The focus of the present work aims at exploring the hydrodynamic production of bio-based materials from an experimental and numerical point-of-view. The transition of biopolymer or colloidal dispersions to visco-plastics with high yield stress is largely affected by the hydrodynamic stability and diffusivity of a reactive agent. To produce new bio-based products which material properties can compete with those that are made with more conventional materials, such as nylon, kevlar fibre, and synthetic organic polymers, it is crucial that we explore the chemical and hydrodynamic stability during formation. We investigate the transition of biopolymer and colloidal dispersions from a weak to strong visco-plastic fluid with high yield stress in a reacting Hele-Shaw cell, or thin gapped channel. We track the interface of reaction using optical coherency tomography (OCT) and confocal microscopy through particle image velocimetry (PIV) analysis. The results suggest that multilayer reacting flows of biopolymer and nano-cellulose dispersions are hydrodynamically stable, which is largely because surface tension is negligible at the reacting front. Numerical tools are used to assess the effects of reaction rates, and reversibility on the stability of the reacting front. Up to now we have limited the work to hydrogels which form from cross-linking or Van der Waals forces, both of which develop from one way reactions. These findings give rise to a number of opportunities in the production of biomaterials outside of nano-cellulose or biopolymeric threads.

Hydrodynamic stability of reacting multilayer flows in a Hele-Shaw cell

253rd National Meeting (2017)

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