A commercially important polyelectrolyte, xanthan, was chosen for
a systematic analysis of the relationship between molecular
conformation and surface properties. In the first study the effects
of ionic strength, xanthan concentration and temperature on the
xanthan molecular conformation were investigated by potentiometric
titration. The effects of the same factors and of the degree of
ionization on the surface tension of xanthan solutions were then
analyzed by the drop weight and the Wilhelmy plate methods.
Potentiometric titration studies showed that the ordered xanthan
conformation is stabilized mainly by hydrogen-bonds which can be
disrupted by increasing the electrostatic potential of the molecule or by increasing the solution temperature. Adding salt or increasing
the xanthan concentration did not affect the secondary structure.
Surface tension studies showed that the random coil is more
surface active than the helix xanthan structure. The rate of xanthan
adsorption at the interface of the random coil is also faster than
that of the helix structure. Surface tension was also shown to be
dependent on the electrostatic potential of the polyelectrolyte.
Added salt screened the electrostatic repulsive force and therefore
decreased the surface tension of xanthan solution. / Graduation date: 1987
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/27110 |
| Date | 01 July 1986 |
| Creators | Young, San Land |
| Contributors | Torres, J. Antonio |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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