To see the other types of publications on this topic, follow the link: Rheological properties.
Dissertations / Theses on the topic 'Rheological properties'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Rheological properties.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Scott, Shane. "Rheological Properties of Protein Hydrogels." Thesis, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/20565.
Full textAbstract:
Certain hydrogel forming de novo proteins that utilize different crosslinking
methods are studied experimentally on a rheometer. The stress reaxation
modulus of CRC, a telechelic, triblock protein, is shown to be that of
a stretched exponential function with a value of β ≅ 0.5. The insertion of
an integrin binding domain and changes in pH within the range 6.5–8.5 are
shown not to significantly affect the resulting rheological behavior. A selective
chemical crosslinker is used on CRC hydrogel systems and is shown to
change the rheological behavior of the system to that of a combination of a
chemically and physically crosslinked system. Chemically crosslinked hydrogels
composed of W6, a wheat gluten-based protein, demonstrate a storage
modulus weakly dependent on the angular frequency that is much greater
than the loss modulus, with a modulus concentration dependence of c^9/4.
2
Yeong, Shoot Klan. "Rheological properties of lubricating grease." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251581.
Full text
3
Gallat, Stephanie. "Rheological properties of reworked butters." Thesis, University of Reading, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259761.
Full text
4
Moolman, Pieter Lafras. "Rheological model for paint properties." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/1110.
Full textAbstract:
Thesis (PhD (Process Engineering))--Stellenbosch University, 2008.The feasibility of predicting paint properties directly from the raw material formulation as well as the rheological data is investigated in this study. Although extensive work has been carried out on the prediction of paint properties in terms of the raw material data, very little research has been carried out on the prediction of paint properties in terms of the rheological data. Little is known about the relationship between fundamental rheological properties and real-world performance. The paint under investigation consists of fourteen raw materials. These raw materials interact in a very complex manner to produce certain desired paint properties. Evaluation of these interactions in terms of constitutive equations is almost impossible and the relationships between paint properties, raw materials and rheology can only be modelled in a statistical way. Linear relationships are investigated with linear parameter estimation techniques such as multiple linear regression. However, it has been found that many of these relationships are non-linear and that linear modelling techniques are no longer applicable for certain situations, e.g. at very high concentrations of specific raw materials. Non-linear techniques such as neural networks are used in these situations. The relationship between the raw materials, paint properties and rheology are evaluated using the following three models: · MODEL 1: The relationship between rheology and raw materials · MODEL 2: The relationship between paint properties and raw materials · MODEL 3: The relationship between paint properties and rheology MODEL 1 makes use of techniques such as principal component analysis and preliminary modelling to respectively reduce redundancy and to capture as much data as possible. MODELS 2 and 3 make use of linear screening techniques in order to identify relevant raw materials and paint properties. The validity of every model is checked to ensure that predictions and interpretations are unbiased and efficient. MODEL 1 revealed that emulsion, extender particles, pigment, water, organic pigment and solvent are the six most important raw materials affecting the rheology of the specific paint. The rheology curves that are predicted most accurately by means of multiple linear regression are the “Amplitude Sweep” (AS), “3-Interval-Thixotropy-Test” (3-ITT) and the “Flow Curve” (FC). Non-linear rheological behaviour is encountered at high pigment volume concentrations (PVC) and volume solids (VS), due to the strong dependency of the rheology of the paint on these properties. It has been shown that neural networks perform better than multiple linear regression in predicting the rheological behaviour of these paint samples for which the raw materials vary by more than 20% from the standard formulation. On average, neural networks improve predictability of the rheological parameters of these samples by 54%. The largest improvement in predictability is made on the rheological variable “Extra Low Frequency” value (CXLF), where multiple linear regression resulted in relative errors of 59%, while neural networks resulted in errors of only 5%. Other predictions of rheology curves where neural networks have shown a major improvement on predictability are the “Time Sweep” (TS) – 68% increase in accuracy and “Low Shear” curve (LS) – 63% increase in accuracy. The smallest increase that the neural network had on the predictability of a rheology curve, was a 33% increase in accuracy of the “Amplitude Sweep” (AS) predictions. Multiple linear regression models of MODEL 2 predict the critical paint properties of Opacity, Gloss, Krebs Viscosity and Dry Film Thickness with relative errors smaller than 10%. It has been shown that 90% of all new predictions fall within the allowable error margin set by the paint manufacturer. Paint properties that can be predicted with an expected error of between 10% and 20% are Dry and Wet Burnish, Open Time and Water Permeability. Paint properties that are predicted the most inaccurately by MLR, that results in errors larger than 20% are Dirt Pick-Up and Sagging. Non-linear techniques such as neural networks are used to predict the paint properties of these paint samples for which the raw materials vary by more than 20% from the standard formulation. The neural networks show a major improvement on the predictability of the paint properties for those paint samples that vary more than 20% from the standard formulation. On average, neural networks improve predictability of the paint properties by 47%. The largest improvement in predictability is made on the Wet Burnish20 prediction, where multiple linear regression resulted in relative errors of 66%, while neural networks resulted in errors of only 0.6%. Other paint property predictions where neural networks have shown a major improvement on predictability of 80% or more in accuracy are Gloss – 80% increase in accuracy and Dry Film Thickness – 81% increase in accuracy. The smallest increase that the neural network had on the predictability of a paint property, was a 33% increase in accuracy of the Sag predictions. MODEL 2 makes it possible for the paint manufacturer to test tolerances around certain paint properties during manufacturing. Rheology is still a very under-utilised tool for explaining certain paint properties. MODEL 3 quantified the correlation between fundamental rheological properties and real world performance of a paint. It has been shown that rheological measurements can be used accurately to predict certain critical paint properties such as Opacity, Krebs Viscosity, Dry Film Thickness and Gloss within the allowable error margin given by the paint manufacturer. Multiple linear regression models predict the paint properties of Opacity, Krebs Viscosity and Dry Film Thickness with relative errors smaller than 10%, with rheology as input to the model. A neural network of MODEL 3 was developed to predict the paint properties of those paint samples that vary more than 20% from the standard formulation, by using rheology data as input to the model. The neural networks perform better than multiple linear regression in predicting the paint properties of these paint samples. On average, neural networks that use rheology data as input, predict the paint properties 49% more accurate than equivalent multiple linear regression models. The greatest improvement in model predictability is for Water Permeability - 73% increase in accuracy and Gloss - 70% increase in accuracy....
5
Khan, Shahid Wahab. "Rheological properties of talc-filled polypropylene." Thesis, Loughborough University, 2001. https://dspace.lboro.ac.uk/2134/7567.
