(633c) Impacts of High Shear-Rate Processing on Cellulose Nanofibrils

Cellulose nanomaterials provide a promising avenue for combining composite materials with natural polymers or bio-based plastics, however current studies on rheological characterization at high shear rates is limited. In this study, a capillary rheometer was employed to investigate the rheological characteristics of aqueous nanofibrillated cellulose suspensions (NFCs) at room temperature and shear rates above 1000 s^-1. The shear rate-dependent viscosity of NFCs was characterized and monitored for viscosity-related indicators of fibril decomposition or entanglement due to the stresses induced by the high shear-rate flow. Traditional capillary rheology corrections for entrance pressure loss and Non-Newtonian flow profiles were attempted to compare apparent and true rheological behaviors. Large entanglements of fibrils made the characterization of the suspensions difficult due to their ability to clog the capillary, particularly with fine capillary dimensions. However, appropriate well-characterized preprocessing steps enable significantly improved measurement resolution and could be implemented on a large scale to enhance rheology and modeling analyses for fibril distribution in composite materials.