|
The Shull Group |
||||
93. "Contact Measurement of Internal Fluid Flow within Poly(n-isopryl acrylamide) Gels" Lin, W.-C.; Shull, K.R.; Hui, C.-Y.; Lin, Y.-Y., J. Chem. Phys., 127, 094906 (2007).
Abstract: A technique is presented that is ideally suited for characterizing
the mechanical and transport properties of polymer gels at small strains. A
flat, circular punch and a flat, rectangular punch are used to probe the response
of gels under oscillatory loading conditions. Solvent transport within the
gel is driven by gradients in hydrostatic pressure, giving rise to a dissipative
response quantified by the phase lag between the punch displacement and the
resulting load. By comparing results for different punch sizes, it is possible
to differentiate between dissipation resulting from internal solvent flow and
dissipation due to the viscoelastic character of the polymer network itself.
Use of the technique is illustrated with poly(n-isopropyl acrylamide) (pNIPAM)
gels, which undergo a reversible structural transition just above room temperature.
We show that heterogeneous structure formed above the transition temperature
is not conducive to internal solvent flow within these gels.
Download Journal-formatted pdf
Copyright (2007) American Institute of Physics.
This
article
may
be downloaded for personal use only. Any other use requires prior permission
of
the author
and the American Institute of Physics.