Full textAbstract:
In this study polypropylene was modified by a range of talc (Mg3(OH)2Si4OlO) fillers. Three different types of surface modifiers were also used, two types of silanes (octyltriethoxysilane and y-aminopropyltriethoxysilane) and maleic anhydride modified polypropylene plus polyethylene wax as an external lubricant. A series of compounds were prepared in an APV twin screw compounder, based on talc addition level, morphology, particle size, surface coatings and coupling agents. The study showed that addition of talc to PP increases the shear viscosity and the blend system generally follows the power law in the shear rate range studied. The experimental values obtained with talc-filled PP were compared with theoretical data obtained from the Maron-Pierce type equation. It was found that theory predicts a higher value of relative viscosity for some talc fillers. A model equation is proposed for talc-filled PP that predicts accurately relative viscosity of the compound for different volume fractions of talc filler. PP-filled with talc having predominantly acicular particles (high surface area), shows a highest shear viscosity values, since high surface area fillers tend to increase the occluded polymer increasing the effective filler volume. The addition of a high level of coating decreasess hearv iscosity of the system,a ddition of a reactivec oupling systems lightly increasess hearv iscosity. Wall slip for unfilled PP was consistently evident. The slip velocity increases systematically with shear stress, but there is a critical value below which slip velocity was negligible. Addition of talc decreased the slip velocity at a given stress. A mechanism of slip has been proposed whereby a 'slip layer' on the die surface provides a sharp, low energy interface over which, at sufficiently high shear stress, the fluid PP can slip. A new empirical model has been proposed to predict the slip velocity of filled PP, as a function of talc volume fraction. PP filled with 10 % wt. talc having predominantly acicular particles, showed a higher slip velocity than PP filled with talc of other morphologies. It was observed that slip velocity increased by coating talc (either by use of coating or coupling agents) due to modification of velocity distributions in the flow channel. Extrudate swell increases with increasing shear rate for unfilled and talc-filled PP compounds. Inclusion of talc generally decreases the swell over the entire range of shearr ates studied,b ecauset he addition of talc to PP increasesth e shear/extensional modulus and thereby decreasede lastic strain recovery. No appreciablei nfluence of particle size on swell ratio was observed. Coating talc with octyltriethoxysilane produces higher swell relative to uncoated filled PP, and higher coating levels consistently produced higher swell values. However, coupling agent 7- aminopropyltriethoxsilane and maleic anhydride modified polypropylene both reduced the swell of the filled polymer system, with a more pronounced effect in extension than in shear. Swell decreased with an increase in capillary length-todiameter ratio and increased with increase in shear rate, (or shear stress) with or without coating/coupling agent. Addition of talc fillers delayed the onset of melt fracture and higher loadings of talc completely suppressed the melt fracture in the range of shear rate studied. Melt fracture for unfilled and filled PP has been studied and quantified by the frequency of the melt distortion. A mechanism for polymer melt fracture has been proposed to explain the results, based on the tensile failure of the material in extensional deformation. It was found that shear rate and die L/D ratio were the major causes of changesin severity of melt fracture for the unfilled and talc-filled compoundss tudied. However, talc morphology and particle size did not have significant effects on the severity of melt fracture.
6
Ozer, Barbaros Hamdi. "Rheological properties of labneh (concentrated yoghurt)." Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267428.
Full text
7
Rogers, Michael D. H. "Rheological properties of gelatin/starch composite gels." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ58374.pdf.
Full text
8
Kreiba, Ali. "The rheological properties of aqueous polyacrylamide solutions." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ59314.pdf.
Full text
9
Kulamarva, Arun. "Rheological and thermal properties of sorghum dough." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=98740.
Full textAbstract:
Sorghum is a gluten free cereal and forms the staple diet of a majority of the populations living in the semi-arid tropics dough. It is usually consumed in the form of bread made from the grain flour. Dough made with sorghum flour has poor viscoelastic properties compared to wheat dough and mechanical methods for production of sorghum roti are scarce. This study was conducted to elucidate the rheological and thermal properties of sorghum dough to establish its behavior. The temperature and amount of water used for preparation of the dough and the composition of the flour were varied. Wheat, soya and black gram flours were used to prepare the composite doughs. Sensory characteristics of roti made with these dough samples by the traditional method and mechanical compression were studied. The results are presented and their implications are discussed.
10
Xue, Jun 1966. "Thermal and rheological properties of batter systems." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103018.
Full textAbstract:
Batters are highly complex systems with wide ranging ingredients including flours, water, flavorings, and spices. Interactions between the ingredients determine the performance of batters and the final quality of coated products. Addition of hydrocolloids into batters of different types of flour provides special effects on batter performance. The functionalities of hydrocolloids-flour mixtures in terms of the thermal and rheological properties of the resulting batter systems were investigated in this study.The rheological properties of the batter were determined using a strain/stress control rheometer. A steady state method was used to measure the viscosity as a function of the shear rate varying from 0.5 to 150 s-1 at 15°C. The resulting data was then fitted to the Herschel-Bulkley Model. The viscoelastic properties were monitored as a function of temperature and were determined using a dynamic oscillatory test. Two different temperature profiles were used to simulate cooking and storage processes. Differential scanning calorimetry (DSC) was used to determine thermal properties (namely glass transition temperature, gelatinization temperature, ice melting temperature, and enthalpy) and to describe the phase transitions that occur during heating and cooling processes.
The rheological and thermal properties varied for different types of flours and their combination ratios, as well as different types of hydrocolloids at different concentrations. The replacement of corn flour greatly altered the viscosity and viscoelastic properties of wheat based and rice based batter systems. Using 100% corn flour based batter showed highest yield stress, whereas 100% rice flour based batter did not show any yield stress. Higher temperatures and longer times were required to gelatinize starch at the higher levels of rice flour for each batter system flour mix combination. The various combination ratios of the flours apparently did not significant influence the gelatinization temperatures of the batter systems. However they significantly influence the total enthalpies (DeltaHG) of the various samples. Wheat flour based batters showed the lowest glass transition temperatures. Thermal properties of wheat-based batters were influenced by the replacement of wheat with rice or corn flours. Corn flour based batters required considerably more energy for gelatinization during the cooking process.
Hydrocolloids lowered flow behavior index (n) and increased the consistency index (k) of all batters. The gums also changed the onset temperature of structure development and the storage and loss moduli of the batter systems. Hydrocolloids greatly influenced the thermal properties of batter systems. The gums shifted gelatinization temperature and depressed glass transition temperature of resulting batter systems. Further, MC increased the melting temperature (Tm) for the test batter systems as compared with the values for the control system without methylcellulose (MC). Carboxymethylcellulose (CMC) did not show statistically significant effects on the total enthalpies of ice melting for all samples. However, MC and CMC showed more pronounced effects on rice, corn, and their combined flour based batters than it did on wheat flour based batters. However, this characteristic does not show in batter systems containing xanthan gum.
11
Vernon, Marika Nicole. "Investigating the rheological properties of aerated fluids." Thesis, Lancaster University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340654.
Full text
12
Huang, Tianjian. "Colloidal and rheological properties of carboxylated latices." Thesis, University of Bristol, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385307.
Full text
13
Dimitreli, Georgia. "Rheological and textural properties of processed cheese." Thesis, University of Lincoln, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442498.
Full text
14
Demir, Huseyin. "The stability properties of some rheological flows." Thesis, University of South Wales, 1996. https://pure.southwales.ac.uk/en/studentthesis/the-stability-properties-of-some-rheological-flows(7f0fad05-8228-4494-90be-375d16e0eab4).html.
Full textAbstract:
The stability of wall driven and thermally driven cavity flow is investigated for a wide range of viscous and viscoelastic fluids. The effect of inertia, elasticity, temperature gradients, viscous heating and Biot boundary conditions are of particular interest. Both destabilisation and bifurcation phenomenon are found. For Newtonian constant viscosity flow the instabilities are characterised by a critical Reynolds number which represents the ratio of inertial forces to viscous forces, and instability occurs when the inertial forces become large. For non-Newtonian viscoelastic fluids the instability is characterised by a critical Weissenberg number, which represents the ratio of elastic forces to viscous forces, and instability also occurs when elastic forces dominate the viscous forces. For thermally driven flow the instability is characterised by a critical Rayleigh number, which represents the ratio of temperature gradient to viscosity, and instability occurs when the Rayleigh number become large. In this case the instability is also characterised by both Eckert and Biot number. The work has relevance to thermal convection and mixing processes which occur in the viscous and viscoelastic fluid within the Earth's mantle. Three-dimensional steady and transient flow in a cylindrical cavity and three dimensional steady flow in a spherical cavity, are also considered for both viscous and viscoelastic fluids. Instabilities in these three-dimensional flow depend on the same parameters as the flow in square cavity.
