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Sample records for surface rheological properties

  1. Identification of rheological properties of human body surface tissue.

    Science.gov (United States)

    Benevicius, Vincas; Gaidys, Rimvydas; Ostasevicius, Vytautas; Marozas, Vaidotas

    2014-04-11

    According to World Health Organization obesity is one of the greatest public health challenges of the 21st century. It has tripled since the 1980s and the numbers of those affected continue to rise at an alarming rate, especially among children. There are number of devices that act as a prevention measure to boost person's motivation for physical activity and its levels. The placement of these devices is not restricted thus the measurement errors that appear because of the body rheology, clothes, etc. cannot be eliminated. The main objective of this work is to introduce a tool that can be applied directly to process measured accelerations so human body surface tissue induced errors can be reduced. Both the modeling and experimental techniques are proposed to identify body tissue rheological properties and prelate them to body mass index. Multi-level computational model composed from measurement device model and human body surface tissue rheological model is developed. Human body surface tissue induced inaccuracies can increase the magnitude of measured accelerations up to 34% when accelerations of the magnitude of up to 27 m/s(2) are measured. Although the timeframe of those disruptions are short - up to 0.2 s - they still result in increased overall measurement error. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Probing anisotropic surface properties and interaction forces of chrysotile rods by atomic force microscopy and rheology.

    Science.gov (United States)

    Yang, Dingzheng; Xie, Lei; Bobicki, Erin; Xu, Zhenghe; Liu, Qingxia; Zeng, Hongbo

    2014-09-16

    Understanding the surface properties and interactions of nonspherical particles is of both fundamental and practical importance in the rheology of complex fluids in various engineering applications. In this work, natural chrysotile, a phyllosilicate composed of 1:1 stacked silica and brucite layers which coil into cylindrical structure, was chosen as a model rod-shaped particle. The interactions of chrysotile brucite-like basal or bilayered edge planes and a silicon nitride tip were measured using an atomic force microscope (AFM). The force-distance profiles were fitted using the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, which demonstrates anisotropic and pH-dependent surface charge properties of brucite-like basal plane and bilayered edge surface. The points of zero charge (PZC) of the basal and edge planes were estimated to be around pH 10-11 and 6-7, respectively. Rheology measurements of 7 vol % chrysotile (with an aspect ratio of 14.5) in 10 mM NaCl solution showed pH-dependent yield stress with a local maximum around pH 7-9, which falls between the two PZC values of the edge and basal planes of the rod particles. On the basis of the surface potentials of the edge and basal planes obtained from AFM measurements, theoretical analysis of the surface interactions of edge-edge, basal-edge, and basal-basal planes of the chrysotile rods suggests the yield stress maximum observed could be mainly attributed to the basal-edge attractions. Our results indicate that the anisotropic surface properties (e.g., charges) of chrysotile rods play an important role in the particle-particle interaction and rheological behavior, which also provides insight into the basic understanding of the colloidal interactions and rheology of nonspherical particles.

  3. d-α-tocopherol nanoemulsions: Size properties, rheological behavior, surface tension, osmolarity and cytotoxicity

    Directory of Open Access Journals (Sweden)

    M.C. Teixeira

    2017-02-01

    Full Text Available The aim of this study was the assessment of the physicochemical stability of d-α-tocopherol formulated in medium chain triglyceride nanoemulsions, stabilized with Tween®80 and Lipoid®S75 as surfactant and co-surfactant, respectively. d-α-tocopherol was selected as active ingredient because of its well-recognized interesting anti-oxidant properties (such as radical scavenger for food and pharmaceutical industries. A series of nanoemulsions of mean droplet size below 90 nm (polydispersity index < 0.15 have been produced by high-pressure homogenization, and their surface electrical charge (zeta potential, pH, surface tension, osmolarity, and rheological behavior, were characterized as a function of the d-α-tocopherol loading. In vitro studies in Caco-2 cell lines confirmed the safety profile of the developed nanoemulsions with percentage of cell viability above 90% for all formulations.

  4. Comprehensive study of rheological and surface properties of the selected slag system in the context of its internal structure

    OpenAIRE

    Řeháčková, Lenka; Dudek, Rostislav; Rosypalová, Silvie; Matýsek, Dalibor; Dobrovská, Jana

    2016-01-01

    Rheological (dynamic viscosity, flow curves) and surface properties (surface tension) of real slag system were experimentally investigated. Measurements of dynamic viscosity were performed with use of the high-temperature viscometer Anton Paar FRS 1 600. The method of sessile drop was used for measurement of surface tension. Surface tension and dynamic viscosity were measured in the temperature interval from 1 200 to 1 600 °C. The structural characteristics of the selected samples...

  5. Surface rheology and interface stability.

    Energy Technology Data Exchange (ETDEWEB)

    Yaklin, Melissa A.; Cote, Raymond O.; Moffat, Harry K.; Grillet, Anne Mary; Walker, Lynn; Koehler, Timothy P.; Reichert, Matthew D. (Carnegie Mellon University, Pittsburgh, PA); Castaneda, Jaime N.; Mondy, Lisa Ann; Brooks, Carlton, F.

    2010-11-01

    We have developed a mature laboratory at Sandia to measure interfacial rheology, using a combination of home-built, commercially available, and customized commercial tools. An Interfacial Shear Rheometer (KSV ISR-400) was modified and the software improved to increase sensitivity and reliability. Another shear rheometer, a TA Instruments AR-G2, was equipped with a du Nouey ring, bicone geometry, and a double wall ring. These interfacial attachments were compared to each other and to the ISR. The best results with the AR-G2 were obtained with the du Nouey ring. A Micro-Interfacial Rheometer (MIR) was developed in house to obtain the much higher sensitivity given by a smaller probe. However, it was found to be difficult to apply this technique for highly elastic surfaces. Interfaces also exhibit dilatational rheology when the interface changes area, such as occurs when bubbles grow or shrink. To measure this rheological response we developed a Surface Dilatational Rheometer (SDR), in which changes in surface tension with surface area are measured during the oscillation of the volume of a pendant drop or bubble. All instruments were tested with various surfactant solutions to determine the limitations of each. In addition, foaming capability and foam stability were tested and compared with the rheology data. It was found that there was no clear correlation of surface rheology with foaming/defoaming with different types of surfactants, but, within a family of surfactants, rheology could predict the foam stability. Diffusion of surfactants to the interface and the behavior of polyelectrolytes were two subjects studied with the new equipment. Finally, surface rheological terms were added to a finite element Navier-Stokes solver and preliminary testing of the code completed. Recommendations for improved implementation were given. When completed we plan to use the computations to better interpret the experimental data and account for the effects of the underlying bulk

  6. Dilational surface rheology of polymer solutions

    International Nuclear Information System (INIS)

    Noskov, B A; Bykov, A G

    2015-01-01

    The review concerns main achievements in dilational rheology of polymer adsorption films at the gas/liquid interfaces reported in the last fifteen years. The theoretical foundations of methods of surface rheology and the key results obtained in studies of solutions of amphiphilic nonionic polymers, polyelectrolytes, proteins and their complexes with low-molecular-mass surfactants are discussed. Interest in the surface dilational rheology is mainly caused by a small number of available experimental methods for investigation of the surface of liquids, by the fact that traditional methods of measurement of the surface tension that are widely used in studies of solutions of low-molecular-mass surfactants provide little information when applied to polymer solutions owing to very slow establishment of equilibrium as well as by weak dependence of the surface tension on the polymer concentration. Progress in the surface rheology is driven by the recent studies of the stability of foams and emulsions that demonstrated a key role of the dilational surface rheological properties in the dynamics of liquid-phase disperse systems. The bibliography includes 191 references

  7. Rheological properties of soil: a review

    Science.gov (United States)

    Zhu, Guangli; Zhu, Long; Yu, Chao

    2017-05-01

    Recently rheological methods have been applied to investigate the mechanical properties of soil micro-structure. Rheological techniques have a number of quantitative physically based measurements and offer a better understanding of how soil micro-structure behaves when subject to stress. Rheological material is refers to deformation properties similar to the solid and flow properties similar to the liquid of bound water and colloidal substances under stress. Soil rheology is divided into fluid rheology and plasticity rheology. Fluid rheology is produced by rheological material. Plasticity rheology mainly refers to the sliding and peristaltic between soil solid particles under shear stress. It is generally believed that the soft soil rheology mainly belongs to fluid rheology, while the rheology of sand and other coarse grained soil mainly belongs to plasticity rheology. Thus, rheology mechanisms of soft soil and sand are different. This paper introduces the methods of the research progress on the rheology of soil, in the soil rheological mechanism, rheological model and rheological numerical aspects of the research at home and abroad were summarized and analysed, discussed the problems existed in related research, and puts forward some suggestions for the future study on the rheology of soil.

