Cellulose nanocrystals (CNC) are intriguing renewable nanostructured building blocks for functional materials. CNCs produced by sulfuric acid hydrolysis readily form chiral nematic (cholesteric) liquid crystalline phases in water above a critical concentration. Understanding the shear alignment and post-shear relaxation of CNC dispersions is important for producing materials with controlled optical and mechanical properties. Both RheoSANS and Rheo-Optics are powerful techniques for understanding the effects of shear on both viscosity and microstructure. In this work isotropic, biphasic, liquid crystalline, and gel dispersions of CNC in deuterium oxide (D<sub>2</sub>O) were investigated using RheoSANS and analogous dispersions in water were investigated using Rheo-Optics. Plots of order parameter versus shear rate showed three distinct rheological regions over a range of biphasic concentrations. In addition, both RheoSANS and Rheo-optics were used to understand the post-shear relaxation of CNC dispersions. The findings are significant for both processing and increasing fundamental understanding of the effects of shear on CNC alignment.

Using Rheo-SANS and Rheo-Optics to understand the shear response of cellulose nanocrystal dispersions

256th National Meeting (2018)

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