Physical and structural properties of barley (1→3),(1→4)-β-D-glucan III.: Formation of aggregates analysed through its viscoelastic and flow behaviour

The rheological properties (flow and viscoelastic) of barley beta-glucan in aqueous solution have been studied. The results shed light on the association behaviour of these macromolecules and even on the formation of network-like structures under certain circumstances. The concentrations used for this study were both in the dilute and in the semidilute regime, close to the critical value where overlap of macromolecular 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 capillary viscometry and light scattering, which operate in the dilute solution regime, where no overlapping of the chains is expected. The influence of the molecular weight of the samples, the temperature and the ionic strength on the flow and oscillatory shear measurements has been studied. 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.