PHYSICAL AND STRUCTURAL-PROPERTIES OF BARLEY (1-]3),(1-]4)-BETA-D-GLUCAN III - FORMATION OF AGGREGATES ANALYZED THROUGH ITS VISCOELASTIC AND FLOW BEHAVIOR

The rheological properties (flow and viscoelastic) of barley beta-gluc an in aqueous solution have been studied. The results shed light on th e association behaviour of these macromolecules and even on the format ion of network-like structures under certain circumstances. The concen trations used for this study were both in the dilute and in the semidi lute regime, close to the critical value where overlap of macromolecul ar coils sets in. However, the association behaviour detected in such a regime and together with the present experimental techniques, agrees with previous results obtained with other techniques such as capillar y viscometry and light scattering, which operate in the dilute solutio n regime, where no overlapping of the chains is expected. The influenc e of the molecular weight of the samples, the temperature and the ioni c strength on the flow and oscillatory shear measurements has been stu died. The preparation of samples and their thermal history have proved to be important factors in the development of associated structures, both affecting the results. (C) 1997 Elsevier Science Ltd.