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

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Multiscale Structures in Polymers and
NanocompositesSanjeeva Murthy, Rutgers
University, DMR 0513926
The influence of hierarchical structure in
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
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) with light, x-rays
or neutrons. This method, illustrated in Figure
1, shows that almost all classes of SAS patterns
can be conveniently described in elliptical
coordinates (Polymer, 2007, 483393-3399). Investi
gation 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 1 Full pattern description of the SAS
patterns in elliptical cylindrical coordinates
(a) Bar pattern (b) Four-point tilted-in
pattern (c) Four-point butterfly pattern (d)
Overlay of the data on the elliptical grid (by ?
Eigen Vector Research Inc.) (e) Double ellipse
analysis of the butterfly pattern
Figure 2 Comparison of Spectra 900 fibers
damaged at ballistic (left) and quasi static
(right) strain rates. The micrograph on the left
displays crazing, while that on the right shows
plate formation.
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Multiscale Structures in Polymers and
NanocompositesSanjeeva Murthy, Rutgers
University, DMR-0513926

• Outreach
• The software developed in this program to fit the
  small-angle scattering data in elliptical
  coordinate is being rendered user-friendly by
  adding graphic-user interfaces for distribution
  to others in the polymer community, especially to
  the users of the beam-lines at the Argonne Photon
  source.
• PIs lab hosted high school students (raising
  seniors) from NY city during one summer. They
  worked in the lab preparing nanoclay filled
  composites and correlating process, structure and
  properties.
• PI organized two polymer sessions and workshops
  (2003 and 2007) at the Denver X-ray conference.
  Both were successful as measured by the number of
  participants at the workshop and the special
  sessions.
• PI has integrated his laboratory with a Green
  Chemistry program, being spearheaded by
  University of Massachusetts, by working on
  microphase separated copolymers relevant to green
  polymers.

Educational Activities A post doctoral student
(Dr. Fahmi Bedoui), while being actively involved
in this project over the past year, is helping
several undergraduates and graduate students in
their research. One of the student working on
this project, Wenjie Wang, was selected through a
competitive process to attend a the summer school
on x-ray and neutron scattering at the Argonne
National Laboratory. He and another student
(Chuang Deng) spend two weeks getting trained on
the use of molecular dynamics simulation software
at Dr. Goddards lab (Caltech) hand have since
been using this software. An undergraduate, Paul
Mark, who was involved in this projects is now a
going to be a graduate student in Materials
Science. A McNair Scholar, a Junior
undergraduate, Desmond Nzi, worked one summer in
the PIs laboratory preparing solvent-spun
fibers. The PI developed and taught a graduate
polymer course and a seminar course on polymers,
both the first at the University of Vermont.