SANS Study of Polyethylene Crystallization from Solution

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SANS Study of Polyethylene Crystallization from
Solution Howard Wang, Michigan Technological
University, DMR-0348895

• Crystallization of polyethylene from
  concentrated solutions has been studied using
  small angle neutron scattering (SANS).
• The detection sensitivity of the volume fraction
  degree of crystallinity is estimated to be 10-5,
  which allows for the measurement of the very
  early stages of crystal growth.
• There is no evidence of diverging or
  spinodal-decomposition-like density fluctuations
  during the early stage of crystallization in
  polyethylene solutions.
• The importance of background subtraction has been
  suggested in evaluating the small angle x-ray
• scattering data.

(A)
(A) SANS spectra of the f0 0.24 PE solution
after cooling from 120.0 oC to various
temperatures. The low temperature (85.0, 90.0
and 95.0 oC) spectra show both the characteristic
form and structure factors of stacked lamellae.
(B) Illustration of excess signals and simulated
spectra for a typical small angle x-ray
scattering experiment.
(B)

• Time-resolved ultra-SANS has also been used to
  study the early stage kinetics of the lamellar
  lateral growth.

Publications 1. Wang, H., et al., Appl. Phys.
Lett., 88, 213111 (2006). 2. Wang, H., Polymer,
47, 4897 (2006). 3. Wang, H., book chapter in
Lecture Notes in Physics Polymer
Crystallization, Reiter, G. and Strobl, G., Ed.
Springer-Verlag, 2006. 4. Wang, H., et al.,
Chem. Phys. Lett. 416, 182 (2005)
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SANS Study of Polyethylene Crystallization from
Solution Howard Wang, Michigan Technological
University, DMR-0348895
Education at Graduate and Undergraduate Levels
Two Ph.D. students Kaikun Yang (3nd yr), Yayong
Liu (2nd yr) One post-doctoral fellow Dr.
Narayan Ch Das One Materials Science
Engineering undergraduate student Kevin Baker
Developed courses Introduction to Polymer
Engineering, Soft Materials, and
Bioapplications of Nanotechnology

• Outreach to K-12
• The PI has introduced polymer and nanotechnology
  components to several outreach programs at the
  Michigan Tech, including the Women in
  Engineering, Exploration in Engineering and
  Summer Youth Programs, in which many participants
  are woman and minority high school students from
  local Indian reservation and Detroit urban areas.

• The participants in Woman in Engineering and
  Exploration in Engineering make PDMS elastic
  balls and test the mechanical properties they
  also make fiber reinforced composite boats and
  test sail on the Portage lake.