15
Li, Chuanping. "Rheological Properties of Aqueous Nanometric Alumina Suspensions." Washington, D.C. : Oak Ridge, Tenn. : United States. Dept. of Energy. Office of Science ; distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2004. http://www.osti.gov/servlets/purl/835308-5NQETg/webviewable/.
Full text
16
Jampen, Stephan. "Rheological properties of gellan gels containing filler particles." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ35899.pdf.
Full text
17
Pristavita, Ramona. "Transferred arc production of fumed silica : rheological properties." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99787.
Full textAbstract:
The thermal plasma production of fumed silica in a transferred arc consists of the decomposition of quartz to SiO (g) and oxygen followed by an oxidizing quench back to SiO2. The particles formed have diameters of the order of 10 to 20 nm and are linked in a three dimensional branched chain aggregate. Previous work by Addona and Munz (1999) demonstrated the technical feasibility of producing fumed silica using this method, but was unable to demonstrate the special rheological properties of the powder. The most important characteristic of fumed silica is the presence of hydroxyls on the surface of the particles, in the form of isolated hydroxyl groups, hydrogen-bonded hydroxyl groups and siloxane groups.In the present work, we studied the changes in the powder quality by varying the quench conditions used for the production of the powder and by agglomerating the obtained particles. The fumed silica was agglomerated by conveying in a length of tubing with sharp bends. The powder was characterized using BET, Viscosity tests, FT-IR, TEM, SEM and XRD. The product was compared to both a commercial product (Aerosil 200) and the material previously produced by Addona. Tests were done before and after the agglomeration experiments.
The experimental results showed that the agglomeration had no effect on the powder's rheological properties. We concluded that the smaller viscosity values obtained for the plasma produced fumed silica were due to the lack of the free hydroxyl groups from the surface of the particles.
18
Cao, E. "Electrochemical and rheological properties of Na-attapulgite suspensions." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636203.
Full textAbstract:
An electron microscopic study of Na-attapulgite particles showed their lath-like habit with aspect ratios of approximately 100:3:1 (length:width:thickness). The average length of the particles is 0.951 μm. The nature and density of titratable surface charge was studied using an automatic potentiometric and titration apparatus. The results revealed that both positive and negative charges develop at the edges of the particles. The point of zero net proton charge (PZNPC) of the edges is at pH 6~7 depending on the electrolyte (NaCl) concentration (c). Electrophoretic mobility determined (using a Malvern Zeta Sizer II) over a range of pH and electrolyte concentrations showed a significant influence of the edge titratable charges on the electrokinetic properties. Particle size analysis (in suspension) using the technique of photon correlation spectroscopy (PCS) suggested that measurements of mobility reflect the electrokinetics motion of single laths at pH<6 and c<10-3 NaCl. However small aggregates form the electrokinetic units at pH<6 and/or high electrolyte concentrations. Conversion of mobility to zeta potentials proved difficult due to the lack of a suitable theory for the electrophoresis of lath-like and non-uniformly charged particles. An approximate method (Williams & Williams, 1978) was applied for resolving zeta potentials into separate face and edge components. The linear viscoelastic behaviour of concentrated Na-attapulgite suspensions was investigated using the techniques of shear wave propagation and forced non-resonant dynamic oscillation.
19
Khatkar, Bhupendar Singh. "Functional and dynamic rheological properties of wheat gluten." Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319243.
Full text
20
Deng, Linhong. "Electrical and rheological properties of blood and haemorheometry." Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248773.
Full text
21
Gładkowska-Balewicz, Izabela. "Mixed fluid gels formation, structure and rheological properties." Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7263/.
Full textAbstract:
'Fluid gel' consists of gel particles in a non-gelling medium and its particles are able to mimic fat globules and their bulk rheological behavior in emulsions based food products. The formation of single single polysaccharide fluid gel structure has been well described in the literature. However, mixed fluid gels have a potential of greater control over texture and in use performance but mechanisms governing their structure formation are not very well understood yet. This research aims to contribute to this understanding by investigation of structure formation of mixed fluid gels formed from various red algal polysaccharides, starch and its derivatives. A combination of rheological, calorimetric and optical microscopy analysis were used to investigate how presence of an additional co-solute and manipulation of process parameters during gelation (shear rate and the cooling rate) impact on final structure and rheological properties. It was observed that mixed fluid gel structures were formed as a result of physical entrapment of additional co solute. If gelation of the red algal polysaccharide occurred, the size of formed aggregates decreased with a decrease in red algal polysaccharide charge density. Applied shear rate was more effective structure modifier in mixtures with starch, whereas cooling rate in mixtures containing maltodextrin.
22
Dhameri, Sulaiman Ali A. "Rheological Properties and Decomposition Rates of Gellan Gum." University of Toledo / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1562780919692096.
Full text
23
Han, Long. "Study of the rheological properties of Nomex fibrids." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=2205.
Full textAbstract:
Thesis (M.S.)--West Virginia University, 2001.Title from document title page. Document formatted into pages; contains ix, 110 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 54-59).
24
Mård, Moa. "Use of Rheological Properties to Predict Extrusion Parameters." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-266158.
Full textAbstract:
Paxymer AB is a company that manufactures and sells flame retardants for plastics, based on their patented technology. The flame retardants are often sold as a master-batch that the customers mix into their own plastic products. Paxymer has two master-batches with the exact same formulation, but are produced with different temperature profiles. The high temperature extrusion process produces pellets with good properties whereas the low temperature process do not. The aim of this study was to define what rheological properties are important in the extrusion process, and how they can be correlated to the pellet quality. The aim was also to predict the processing parameters for the low temperature extrusion process to improve the pellet quality. The rheological behavior of the two master-batches was investigated through analysis of the batches, as well as their additional components, in the rheometer. According to the results the viscosity of the melt is very temperature dependent, and were found to be significantly lower for the high temperature process. My studies show that the poor pellet quality in the low temperature process is most likely due to the high melt viscosity, which leads to poor mixing of the components. To get equal melt viscosity in the low temperature process as in the high temperature process, I found that the screw speed and feed rate in the extruder needs to be increased. According to my analysis the desired screw speed should be approximately 500 rpm if the temperature was increased with 10°C. To get the right viscosity at the die exit, the feed rate would need to be 20 kg/h.Paxymer är ett företag som tillverkar och säljer flamskyddsmedel för plaster, baserad på deras patenterade teknik. Flamskyddsmedlet säljs oftast som en master-batch vilket kunderna blandar ner i deras egna plastmaterial. Paxymer har två master-batches med samma innehåll men som är tillverkade med olika temperaturprofiler. Tillverkningsprocessen med högre temperaturprofil producerar pellets med hög kvalitet och processen med lägre temperaturprofil gör inte det. Syftet med den här studien var att ta reda på vilka reologiska egenskaper som är betydande för framställningen av pellets med god kvalitet. Ett ytterligare syfte med projektet var att förutsäga extruderingsparametrar för processen med lägre temperatur för att uppnå en bättre kvalitet. De reologiska egenskaperna för båda master-batcherna och deras innehållande komponenter analyserades i en reometer. Enligt mina resultat så är plastsmältans viskositet väldigt temperaturberoende och visade sig därför vara betydligt lägre vid extruderingsprocessen med högre temperaturprofil. Den låga produktkvaliteten från processen med låg temperaturprofil beror sannolikt på att smältans viskositet var för hög, vilket leder till sämre blandning av komponenterna. För att få samma viskositet på smältan vid den lägre temperaturen i extrudern, som vid den högre temperaturen, så måste hastigheten på skruven samt inmatningshastigheten ökas. Enligt mina analyser så måste hastigheten på skruven ökas till 500 rpm om temperaturen även höjs med 10°C. För att få rätt viskositet i matrishålen så måste inmatningshastigheten öka till 20 kg/h.
