Viskoossuses

Viskoossuses is a term used in theoretical discussions of rheology to describe a conceptual class of viscoelastic fluids that combine high viscosity with a pronounced elastic response. The name blends “viscosity” with a suffix indicating a class of substances, and it is used to explore how materials can transition between viscous and elastic behavior under different conditions.

Characteristics of viskoossuses include a broad relaxation spectrum, time-dependent strain (creep and recovery), and non-Newtonian flow behavior. Depending on the subtype or state, they may exhibit shear-thinning, shear-thickening, or nearly Newtonian flow at high shear rates. In oscillatory rheology, viskoossuses are described as having a notable storage modulus G' and loss modulus G'', with the ratio G'/G'' signaling the balance between elasticity and viscosity. Temperature and composition influence relaxation times and apparent viscosity.

Modeling of viskoossuses often uses generalized viscoelastic models, such as Maxwell, Kelvin-Voigt, or Oldroyd-B frameworks, or fractional-derivative approaches to capture broad relaxation spectra. Experimental characterization relies on rheometry, including oscillatory tests to obtain G' and G'', creep tests to measure time-dependent deformation, and rate-dependent flow curves.

Relationship to real materials: while viskoossuses are primarily a theoretical construct, they are intended to describe or compare real substances such as concentrated polymer solutions, gels, and complex suspensions that show strong viscoelastic effects. The term is not widely standardized and appears mainly in teaching and speculative discussions rather than as an established category.

See also: viscoelasticity, rheology, non-Newtonian fluids.