Birefringent properties of aqueous cellulose nanocrystal suspensions

Birefringence measurements of aqueous cellulose nanocrystal (CNC) suspensions are reported. Seven suspensions with concentrations between 0.7 and 1.3% per weight are sheared in a Taylor-Couette type setting and characterized using a birefringent measurement technique based on linear polarized light and acquisition with a polarization camera. Steady state measurements with shear rates up to 31 1/s show extinction angles of 23°–40° and birefringence in the order of 1e–5. The findings demonstrate the utility of CNC suspensions for flow birefringence studies.