Studies on rheological, thermal, and morphological properties of methylcellulose gel in aqueous medium

Abstract

The rheological, morphological, and thermal behavior of aqueous methylcellulose (MC) gels was investigated by optical microscope, dynamic mechanical analyzer (DMA), and differential scanning calorimeter. The double crossover between the storage modulus and loss modulus during the frequency scan in DMA suggests the transition from gel to sol state. These gel networks are comprised of bead-rod structures, which is visible under the optical microscope. Furthermore, the degelation mechanism of gels comprises of the thermodynamic viable bead burst phenomenon. The reheated samples of MC under dynamic compression show partial irreversibility of the MC aqueous system, indicating the possible presence of weakly coupled random coils and helix. The phenomenon of turbidity of MC aqueous gels is discussed with the help of a large bead model, in which the small-sized beads present in aqueous solution collide with each other to form large beads. FIG. 4. (a) Plot between storage and loss modulus as a function of frequency Hz for 5 wt% MC-4000 gel at 50 C. (b) Plot between storage and loss modulus as a function of frequency Hz for 5 wt% MC-1500 gel at 50 C. (c) Plot between storage and loss modulus as a function of frequency Hz for 5 wt% MC-4000 gel at 80 C. (d) Plot between storage and loss modulus as a function of frequency Hz for 5 wt% MC-1500 gel at 80 C. (e) Plot between storage and loss modulus as a function of frequency Hz for 5 wt% MC-25 gel at 80 C. [Color figure can be viewed at wileyonlinelibrary.com]