Jiang, Bin, Kasapis, Stefan and Kontogiorgos, Vassilis (2011) Combined use of the free volume and coupling theories in the glass transition of polysaccharide/co-solute systems. Carbohydrate Polymers, 83 (2). pp. 926-933. ISSN 0144-8617

The structural properties of the glass dispersion in agarose, �-carrageenan and deacylated gellan with
co-solute (glucose syrup) at 80.0% (w/w) solids were studied. Investigative techniques were smalldeformation
stress relaxation and dynamic oscillation on shear. Vitrification was monitored between −2
and −50 ◦C with continuous thermal runs and isothermal frequency or time sweeps obtained at constant
temperature intervals. The time–temperature superposition principle was utilized to compose master
curves. The Williams, Landel and Ferry equation was able to pinpoint the network Tg for these systems
as the turning point from the predictions of the free volume theory in the transition region to those of
the reaction rate theory at the glassy state. Further insights into the physics of intermolecular interactions
at the vicinity of Tg were obtained using the coupling model of molecular dynamics in the form of
the Kohlrausch, Williams and Watts function. The model described well the spectral shape of the local
segmental motions in polysaccharide/co-solute samples at the short-time region of the stress–relaxation
master curve. Analysis provided the intermolecular interaction constant and apparent relaxation time,
which are valuable parameters for the elucidation of structural morphology at Tg.

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