25
Arrieta-Martinez, Melania. "Biochemical and rheological properties of waxy wheat flour dough." Thesis, Kansas State University, 2016. http://hdl.handle.net/2097/34455.
Full textAbstract:
Master of ScienceDepartment of Grain Science and Industry
Yong-Cheng Shi
Jon Faubion
The rheological properties of two waxy and two normal wheat flours were investigated and the observed differences between them were explained by biochemical analysis. Protein analysis showed that waxy flour had lower polymeric to monomeric ratio (0.70 and 0.58 for waxy flour compared to 0.75 and 0.76 for normal flour) and higher gliadin content in waxy wheat dough (43.9 and 47.3 for waxy wheat dough compared to 41.0 and 41.7 for normal wheat dough). Waxy flour had high amounts of insoluble (IPP) and unextractable (UPP) polymeric protein despite the poor dough forming properties of the waxy flours, contrary to previous correlations made between IPP, UPP and dough strength. Gluten index determination showed a clear difference between waxy and normal flour; there was no gluten aggregation when the waxy samples were tested. The determination of gluten index done on a variety of water washed flour samples indicated that the water-extractable fraction may contain compounds that affect gluten aggregation. HPLC analysis coupled with arabinose/xylose ratio and viscosity determination of the water extractable portion of the flour indicated that water extractable arabinoxylans (WEAX) in waxy wheat flour were different in composition and conformation. Further research is needed to determine if they could be responsible for the lack of gluten aggregation in waxy flour.
26
Kambara, Hajime. "The rheological properties of aluminum borate whisker filled resins." Case Western Reserve University School of Graduate Studies / OhioLINK, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=case1057599821.
Full text
27
Øfsdahl, Ellen. "Fibre-reinforced Self-compacting Concrete : Prediction of Rheological Properties." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for konstruksjonsteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18826.
Full textAbstract:
The purpose of this thesis is to investigate the relationship between measured rheology and proportioning properties with particular attention to maximum packing fraction, thickness of fiber lubricating matrix and fiber rotational overlap.This is done by conducting experiments on fresh concrete where the amount of matrix and fibres are varied, and comparing the rheological results with the proportioning parameters.The importance of an accurate grading curve is also evaluated.The hypothesis is that it is possible to find a correlation between calculated proportioning parameters and resulting rheology that will enable prediction of rheological properties.The results show that the variation in grading curve for the same aggregate is not very relevant to the proportioning parameters.The air content is shown to be of great importance regarding the correlation between matrix volume and packing fraction. Also it is found that it can be possible to predict the air volume based on matrix volume and fiber content.
28
Suzuki, Shinya. "Rheological Properties of Telechelic Associative Polymer in Aqueous Solution." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/200500.
Full text
29
Speers, Robert Alexander. "Rheological and colloidal properties of commercial brewing yeast suspensions." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/31517.
Full textAbstract:
A three part study was carried out to examine rheological, colloidal and floe microstructural aspects of industrial brewing yeast strains. Following a review of the literature, the rheological properties of four yeast strains (two flocculent ale and lager types and their non-flocculent variants) were examined. In related colloidal studies, orthokinetic flocculation rates of these strains as well as their cell surface charge were determined. Floc microstructure was characterized using both light and scanning electron microscopy. In a summary chapter, the cell floc model (a modification of Hunter's elastic floc model) was used to the explain the rheological and colloidal behaviour of brewing yeast suspensions.
Flow behaviour studies of the commercial yeast suspensions suspended in a calcium-containing sodium acetate buffer revealed that yeast flocculent characteristics had an important influence on their suspension flow behaviour. As cell concentrations increased, suspension flow properties become increasingly non-Newtonian and could be described by the Casson model at low rates of shear and the Bingham model at shear rates above 100 s⁻¹. The cell floc model was proposed to explain the Bingham flow behaviour of these csuspensions. The Bingham yield stress in these suspensions was believed to be a function of the orthokinetic capture coefficient, cell volume and the energy to break up doublet cells. Increasing temperature tended to lower the Bingham yield stress in lager strains and increase the yield stress in ale strains. A semi-empirical explanation for the viscosity increase of deflocculated cell suspensions and the estimation of pseudo-capture coefficients was presented.
Furthermore, studies of the flow behaviour of yeast strains suspended in decarbonated ale and lager beer revealed that: 1) suspensions of flocculent strains show
higher yield stress values than their non-flocculent variants, 2) ale strain suspensions tended to have higher yield values than the lager strains and 3) yeast dispersed in beer had higher yield stress values than when suspended in buffered calcium suspensions. This last observation was believed to reflect the influence of ethanol on the cell binding process which has important implications for future measurements of yeast flocculation.
Colloidal studies revealed for the first time, that the orthokinetic rate of flocculation of brewing yeast cells could be modelled by a first order equation, as predicted by fundamental colloid theory. While subject to considerable variation, measured rate constants led to the calculation of orthokinetic capture coefficients. Yeast cell zeta potential values generally agreed with literature data but could not be employed in the DLVO model of colloid flocculation to explain measured orthokinetic capture coefficient values. Examination of the cell zeta potential data indicated that the data had non-normal distributions.
SEM examination of the four industrial yeast strains suggested that a number of distinct structures mediated cell-to-cell interaction and that intra-strain differences occurred. These findings, along with the observation of non-normal surface charge distributions, indicated that these industrially pure strains had undergone substantial variation. Treatment of the flocculent cells with pronase tended to reduce cell-to-cell contacts.
In the summary chapter the cell floe model was employed to describe the rheological behaviour of the yeast suspensions. Estimation of the force needed to separate doublet yeast cells were made using critical shear rate data (i.e., the point at which Bingham flow begins). This estimate was similar to that reported for single antibody bonds and may be due to the presence of lectin-like structures on the yeast cell wall.Land and Food Systems, Faculty of
Graduate
30
Wu, Min. "Effects of dispersion on rheological properties of filled polypropylene." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0007/MQ42930.pdf.
Full text
31
Md, Yusoff Nur Izzi. "Modelling the linear viscoelastic rheological properties of bituminous binders." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/12582/.