  8. Surface shear rheology of saponin adsorption layers.

    Science.gov (United States)

    Golemanov, Konstantin; Tcholakova, Slavka; Denkov, Nikolai; Pelan, Edward; Stoyanov, Simeon D

    2012-08-21

    Saponins are a wide class of natural surfactants, with molecules containing a rigid hydrophobic group (triterpenoid or steroid), connected via glycoside bonds to hydrophilic oligosaccharide chains. These surfactants are very good foam stabiliziers and emulsifiers, and show a range of nontrivial biological activities. The molecular mechanisms behind these unusual properties are unknown, and, therefore, the saponins have attracted significant research interest in recent years. In our previous study (Stanimirova et al. Langmuir 2011, 27, 12486-12498), we showed that the triterpenoid saponins extracted from Quillaja saponaria plant (Quillaja saponins) formed adsorption layers with unusually high surface dilatational elasticity, 280 ± 30 mN/m. In this Article, we study the shear rheological properties of the adsorption layers of Quillaja saponins. In addition, we study the surface shear rheological properties of Yucca saponins, which are of steroid type. The experimental results show that the adsorption layers of Yucca saponins exhibit purely viscous rheological response, even at the lowest shear stress applied, whereas the adsorption layers of Quillaja saponins behave like a viscoelastic two-dimensional body. For Quillaja saponins, a single master curve describes the data for the viscoelastic creep compliance versus deformation time, up to a certain critical value of the applied shear stress. Above this value, the layer compliance increases, and the adsorption layers eventually transform into viscous ones. The experimental creep-recovery curves for the viscoelastic layers are fitted very well by compound Voigt rheological model. The obtained results are discussed from the viewpoint of the layer structure and the possible molecular mechanisms, governing the rheological response of the saponin adsorption layers.

  9. Rheological Properties of Aqueous Nanometric Alumina Suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chuanping [Iowa State Univ., Ames, IA (United States)

    2004-01-01

    Colloidal processing is an effective and reliable approach in the fabrication of the advanced ceramic products. Successful colloidal processing of fine ceramic powders requires accurate control of the rheological properties. The accurate control relies on the understanding the influences of various colloidal parameters on the rheological properties. Almost all research done on the rheology paid less attention to the interactions of particle and solvent. However, the interactions of the particles are usually built up through the media in which the particles are suspended. Therefore, interactions of the particle with the media, the adsorbed layers on the particle surface, and chemical and physical properties of media themselves must influence the rheology of the suspension, especially for the dense suspensions containing nanosized particles. Relatively little research work has been reported in this area. This thesis addresses the rheological properties of nanometric alumina aqueous suspensions, and paying more attention to the interactions between particle and solvent, which in turn influence the particle-particle interactions. Dense nanometric alumina aqueous suspensions with low viscosity were achieved by environmentally-benign fructose additives. The rheology of nanometric alumina aqueous suspensions and its variation with the particle volume fraction and concentration of fructose were explored by rheometry. The adsorptions of solute (fructose) and solvent (water) on the nanometric alumina particle surfaces were measured and analyzed by TG/DSC, TOC, and NMR techniques. The mobility of water molecules in the suspensions and its variation with particle volume fractions and fructose additive were determined by the 17O NMR relaxation method. The interactions between the nanometric alumina particles in water and fructose solutions were investigated by AFM. The results indicated that a large number of water layers were physically bound on the particles

  10. Rheological properties of olefinic thermoplastic elastomer blends

    NARCIS (Netherlands)

    Sengers, W.G.F.

    2005-01-01

    Thermoplastic Elastomers (TPE) are a class of materials that have rubber-like properties and can be processed like thermoplastic polymers. In this thesis, the rheological properties of two TPE blends are correlated to their morphology. The thermoplastic vulcanisates (TPV) consist of micron-sized,

  11. INVESTIGATION RHEOLOGICAL PROPERTIES OF PVC-BASED

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    S. I. Niftaliev

    2014-01-01

    Full Text Available Summary. Obtained hydrophobic filler compositions based on PVC from calcium carbonate, which is a byproduct in the preparation of mineral nitrogen fertilizers. The methods for pretreatment of the chalk used as a filler in PVC compositions. Conducted modifying the properties of chalk with hydrophobic additives: stearic acid, zinc stearate, calcium stearate. When stearic acid treated chalk heating leads to an interaction with the surface layers of calcium carbonate, a thin film of calcium stearate. Therefore, more cost-effective to create compositions with PVC content of one percent of calcium stearate as its hydrophobic surface is easily wetted by the polymer matrix, which provides rapid mixing of PVC compounds. As a result, the excipient serves as an additional stabilizer, providing higher thermal stability of PVC products, compared with its values for the composition of the compared with the other ingredients. Extrusion processes that are central to the processing of PVC compounds filled by acting them filler, fractional increase heat and accelerate melting and increase output. The rheological properties of polymeric compositions created PVC. A significant reduction in viscosity observed for water repellent based on stearic acid. Study viscosity characteristics for hydrophobic additives showed that their activity increased in the series: zinc stearate, calcium stearate, stearic acid. It was established that modifying additives used in the preparation of hydrophobic carbonate filler PVC compositions exhibit both plasticizers and stabilizing properties.

  12. Rheological properties of disintegrated sewage sludge

    Science.gov (United States)

    Wolski, Paweł

    2017-11-01

    The rheology of the sludge provides information about the capacity and the flow, which in the case of project tasks for the hydraulic conveying installation is an important control parameter. Accurate knowledge of the rheological properties of sludge requires the designation of rheological models. Models single and multiparameter (Ostwald, Bingham, Herschel-Bulkley'a, and others) allow an approximation of flow curves, and the determination of the boundaries of the flow of modified sludge allows you to control the process compaction or are dewatered sludge undergoing flow. The aim of the study was to determine the rheological parameters and rheological models of sludge conditioned by physical methods before and after the process of anaerobic digestion. So far, studies have shown that the application of conditioning in the preparation of sewage sludge increases shear stress, viscosity as well as the limits of flow in relation to the untreated sludge. Offset yield point by the application of a conditioning agent is associated with decreased flowability tested sludge, which has also been observed by analyzing the structure of the prepared samples. Lowering the yield point, and thus the shear stress was recorded as a result of the fermentation test of disintegrated sludge.

  13. Salt effects on the air/solution interfacial properties of PEO-containing copolymers: equilibrium, adsorption kinetics and surface rheological behavior.

    Science.gov (United States)

    Llamas, Sara; Mendoza, Alma J; Guzmán, Eduardo; Ortega, Francisco; Rubio, Ramón G

    2013-06-15

    Lithium cations are known to form complexes with the oxygen atoms of poly(oxyethylene) chains. The effect of Li(+) on the surface properties of three block-copolymers containing poly(oxyethylene) (PEO) have been studied. Two types of copolymers have been studied, a water soluble one of the pluronic family, PEO-b-PPO-b-PEO, PPO being poly(propyleneoxyde), and two water insoluble ones: PEO-b-PS and PEO-b-PS-b-PEO, PS being polystyrene. In the case of the pluronic the adsorption kinetics, the equilibrium surface tension isotherm and the aqueous/air surface rheology have been measured, while for the two insoluble copolymers only the surface pressure and the surface rheology have been studied. In all the cases two different Li(+) concentrations have been used. As in the absence of lithium ions, the adsorption kinetics of pluronic solutions shows two processes, and becomes faster as [Li(+)] increases. The kinetics is not diffusion controlled. For a given pluronic concentration the equilibrium surface pressure increases with [Li(+)], and the isotherms show two surface phase transitions, though less marked than for [Li(+)]=0. A similar behavior was found for the equilibrium isotherms of PEO-b-PS and PEO-b-PS-b-PEO. The surface elasticity of these two copolymers was found to increase with [Li(+)] over the whole surface concentration and frequency ranges studied. A smaller effect was found in the case of the pluronic solutions. The results of the pluronic solutions were modeled using a recent theory that takes into account that the molecules can be adsorbed at the surface in two different states. The theory gives a good fit for the adsorption kinetics and a reasonably good prediction of the equilibrium isotherms for low and intermediate concentrations of pluronic. However, the theory is not able to reproduce the isotherm for [Li(+)]=0. Only a semi-quantitative prediction of the surface elasticity is obtained for [pluronic]≤1×10(-3) mM. Copyright © 2013 Elsevier Inc. All

  14. Comparison of rheological, mechanical, electrical properties of HDPE filled with BaTiO{sub 3} with different polar surface tension

    Energy Technology Data Exchange (ETDEWEB)

    Su, Jun [Department of Polymer Science and Engineering, College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009 (China); College of Mechanics Engineering, Nanjing Institute of Industry Technology, Nanjing, 210023 (China); Zhang, Jun, E-mail: zhangjun@njtech.edu.cn [Department of Polymer Science and Engineering, College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009 (China)

