ISSN:
1435-1536
Keywords:
Diffusing wave spectroscopy
;
light scattering
;
gelation
;
rheology
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract DWS measurements have been made of latex particle mobility in a gelatin solution as the solution is cooled through the sol-gel transition and comparisons made with viscoelastic properties of the same solution obtained using a sensitive rheometer. The DWS correlation functions show the square root dependence on channel time predicted for measurements made with a back-scattering configuration. Over the temperature range in which the gelatin solution viscosity remains independent of shear rate, the DWS relaxation time is proportional to the ratio of dynamic viscosity to absolute temperature (η/T). Viscosity, however, becomes shear rate dependent as the solution gels and the correlation breaks down. Through the sol-gel transition, over the measured phase angle range 85–5°, a correlation is observed between DWS relaxation time and the reciprocal of the tangent of that phase angle, a measure of the viscoelastic relaxation behaviour. Beyond this region, DWS relaxation time passes through a maximum, associated with which is a decline in correlation function amplitude. It is suggested that this behaviour is associated with the freezing out of longer-lived relaxation modes in the gel.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01182439
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