Full textAbstract:
Rheology involves the study and evaluation of the flow and permanent deformation of time-and temperature-dependent materials, such as bitumen, that are stressed through the application of a force. The fundamental rheological properties of bituminous materials including bitumen are normally measured using a dynamic shear rheometer (DSR), from low to high temperatures. DSR is a powerful tool to measure elastic, viscoelastic and viscous properties of binders over a wide range of temperatures and frequencies, provided the tests are conducted in the linear viscoelastic region. Therefore, the study of bitumen rheology is crucial since its reflects the overall performance of a flexible pavement. However, it is well known that the DSR also has limitations, where the measurements are exposed to compliance (testing) errors particularly at low temperatures and/or high frequencies. In addition, conducting laboratory tests are known to be laborious, time consuming and require skilled personnel. Therefore, this research is conducted to elucidate a better understanding of the rheological properties and modelling procedures of bitumens and bituminous binders. Various materials such as unmodified bitumens, polymer-modified bitumens (PMBs) and bitumen-filler mastics, unaged and aged samples, are used in this study. An extensive literature review was undertaken to identify reliable models that can be considered as a valuable alternative tool to describe or fit the rheological properties of bitumen. These properties are commonly presented in terms of complex modulus and phase angle master curves, together with the determination of shift factor values at a particular reference temperature. In general, the complex modulus and phase angle master curves can be modelled using different techniques; nomographs, mathematical equations and mechanical models. However, the nomographs have become obsolete in recent years and tended to be replaced by the two latter models. Those models are able to satisfactorily describe the rheological properties of unmodified bitumen. However, the observations suggest a lack of agreement between measured and predicted rheological properties for binders that contain a phase transition, such as found for highly crystalline bitumen, structured bitumen with high asphaltenes content and highly modified bitumen. An attempt was made to evaluate the validity of several mathematical equations and mechanical element approach using unaged and aged unmodified bitumens and PMBs database. It is observed that the Sigmoidal, Generalised Logistic Sigmoidal, Christensen and Anderson (CA), and Christensen, Anderson and Marasteanu (CAM) Models are able to satisfactorily describe the rheological properties of unmodified bitumens. Nevertheless, they suffer from the same drawbacks where the presence of highly EVA semi-crystalline and SBS elastomeric structures render breakdowns in the complex modulus master curves. Similar discrepancies are observed when one of the mechanical models (the 2S2P1D Model) is used. To construct the master curves, different shifting methods are available. It is found that a numerical shift produced the best fit between measured and modelled data, followed by the Laboratoire Central des Ponts et Chaussées (LCPC) approach, William, Landel and Ferry (WLF), Modified Kaelble, Viscosity Temperature Susceptibility (VTS), Arrhenius and Log-Linear methods. A temperature range from 10 to 75oC is used in this study. It is worth mentioning that most of the methods are empirical and might not be applicable for all materials. Finally, the phase angle master curves must also not be neglected to yield a complete rheological properties of binders. The statistical analysis between measured and modelled data shows that the Fractional Model yielded the best correlation for a temperature range from10 to 75oC, followed by the Al-Qadi and Co-workers, CAM, CA and Kramers-Kronig relationships. An anomaly is observed between measured and descriptive data of the Kramers-Kronig relationship particularly at high frequencies and/or low temperatures. The Fractional Model is not considered suitable for practical purposes due to the high number of coefficients that need to be solved.
32
McCormack, R. J. "The rheological and transport properties of deep mantle materials." Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1356653/.
Full textAbstract:
This Ph.D. project was an experimental study of the rheological and transport properties of deep earth materials. It was conducted using high pressure and high temperature experiments on analogue phases and systems. Much of the research was focused on the D’’ region of the lower mantle and in particular on the post-perovskite phase present in that region. Analogue materials were used as the post-perovskite present in the lower mantle, MgSiO3, is not stable at conditions experimentally accessible with multi-anvil devices. Measurement of rheological properties of post-perovskite analogue phases was mostly performed using the d-Dia apparatus, which is a multi-anvil deformation device. These studies included the deformation of the CaPtO3 post-perovskite phase under pure shear; relative strength measurements of the perovskite and post-perovskite phases of CaIrO3 under simple shear and relative strength measurements of the NaCoF3 perovskite and post-perovskite phases under pure shear. Studies of the transport properties of deep earth materials were also undertaken. One such study focused on the anisotropy of diffusion of major ions in the post-perovskite structure. It was undertaken using inter-diffusion of Ir and Pt ions in CaIrO3 single crystals at high pressure and temperature. Another study investigated the possibility of the Reynolds’ dilatancy effect operating in the lower mantle. This study was conducted using the d-Dia apparatus and the imaging capabilities at a synchrotron light source. The final part of the project was the development of the new high pressure apparatus, the DT-Cup. This will allow future deformation experiments to be conducted at higher pressures than are currently accessible using multi-anvil devices. This will increase the range of post-perovskite analogue materials whose rheological properties can be quantitatively studied.
33
Hort, Joanne. "Cheddar cheese : its texture, chemical composition and rheological properties." Thesis, Sheffield Hallam University, 1997. http://shura.shu.ac.uk/19833/.
Full textAbstract:
Procedures associated with Quantitative Descriptive Analysis were used to identify and subsequently train a panel to quantify the perceived textural attributes of Cheddar cheese. Seventeen types of Cheddar were assessed by the panel for creaminess, crumbliness (fingers), crumbliness (chewing), firmness, graininess, hardness (first bite), hardness (cutting), and springiness. Cluster and Principal Component analyses of the sensory data revealed that the cheese samples could be subdivided into young, mature and extra mature Cheddars in terms of the textural attributes measured. The panel was also able to distinguish between the low fat and genuine Cheddars. The percentage fat, moisture and salt contents and the pH level of the seventeen Cheddar samples were established. An inverse correlation between fat and moisture content and a positive correlation between pH level and salt content were observed. The rheological properties were measured using three tests performed on an Instron Universal Testing Machine - a compression test, a cutting test and a stress relaxation test - and, where appropriate, were reported in terms of true stress and true (Hencky) strain curves. The viscoelastic properties of Cheddar observed during stress relaxation tests were modeled using a Generalised Maxwellian model consisting of two exponential elements and a residual term. Considerable variation in all the rheological properties was observed amongst the Cheddar samples. The rheological parameters did not distinguish between the samples to the same extent as the sensory assessment. However, Cluster Analysis of the rheological data did differentiate between the rheological profiles of the young (mild & medium) and the remaining mature/extra mature samples. The relationships between the textural attributes and the chemical and rheological parameters were investigated. No relationship between chemical composition and texture was identified, but correlations between the rheological parameters and the textural attributes were not uncommon. Multiple regression techniques were employed to construct mathematical models to predict the textural attributes from the rheological data. Successful models were constructed utilising parameters from the compression and cutting tests for all the attributes apart from creaminess. More precise models were constructed for firmness, springiness and crumbliness (fingers) where the action of the instrumental test from which the rheological parameters were obtained resembled the test method used by the panel. The chemical, textural and rheological properties of an English Cheddar were determined at various stages during its ripening period to investigate any changes that occurred. A slight increase in pH was the only chemical change recorded. Progressive changes in the majority of the textural attributes were observed. The most dramatic changes included a decrease in springiness and an increase in creaminess. A changing rheological profile was also observed during maturation, a decreasing strain at fracture being the most notable development. The sequence of changes in both the textural and rheological properties was divided into three fairly distinct phases, the initial stage reflecting the developments necessary before the cheese would be suitable for retail sale and the final stage including the development of the necessary textural attributes characteristic of a Mature English Cheddar. It was evident that the timing of the maturation period was pertinent to the development of textural attributes characteristic of particular maturities of Cheddar cheese. The textural attributes of the maturing Cheddar were also predicted at each stage of maturation using the mathematical models constructed in the initial study. Accurate predictions were made for all the attributes except crumbliness (chewing) and graininess.
34
Gutsul, O. V. "The rheological and electrical properties of polymer-colloid solutions." Thesis, БДМУ, 2020. http://dspace.bsmu.edu.ua:8080/xmlui/handle/123456789/18320.
Full text
35
Alin, Maishah. "Effect of rejuvenators on rheological properties of asphalt binders." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1525216636988378.
Full text
36
Tatsumi, Daisuke. "Rheological properties and network structures of cellulose fiber suspensions." Kyoto University, 2006. http://hdl.handle.net/2433/144088.
Full textAbstract:
Kyoto University (京都大学)0048
新制・論文博士
博士(農学)
乙第11850号
論農博第2604号
新制||農||929(附属図書館)
学位論文||H18||N4162(農学部図書室)
24392
UT51-2006-J547
京都大学大学院農学研究科森林科学専攻
(主査)教授 松本 孝芳, 教授 西尾 嘉之, 教授 矢野 浩之
学位規則第4条第2項該当
37
Cavdar, Seda. "Effect Of Different Compositions On Rheological And Mechanical Properties Of Epdm Rubber." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608968/index.pdf.
Full textAbstract:
In this work, EPDM rubber was compounded with increasing amount of filler (FEF N 550 type carbon black), process oil (saturated mineral oil), vulcanizing agent [di (t-butylperoxy) diisopropyl benzene, i.e., BBPIB] and diene [5-ethylidenebicyclo(2.2.1)-hept-2-ene, i.e., ENB] in order to investigate mechanical and rheological properties.