    2016-12-01

    Graphical abstract: - Highlights: • The non-polar and short vinyl groups can greatly reduce G′ of HDPE composites. • Long chains on BaTiO{sub 3} surface enhance the interaction of BaTiO{sub 3} with HDPE. • Polar amino groups on BaTiO{sub 3} surface raise the interaction of BaTiO{sub 3} with HDPE. • Polar amino groups can boost the dielectric constant of HDPE composites. • The potential use in electronic equipment of the KH550 composites is obtained. - Abstract: In this work, three types of coupling agents: isopropyl trioleic titanate (NDZ105), vinyltriethoxysilane (SG-Si151), 3-aminopropyltriethoxysilane (KH550) were applied to modify the surface tension of Barium titanate (BaTiO{sub 3}) particles. The Fourier transform infrared (FT-IR) spectra confirm the chemical adherence of coupling agents to the particle surface. The long hydrocarbon chains in NDZ105 can cover the particle surface and reduce the polar surface tension of BaTiO{sub 3} from 37.53 mJ/m{sup 2} to 7.51 mJ/m{sup 2}, turning it from hydrophilic to oleophilic properties. The short and non-polar vinyl groups in SG-Si151 does not influence the surface tension of BaTiO{sub 3}, but make BaTiO{sub 3} have both hydrophilic and oleophilic properties. The polar amino in KH550 can keep BaTiO{sub 3} still with hydrophilic properties. It is found that SG-Si151 modified BaTiO{sub 3} has the lowest interaction with HDPE matrix, lowering the storage modulus of HDPE composites to the greatest extent. As for mechanical properties, the polar amino groups in KH550 on BaTiO{sub 3} surface can improve the adhesion of BaTiO{sub 3} with HDPE matrix, which increases the elongation at break of HDPE composites to the greatest extent. In terms of electrical properties, the polar amino groups on surface of BaTiO{sub 3} can boost the dielectric properties of HDPE/BaTiO{sub 3} composites and decrease the volume resistivity of HDPE/BaTiO{sub 3} composites. The aim of this study is to investigate how functional groups

  15. Impact of lithospheric rheology on surface topography

    Science.gov (United States)

    Liao, K.; Becker, T. W.

    2017-12-01

    The expression of mantle flow such as due to a buoyant plume as surface topography is a classical problem, yet the role of rheological complexities could benefit from further exploration. Here, we investigate the topographic expressions of mantle flow by means of numerical and analytical approaches. In numerical modeling, both conventional, free-slip and more realistic, stress-free boundary conditions are applied. For purely viscous rheology, a high viscosity lithosphere will lead to slight overestimates of topography for certain settings, which can be understood by effectively modified boundary conditions. Under stress-free conditions, numerical and analytical results show that the magnitude of dynamic topography decreases with increasing lithosphere thickness (L) and viscosity (ηL), as L-1 and ηL-3. The wavelength of dynamic topography increases linearly with L and (ηL/ ηM) 1/3. We also explore the time-dependent interactions of a rising plume with the lithosphere. For a layered lithosphere with a decoupling weak lower crust embedded between stronger upper crust and lithospheric mantle, dynamic topography increases with a thinner and weaker lower crust. The dynamic topography saturates when the decoupling viscosity is 3-4 orders lower than the viscosity of upper crust and lithospheric mantle. We further explore the role of visco-elastic and visco-elasto-plastic rheologies.

  16. Rheological properties of human saliva

    NARCIS (Netherlands)

    Waterman, H.A.; Blom, C.; Holterman, H.J.; 's Gravenmade, E.J.; Mellema, J.

    1988-01-01

    From measurements with a Couette-type viscometer provided with a guard ring it was shown that at the saliva-air interface a protein layer is adsorbed. Measurements of the surface shear modulus of this layer on saliva of 7 healthy subjects were performed at a frequency of about 70 Hz and a

  17. Rheological properties of a nematic cell oriented in a planar manner

    Energy Technology Data Exchange (ETDEWEB)

    Barbero, G., E-mail: giovanni.barbero@polito.i [Dipartimento di Fisica and C. N. I. S. M., Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy)] [Universite de Picardie Jules Verne, Laboratoire de Physique des Systemes Complexes, 33 rue Saint-Leu 80039, Amiens (France); Meyer, C.; Lelidis, I. [Universite de Picardie Jules Verne, Laboratoire de Physique des Systemes Complexes, 33 rue Saint-Leu 80039, Amiens (France)

    2010-05-17

    We propose a simple model to investigate the rheological properties of a nematic cell oriented in a planar manner. The storage and loss modulus are evaluated in the case of strong and weak anchoring conditions. The contribution of the surface viscosity to the rheological parameters is also considered.

  18. Rheological properties of sodium smectite clay

    International Nuclear Information System (INIS)

    Boergesson, L.; Hoekmark, H.; Karnland, O.

    1988-12-01

    The rheological properties of Na-smectite Mx-80 have been investigated by various laboratory tests. The investigations include determination of the hydraulic conductivity, the undrained stress-strain-strength properties, the creep properties, the compression and swelling properties in drained and undrained conditions and the undrained thermomechanical properties. Measurements have been made at different densities, clay/sand mixtures and pore water compositions. The influence of temperature, rate of strain and testing technique has also been considered. The investigation has led to a supply of basic data for the material models which will be used at performance calculations. The results have also increased the general understanding of the function of smectitic clay as buffer material. The microstructural behaviour has been considered at the validation of the different test results and the validity of the effective stress theory has been discussed. Comparisons with the properties of Ca-smectite have also been made. (orig.)

  19. ALTERATION OF RHEOLOGICAL PROPERTIES OF BLOOD AT PATIENTS WITH TONSILLITIS

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    I.A. Zaitseva

    2008-09-01

    Full Text Available Complex research of rheological properties of blood at patients with lacunar tonsillitis lead depending on the period of disease. It is shown, that inflammatory process at patients to a great extent defines disturbances of rheological properties of blood. During normalization of a clinical presentation of disease there is no full recovery of rheological properties of blood due to preservation of blood raised viscosity and low deformability of erythrocytes membranes.

  20. Rheological properties of epoxy/MWCNT suspensions associated with the surface modification of MWCNT by physisorption of aromatic ionic salts

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Yu-Hsun [Institute of Polymer Science and Engineering, National Taiwan University, Taipei 106, Taiwan (China); Lin, King-Fu, E-mail: kflin@ntu.edu.tw [Institute of Polymer Science and Engineering, National Taiwan University, Taipei 106, Taiwan (China); Department of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan (China)

    2016-04-15

    The multi-walled carbon nanotubes (MWCNTs) physisorbed by aromatic ionic salts such as 10-methyl-acridinium iodide (MAcI) were found to well disperse in diglycidyl ether of bisphenol-A epoxy resin. As they were subjected to the rheological study at 30 °C, the gelation of epoxy/MWCNT-MAcI suspension occurred at 0.75 wt% MWCNT-MAcI, which was less than that using pristine MWCNT. As to the viscosity measurements, the dilation effect that the viscosity of epoxy/MWCNT suspension increases with shear rate was found and more pronounced by incorporating MWCNT-MAcI. According to the Thomas-modified Einstein viscosity equation, the dilation effect was attributed to the excess amount of epoxy resin trapping in the aggregated domain of MWCNT. By increasing the shear rate to a certain point, the shear thinning effect that the viscosity decreases with shear rate was also observed. Interestingly, the transition point that the dilation effect changes to shear thinning effect shifted to lower shear rate as the content of MWCNT increased and/or MWCNT-MAcI was incorporated. Notably, better dispersion and less aggregated domains for the suspensions with MWCNT-MAcI compared to pristine MWCNT were further supported by small angle x-ray scattering and transmission electron microscopy. - Highlights: • Dilation effect that viscosity of epoxy/MWCNT suspension increases with shear rate was discovered. • Dilation effect was attributed to the excess epoxy resin trapping in the aggregated domain of MWCNT. • The transition point that the dilation effect changes to shear thinning effect was observed.

  1. The influence of the size and surface modification of TiO2 nanoparticles on the rheological properties of alkyd resin

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    Radoman Tijana

    2013-01-01

    Full Text Available Spherical TiO2 particles of different size were dispersed in alkyd resin based on soybean oil. Four samples of TiO2 particles were used, three commercial and one obtained by acid catalyzed hydrolysis of titanium tetraisopropoxide. The size of the synthesized nanoparticles was determined by transmission electron microscopy. Surface modification of TiO2 nanoparticles was performed with propyl gallate and lauryl gallate. The influence of the size of TiO2 nanoparticles, their concentration and type of the surface modification on the rheological properties of alkyd resin was investigated. The obtained results have shown that the viscosity of the prepared dispersions was higher than viscosity of the pure resin, it increases with decreasing particle diameter and decreases with frequency increase. Surface modified particles showed higher influence on the viscosity of alkyd resin than unmodified, because their hydrodynamic volume is higher due to the presence of the adsorbed gallates, leading to the increase of effective volume fraction of particles in dispersion. For the lowest TiO2 concentration, the viscosity was higher for sample modified with lauryl gallate, due to the higher thickness of the adsorbed layer. The increase of concentration, because of less dispersion stability of the particles modified with propyl gallate, leads to particles agglomeration. The presence of agglomerates, which was confirmed by a change in the slope of the functional dependence of storage modulus on loss modulus, leads to a rapid increase in viscosity. [Projekat Ministarstva nauke Republike Srbije, br. 172062 i br. 45020

  2. Rheological properties of cupuassu and cocoa fats

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    Gioielli, L. A.

