement mechanism considered in this study was through the stiffening of the micron sized fiber elements via a CNC-epoxy coating. A hierarchical analytical modeling approach was used to estimate the elastic properties spanning three different structural features; i) micromechanics for CNC-epoxy properties, ii) laminate theory for fiber elements coated with CNCepoxy, and iii) a 2-D network model for an assembly of interconnected fiber elements. The extent to which CNCepoxy coating can stiffen a fiber element was dependent on the CNC volume fraction, CNC-epoxy layer thickness, CNC alignment, CNC aspect ratio, and the original stiffness of the fiber element. Calculations suggest there is a potential for CNC additions to stiffen network structures, the extent to which is strongly depending on the initial fiber element stiffness. Incorporation of limited experimental observations into the model and fiber element properties typical of fibers used in paper products, however, suggests that the enhancement of CNCs on a wood fiber element and thus on the network structure, may be limited.