Rheological behavior of aqueous mullite-albumin-methylcellulose systems

In this work, the thermogelling behavior of aqueous mullite-bovine serum albumin (BSA) suspensions was studied by dynamic rheology in order to determine the experimental conditions that must be used to form mullite green bodies by thermal consolidation. Viscoelastic properties (G′ and G′′) as a function of temperature (30-95 °C) and time were determined by temperature sweep tests and time sweep tests, respectively. On the other hand, the influence of methylcellulose (MC) (2 wt%) as a binder on the viscoelastic properties of the aqueous mullite-protein system as a function of both experimental parameters (temperature and time) was also studied. In addition, shear flow properties of aqueous mullite (40 vol%; 0.45 wt% of polyacrylic polyelectrolyte as a dispersant)-BSA (10 and 15 vol%)-MC (2 wt%) suspensions were analyzed to obtain information on the rheological behavior of the suspensions at room temperature. The results obtained showed that the presence of mullite particles and MC changed the onset temperature of gelation of the protein and increased the gelation time. Thus, both the mullite particles and methylcellulose intervened in the formation of the developed protein gel.