    2004-06-01

    Full Text Available Cocoa butter is an important ingredient in chocolate formulation as it dictates the main properties (texture, sensation in the mouth, and gloss. In the food industry, the texture of fat-containing products strongly depends on the macroscopic properties of the fat network formed within the finished product. Cupuassu ( Theobroma grandiflorum , Sterculiaceae is an Amazonian native fruit and the seeds can be used to derive a cocoa butter like product. In general, these fats are similar to those of cocoa, although they are different in some physical properties. The objective of this study was to analyze several properties of the cupuassu fat and cocoa butter (crystal formation at 25 ° C, rheological properties, and fatty acid composition and mixtures between the two fats (rheological properties, in order to understand the behavior of these fats for their use in chocolate products. Fat flow was described using common rheological models ( Newton , Power Law, Casson and Bingham plastic.La manteca de cacao es un ingrediente muy importante en la formulación de chocolates y es responsable de la mayor parte de sus propiedades (textura, palatibilidad y brillo. En la industria de alimentos, la textura de productos que contienen grasa depende enormemente de las propiedades macroscópicas de la red cristalina de la grasa en el producto final. El cupuaçu es una fruta nativa de la región amazónica y sus semillas pueden ser usadas para obtener una grasa semejante a la manteca de cacao. En general, esta grasa es similar a la manteca de cacao, pero difiere en algunas de sus propiedades fisicas . El objetivo de este estudio fue analizar algunas propiedades de la grasa de cupuaçu y de la manteca de cacao (formación de cristales a 25 °C, propiedades reológicas y composición en ácidos grasos y de algunas mezclas entre las dos grasas (propiedades reológicas, a fin de conocer el comportamiento de estas grasas para ser usadas en productos de la industria

  3. Simple Rheological Analysis Method of Spinnable-Polymer Flow Properties Using MFI Tester

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    Basel Younes

    2015-01-01

    Full Text Available Rheological characterization of polymers explains the flow behaviour and viscoelastic properties and tests fibre-forming ability. The current method investigates the viscoelastic properties and morphology of polymers and finds the rheological data and the right polymer viscosity, which is determining the best processing temperature. The right processing temperature saves the power, the material, and the time needed for production. After calculating polymers viscosity by using MFI tester, the method investigates rheological properties and surface shape at different temperatures and loads. The method could apply to other polymers to find the viscosity-temperature change and to set the best processing temperature.

  4. INVESTIGATION OF RHEOLOGICAL PROPERTIES OF MODIFIED BITUMEN

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    Erofeev Vladimir Trofimovich

    2016-08-01

    Full Text Available At the present time the most widely used type of road pavement is asphalt-concrete pavement produced on the basis of oil bitumen. One of the efficient ways to increase the quality and durability of asphalt-concrete pavement is modification of bitumen. Though Russian specialists still don’t have the global view of the ideal and real asphalt cement, the requirements to its quality and durability indicators in the composition of road structure haven’t yet formed. The authors present the investigation results of the properties of oil asphalt cement containing 0.5-2.0% of modifier “Olazol”. The physical, mechanical and rheological properties of the modified bitumen are determined. The dependences of the dynamic viscosity of the modified bitumen from the quantity of introduced modifier, shear rate and reheat temperature are analyzed.

  5. Rheological and microstructural properties of Irradiated starch

    International Nuclear Information System (INIS)

    Atrous Turki, Hager

    2011-01-01

    Gamma irradiation ia s fast and efficient method to improve the functional properties of straches. Wheat and potato starches were submitted, in the present study, at 3,5,10 and 20 kGy radiation dose. The changes induced by irradiation on the rheological properties of these starches showed a decrease in the viscosity with increasing radiation dose. Chemicals bond's hydrolysis has been induced by free radicals that have been identified by EPR. Wheat starch presents five EPR signals after irradiation, whiles potato starch has a weak EPR signal. On the other hand, irradiation caused decrease in amylose content. This decrease is more pronounced in potato starch. Dry irradiated starch's MEB revealed no change in the shape, size and distribution of the granules. While, the observation of wheat starch allowed the complete disappearance of the granular structure and the dissolution of its macromolecules after irradiation which justifies the significant decrease in wheat starch's viscosity irradiated at 20 kGy.

  6. The Bioadhesive and Rheological properties of some fluconazole gels

    African Journals Online (AJOL)

    An oscillatory rheological technique was employed using a parallel plate viscometer to determine the rheological properties of the formulations. Two dyes, erythrosine and amaranth were added to elucidate diffusional processes occurring during mucociliary transport of the gels. The results obtained indicate that high ...

  7. Rheological properties of boehmite sols during ageing at room ...

    Indian Academy of Sciences (India)

    Keywords. Boehmite sol; rheology; shear thinning; yield stress; viscoelasticity; gel point. Abstract. Boehmite sols were obtained by peptizing boehmite precipitates with glacial acetic acid. The sols were aged at room temperature (30 ± 1°C) under closed condition. Rheological properties of the sols were studied at different ...

  8. Bioactive and rheological properties of rose hip marmalade

    OpenAIRE

    Sagdic, Osman; Toker, Omer Said; Polat, Busra; Arici, Muhammet; Yilmaz, Mustafa Tahsin

    2015-01-01

    In this study, bioactive (total phenolic, antioxidant and antiradical activity) and rheological properties (steady and dynamic) of rose hip marmalade were investigated. Bioactive properties were determined in rose hip marmalade and extract. Extract had higher total phenolic content (38.5 mg GAE/g dry extract), antioxidant activity (124 mg AAE/g dry extract) and antiradical activity (49.98 %) than marmalade. Steady and dynamic rheological properties of the marmalade were determined at differen...

  9. Biodegradable compounds: Rheological, mechanical and thermal properties

    Science.gov (United States)

    Nobile, Maria Rossella; Lucia, G.; Santella, M.; Malinconico, M.; Cerruti, P.; Pantani, R.

    2015-12-01

    Recently great attention from industry has been focused on biodegradable polyesters derived from renewable resources. In particular, PLA has attracted great interest due to its high strength and high modulus and a good biocompatibility, however its brittleness and low heat distortion temperature (HDT) restrict its wide application. On the other hand, Poly(butylene succinate) (PBS) is a biodegradable polymer with a low tensile modulus but characterized by a high flexibility, excellent impact strength, good thermal and chemical resistance. In this work the two aliphatic biodegradable polyesters PBS and PLA were selected with the aim to obtain a biodegradable material for the industry of plastic cups and plates. PBS was also blended with a thermoplastic starch. Talc was also added to the compounds because of its low cost and its effectiveness in increasing the modulus and the HDT of polymers. The compounds were obtained by melt compounding in a single screw extruder and the rheological, mechanical and thermal properties were investigated. The properties of the two compounds were compared and it was found that the values of the tensile modulus and elongation at break measured for the PBS/PLA/Talc compound make it interesting for the production of disposable plates and cups. In terms of thermal resistance the compounds have HDTs high enough to contain hot food or beverages. The PLA/PBS/Talc compound can be, then, considered as biodegradable substitute for polystyrene for the production of disposable plates and cups for hot food and beverages.

