Researchers have long recognized that the interface between the fibers and the resin in advanced composites is actually an interphase—a region with unique properties that have a tremendous influence on the behavior of the materials. Much effort has been devoted to understanding this region and controlling it to achieve mechanical properties tailored to specific functions and applications.

Now, tools and techniques being developed under a CMR project led by Eric Furst offer new capabilities for viewing the phenomena that occur in the interphase, observing their effects on material behavior, and manipu-
lating them to yield materials with unique properties.

UD logo assembled from 3 micron polystyrene particles using 25 time-shared optical traps. The scale bar is 10 microns.

TOP STORY
CCM and ARL to Develop Micro-scale Optical Devices

An Assistant Professor in the Department of Chemical Engineering, Furst joined the UD faculty in 2001. He has been working in the area of complex fluid and polymer microrheology since he was a postdoctoral fellow at the Institut Curie in France after completing his Ph.D. at Stanford University in 2000.

“This is a fairly new area,” Furst says. “We're developing advanced experimental techniques—including optical tweezers, microrheology and confocal microscopy—to understand the fundamental nano- and microscale properties that govern how nanoscale regions like the interphase develop and respond to external forces.”

“We can now actually capture the formation of local properties in polymer systems—for example, observing the point at which a solid develops from a liquid,” he continues. “In the CMR program, we're working to apply that knowledge to materials of interest to the Army for applications such as improved vehicular armor and personal protective equipment.”

 Furst Research Group
From back to front: Alexander Meyer, Cecile Veerman, Myung Han Lee, Indira Gopal, Eric Furst, Hongguang Huo, Frances Spinelli, Ji Yeon Huh, Becky Gable, John Pantina, Sven Reynaert (visiting from Katholieke University, Leuven), Jonathan Edwards, Matthew Rosborough, Travis Larsen and Tristan Willliams. Not shown: Pushkar Lele, Bumjun Park and Manesh Mittal.

“It's amazing how much effect this tiny region—with fibers as small as a micron in length—has on the overall mechanical properties of fiber-reinforced polymers,” he adds. “We're particularly interested in investigating nonlinear rheology in order to understand the phenomena that give rise to properties like shear thickening fluids.”

Furst's colleague Norm Wagner has collaborated with the Army in this area to create “liquid armor,” which capitalizes on the nonlinear rheological behavior of certain fluids that stiffen when they are physically disturbed. “This is a very complex phenomenon, and the more we understand it, the better able we will be to exploit it for both defense and civilian applications,” Furst says.

“By applying these tools,” he concludes, “we have an unprecedented ability to guide assembly, deform structures, measure stress, and study dynamics at a microscopic scale to better understand and control material properties and responses.”

While Furst's work has applications beyond composites—for example, in paints, coatings, and biomedical materials—it is a perfect fit in the CMR program, with its focus on innovative multifunctional lightweight hybrid composites with improved in material properties via tailoring the microstructures of the constituent materials.

“We are very pleased to have Eric collaborating with us through the CMR program,” says Center Director Jack Gillespie. “Our ability to understand the highly critical interphase region in advanced composites continues to improve with the development of increasingly sophisticated techniques like the ones Eric is developing and applying. The potential for these materials is almost limitless when we have the ability to observe and manipulate at this scale.”

OTHER NEWS

CCM Hosts Engineering Session for High School Students -

On Saturday, December 10, 2005, 20 high school students and their counselors from the Georgetown Upward Bound Math & Science Center came to UD's Newark campus.  Following a visit with UD Admissions, they moved to the Composites Manufacturing Science Lab, where they shared a bit of their background and were given an overview of the College of Engineering.  Then it was time for the fun.

Graduate students Jennifer O'Donnell (PhD candidate in chemical engineering) led half the group through a Polymers Cross-linking activity, where they not only learned how polymer chains are formed, but they actually made some "slime."  Meanwhile, Justin Clews (PhD student in materials science & engineering) brought the other half of the group into one of CCM's testing labs. He showed them several different composite beams that he had pre-assembled, describing their makeup and having the students guess what would happen when the different beams were placed in the Instron testing machine where they were tested to failure under three-point bending. The beam's had maximum failure loads ranging from approximately 400 lbs to 1200 lbs, resulting in load to weight ratios ranging from 1400 to 4000, depending on the beam's makeup. The groups then swapped areas, so that everyone participated in both the polymers and composites activities.


