The Rheology Behavior of Aramid and Cellulose Nanowhisker Suspensions

The flow responses of aramid and cellulose nanowhisker (fibrids) or CNCs (cellulose nanocrystal) suspended in a sulfuric acid and water respect at loadings of about 17% weight fraction was determined in transient shear flow. The effect of temperature and shearing conditions were examined. Aramid solution exhibits strong shear thinning with power law indices about 0.2-0.3, and cellulose nanowhisker suspension indices is below 0.15. Formation of an interacting flocculated network at rest is the reason for the large relative viscosity and offers the least flow resistance during shear flow. The structure formed at rest is easily destroyed, and this is the reason for the observed shear thinning. Evolution of shear stress data versus time over four of shear rate were described the structure of nematic phase in aramid\sulfuric acid solution. Also shear rheology results of nanowhisker/water suspension show shear thinning behavior, and behave as a plastic system at different temperature. For spinning process, the aramid\sulfuric acid dope through the air gap entered into cold water. Orientation of polymer solution emerged from the spinneret and through very high extensional shear in the air gap resulted in excellent tensile properties of the final spun fibers.