  10. THERMOPHYSICAL AND RHEOLOGIC PROPERTIES OF BIOOIL SAMPLES

    Directory of Open Access Journals (Sweden)

    Monika Bozikova

    2013-09-01

    Full Text Available This article deals with thermal properties of selected biooils Plahyd S biooil No1 and Plahyd N biooil No2 and rheologic properties of rapeseed oil. Plahyd S is a synthetic, rapidly biodegradable fluid which is based on sustainable raw materials. It is exceptionally suitable for applications in mobile and stationary hydraulic systems. Plahyd N is multigrade hydraulic oil based on rapeseed oil used in agricultural and construction machinery. For thermal parameters measurements was used Hot wire method. The experiment is based on measuring of the temperature rise vs. time evaluation of an electrically heated wire embedded in the tested material. The thermal conductivity is derived from the resulting change in temperature over a known time interval. Dependency of material resistance against the probe rotation was used at measurement of rheologic properties with instrument viscometer Anton Paar DV 3P. For two samples of biooils Plahyd N and Plahyd S were determined basic thermophysical parameters thermal conductivity, thermal diffusivity and volume specific heat. For each biooil samples were made two series of measurements. In the first series were measured thermal conductivity and thermal diffusivity at constant room temperature 20 C. Every thermophysical parameter was measured 10 times for each sample. The results were statistically processed. For biooil No1 thermal conductivity was 0.325 W*m 1 .K1 , it was higher value than we obtained for biooil No2 0.224 W*m 1 .K 1 . The similar results were obtained for thermal diffusivity of biooil No1 2.140.10 7 m 2 *s 1 and biooil No2 2.604.10 7 m 2* s 1 . For samples with constant temperature were calculated basic statistical characteristics as standard deviation for biooil No1 0.056 W*m 1*K 1 and biooil No2 0.054 W*m 1*K 1; probable error of the arithmetic average for biooil No 1 0.012 W*m 1*K 1 and biooil No 2 0.005 W*m 1*K 1, relative probable error in for biooil No1 3.69 per cent and biooil No2 2

  11. Surface nucleation in complex rheological systems

    Science.gov (United States)

    Herfurth, J.; Ulrich, J.

    2017-07-01

    Forced nucleation induced by suitable foreign seeds is an important tool to control the production of defined crystalline products. The quality of a surface provided by seed materials represents an important variable in the production of crystallizing layers that means for the nucleation process. Parameters like shape and surface structure, size and size distribution of the seed particles as well as the ability to hold up the moisture (the solvent), can have an influence on the nucleation process of different viscous supersaturated solutions. Here the properties of different starch powders as seeds obtained from corn, potato, rice, tapioca and wheat were tested. It could be found, that the best nucleation behavior of a sugar solution could be reached with the use of corn starch as seed material. Here the surface of the crystallized sugar layer is smooth, crystallization time is short (<3 h) and the shape of the product is easily reproducible. Beneficial properties of seed materials are therefore an edged, uneven surface, small particle sizes as well as low moisture content at ambient conditions within the seed materials.

  12. Effect of ?-cyclodextrin on Rheological Properties of some Viscosity Modifiers

    OpenAIRE

    Rao, G. Chandra Sekhara; Ramadevi, K.; Sirisha, K.

    2014-01-01

    Cyclodextrins are a group of novel excipients, extensively used in the present pharmaceutical industry. Sometimes they show significant interactions with other conventional additives used in the formulation of dosage forms. The effect of β-cyclodextrin on the rheological properties of aqueous solutions of some selected viscosity modifiers was studied in the present work. β-cyclodextrin showed two different types of effects on the rheology of the selected polymers. In case of natural polymers ...

  13. Rheological and textural properties of cosmetic emulsions

    Czech Academy of Sciences Publication Activity Database

    Morávková, Tereza; Štern, Petr

    2011-01-01

    Roč. 21, č. 3 (2011), č. článku 35200. ISSN 1430-6395 Institutional research plan: CEZ:AV0Z20600510 Keywords : cosmetic emulsions * rheology * texture * sensory analysis * psychorheology Subject RIV: BK - Fluid Dynamics Impact factor: 1.000, year: 2011

  14. Investigations of Physical and Rheological Properties of Aged Rubberised Bitumen

    Directory of Open Access Journals (Sweden)

    Asim Hassan Ali

    2013-01-01

    Full Text Available Several road pavement distresses are related to rheological bitumen properties. Rutting and fatigue cracking are the major distresses that lead to permanent failures in pavement construction. Influence of crumb rubber modifier (CRM on rheological properties of bitumen binder such as improvement of high and intermediate temperatures is investigated in the binder’s fatigue and rutting resistance through physical-rheological changes in this research. The bitumen binders were aged by rolling thin film oven (RTFOT to simulate short-term aging and pressure aging vessel (PAV to simulate long-term aging. The effects of aging on the rheological and physical properties of bitumen binders were studied conducting dynamic shear rheometer test (DSR, Brookfield viscometer test, softening point test, and penetration test. The results showed that the use of rubberised bitumen binder reduces the aging effect on physical and rheological properties of the bitumen binder as illustrated through lower aging index of viscosity, lower aging index of , and an increase in with crumb rubber modifier content increasing, indicating that the crumb rubber might improve the aging resistance of rubberised bitumen binder. In addition, the results showed that the softening point increment ( and penetration aging ratio (PAR of the rubberised bitumen binder decreased significantly due to crumb rubber modification. Furthermore, the higher crumb rubber content, the lower after PAV aging, which led to higher resistance to fatigue cracking bitumen.

  15. Rheological properties of soybean protein isolate gels containing emulsion droplets

    NARCIS (Netherlands)

    Kim, K.H.; Renkema, J.M.S.; Vliet, van T.

    2001-01-01

    Rheological properties of soybean protein gels containing various volume fractions oil droplets have been studied at small and large deformations. Dynamic viscoelastic properties of soybean protein isolate gels were determined as a function of the volume fraction of oil droplets stabilised by the

  16. Changes in Rheological Properties and Heavy Metal Content of an ...

    African Journals Online (AJOL)

    Prof. Ogunji

    Results also showed significantly (p=0.05) higher maize height and yield in ash amended plots relative to the control. Ash application is recommended since it improves soil properties and increase maize yield. Keywords: Ash, rheological properties, heavy metal, maize yield. Correspondence: cnmbah10@yahoo.com.

  17. Research on rheological properties of micro-fine grouting cement

    Energy Technology Data Exchange (ETDEWEB)

    Guan, X.; Wang, Y.; Yang, L. [Jiaozuo Institute of Technology, Jiaozuo (China). Dept. of Resource and Material Engineering

    2003-06-01

    This article studies the influence of the fineness of cement, fly ash (FA), its composite admixture and the amount and method by which they are mixed with superplasticizer on the rheological properties of micro-fine cement. By means of modern instruments and technologies (such as XRDF, SEM, laser granulometer and superficial-potential apparatus etc.), the article studies the mineral compositions, the appearance character of the grains, particle size distribution and superficial potential of FA and its composite materials. The reducing mechanism of FA is thoroughly analysed. The study shows that FA and its composite admixture are excellent components which can effectively improve the rheological properties of micro-fine cement, and that the superplasticizer has a saturation point and the mixing method has a great influence on the rheological properties. 8 refs., 7 figs., 6 tabs.

  18. Comparison of Rheological Properties of Hopped Wort and Malt Wort

    Directory of Open Access Journals (Sweden)

    Petr Trávníček

    2015-01-01

    Full Text Available The aim of this work is determination rheological properties of hopped wort and malt wort and their comparison. In the paper following rheological properties has been described: the dependence of viscosity on a temperature of a sample and hysteresis loop test. The time dependence test was performed for a confirmation thixotropic behaviour. Based on measured values Arrhenius mathematical model has been applied. The activation energy was determined by using of this model. Tests have been carried out in the temperature range from 5 °C to 40 °C. Rheological tests proved that malt wort behaves as Newtonian fluid in all temperatures and hopped wort behaves as non-Newtonian fluid at low temperatures. Thixotropic behaviour is caused by the content of the rests of hops heads or malt scraps.

  19. Comparison of rheological properties of varietal grape seed oils

    Directory of Open Access Journals (Sweden)

    Patrik Burg

    2018-02-01

    Full Text Available The aim of this work was to determine the rheological properties of grape seed oils from different varieties selected at different temperatures. Measurement of the rheological properties of grape seed oils was performed on the instrument Anton Paar MCR 102. The rheological properties of the liquid have been performed at temperatures of 0 °C, 15 °C, 30 °C, 45 °C and 60 °C. The density of measured samples ranged from 0.905 ±0.002 to 0.948 ±0.002 g.mL-1. Subsequently, there were determined viscosity values at a shear rate of 5 s-1. As expected, the viscosity decreased with increasing temperature. Highest viscosity values reached grape seed oil of variety Pinot gris where at 0 °C the viscosity reached 0.206 ±0.037 Pa s. Samples measured at 0 °C showed non-Newtonian behavior, while at higher temperatures liquids behave as Newtonian substances. All grape seed oils samples exhibit non-Newtonian behavior at lower temperatures. In experiments carried out at 0 °C, it was observed that the tested samples tends to behave as shear-thinning system with thixotropic properties. At higher temperatures was, in line with other scientific works, observed that samples behave as Newtonian fluids. Knowledge of the rheological properties of oils are very important for their processing, storage, and may affect their quality.

