Emilio Tozzi
UW-Madison Chemical Engineering Dept.
1415 Engineering Dr Madison, WI 53706 - 1691
Klingenberg Research Group
Rm 4727 Engineering Hall
Office Phone: (608) 265-3786

Research: Fiber hydrodynamics and Carbon Nanotube Filled Composites.

Fiber Hydrodynamics

Fiber shape has a great influence in the motion and rheology of fiber suspensions. Characterization of fibers and prediction of fiber dynamics is of great industrial importance, with examples including composite processing and the pulp and paper industry.

We developed methods to compute fiber hydrodynamic properties for fibers of arbitrary shape and aspect ratio. We performed simulations to study how fiber shape affects sedimentation, dynamics in shear flow and intrinsic viscosity of suspensions.

Comparison with known theoretical results and sedimentation experiments confirmed the accuracy of the methods. Simulations allowed us to find fiber shape measures that correlate well to suspension properties.

Presentations

E. J. Tozzi, D. J. Klingenberg, C. T. Scott, D. Vahey, Effects of fiber shape on fiber settling dynamics,The Society of Rheology 78th Annual Meeting, Portland, Maine, October 8-12, 2006

E. J. Tozzi, C. T. Scott, D. Vahey, D. J. Klingenberg , Effects of fiber shape on fiber settling dynamics and suspension viscosity, Progress in Paper Physics Conference PPP2006, Oxford, Ohio, 10-1-2006

E.J. Tozzi, D.J. Klingenberg, C.T. Scott, and P. Miettinen, “Simulations of Flexible Fiber Suspensions,” U.S.D.A. Forest Products Lab TAPPI/AF&PA Advisory Board meeting, Madison, WI, May 2005.

Tozzi, Emilio J.; Klingenberg, Daniel J.; Scott, C. Tim; Miettinen, Pasi 2005. Simulations of flexible fiber suspensions Proceedings of the 2005 TAPPI Practical Papermaking Conference : 2005 May 22-26, Milwaukee, WI. Atlanta, GA : TAPPI Press, 2005.

E. Tozzi, C. T. Scott, and Daniel J. Klingenberg, Effect of fiber shape on the rheology of fiber suspensions, 76 Annual meeting Society of Rheology, Lubbock, Texas, 2-13-2005

CNT Composites Modeling

Carbon nanotubes can be used as conductive fillers with very low percolation thresholds[1,2]. Since high conductivities can be achieved with very small amounts of filler the composite retains the polymer bulk properties.

The materials pose several experimental and theoretical challenges. Results from experiments show wide variations, which are attributed to differences in processing conditions.

We use dynamic simulations to predict the evolution of CNT suspension structures under different flows and fields. We study nanotube aggregation, dispersion and how these phenomena influence the final electrical and thermal conductivities of the composite.

References

1. Sandler J.K.W., Kirk J. E., Kinloch I.A., Shaffer M.S.P., Windle A. H., Ultra-low percolation threshold in carbon-nanotube-epoxy composites , Polymer, 44, 5893-5899, (2003)

2. Bryning M. B., Islam M. F., Kikkawa J. M., Yodh A. G., Very Low Conductivity Threshold in Bulk Isotropic Single-Walled Carbon Nanotube-Epoxy Composites, Advanced materials, 17, 1186-1191 (2005)

LINKS