Under the guidance of grad student Justin Clews, students test a variety of composite sandwich beams using three-point bending in order to understand the influence various materials have on a structure's mechanical properties.


Students make slime by mixing PVA (Polyvinyl Alcohol) and Sodium Metaborate (Borax), illustrating how two different chemicals, when mixed correctly, can make a very different (and fun) substance.

Barbara Johnson, TRIO Program Developer at the Upward Bound Math & Science Center, spoke of her experience. "Ryan Brown, Math & Science Program Manager, and Becky Evaristo, MS Student Enrichment Coordinator, said the visit with the Engineering College was excellent. Thank you for coordinating this educational s ession for the twenty Math & Science Center participants.Those attending were introduced to the field of engineering and now have a better understanding of what a variety of directions engineers can go. Thank you for providing this overview. Engineering is such an important field for the students to be aware of - and they don't learn about it in high school - they need this kind of exposure to understand the potential possibiliti es .  I wish I had been encouraged to enter engineering - although my father and my brother are mechanical engineers, no one thought about advising me regarding this field. Jennifer and Jason were spectacular with the demonstrations and making the slime. The students will remember their experiences at UD Engineering!"

CCM-Affiliated Faculty Member Wins ASCE Award
Professor Dennis Mertz, who has worked on past and current CCMcomposite bridge projects, has been
recognized with an award from the American Society of Civil Engineers.. Full Story in UDaily

Tsu-Wei Chou named AIAA fellow
Tsu-Wei Chou, Pierre S. du Pont Chair of Engineering, has been named a fellow of the American Institute of Aeronautics and Astronautics (AIAA). Full Story in UDaily

CCM Introduces New CDS Community Newsletter
Our second CDS Newsletter has some exciting new changes with the Composites Design Software Suite which include a new Java based Application server with customer feedback features, new and more streamlined installation packages and the release of CDS-MICRO v2.0. Go to CDS Newsletter

CONSORTIUM

CCM would like to welcome B/E Aerospace, Miami, FL, and Dassault-Aviation, Paris, France, to the to the University-Industry Consortium.

NEW PUBLICATIONS

Conference Proceedings

Amouroux, S. C., D. Heider, S. Lopatnikov, and J. W. Gillespie, Jr., “On the Role of Membrane to Improve Quality of VARTM-Processed Composites,” American Society for Composites (ASC) 20th Annual Technical Conference, Drexel University, Philadelphia, PA , Sept. 7-9, 2005.

Amouroux, S. C., D. Heider, S. Lopatnikov, and J. W. Gillespie, Jr., “Membrane-Based VARTM: Membrane and Resin Interactions,” SAMPE Fall Technical Conference (37th ISTC), Seattle, WA, Oct. 31 – Nov. 3, 2005.

Journals

Li, X., K . Sarkar, “Effects of Inertia on the Rheology of a Dilute Emulsion of Viscous Drops in Steady Shear,” Journal of Rheology, 49, pp.1344-1395, 2005.

Chatterjee, D., K. Sarkar, and P. Jain, “Ultrasound Mediated Destruction of Contrast Microbubbles used for Medical Imaging and Drug Delivery, Physics of Fluids, 17, 100603, 2005.

Sarkar, K., WT Shi, D. Chatterjee and F. Forsberg, “Characterization of Ultrasound Contrast Microbubbles using in Vitro Experiments and Viscoelastic Models for Encapsulation,” Journal of the Acoustical Society of America, 118, pp. 539-550, 2005.

Li, X., and K. Sarkar, “Numerical Investigation of the Rheology of a Dilute Emulsion of Drops in an Oscillating Extensional Flow,” Journal of Non-Newtonian Fluid Mechanics, 102, pp. 263-280, 2005.

Chatterjee, D., K. Sarkar, P. Jain, and N. Schreppler, “On the Suitability of Broadband Attenuation Measurement for Characterizing Contrast Microbubbles,” Ultrasound in Medicine and Biology, 31 , pp. 781-786, 2005.

Li, X., and K. Sarkar, “Drop Dynamics in an Oscillating Extensional Flow at Finite Reynolds Numbers,” Physics of Fluids, 17, 027103, 2005.

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