  20. Rheological properties of nanocrystalline cellulose suspensions.

    Science.gov (United States)

    Chen, Yang; Xu, Chunjiang; Huang, Jing; Wu, Defeng; Lv, Qiaolian

    2017-02-10

    Rheological behavior, including linear and nonlinear, as well as transient rheology of nanocrystalline cellulose (NCC) suspensions was studied in this work. Two kinds of polymer solutions, aqueous poly(vinyl alcohol) (PVA) with flexible chain structure and aqueous carboxymethyl cellulose (CMC) with semi-rigid chain structure, were used as the suspension media to further explore the role that the interactions among NCC and polymers played during shear flow. The results reveal that NCC has lower values of percolation threshold in the PVA solution than in the CMC one during small amplitude oscillatory shear (SAOS) flow because the flexible PVA chain has higher adsorbed level onto NCC particles than the negatively charged semi-rigid CMC chain, which is further confirmed by the Fourier transformed infrared (FT-IR) spectroscopy tests. As a result, the NCC suspension shows a weak strain overshoot in PVA solution during large amplitude oscillatory shear (LAOS) flow, which cannot be seen on the one in CMC solution. During startup shear flow, both of these two suspensions show evident stress overshoot behavior with the strain-scaling characteristics, indicating the formation of ordered long-term structure of rod-like NCC particles with self-similarity during flow. However, NCC suspension have far stronger stress overshoot response in CMC solution relative to the one in PVA solution. A possible synergy mechanism between NCC and CMC chain is hence proposed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Rheological properties of boehmite sols during ageing at room ...

    Indian Academy of Sciences (India)

    Boehmite sols were obtained by peptizing boehmite precipitates with glacial acetic acid. The sols were aged at room temperature (30 ± 1°C) under closed condition. Rheological properties of the sols were studied at different ageing times. The sol characteristics were interpreted by measuring their viscosity, areas of ...

  2. Rheological properties of Danwake flour blends from sorghum ...

    African Journals Online (AJOL)

    The rheological properties of seven danwake flour blend formulations from sorghum, wheat and cassava bases were investigated. The different ingredients in the danwake were sorghum flour, cowpea flour, wheat flour, cassava flour, baobab leaf powder, and trona (sodium sesquicarbonate) (kanwa). The viscosity of the ...

  3. Effects of iron supply on the rheological properties and sensory ...

    African Journals Online (AJOL)

    The most basic is the world wheat crops. In Iran Bread is a staple food staple Food and because, as a bearer of good food to enrich bread with iron has been considered. The effect of flour fortification star with iron, folic acid, the chemical properties (dry gluten, wet gluten, gluten-free number, protein and Ddzlny) Rheological ...

  4. Bitumen and heavy oil rheological properties: reconciliation with viscosity measurements

    Czech Academy of Sciences Publication Activity Database

    Bazyleva, A.B.; Hasan, M.D.A.; Fulem, Michal; Becerra, M.; Shaw, J.M.

    2010-01-01

    Roč. 55, č. 3 (2010), s. 1389-1397 ISSN 0021-9568 Institutional research plan: CEZ:AV0Z10100521 Keywords : Athabasca bitumen * Maya crude oil * rheological properties * viscosity measurements Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.089, year: 2010

  5. Shear rheological properties of fresh human faeces with different ...

    African Journals Online (AJOL)

    2014-03-11

    Mar 11, 2014 ... Short communication. Shear rheological properties of fresh human faeces with different moisture content. SM Woolley1, RS Cottingham1, J Pocock1 and CA Buckley1*. 1Pollution Research Group, School of Engineering, University of KwaZulu-Natal, King George V Avenue, Berea 4041, South Africa.

  6. Rheological properties of cementitious materials containing mineral admixtures

    Energy Technology Data Exchange (ETDEWEB)

    C.K. Park; M.H. Noh; T.H. Park [Korea Institute of Industrial Technology, Cheonan (Republic of Korea)

    2005-05-01

    The rheological properties of cementitious materials containing fine particles, such as mineral admixtures (MA), were investigated using a Rotovisco RT 20 rheometer (Haake) with a cylindrical spindle. The mineral admixtures were finely ground blast furnace slag, fly ash and silica fume. The cementitious materials were designed as one, two and three components systems by replacement of ordinary Portland cement (OPC) with these mineral admixtures. The rheological properties of one-component system (OPC) were improved with increasing the dosage of PNS-based superplasticizer. For two-components systems, yield stress and plastic viscosity decreased with replacing OPC with blast furnace slag (BFS) and fly ash (FA). In the case of OPC-silica fume (SF) system, yield stress and plastic viscosity steeply increased with increasing SF. For three components systems, both OPC-BFS-SF and OPC-FA-SF systems, the rheological properties improved, compared with the sample with SF. In the two and three components systems, the rheological properties of samples containing BFS improved much more than with FA replacement alone.

  7. Effect of solution physical chemistry on the rheological properties of ...

    African Journals Online (AJOL)

    Knowledge on rheological properties of sludge is important for the design of pumping and transport facilities and as a tool in process control during treatment. Concentrated activated sludge is known to behave as a non-Newtonian material. The contribution to non- Newtonian behaviour is believed to originate from the ...

  8. Rheological properties of agar and carrageenan from Ghanaian red seaweeds

    DEFF Research Database (Denmark)

    Rhein-Knudsen, Nanna; Ale, Marcel Tutor; Ajalloueian, Fatemeh

    2017-01-01

    Red seaweeds contain unique galactose-rich hydrocolloids, carrageenans and agar, which find use as gelling agents in high value applications. This study examined the chemical and rheological properties of hydrocolloids from selected wild red seaweed species collected in Ghana: Hypnea musciformis ...

  9. Pasting and rheological properties of quinoa-oat composites

    Science.gov (United States)

    Quinoa (Chenopodium, quinoa) flour, known for its essential amino acids, was composited with oat products containing ß-glucan known for lowering blood cholesterol and preventing heart disease. Quinoa-oat composites were developed and evaluated for their pasting and rheological properties by a Rapid ...

  10. The rheological and fracture properties of Gouda cheese

    NARCIS (Netherlands)

    Luyten, H.

    1988-01-01

    The rheological and fracture behaviour of Gouda cheese was studied. Methods for determining these properties of visco-elastic materials are described. Application of the theory of fracture mechanics, after modification and expansion, to visco-elastic materials with a

  11. Rheological properties of crumb rubber modified bitumen containing antioxidant

    International Nuclear Information System (INIS)

    Mohamed, A. A; Omar, Husaini; Hamzah, M.O; Ismail, H.

    2009-01-01

    Rheology has become a useful tool in the characterization of the bitumen performance on the pavement. Visco-elastic properties of crumb rubber modified bitumen with antioxidants (CR30) were determined by the means of rheological measurement. This measurement led to a better knowledge of bitumen behavior that occurs when subjected to different thermal and mechanical conditions, as seen during road construction and services in the field. Dynamic Shear Rheometer (DSR) was used to characterize the rheology of the binders before and after oven aging. The binders were aged for 3 and 9 days. Results of a compatibility test showed that the addition of CR30 modified bitumen is compatible with the base bitumen. The results of unaged samples indicated that the addition of 1% CR30 and 5% CR30 modified binders caused an increase in G value as a result of the rheological changes. Results showed that aging has significant influence on bitumen rheology, by increasing complex modulus and decreasing phase angle. (author)

  12. Rheological properties of whey proteins concentrate before and

    Directory of Open Access Journals (Sweden)

    Zoran Herceg

    2001-04-01

    Full Text Available Hydrocolloids are long-chain polymers, used in food production at small quantities (from 0,05 to 5 % to achieve appropriate rheological properties, prevent syneresis, increase the viscosity and stability of foodstuffs and for crystallization process control. The aim of this work was to investigate the influence of tribomechanical micronization of powdered whey protein concentrate on the rheological properties of whey proteins model systems as well as the influence of severalcarboxymethylcellulose hydrocolloids addition in such systems.Measurements were done using rotational viscosimeter, Brookfield DV-III at temperature 20 oC. The rheological parameters were determined by powerlaw model. The results of investigation have shown that all investigated systems are non-Newtonian. Depending on the pretreatment of whey proteins and the mass fractions of hydrocolloids they exhibited pseudoplastic or dilatant properties.Particle size analysis was performed using Fritsch – laser particle sizer “analysette 22”. The operation of tribomechanical micronization caused the decreasing of particle size and incrasing specific area of whey proteins. Tribomechanical treatment of whey proteins had significant influence on the rheological parameters and the type of flowing.

  13. Rheology of Prepreg and Properties of Silica/bismaleimide Matrix Copper Clad Laminate

    Directory of Open Access Journals (Sweden)

    DAI Shankai

    2017-08-01

    Full Text Available The effects of the silica surface treated by coupling agents KH550, KH560 and KH570 on the rheological properties of bismaleimide (BMI resin system were investigated. The rigidity, coefficient of thermal expansion (CTE and thermal stability of the copper clad laminate (CCL were studied by DMA, TMA and TGA. The resin system containing silica surface treated by KH-560, comparing to KH550, KH570 and without surface treatment resin system has better rheological properties and low melt viscosity. The comprehensive properties of the copper clad laminate can be effectively improved by the introduction of silica in the resin system, exhibiting higher storage modulus and lower CTE compare to no silica in the CCL. When the silica mass fraction is 50%, the storage modulus is increased by 83% at 50℃, and the CTE below the glass transition temperature is decreased by 153%.

