how to walk on water and survive bullet impacts? rheology of complex fluids and simulated polymer...
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How to walk on water and survive bullet impacts?
Rheology of complex fluids and simulated polymer gels
Explore SDSU 2012Joris Billen
PhD Candidate Computational Science San Diego State University & Claremont Graduate University
Supervisor: Prof A. Baljon,Department of Physics (SDSU)
What is a complex fluid?• Complex fluids are everywhere:
• Kitchen (chocolate, mayonaise, milk, ketchup)
• Human body (blood, mucus)• Products (Cosmetics, liquid crystals,
Shaving cream)• Fluids showing non-linear viscous
behaviours, as well as viscoelastic materials, are Complex Fluids.
• But …what is non-linear viscous and viscoelastic behavior?
Visco-elastic behavior
After application of a stress…
Permanent deformation: Viscous Restores initial configuration: ElasticTemporary restoration: Visco-elastic
• Tendons, ligaments, polymers, toothpaste, gels,…
Non-linear viscous behavior: Newtonian VS non-Newtonian?
Slope=viscosity
Non-linear viscous behavior: Newtonian VS non-Newtonian?
shear thinning
shear thickening
How to walk on water?
viscosity
Shear thickening
How to survive bullet impacts?
viscosity
Shear thickening
Shear thinning
viscosity
Polymer = repeating units of monomers
Polymers
Associating polymer gels
Reversible NetworkPolymer chains in a solvent
Rheological response gel
Shear rate
Vis
cosi
ty
[J.Sprakel et al., Soft Matter (2009)]
NewtonianShear thickening
Shear thinning
ApplicationsWound dressings
Cartilage replace-ment / implants
Contact lenses
Actin filaments
Paintball fill
Injectable gels
Controlled drug delivery
Self-healing materials
So … what do you do all day?
Modeling the physics of a polymer gel
Computer simulations of polymer gels
1000 polymer chains of 8 beads long
However …we don’t work with pictures but with files of -coordinates of atoms-connections in network
Computer simulations of polymer gels
Calculate properties that are impossible to measure experimentally
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Our work on the cover of a magazine
J. Billen, M. Wilson, A. Rabinovitch, A. R. C. Baljon, Europhys. Lett. 87 (2009) 68003.
Structure gel networksimilar to robustcomputer networks
Thank you for your attention!
Non-Newtonian Dubstep