Effect of Increasing amount of filler was investigated by using FEF N 550 type carbon black in 35, 70, 87.5, 105 phr. Decrease in scorch times of vulcanization reactions, ts2 (25, 21, 19, and 18 s, respectively) and slight increase in rate constants for vulcanization reactions (0.0270, 0.0274, 0.0301 and 0.0302 s-1, respectively) were explained in terms of nature of semi-active filler.
Effect of increasing amount of process oil was investigated by using saturated mineral oil (TUDALEN 3909) in 15, 30, 45 phr. Scorch time for vulcanization reaction and rate constants were measured as 95, 103, 97 s and 0.0277, 0.0274, 0.0291 s-1, respectively.
Effect of increasing amount of vulcanizing agent was investigated by using BBPIB (PERKADOX 14/40 MB-gr) in 2.5, 5, 7.5, 10 phr. The compound with 5 phr vulcanizing agent gave optimum rheometer data, crosslink density,, ultimate tensile strength, hardness, deflection and damping. Vulcanization reaction rate constant reached 0.0335 s-1 with 7.5 phr vulcanizing agent.
Effect of increasing ENB ratio was investigated by using 4 different EPDM with ENB ratios 5.0, 5.6, 7.5, 8.9%. With two different cure systems, compounds with 5.6 and 7.5% ENB ratio gave optimum results. Vulcanization cure time, reaction rate constant and compression set properties changed in irregular manner.
38
Chen, Shukun. "Rheological Properties of Oil in Water Emulsions and Particulate Suspensions." Doctoral thesis, Norwegian University of Science and Technology, Department of Chemical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2155.
Full textAbstract:
This thesis aims at a better understanding of the rheologicalproperties of the important colloids in oil industry, i.e. suspensions, emulsions and waxes.
The rheology of suspension system is a complex field influenced by a large range of variables. In this work, we mainly focused on the rheological properties of suspensions as a function of volume fraction of particles, particle size, surface properties, shear rate, and the nature of continuous mediums. The investigated suspensions behaved as Newtonian fluids at dilute concentration, whereas, shear thinning properties were observed at high volume fractions. The shear thinning effect increased with decreasing particle size. Ionic strength and pH are both factors affect particle interactions and consequently the rheological properties of suspensions: large and strong aggregates were formed at the isoelectric point, due to the strong attraction between particles at this point. The larger aggregates results in higher viscosity, yield stress, storage moduli and shear thinning effects. The relative viscosity of all the suspensions can be reasonably well fitted with the Krieger and Dougherty model.
Wax precipitation and deposition is a recurring challenge in transportation of crude oil. To better understand and explain these phenomena, the crystal growth of two model waxes was determined as a function of concentration, cooling rate and cooling conditions (static or dynamic). The flow and viscoelastic behaviours were investigated around the wax precipitation temperature, and the yield stress was determined after both dynamic and static cooling. Interpretation of the results was carried out in view of crystal growth and microstructure of the wax crystals.
Rheological properties of wax containing water-in-oil emulsions stabilized by asphathenes were also studied. Temperature scans of viscosity, flow measurements and yield stress measurements were carried out on these systems. The effects of water cut, amount of asphaltenes and amount of waxes were investigated. Wax content and water cut have the most pronounced effect upon the viscosity and yield stress of the systems.
39
Oztoprak, Ayse Feray. "Investigation Of The Rheological Properties Of Cayirhan Coal-water Mixtures." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607861/index.pdf.
Full textAbstract:
In this thesis, coal-water mixtures (CWM) with Çayirhan lignite were prepared to optimize the parameters of CWM having an ideal behavior which means that at maximum coal loading, relatively stable at static and dynamic conditions and exhibit low viscosity. For this purpose, the effect of the parameters such as pulp density, amount of chemical agents, particle size distribution, addition of methanol and pulp pH were investigated. Results showed that increasing pulp density negatively affects viscosity and allowable maximum pulp density was obtained as 60% when the particle size distribution has a d50 value of 22.82 µ
m. The optimum amount of chemical agent was found as 0.9%, having 10% Na-CMC (Sodium Carboxymethyl Cellulose) and 90% PSS (Polystyrene Sulfonate). Minimum viscosity was achieved when the pulp pH was in natural conditions (pH=6.85). Addition of methyl alcohol increased the viscosity of CWM.
40
Ozaki, Hiroto. "Study of Network Structures and Rheological Properties of Physical Gels." Kyoto University, 2017. http://hdl.handle.net/2433/227633.
Full text
41
Park, Hee Eon 1972. "Effect of pressure on the rheological properties of three polyethylenes." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31066.
Full textAbstract:
The effect of pressure on the viscosity of polyethylenes was studied using a newly developed high-pressure, sliding-plate rheometer. The rheometer subjects the sample to a homogeneous pressure and temperature at levels up to 70 MPa and 225°C. Simple shear is generated in the sample, and the resulting shear stress is measured locally in the center of the sample by means of a shear stress transducer. Viscosity curves were generated at four pressures from 0.1 to 70 MPa, and it was found that the pressure data could be shifted onto the ambient pressure curves by means of a pressure shift factor. The viscosity increases exponentially with pressure. Long chain branching increases the pressure sensitivity, but the polydispersity has little effect.The effect of pressure on the creep behavior of polyethylenes was also studied. It was observed that pressure decreases the creep compliance. Careful tuning the controller is required to obtain reliable data when operating the rheometer in the creep mode.
42
Mahi, Hassanabadi Hojjat. "Relations between microstructural development and rheological properties in polymer nanocomposites." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/30345/30345.pdf.
Full textAbstract:
Cette thèse porte principalement sur la compréhension des relations entre la microstructure et les propriétés rhéologiques des nano-composites à base d’un copolymère d’éthylène-acétate de vinyle (EVA). La première partie de l'étude concerne les nano-composites d’EVA avec de la cellulose nanocrystalline (NCC). Cette partie cherche à inférer la structure d’échantillons inconnus à l’aide de mesures rhéologiques. En analysant les propriétés obtenues par des mesures rhéologiques en cisaillement et en élongation, les principaux mécanismes étant à l’origine du renforcement de ces nano-composites sont étudiés en détail. Dans la deuxième partie du travail, on s’intéresse aux nano-composites contenant des particules isométriques (CaCO3) et anisométrique (argile). L'objectif est de déterminer l'effet de variables structurelles comme les interactions polymère-particule et particule-particule, l'état de dispersion, et en particulier la forme des particules sur les propriétés finales. Les mécanismes par lesquels ces paramètres influencent les propriétés rhélogiques ont été abordés en lien avec les prédictions par un modèle de fonction moléculaire de contrainte (MSF). Il a été constaté que plus les particules sont non-isométriques, plus les interactions polymère-particule et les interactions entre les particules sont élevées. Ainsi, l'effet de l’argile est beaucoup plus important que celui du CaCO3, et ce pour presque tous les comportements rhéologiques étudiés. La plupart des paramètres rhéologiques ont montré une divergence autour du seuil de percolation. Par conséquent, les modèles basés sur la dynamique des chaînes (modèle MSF) ne peuvent prédire le comportement après la percolation. Pour les systèmes percolés, les modèles basés sur le réseau fractal, qui considèrent les interactions entre les particules, ont été utilisés.The main objective of this thesis is to understand the relations between microstructure and rheological properties of polymer nano-composites based on ethylene vinyl acetate (EVA) copolymer. The first part of the study is related to EVA-nano crystalline cellulose (NCC) composites. As a first step, determination of the unknown structure of the samples using rheological methods was investigated. By analyzing the properties obtained under shear and extensional deformations, the mechanisms leading to polymer reinforcement were investigated in details. In the second part, nano-composites containing isometric (CaCO3) and anisometric (clay) particles were used. The focus here was to determine the effect of structural variables such as polymer-particle and particle-particle interactions, state of dispersion, and in particular particle shape on the final properties of these nano-composites. The mechanisms involving these parameters were investigated through rheological properties and discussed with respect to experimental data. Predictions via the molecular stress function (MSF) model are also presented. It was found that higher particle anisomety led to greater polymer-particle and particle-particle interactions. Therefore, the effect of clay was much higher than CaCO3 on almost all the rheological parameters studied. But, lower predictability was found around the percolation concentration. Consequently, while a model based on chain dynamics could predict the behavior below percolation, such model failed to predict the response at higher concentrations. For percolated systems, models based on fractal networks, which include particle-particle interactions, were used.
