Viscoelastic properties of xanthan gels interacting with cations

Viscoelastic properties of gels were greatly affected by xanthan gum concentration and types of cations. The storage moduli (G(1)), measured at 1.0 Hz, were 8.3, 10, and 2700 Pa for xanthan gels at 0.5% polymer concentration and 37, 42, and 13000 Pa for xanthan gels at 1.0% polymer concentration in the presence of Na+, Ca2+, or Fe3+, respectively. The elastic recovery was 27.9, 61.6, and 66.3% for 0.5% xanthan gels, and 38.5, 22.5, and 69.1% for 1.0% xanthan gels, in the presence of Na+, Ca2+, or Fe3+, respectively. The generalized Kelvin model simulated creep compliance and ferric ion was an excellent crosslinker for a rigid, firm gel.