Layered organization of anisometric cellulose nanocrystals and beidellite clay particles accumulated near the membrane surface during cross-flow ultrafiltration: In situ SAXS and ex situ SEM/WAXD characterization

Abstract

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Breakdown and buildup mechanisms of cellulose nanocrystal suspensions under shear and upon relaxation probed by SAXS and SALS

“…The morphology of the CNCs considered in this work and their phase diagram in aqueous suspension have been studied in detail in previous publications (Gicquel et al, 2019;Semeraro et al, 2020). SAXS data from diluted suspensions at rest, assuming a parallelepipedal shape for the sonicated CNCs, gave 121 × 20 × 5 nm 3 average dimensions.…”

“…Figure 3a shows the azimuthally-averaged scattering intensity, I(q), of CNC suspensions plotted over a broad q-range combining SAXS and SALS data of suspensions at rest. The mean interparticle distance d as well as the phase diagram of these sonicated CNC suspensions as a function of CNC concentration have previously been studied (Gicquel et al, 2019;Semeraro et al, 2020). The mean interparticle distance between the elementary CNCs has been deduced from the scattering intensities of CNC suspensions probed by SAXS.…”

“…In order to improve the development of nanocellulosebased materials, several processes involving shear flow or pressure forces have been subject of in situ structural investigations. For example, time-resolved in situ small-angle X-ray scattering (SAXS) was successfully employed to access the structural organization and growth of accumulated particles near the membrane surface during cross-flow ultrafiltration (Jin et al, 2015;Rey et al, 2019;Semeraro et al 2020). In situ and real time grazing-incidence wide-angle X-ray scattering (GIWAXS) was used to investigate the influence of suspension concentration, shear-cast velocity, and drying temperature on the ordering of the CNCs during the casting process (Sanchez-Botero et al, 2018).…”

Orientation of Cellulose Nanocrystals Controlled in Perpendicular Directions by Combined Shear Flow and Ultrasound Waves Studied by Small-Angle X-ray Scattering

“…SAXS data from diluted suspensions at rest, assuming a parallelepipedal shape for the sonicated CNCs, gave 121 × 20 × 5 nm 3 average dimensions. 15,44,54 Shear flow/US-Cell. A Shear flow/US-Cell composed of a parallelepipedic channel containing an immersed vibrating blade was developed to, on one hand, apply shear flow and/or ultrasonic waves to the feed suspensions and, on the other hand, to monitor in situ the dynamical structural organization changes by SAXS.…”

“…This includes shear flow field, [9][10][36][37][38][39][40][41][42][43][44] magnetic field, 45,49 electric field, 29 surface tension in drying processes, 19,20,50,51 and pressure forces in membrane separation processes. [52][53][54] More specifically, the effect of shear flow on the structural organization of CNCs have been extensively explored from a fundamental 9,10,36-41-44,51,54-56 to an industrial point of view in several processes inducing a flow. 12,19,20,26,27,30,[57][58][59][60][61][62] Ultrasound waves during cross-flow ultrafiltration processes were applied and revealed an alteration of the structural organization of CNCs within the concentrated layers deposited near the membrane surface.…”