| NSF Org: |
CBET Division of Chemical, Bioengineering, Environmental, and Transport Systems |
| Recipient: |
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| Initial Amendment Date: | September 12, 2019 |
| Latest Amendment Date: | September 12, 2019 |
| Award Number: | 1931681 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Ron Joslin
rjoslin@nsf.gov (703)292-7030 CBET Division of Chemical, Bioengineering, Environmental, and Transport Systems ENG Directorate for Engineering |
| Start Date: | January 1, 2020 |
| End Date: | December 31, 2023 (Estimated) |
| Total Intended Award Amount: | $304,023.00 |
| Total Awarded Amount to Date: | $304,023.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
526 BRODHEAD AVE BETHLEHEM PA US 18015-3008 (610)758-3021 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
111 Research Dr. Bethlehem PA US 18015-4731 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): |
FD-Fluid Dynamics, Special Initiatives |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.041 |
ABSTRACT
Coatings impact many applications, including consumer products, medicine, food, and engineering applications, typically serve one of three purposes: to protect and extend the life of a product, to improve aesthetics, or to add new functionality. Small defects that form during solidification of a fluid film coating can harm the ultimate functionality of the coating. In a single automotive plant, painting accounts for 60% of the energy consumption, and refinishing to repair defects can cost more than $10 million/year. There are few methods capable of non-invasive tracking of the coating properties during drying. The objective of this project is to develop the capability to measure the transient viscosity and flow of a drying coating with time- and space- resolved optical measurements. The underlying knowledge gained via this project in relation to how transient rheology affects fluid flow will be applicable to a multitude of coating manufacturing processes. The project will have significant impact on coatings design and processing, help to bridge the gap between academia and industry, and include outreach to the science, technology, engineering, and math communities.
The research objective of this proposal is to measure the transient rheology and kinematics of a drying complex fluid. Traditional macroscopic rheological techniques require physical contact with the coating during the measurement (i.e. the technique is invasive and alters drying) and are unable to spatially resolve rheological changes within the coating. This project will be enabled by non-invasive, high temporal and spatial resolution optical techniques to measure the time- and space-resolved rheology and flow in model complex fluids. Specifically, the research goals are to (1) measure the spatial dependence of rheology in a drying thin film with varied viscosity, (2) to determine and implement a suitable method of convection correction for thin films of drying viscoelastic fluids, and (3) to measure the impact of formulation and substrate angle on the transient convection cell structure and related microstructure formation in thin films of drying viscoelastic fluids. The proposed work on model ~0.100 mm thin films will be applicable to a broad set of applications and will complement ongoing work the industrial partner, PPG. When successful, this research will significantly enhance the design and processing of coatings for a wide range of applications.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
In a collaboration with Professor Christopher Wirth at Case Western University and researchers at PPG, this GOALI investigated the microrheology of paints during drying. This was enabled using ideal transparent formulations of urethane-based paints having varying initial solids content and added particles that move due to Brownian motion and convection. Separation of Brownian and convective motion allows microrheology during drying to estimate the paint rheology from original formulation and drawdown to final drying, undergoing changes in both viscosity and elasticity. In early stages of drying, the apparent viscosity measured was significantly lower than the original formulations having viscosity that does not display significant shear thinning using traditional small angle oscillatory shear rheology. Convection cells that form are observed and alter the local rheological properties before resulting in non-isotropic film properties. The decay of velocity drops quickly in the early stages of drying in about the same time when the viscosity is seen to rise significantly and the film begins to deviate from Newtonian behavior. The dried paint displayed significant heterogeneity in the distribution of tracer particles due to the convection cells and gravitational settling. Localized evaporation set by having a template generates buckling patterns that have waves rather than the signatures of convection cells from free evaporation as a result of a gradient in Marangoni stress at the free surface. This project supported 1 postdoctoral research associate and several undergraduate students training them in the areas of . This work will be featured in one review article, one methods article and two research papers, at the American Institute of Chemical Engineering Annual meetings, the American Chemical Society Colloids and Surface Science Symposia, the Society of Rheology Annual meetings, and several invited talks. This work was also selected as 2nd place for the Gallery of Rheology contest for the Society of Rheology in 2022 and featured in the Rheology Bulletin.
Last Modified: 04/27/2024
Modified by: James F Gilchrist
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