The velocity, shear-rate, variable viscosity, and variable power-law index profiles are calculated for non-Newtonian fluids using the finite difference method. The calculations are carried out for an actual viscosity function obtained by a cilrve fit through measured data and for the corresponding power law model, the simplest and most often used form for non­ Newtonian viscosity function appro...

Most polymers solidify into a glassy amorphous state, accompanied by a rapid increase in the viscosity when cooled below the glass transition temperature (T(g)). There is an ongoing debate on whether the T(g) changes with decreasing polymer film thickness and on the origin of the changes. We measured the viscosity of unentangled, short-chain polystyrene films on silicon at different temperature...

Molecular architecture plays a key role in determining the physical properties and emergent functional properties of polymeric materials. Despite recent progress in the synthesis of structurally defined polymers, we still lack a complete understanding of how the emergent properties of topologically complex polymers arise from molecular-scale phenomena. In this work, we study the nonequilibrium ...

Additives were tested for their ability to modify the rheology of lignocellulosic biomass. Additive types included water-soluble polymers (WSPs), surfactants, and fine particles. WSPs were the most effective rheological modifiers, reducing yield stresses of concentrated biomass by 60–80% for additive concentrations of 1–2 wt. % (based on mass of dry biomass solids). Yield stress and plastic vis...

In this article six new copoly(amide-imide)s (11a-c) were synthesized through the directpolycondensation reaction of 1,3-bis[4,4'-(trimellitimido) phenoxy] propane (6) with 3,3'-diamino diphenyl sulfone (7), 4,4'-diaminodiphenyl ether (8) and 1,5-naphtalene (9) in thepresence of fumaric acid (10) as a second diacid in a medium consisting of N-methyl-2-pyrrolidone, triphenyl phosphite, calcium c...

Floating dosage forms of acetylsalicylic acid, used for its antithrombotic effect, were developed to prolong gastric residence time and increase bioavailability. In the two-layer tablet formulation, hydroxypropyl methylcellulose (HPMC) of high viscosity and an effervescent mixture of citric acid and sodium bicarbonate formed the floating layer. The release layer contained the drug, direct table...

Rheological studies of the ceramic based concentrated titania nanoparticle dispersions showed a clear correlation between molecular structure of the cationic polymers used as dispersants and the viscosity of the slurries. Dynamic viscosity of the electrostatically stabilized alkaline (pH 10.0) dispersions of the bare titania nanopowders with a solid loading of 15 – 25 wt.% was rather high (abou...

The paper discusses a model of viscosity η of glassforming melts in an attempt to predict the dependence of η on temperature T and on pressure P. The equation, derived here, describes with excellent accuracy all existing experimental viscosity data including those of glassforming melts, igneous materials and polymers. It is demonstrated that the activation energy E(Tg) can be expressed through ...