Birefringent properties of aqueous cellulose nanocrystal suspensions

Abstract

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.

Integrated photoelasticity measurements of a three-dimensional laminar flow: second-order stress terms in the stress-optic law

“…The CNC suspension is then sonicated using an ultrasonic processor (UX-300, Mitsui Electric Co. Ltd.) for 10 minutes. The ultrasonic processor also reduces the error between the experimental and theoretical orientation, as reported in a previous study [15,16]. The concentration of the CNC suspension is set to 0.5 wt%.…”

“…The integrated photoelasticity requires the use of Mueller calculus (calculations using the Stokes parameter and the Mueller matrix) as well as the stress-optic law [13,14], as described later in Section 2. 1. In recent years, there have been some reports on the application of photoelasticity to quasi-two-dimensional fluid flows [15][16][17][18][19]. In particular, several measurements have used an aqueous cellulose nanocrystal suspension (hereinafter, CNC suspension) as the photoelastic fluid [15,[20][21][22] to show that the above two-dimensional measurement principle can be successfully applied [23,24].…”

“…1. In recent years, there have been some reports on the application of photoelasticity to quasi-two-dimensional fluid flows [15][16][17][18][19]. In particular, several measurements have used an aqueous cellulose nanocrystal suspension (hereinafter, CNC suspension) as the photoelastic fluid [15,[20][21][22] to show that the above two-dimensional measurement principle can be successfully applied [23,24]. These studies have shown the great potential of photoelasticity for flow field measurements.…”

Naturally derived colloidal rods in microfluidic flows

“…CR are usually optically positive, so that the orientation of the slow optical axis, , captures the direction of orientation of the rods. 35 For each volumetric flow rate ( , m /s), FIB provides the spatial distribution of the birefringence, , [shown in the normalized form as , where is the mass fraction of the CR, in Fig. 3(c) ] and the orientation of the slow optical axis, [ Fig.…”

Alignment–Rheology Relationship of Biosourced Rod-Like Colloids and Polymers under Flow

“…A similar exponential relationship was shown for monodisperse filamentous viruses by Lang et al using a rheo-SANS setup. , More recently, Calabrese et al, coupling microfluidics with flow-induced birefringence (FIB) could verify the exponential viscosity decay with the increasing extent of particle alignment, in analogy with the studies of Förster et al and Lang et al , Nonetheless, it is unclear to what extent this exponential relationship is a general feature of RC and RP fluids. In other studies, the extent of RC/RP alignment and the resulting shear viscosity have been investigated (via FIB and rheo-scattering) but have not been directly linked. − In the present work we explore the relationship between RC and RP alignment and the resulting rheological properties (alignment–rheology relationship) for a wide variety of naturally derived RC and RP with significantly distinct morphology, length scales, and flexibility. As model biosourced RC, we use cellulose nanocrystals (CNC), TEMPO-oxidized cellulose nanofibrils (OCNF) with two different average contour lengths, and a filamentous virus ( Pseudomonas phage, Pf1).…”