Rheological properties of isotropic solutions and gel structures of lysozyme-sodium dodecyl sulfate mixtures in water are investigated. Isotropic solutions behave as Newtonian fluids with very low viscosity values. For the lysozyme solutions the intrinsic viscosity and the Huggins coefficient were calculated on the basis of the Mooney equation. Above a certain yield stress value, the viscosity of the gel samples decreases continuously in the whole range of the shear rate. Dynamic rheological experiments show weak gel behavior where the storage modulus and the loss modulus are almost parallel and are frequency-dependent. A belated gel stage with very slow kinetics has been characterized. There is a substantial enhancement of the gel strength by ageing since the belated gel stage manifests a higher yield stress value and a higher storage modulus than the initial gel stage. The gels are stable in the temperature range between 10 and 32degreesC.
Subject classification (UKÄ)
- Physical Chemistry