  14. Study on the effect of polymeric rheology modifier on the rheological properties of oil-based drilling fluids

    Science.gov (United States)

    Ma, C.; Li, L.; Yang, Y. P.; Hao, W. W.; Zhang, Q.; Lv, J.

    2018-01-01

    A new type of polymeric rheology modifier was synthesized by suspension polymerization, and the effect of rheology modifier on the rheological properties of oil-based drilling fluids was investigated. The results indicated that the obtained polymer had good capacity of improvement of shearing force of oil-based drilling fluids under high temperature and high pressure conditions. Moreover, the obtained polymer can improve the stability of oil-based drilling fluids greatly. As a result, the obtained polymer is a good rheology modifier for oil-based drilling fluids, and it can optimize oil-based drilling fluid system with good rheological properties, good static suspension ability for cuttings and environmental protection function. It can play an essential role in safe drilling jobs and improvement of drilling efficiency.

  15. An acidic heteropolysaccharide from Mesona chinensis: Rheological properties, gelling behavior and texture characteristics.

    Science.gov (United States)

    Lin, Lihua; Shen, Mingyue; Liu, Suchen; Tang, Wei; Wang, Zhijun; Xie, Mingyong; Xie, Jianhua

    2018-02-01

    Polysaccharide from Mesona chinensis is becoming increasingly attractive focus because of its gelling property and biological activities. In this study, the rheological properties of an acidic heteropolysaccharide from Mesona chinensis (MCP) were investigated in dilute and semidilute solutions. Dynamic rheology was systematically conducted to investigate the effects of concentration, temperature, pH values, salts and freeze-thaw variations on the rheological properties of MCP. Results showed that the rheological properties of MCP exhibited pseudoplastic characteristic and "gel-like" behavior by the flow behavior detection. A closed hysteresis loop was formed when the MCP concentration reached 4%, and the Gel was generated when the MCP concentration reached 5%. The storage modulu (G') and loss modulu (G″) of MCP solution were increased with increasing oscillation frequency at concentration of 4% and 5%. The phase angel (tanδ) was less than 1, indicating MCP was a weak gel in linear viscoelastic region. The gel exhibited favourable textural properties when MCP at concentration 5%. The scanning electron microscope (SEM) verified MCP had a unique lotus leaf-like shape with some small irregular round-like rods surface morphology. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Rheological Properties of Calcium Hydroxylapatite With Integral Lidocaine.

    Science.gov (United States)

    Meland, Melissa; Groppi, Chris; Lorenc, Z Paul

    2016-09-01

    Calcium hydroxylapatite with integral lidocaine, CaHA (+), received FDA approval in 2015 and CE mark approval in 2016. This formulation has been associated with significant pain reduction compared to CaHA. In a previous rheometry study, CaHA without lidocaine demonstrated higher viscosity and elasticity when compared with hyaluronic acid fillers. To compare the rheological properties of CaHA (+) lidocaine to CaHA without lidocaine and to compare the rheological measures of CaHA (+) to 5 cross-linked hyaluronic acid (HA) fillers with integral 0.3% lidocaine. The rheological properties of complex viscosity (η*) and elastic modulus (G') were measured for 2 types of CaHA fillers [CaHA without lidocaine and CaHA (+) with integral 0.3% lidocaine] and 5 HA fillers using an oscillation frequency sweep at a sheer stress of 5 pascal tau (Pa) and an interpolation of 0.7 Hz. CaHA with and without integral lidocaine demonstrate similar η* and G' measurements. CaHA with and without integral lidocaine demonstrates higher η* and G' compared with HA fillers with integral lidocaine. CaHA with integral lidocaine has a similar rheological profile to CaHA without lidocaine: the highest η* and G' compared with available HA fillers with integral lidocaine. J Drugs Dermatol. 2016;15(9):1107-1110.

  17. Rheological properties of kaolin and chemically simulated waste

    International Nuclear Information System (INIS)

    Selby, C.L.

    1981-12-01

    The Savannah River Laboratory is conducting tests to determine the best operating conditions of pumps used to transfer insoluble radioactive sludges from old to new waste tanks. Because it is not feasible to conduct these tests with real or chemically simulated sludges, kaolin clay is being used as a stand-in for the solid waste. The rheology tests described herein were conducted to determine whether the properties of kaolin were sufficiently similar to those of real sludge to permit meaningful pump tests. The rheology study showed that kaolin can be substituted for real waste to accurately determine pump performance. Once adequately sheared, kaolin properties were found to remain constant. Test results determined that kaolin should not be allowed to settle more than two weeks between pump tests. Water or supernate from the waste tanks can be used to dilute sludge on an equal volume basis because they identically affect the rheological properties of sludge. It was further found that the fluid properties of kaolin and waste are insensitive to temperature

  18. Rheological properties of polysaccharides from Dioscorea opposita Thunb.

    Science.gov (United States)

    Ma, Fanyi; Zhang, Yun; Liu, Nanhua; Zhang, Jie; Tan, Gaixiu; Kannan, Balan; Liu, Xiuhua; Bell, Alan E

    2017-07-15

    This study investigated the chemical components and rheological properties of polysaccharides from Dioscorea opposita Thunb. Graded alcohol precipitation was used to extract Dioscorea opposita polysaccharide samples (S1, S2, S3 and S4). The monosaccharides, amino acid content and molecular weight of each sample were measured and compared. The rheological properties of the polysaccharide samples at different concentrations, temperatures and pH values were studied. The rheological properties of S1, S2 and S3 exhibited pseudoplastic properties and "gel-like" behaviour. The viscosity of S1 was improved with rising temperatures, especially temperatures higher than 80°C, which may be caused by the starch gelatinisation. The acidic and basic environments may break the structures of S3 and S4. However, the extreme conditions improved the viscosity of S1. This work was a basic investigation of the Dioscorea opposita polysaccharides, contributing to the function of yam products and applications of natural thickeners in the food industry. Copyright © 2017. Published by Elsevier Ltd.

  19. Evaluating the Rheological Properties of Waste Natural Rubber Latex Modified Binder

    Science.gov (United States)

    Khatijah Abu Bakar, Siti; Ezree Abdulah, Mohd; Mustafa Kamal, Mazlina; Rahman, Raha Abd; Arifin Hadithon, Kamarul; Buhari, Rosnawati; Tajudin, Saiful Azhar Ahmad

    2018-03-01

    Road surface is designed to be the durable surface material to sustain the traffic loading. However, due to physical and mechanical stress, pavement deterioration is accelerated. Thus, modifying conventional bitumen by improving its properties is seen as the best method to prolong pavement in-service life. The purpose of this paper is to study the effect of waste natural rubber (NR) latex on rheological properties of bitumen. Conventional bitumen PEN 80/100 was modified with different content of waste NR latex using a high shear mixer at temperature of 150°C. The modified binder properties were characterized by conducting physical test (i.e. softening point, penetration and penetration index) and rheological test (i.e. dynamic shear rheometer, DSR). Results showed that, the addition of waste NR latex improved the rheology properties, which indicates by improving of rutting factor (G*/sin δ). This properties improvement has also shows a potential to resist deformation on road surface despite of high traffic loading.

  20. Evaluating the Rheological Properties of Waste Natural Rubber Latex Modified Binder

    Directory of Open Access Journals (Sweden)

    Abu Bakar Siti Khatijah

    2018-01-01

    Full Text Available Road surface is designed to be the durable surface material to sustain the traffic loading. However, due to physical and mechanical stress, pavement deterioration is accelerated. Thus, modifying conventional bitumen by improving its properties is seen as the best method to prolong pavement in-service life. The purpose of this paper is to study the effect of waste natural rubber (NR latex on rheological properties of bitumen. Conventional bitumen PEN 80/100 was modified with different content of waste NR latex using a high shear mixer at temperature of 150°C. The modified binder properties were characterized by conducting physical test (i.e. softening point, penetration and penetration index and rheological test (i.e. dynamic shear rheometer, DSR. Results showed that, the addition of waste NR latex improved the rheology properties, which indicates by improving of rutting factor (G*/sin δ. This properties improvement has also shows a potential to resist deformation on road surface despite of high traffic loading.

  1. Rheological and thermal properties of PP-based WPC

    Science.gov (United States)

    Mazzanti, V.; Mollica, F.; El Kissi, N.