43
Jones, Guy Matthew John. "Rheological properties of gelatin, carrageenan and locust bean gum mixtures." Thesis, University of Nottingham, 2004. http://eprints.nottingham.ac.uk/11635/.
Full textAbstract:
This thesis reports data on blends of carrageenan (0.3%w/w) and locust bean gum (0.3%w/w) in the presence of biopolymers, particularly gelatin of varying concentration. Particular attention is given to their behaviour on autoclaving since this is relevant to one of the most important applications of these materials as gelling agents in canned meat products. It was shown there is such 3% gelatin could be found in the gelling system as a result of from collagen in the meat. Gelatin at this level generally reduced the strength of non-autoclaved carrageenan and LBG gels but enhanced autoclaved gels. Studies of turbidity and rheology suggested that the effect was due to phase separation. Investigation of viscosity after autoclaving produced evidence to support the hypothesis that gelatin protected LBG from thermal degradation. For industrial LBG this was not, however, observed by direct molecular weight measurement, although such effects were seen for pure LBG. Interesting differences between the gel strength response between low and high ionic strength buffers were found. It was concluded that textural performance in real products was sensitive to a range of factors (salt, impurities, presence of gelatin) and would be interpreted by a combination of degradation and phase separation theory. Implications for the industry are discussed.
44
Shen, Bin. "Experimental approaches for determining rheological properties of cement-based extrudates /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202003%20SHEN.
Full textAbstract:
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003.Includes bibliographical references (leaves 120-125). Also available in electronic version. Access restricted to campus users.
45
Shamu, John. "On the measurement and application of cement grout rheological properties." Licentiate thesis, KTH, Jord- och bergmekanik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-251745.
Full textAbstract:
The rheological properties of cement-based grouts play a key role in determining the final spread in grouted rock formations. Rheologically, cement grouts are known to be complex thixotropic fluids, but their steady flow behavior is often described by fitting the simple Bingham constitutive law to flow curve data. The resultant Bingham parameters are then used in grouting design of e.g. tunnels, to estimate the penetration length. Since cement grouts are thixotropic suspensions, the interpretation of their flow curves as obtained from flow sweeps in concentric cylinder rotational rheometers is often complicated by: the presence of wall slip, sedimentation and unstable flow at low shear rates. A systematic approach to study these effects within the constraints of the concentric cylinder geometry (Couette) and for different cement grout concentrations was carried out as part of the Licentiate research work. Of particular interest was the influence of geometry and flow sweep measurement interval on flow curves, including the characteristic unstable flow branch that appears at applied shear rates that are below the critical shear rate. The unstable flow branch observed below the critical shear rate has been described as a characteristic feature in the flow curves of thixotropic suspensions, e.g. cement grouts, laponite. From a practical standpoint, this information can then be readily used to improve rheological measurements of cement grouts. The existence of the critical shear rate below which no stable flow occurs, plus the complex wall slip phenomenon are then discussed by considering how they affect actual spread in rough and smooth rock fractures. Another major part of the research presented in this thesis relates to the measurement of model yield stress fluid (YSF), i.e. Carbopol, velocity profiles within the radial flow geometry. Radial flow between parallel plates, is an idealized fundamental flow configuration that is often used as a basis for grout spread estimation in planar rock fractures. Compared to other flow configurations with YSFs, e.g. channels, only a limited amount of work has presented analytical solutions, numerical models and especially experimental work for radial flow. Thus, as a first step towards more systematic studies of the plug flow region of YSFs in radial flow the current work presents the design, manufacture and for the first time velocity profile measurements that were conducted by using the pulsed Ultrasound Velocity Profiling (UVP) technique. The current observations for tests carried out with different disk spacings and flow rates show a distinct plug region, coupled with wall slip effects for the Carbopol model YSF fluid that was used. The theoretically predicted velocity profiles and the measured ones agree reasonably well, and the main discrepancies are discussed. Future studies, would then be targeted at improving the current experimental setup, for detailed measurements of the plug flow region along the radial length, which remains a challenging issue for studies on YSFs and engineering applications such as rock grouting design.Cementbaserade injekteringsmedels reologiska egenskaper har en stor påverkan på strömning och inträngningslängd i sprickigt berg. Medlens reologi är komplex, inklusive tixotropi, men strömningen beskrivs ändå oftast med den enkla linjära Bingham modellen i injekteringssammanhang. De två parametrarna från denna modell, flytgräns och viskositet, används sedan inom injekteringsdesign, för t.ex. tunnlar och dammar, för att bedöma inträngningen. Eftersom cementbaserade medel är tixoptropa suspensioner försvåras utvärderingen vid mätning med konventionella rotationsviskometrar på grund av glidning vid fasta begränsningsytor, sedimentation/separation av partiklarna och instabila flöden vid låga deformationshastigheter. En systematisk mätprocedur för att studera ovanstående problem med rotationsviskometer och koncentriska cylindrar samt olika vanliga vattencementtal, har utförts inom ramen för detta licentiatarbete. Av särskilt intresse har varit att studera effekten av olika geometrier och tidsintervallet mellan mätningarna, inklusive den instabila delen av flödeskurvan då deformationshastigheten är lägre än ett kritiskt värde. Denna del av kurvan har i litteraturen beskrivits som karakteristisk för tixotropa suspensioner, som t.ex. cementbaserade injekteringsmedel. Praktiskt kan ovanstående kunskap användas för att förbättra mätningen av de reologiska egenskaperna. Existensen av en kritisk deformationshastighet under vilken det inte finns något stabilt flöde, i kombination med glidning vid fasta begränsningsytor, diskuteras särskilt med hänsyn till dess påverkan på faktisk inträngning i släta och råa bergsprickor. Ett annat fokus i licentiatarbetet har varit att studera icke-Newtonska modellvätskors (Carbopol) radiella strömning mellan parallella plattor. Denna typ av strömningsgeometri används ofta som en idealiserad konfiguration för strömning i bergsprickor. I jämförelse med andra enklare geometrier, finns endast en begränsad forskning utförd för denna geometri både då det gäller analytiska och numeriska beräkningar men framförallt då det gäller experiment. Som ett första steg inför en mer systematisk undersökning av icke-Newtonsk radiella strömning presenteras i detta arbete framtagandet av en fysisk laboratoriemodell där hastighetsprofilerna mellan plattorna för första gången visualiserats med hjälp av ultraljud. De utförda mätningarna med tre olika öppningar mellan plattorna sam tre olika värden på det konstanta flödet, visar på en distinkt plugg som är ett resultat av vätskans flytgräns samt glidning i gränsskiktet mellan vätskan och plattornas fasta begränsningsytor. En jämförelse mellan uppmätta hastighetsprofiler och analytiskt beräknade diskuteras där resultaten överensstämmer relativt väl, med beaktande av de långtgående förenklade antaganden som krävs för beräkningarna. Fortsatta studier kommer att fokuseras på att förbättra laboratoriemodellen för en mer detaljerad studie av icke-Newtonska vätskors strömning och hur pluggen utvecklas under den radiella inträngningen, vilket fortsättningsvis är av betydelse för design av injektering i bergsprickor.
