Numerical analysis of slot die coating of nanocellulosic materialsShow others and affiliations
2021 (English)In: TAPPICon LIVE 2021, TAPPI Press, 2021, p. 63-73Conference paper (Refereed)
Abstract [en]
Nanocellulosic coatings as a food-packaging material are of commercial interest due to their non-toxic nature, renewability, and excellent barrier properties. Complex shear-thinning rheology poses challenges in designing and sizing equipment to pump, mix, and process the suspension and actual coating process. This study aims to determine the effectiveness of computation fluid dynamics (CFD) in predicting nanocellulosic suspension flow in light of existing rheological data. We employ and compare three distinct rheological models to characterize the rheology and flow of nanocellulose suspensions through a slot-die coater, where the model parameters are established from existing slot-rheometry measurements. A volume-of-fluid (VoF) based finite volume method is employed to simulate the flow in a slot-die operated in an unconventional metering mode. Results with the Casson model predicts the presence of unyielded regions in the flow, which was not captured using the power-law model. These stagnation regions will incur coatability issues stemming from flow intermittencies and lead to potential defects in the coating layer, including fracture. The results suggest that a rheological model that includes yield stress should be considered while modeling such flows. A need for better rheological data to model nanocellulosic flows, especially at high consistencies and shear-rates, is also highlighted.
Place, publisher, year, edition, pages
TAPPI Press, 2021. p. 63-73
Keywords [en]
Coatings, Computational fluid dynamics, Elasticity, Finite volume method, Non Newtonian flow, Packaging materials, Shear flow, Shear thinning, Yield stress, Barrier properties, Computation fluid dynamics, Food-packaging materials, Non-toxic, Rheological data, Rheological models, Shear-thinning rheology, Slot dies, Slot-die coatings, Suspension flows, Suspensions (fluids)
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
URN: urn:nbn:se:kau:diva-91288Scopus ID: 2-s2.0-85130156193ISBN: 9781713848370 (print)OAI: oai:DiVA.org:kau-91288DiVA, id: diva2:1682054
Conference
TAPPICon LIVE 2021, 3 October 2021 through 6 October 2021
2022-07-082022-07-082022-10-06Bibliographically approved