2020/09/18 by Vincenzo Calabrese, Simon J. Haward, Amy Q. Shen · 18 citations
Engineering · Materials Science · Physics and Astronomy · #Advanced Cellulose Research Studies #Colloid #Electrohydrodynamics and Fluid Dynamics #Extensional definition #Innovative Microfluidic and Catalytic Techniques Innovation #Kinematics #Rod #Shear (geology) #Shear flow #Shear rate #Shearing (physics) #Velocimetry #cond-mat.soft
paper · pdf · doi:10.1021/acs.macromol.0c02155
arxiv created 2020/09/18 · openalex created_date 2020/09/25 · openalex publication_date 2021/02/04 · arxiv updated 2021/06/09 · openalex updated_date 2026/08/06
High Resolution Image Download MS PowerPoint Slide Cellulose nanocrystals (CNC) can be considered as model colloidal rods and have practical applications in the formation of soft materials with tailored anisotropy. Here, two contrasting microfluidic devices are employed to perform an experimental quantification of the role of shearing and planar extensional flows on the alignment of a dilute CNC dispersion. Characterization of the flow field by microparticle image velocimetry is coupled to flow-induced birefringence analysis to quantify the deformation rate–alignment relationship. The deformation rate required for CNC alignment is 4× smaller in extension than in shear. The birefringence signal rising from the CNC alignment in shear and extension can be scaled on a single master curve using a Péclet number that accounts for the shear and extensional viscosity of the solvent fluid, respectively. Based on this simple scaling relationship, it is possible to anticipate the alignment of rigid colloidal rods under purely extensional deformation by knowing the respective alignment profile in a shearing flow that is more accessible via multiple rheo-optical techniques. Quantification of the differences between shearing and extensional kinematics at aligning colloidal rods establishes coherent guidelines for the manufacture of structured soft materials.