QC 20190521
46
Budelli, Eliana. "Development of ultrasonic shear wave elastography for rheological properties assessment." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC130.
Full textAbstract:
L’élastographie par ondes de cisaillement consiste essentiellement en deux étapes: d'abord, une onde de cisaillement est générée en appliquant soigneusement une source contrôlée externe (par exemple actionneur mécanique ou force de rayonnement ultrasonore); Alors les déplacements induits sont imagés et l'élasticité tissulaire est déduite de la propagation d'onde de cisaillement mesurée. Cependant, avec les techniques d'élastographie actuellement disponibles, l'estimation quantitative correcte de la viscosité n'est pas possible. Dans ce contexte, le but principal de cette thèse est double: d'abord, développer un outil capable d'estimer simultanément les propriétés viscoélastiques d'un solide souple, notamment en utilisant l'imagerie par cisaillement supersonique, puis de l'appliquer aux certains problèmes rencontrés en médecine et l'industrie alimentaire.La première étape consiste à utiliser la technique SSI pour générer des cartes de vitesses des ondes de cisaillement dans des milieux solides mous et isotropes. Dans ce contexte, cette technique a été utilisée pour évaluer le processus de coagulation du lait. Au cours de cette étape, les limites de la technique SSI pour obtenir une caractérisation rhéologique complète des solides viscoélastiques sont mis en évidence. Pour parvenir à cette caractérisation, la vitesse de propagation ondes de cisaillement et la absorption que l’onde subi en traversant le milieu doivent être évalués à la fois. Compte tenu des caractéristiques de la technique SSI, en raison des effets de diffraction due à la taille finie des sources, l’absorption ne peut pas être obtenue correctement de façon quantitative.La partie centrale de la thèse porte sur l’étude des avantages et des ses limites de la correction des effets de diffraction de la technique SSI à partir d’une approximation cylindrique. Cette étude a été réalisée expérimentalement en comparant les résultats obtenus avec ceux des simulations numériques. L’étude a montré que la correction cylindrique est utile pour estimer l'atténuation provoquée par l'absorption dans certaines conditions. Une fois déterminé la zone de validité de la procédure de correction, des cartes des vitesses et des cartes d'atténuation ont était obtenus. Ces cartes ont permis t la caractérisation rhéologique complète des milieux étudiés.Une fois validé cette correction nous avons procédé à réaliser trois applications d'intérêt pour obtenir les propriétés rhéologiques, une pour l’ industrie alimentaire et deux pour la médecine clinique : a) suivie et étude du processus de coagulation du lait b) suivie et étude de processus de la coagulation du sang in vitro, c) des expériences de caractérisation rhéologique du foie in vivo. Finalement, une étude de la correction cylindrique mis en œuvre a été utilisée pour caractériser rhéologiquement des solides mous avec isotropie transversale. Milieux avec différents degrés d'anisotropie ont été analysés à l'aide de simulations numériques. Les résultats obtenus montrent que pour de faibles niveaux d’anisotropie la correction cylindrique s’avère utile avec une erreur raisonnable. Pour des degrés plus élevés d'anisotropie la correction cylindrique conduit à des erreurs majeures dans l'estimation de l'atténuation. Des mesures des coefficients d’absorption ont été réalisées dans des phantoms de gel anisotropes et dans des échantillons de viande de bœuf avec des tissues musculaireShear wave elastography consists essentially of two steps: first, a shear wave is generated by an external controlled source (eg mechanical actuator or ultrasonic radiation force); then the induced displacements are imaged and the tissue elasticity is deduced from the measured shear wave propagation. However, with the currently available elastographic techniques, a quantitative estimation of viscosity is not possible. In this context, the objective of this thesis is twofold: first, to develop a tool capable of estimating the viscoelastic properties of a soft solid, in particular by using supersonic shear imaging (SSI), and then to apply it to some problems encountered in medicine and the food industry.The first stage consisted in using the SSI technique to generate shear wave velocity maps in soft, isotropic solid media. In this context, this technique was used to evaluate the milk coagulation process. During this stage, limitations of the SSI technique to obtain a complete rheological characterization of viscoelastic solids were demonstrated. To achieve this characterization, the velocity of the shear waves and the absorption generated when passing through the medium must be evaluated at the same time. Given the characteristics of the SSI technique, the absorption cannot be directly quantified due to diffraction.The central part of the thesis focuses in the study of the advantages and limitations of using a cylindrical approximation to correct the diffraction effects. This study was carried out experimentally and through numerical simulations. The study showed that cylindrical correction is useful for estimating the attenuation caused by absorption under certain conditions. After determining the validity zone of the correction, velocity and attenuation maps were obtained. These maps allowed the complete rheological characterization of the studied media.Once the correction was validated, three applications of interest were carried out to obtain rheological properties, one for the food industry and two for clinical medicine: a) monitoring the process of milk coagulation through storage and loss moduli maps b) following in vitro blood coagulation processes, c) rheological characterization experiments of the liver in vivo. Finally, the application of the cylindrical correction to characterize transversely isotropic soft solids was studied. Media with different degrees of anisotropy were analyzed through numerical simulations. The results obtained showed that for low levels of anisotropy the cylindrical correction proves useful within a reasonable error. For higher degrees of anisotropy the cylindrical correction leads to major errors in the estimation of the attenuation. Measurements of the absorption coefficients were performed in anisotropic gel phantoms and in beef samples with muscle tissue
47
Pai, Anand S. "MICRO-RHEOLOGICAL ASSESSMENT OF NEUTROPHIL MECHANICAL PROPERTIES FOLLOWING ADHESION IN A MODEL CAPILLARY." Ohio University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1156386677.
Full text
48
O'Keefe, Samantha Jane. "A study of the rheological properties of polymer modified cement pastes." Thesis, University of the West of England, Bristol, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293326.
Full textAbstract:
The work outlined in this thesis describes how rheological techniques can be used to gain insight into the behaviour of complex hydrating systems. These techniques are currently used to elucidate interparticle interactions of concentrated colloidal dispersions. Those used here were stress relaxation, pulse shearometry and oscillation. These enabled parameters such as the dynamic moduli, relaxation moduli, relaxation spectrum and limiting moduli to be obtained. These all give a measure of the strength of interaction of the colloidal system under different conditions, without reducing these interactions by inducing flow. Calorimetric data was obtained for a hydrating cement paste. The particle and floc size of this cement was also measured. The data were found to be in accord with one another, and with current theories of the hydration processes of cement. In combination with the rheological parameters measured this enabled the extent and strength of attraction between the particles of a cement paste to be determined, as a function of the age of the paste. The adsorption characteristics of surfactant on cement were measured, as was the effect of surfactant on the particle and floc size of hydrating cement. Coupled with a measure of the rheological parameters of the cement-surfactant system, an understanding of the effect of surfactant on a hydrating cement paste was obtained. Similarly the effect of the addition of styrene-butadiene polymer latex particles, with and without excess added surfactant, was able to be determined. This information was obtained for hydrating cement pastes, both in the presence and absence of added polymer, at both ambient and non-ambient temperatures.
49
Brust, Matthias [Verfasser], and Christian [Akademischer Betreuer] Wagner. "Rheological properties of red blood cells / Matthias Brust. Betreuer: Christian Wagner." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2013. http://d-nb.info/1053031017/34.
Full text
50
Al-Assaf, Saphwan. "Rheological properties and free radical stability of cross-linked hyaluronan (Hylan)." Thesis, University of Salford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244875.
Full text