Effect of concentration and temperature on the rheological behavior of collagen solution

Dynamic viscoelastic properties of collagen solutions with concentrations of 0.5–1.5% (w/w) were characterized by means of oscillatory rheometry at temperatures ranging from 20 to 32.5 °C. All collagen solutions showed a shear-thinning flow behavior. The complex viscosity exhibited an exponential increase and the loss tangent decreased with the increase of collagen concentration (CCOL) when the CCOL ≥ 0.75%. Both storage modulus (G′) and loss modulus (G″) increased with the increase of frequency and concentration, but decreased with the increase of temperature and behaved without regularity at 32.5 °C. The relaxation times decreased with the increase of temperature for 1.0% collagen solution. According to a three-zone model, dynamic modulus of collagen solutions showed terminal-zone and plateau-zone behavior when CCOL was no more than 1.25% or the stated temperature was no more than 30 °C. The concentrated solution (1.5%) behaved being entirely in plateau zone. An application of the time–temperature superposition (TTS) allowed the construction of master curve and an Arrhenius-type TTS principle was used to yield the activation energy of 161.4 kJ mol−1.