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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Rheology of methylcellulose solutions

Shangraw, Ralph F. January 1958 (has links)
Thesis (Ph. D.)--University of Michigan, 1958.

Rheology of methylcellulose solutions

Shangraw, Ralph F. January 1958 (has links)
Thesis (Ph. D.)--University of Michigan, 1958.

Analysis of drilling fluid rheology and tool joint effect to reduce errors in hydraulics calculations

Viloria Ochoa, Marilyn 30 October 2006 (has links)
This study presents a simplified and accurate procedure for selecting the rheological model which best fits the rheological properties of a given non- Newtonian fluid and introduces five new approaches to correct for tool joint losses from expansion and contraction when hydraulics is calculated. The new approaches are enlargement and contraction (E&C), equivalent diameter (ED), two different (2IDs), enlargement and contraction plus equivalent diameter (E&C+ED), and enlargement and contraction plus two different IDs (E&C+2IDs). In addition to the Newtonian model, seven major non-Newtonian rheological models (Bingham plastic, Power law, API, Herschel-Bulkley, Unified, Robertson and Stiff, and Casson) provide alternatives for selecting the model that most accurately represents the shear-stress/shear-rate relationship for a given non- Newtonian fluid. The project assumes that the model which gives the lowest absolute average percent error (EAAP) between the measured and calculated shear stresses is the best one for a given non-Newtonian fluid. The results are of great importance in achieving correct results for pressure drop and hydraulics calculations and the results are that the API rheological model (RP 13D) provides, in general, the best prediction of rheological behavior for the mud samples considered (EAAP=1.51), followed by the Herschel-Bulkley, Robertson and Stiff, and Unified models. Results also show that corrections with E&C+2IDs and API hydraulics calculation give a good approximation to measured pump pressure with 9% of difference between measured and calculated data.

The use of large transient deformations to elucidate structural phenomena and evaluate network models for molten polymers /

Tsang, William Kuen Wai. January 1980 (has links)
That some kind of network plays a central role in the rheology of high molecular weight, amorphous polymers is inferred from such phenomena as a change in the slope of the curve of viscosity versus molecular weight and the plateau in the stress relaxation curve. However, these data give no explicit information about the rates of network destruction and reformation. A new method which involves the reduction in shear rate in transient shearing flow was used to obtain such network kinetics information for three polyethylene melts at 170(DEGREES)C. / Other methods of characterization have also been used. These include steady simple shear, small amplitude oscillatory shear, large amplitude oscillatory shear and transient uniaxial extensional flow. All of the above methods involve different types of deformation in both linear and nonlinear viscoelastic regions. These data were used to test the predictive abilities of two constitutive equations inspired by network theory.

Particle interactions in Couette flow.

Darabaner, Carole Lee. January 1966 (has links)
No description available.

Behaviour of molten polyolefins extruded from an annular die

García-Rejón, Andrés. January 1979 (has links)
In the extrusion blow molding process, the behaviour of the parison prior to inflation is of central importance. Properties of the finished article, such as wall thickness and thickness uniformity, are determined by the simultaneous phenomena of swell and sag. / In the present study, an apparatus was built to study the behaviour of the extrudate from an annular die under isothermal conditions. First, sag was eliminated by extruding into an oil bath, and both thickness and diameter swell were determined as functions of time. Then, extruding into heated air, sag behaviour was observed. / These procedures allowed the study of the individual contributions of swell and sag to the overall parison behaviour. / Three high density polyethylene resins and a polypropylene resin were studied. The materials were thoroughly characterized to obtain the traditional rheological properties. In addition, an extensional rheometer was modified to measure the viscosity under uniaxial extension. / A model to predict the total length of the parison at any given time is proposed. This model is expressed in terms of rheological properties of the materials and process variables only.

Interaction of colloidal particles in shear flow

Ven, Theodorus Gertrudus Maria van de. January 1975 (has links)
No description available.

Zeolites in ceramic suspensions : a study of rheological effect

Davies, Russell Martin January 2003 (has links)
Molecular sieves with low silicon to aluminium ratio exhibit high ion-exchange capacity and fast exchange kinetics for the removal of divalent cations, such as Mg2 +, Ca2 + and Sr>. Owing to their unique structure and properties and the similarity of their composition to many ceramic materials, zeolites are also promising materials for use in the ceramics industry. The processing of modem ceramics formulations, e.g. glaze and coating suspensions. generally requires constant rheological characteristics over time. Glaze suspension rheology. however. usually changes with time due to the continual dissolution of the solid fraction, i.e. the frit. This study, therefore, evaluates the suitability of zeolites as ion exchangers and rheological stabilisers for the glaze industry. It is important that the zeolites in question are able to withstand the conditions of high shear and temperature experienced during ball milling without loss of crystallinity. This is detennined in this study using a variety of techniques including TGA, XRD, XRF. SEM. FTIR, zeta potential and particle size measurements. Other important properties of zeolites include their surface charge characteristics, ion exchange capacity and rheology modifying behaviour. These properties are evaluated using zeta potential, ICP. and rheology measurements respectively. Zeta potential measurements show that the surface charge properties of zeolites are a function of the silica and alumina components at the surfaces of the respective structures. i.e. the silicon to aluminium ratio. TGA, XRD, XRF, FTIR, ICP and zeta potential results show that the crystallinity of each zeolite analysed is independent of ball milling, whereas, ion exchange capacity decreases significantly after milling. The ion exchange capacity of each zeolite, however, is sufficient to cause a marked decrease in the total divalent ion concentration in the liquid phase of each glaze suspension after milling. The monovalent ion concentration in the liquid phase of each suspension may increase or decrease depending on the type of zeolite employed. The changing rheology of each suspension, on zeolite addition, also varies depending on the initial composition of the glaze components, the liquid phase ion concentration and the type of zeolite used. Time resolved measurements show that the rheology of each suspension, in the presence of zeolite, continues to change up to eight weeks after milling due to further dissolution of the glaze components. This study, therefore, concludes that although zeolites are effective at modifying the liquid phase ion concentration and rheology of concentrated glaze suspensions, they are unable to completely stabilise suspension rheology over time. The ion exchange ability of zeolites. however, may still prove to be of benefit to the glaze industry, especially in the removal of Ca2+ and Mg2+ ions from hard water sources.

Rheological problems associated with the polymer processing industry

Dowley, John Gordon January 1988 (has links)
No description available.

Rheology of suspensions a study of dilatancy and thirotropy ...

Röder, Hugo Levin. January 1939 (has links)
Proefschrift--Utrecht. / Text in English. Includes index. "Stellingen" (2 leaves inserted). Bibliography: p. [85].

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