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0513926_Murthy

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									  Multiscale Structures in Polymers and Nanocomposites
    Sanjeeva Murthy, Rutgers University, DMR 0513926

The influence of hierarchical structure in             (a)                         (b)                          (c)
polymers and composites on their performance
was studied by investigating the failure
characteristics in different types of materials: a
semicrystalline fiber (ultrahigh modulus
polyethylene, Spectra ), a liquid crystalline
material (polyaramid,Kevlar), and a                  (d)                                (e)
nanocomposite (PAN with carbon fibers).
In the course of this research, a new and
powerful method was developed for analyzing
structural data at nanometer length scales
obtained using small-angle scattering (SAS)          Figure 1: Full pattern description of the SAS patterns in elliptical cylindrical
                                                     coordinates: (a) Bar pattern; (b) Four-point tilted-in pattern; (c) Four-point
with light, x-rays or neutrons. This method,         butterf ly pattern; (d) Overlay of the data on the elliptical grid (by  Eigen
illustrated in Figure 1, shows that almost all       Vector Research Inc.) (e) Double ellipse analysis of the butterf ly pattern
classes of SAS patterns can be conveniently
described in elliptical coordinates (Polymer,
2007, 48:3393-3399).
Investigation of the failure at quasi-static and
ballistic strain-rates in high modulus fibers
shows that the some of the differences in
performance of on strain rate can be related to
vastly different morphology at micrometer length
scales (Figure 2).                                       Figure 2: Comparison of Spectra 900 f ibers damaged at ballistic (lef t)
                                                         and quasi static (right) strain rates. The micrograph on the lef t displays
                                                         crazing, while that on the right shows plate f ormation.
  Multiscale Structures in Polymers and Nanocomposites
    Sanjeeva Murthy, Rutgers University, DMR-0513926

Educational Activities                                    Outreach
                                                          ● The software developed in this program to fit
A post doctoral student (Dr. Fahmi Bedoui), while
                                                            the small-angle scattering data in elliptical
being actively involved in this project over the past
                                                            coordinate is being rendered user-friendly by
year, is helping several undergraduates and graduate
                                                            adding graphic-user interfaces for distribution
students in their research. One of the student
                                                            to others in the polymer community, especially
working on this project, Wenjie Wang, was selected
                                                            to the users of the beam-lines at the Argonne
through a competitive process to attend a the
                                                            Photon source.
summer school on x-ray and neutron scattering at the
                                                          ● PI’s lab hosted high school students (raising
Argonne National Laboratory. He and another
                                                            seniors) from NY city during one summer.
student (Chuang Deng) spend two weeks getting
                                                            They worked in the lab preparing nanoclay
trained on the use of molecular dynamics simulation
                                                            filled composites and correlating process,
software at Dr. Goddard’s lab (Caltech) hand have
                                                            structure and properties.
since been using this software. An undergraduate,
                                                          ● PI organized two polymer sessions and
Paul Mark, who was involved in this projects is now a
                                                            workshops (2003 and 2007) at the Denver X-
going to be a graduate student in Materials Science.
                                                            ray conference. Both were successful as
A McNair Scholar, a Junior undergraduate, Desmond
                                                            measured by the number of participants at the
Nzi, worked one summer in the PI’s laboratory
                                                            workshop and the special sessions.
preparing solvent-spun fibers. The PI developed and
                                                          ● PI has integrated his laboratory with a Green
taught a graduate polymer course and a seminar
                                                            Chemistry program, being spearheaded by
course on polymers, both the first at the University of
                                                            University of Massachusetts, by working on
Vermont.
                                                            microphase separated copolymers relevant to
                                                            green polymers.

								
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