    2014-05-01

    Wood Plastic Composite (WPC) has attracted great interest in outdoor building products for the reduced cost and the possibility of using recycled materials. Nevertheless the material shows two problems: the large viscosity due to the presence of high concentrations of filler and the degradation of cellulose during processing The aim of this work was to investigate the rheological and thermal properties of WPC. The material used for the experiments was a commercial PP-based WPC compound, with different concentrations of natural fibers (30, 50, 70% wt.). The thermal properties were studied to check for degradation of natural fibers during the subsequent rheological tests. Analyzing the storage and loss moduli and the complex viscosity curves obtained using a parallel plate rheometer it was possible to observe some features related to the viscoelastic nature of the composite.

  2. Influence of polymer fibers on rheological properties of cement mortars

    Directory of Open Access Journals (Sweden)

    Malaszkiewicz Dorota

    2017-10-01

    Full Text Available The reinforcing effect of fibers in cement composites often results in the improvement of the brittle nature of cementitious materials. But the decrease in the workability of fresh concrete is often the disadvantage of fibers addition. Conventional single-point workability tests cannot characterize workability of concrete in terms of fundamental rheological parameters. To this end, this paper describes an investigation of the influence of synthetic fiber additions (fiber length in the range 12–50 mm and volume fraction in the range 0–4% on the rheological properties of fiber reinforced fresh mortar (FRFM and development of these properties over time. The rheometer Viskomat XL was used in this study. Within the limitations of the instrument and testing procedure it is shown that FRFMs conform to the Bingham model. Natural postglacial sand 0/4 mm was used as a fine aggregate and cement CEMI 42.5 R was used as a binder. Three commercial synthetic fibers were selected for these examinations. Rheological properties were expressed in terms of Bingham model parameters g (yield value and h (plastic viscosity. Based on the test results it was found out that the fiber type and volume fraction affected both the yield stress and plastic viscosity.

  3. Influence of polymer fibers on rheological properties of cement mortars

    Science.gov (United States)

    Malaszkiewicz, Dorota

    2017-10-01

    The reinforcing effect of fibers in cement composites often results in the improvement of the brittle nature of cementitious materials. But the decrease in the workability of fresh concrete is often the disadvantage of fibers addition. Conventional single-point workability tests cannot characterize workability of concrete in terms of fundamental rheological parameters. To this end, this paper describes an investigation of the influence of synthetic fiber additions (fiber length in the range 12-50 mm and volume fraction in the range 0-4%) on the rheological properties of fiber reinforced fresh mortar (FRFM) and development of these properties over time. The rheometer Viskomat XL was used in this study. Within the limitations of the instrument and testing procedure it is shown that FRFMs conform to the Bingham model. Natural postglacial sand 0/4 mm was used as a fine aggregate and cement CEMI 42.5 R was used as a binder. Three commercial synthetic fibers were selected for these examinations. Rheological properties were expressed in terms of Bingham model parameters g (yield value ) and h (plastic viscosity). Based on the test results it was found out that the fiber type and volume fraction affected both the yield stress and plastic viscosity.

  4. Rheological properties of magneto-responsive copolymer gels

    NARCIS (Netherlands)

    An, H.

    2012-01-01

    New magneto rheological systems that respond mechanically to external homogeneous magnetic fields, namely, physically cross-linked magneto rheological (MR) gels, were synthesized and investigated. Various aspects of the rheological behavior were considered such as linear viscoelastic response for

  5. Effect of enzymatic hydrolysis on surface activity and surface rheology of type I collagen.

    Science.gov (United States)

    Kezwoń, Aleksandra; Chromińska, Ilona; Frączyk, Tomasz; Wojciechowski, Kamil

    2016-01-01

    We describe the adsorption behaviour and rheological properties of a calf skin type I collagen, and of its hydrolysates obtained using a Clostridium histolyticum collagenase (CHC) under moderate conditions (pH 7, 37°C). The effect of CHC concentration (2×10(-9)-2×10(-6)M) and incubation time (35-85min) was studied and optimised to achieve the highest decrease of surface tension and the highest dilational surface viscoelasticity of the adsorbed layers. SDS-PAGE electrophoresis and reverse-phase high performance liquid chromatography (RP-HPLC) were used to characterise the hydrolysis products. The results show that even simple modifications (heat treatment, pH change, partial hydrolysis) of collagen enhances its surface properties, especially in terms of surface dilational elasticity modulus. The use of low enzyme concentration (CHC-to-collagen molar ratio of 4×10(-3)) and short incubation time (<45min) results in moderately hydrolysed products with the highest ability to lower surface tension (γ=53.9mNm(-1)) forming highly elastic adsorbed layers (surface dilational elasticity, E'=74.5mNm(-1)). Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Identification of rheological parameters describing the physico-chemical properties of anaerobic sulphidogenic sludge suspensions

    NARCIS (Netherlands)

    Pevere, A.; Guibaud, G.; Hullebusch, van E.D.; Lens, P.N.L.

    2007-01-01

    This work determined rheological parameters able to describe the rheological properties of the flocculant sludge presents in sulphidogenic anaerobic bioreactors, i.e. a MBR (membrane bioreactor) and a CSTR (continuous stirred tank reactor). Both sludges displayed a non-Newtonian rheological

  7. Studies on rheological, structural, optical, electrical and surface properties of LiMn2O4 thin films by varied spin rates

    Directory of Open Access Journals (Sweden)

    Balakrishnan T.

    2017-10-01

    Full Text Available LiMn2O4 thin films prepared by cost-effective spin coating method using optimized coating conditions are reported. Spin rate was varied and spin rate dependent properties were studied. Prepared films were characterized for their structural, morphological and optical properties. X-ray diffraction study of LiMn2O4 thin films confirmed the cubic spinel structure with the preferred orientation along (1 1 1 plane. Optical absorption studies showed band gap energy of 3.02 eV for the grown LiMn2O4 films. FT-IR bands assigned to asymmetric stretching modes of MnO6 group were located around 623 cm-1 and 514 cm-1 for the LiMn2O4 thin films. The weak band observed at 437 cm-1 was attributed to the LiO4 tetrahedra. The films showed high conductivity value 0.79 S/cm indicating the generation of effective network of the film for enhanced charge transport. AFM micrographs of the LiMn2O4 films deposited at 3000 rpm and 3500 rpm showed uniform distribution of fine grains throughout the surface without any dark pits, pinholes and cracks.

  8. Rheological and physical properties of spray-dried mucilage obtained from Hylocereus undatus cladodes.

    Science.gov (United States)

    García-Cruz, E E; Rodríguez-Ramírez, J; Méndez Lagunas, L L; Medina-Torres, L

    2013-01-02

    This study examines the rheological behavior of reconstituted spray-dried mucilage isolated from the cladodes of pitahaya (Hylocereus undatus), the effects of concentration and its relationship with physical properties were analyzed in reconstituted solutions. Drying process optimization was carried out through the surface response method, utilizing a factorial 2(3) design with three central points, in order to evaluate yield and rheological properties. The reconstituted mucilage exhibited non-Newtonian shear-thinning behavior, which adequately fit the Cross model (R(2)>0.95). This dynamic response suggests a random coil configuration. The steady-shear viscosity and dynamic response are suitably correlated through the Cox-Merz rule, confirming the mucilage's stability of flow. Analysis of the physical properties of the mucilage (Tg, DTP, and particle morphology) explains the shear-thinning behavior. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Alveoconsistograph evaluation of rheological properties of rye doughs

    Energy Technology Data Exchange (ETDEWEB)

    Callejo, M. J.; Bujeda, C.; Rodriguez, G.; Chaya, C.

    2009-07-01

    The aim of this work is to study the effect of rye flour on the rheological properties of doughs. Rye meals of two different extraction rate (65% and 85%) were blended in different proportions with wheat flours. The viscoelastic behaviour of the sample blends was determined by a Chopin alveograph. The effect of rye flour on dough rheology during mixing was determined by a Chopin consistograph. It was found that Chopin Consistograph methodology was not suitable for determining water absorption capacity in blends with rye. It has been confirmed that adjustment of dough hydration in baked products incorporating rye flour must be taken into account, depending not only on the wheat-to-rye ratio but also on the rye meals extraction rate. (Author) 35 refs.

  10. Effects of an amphipathic drug on the rheological properties of the cell membrane.

    Science.gov (United States)

    Bazzoni, G; Rasia, M

    1998-12-01

    Sodium thiopental, as other amphiphilic molecules, interacts with the membrane by inserting into the lipid bilayer and causing alterations of the membrane properties such as curvature and hypotonic lysis resistance. But can it modify the mechanical properties of the membrane? In the present work it was observed that sodium thiopental affected the membrane rheological properties by improving erythrocyte deformability; this effect resulted from a reduction of both the elastic modulus and surface viscosity. In erythrocytes devoid of sialic acid after treatment with neuraminidase, sodium thiopental membrane concentration was significantly higher than in normal cells, suggesting that drug access to the lipid bilayer be facilitated by the absence of the steric and electrostatic barrier of the glycocalyx negative charges. From a rheological point of view, desialated and normal cells showed the same response to the anesthetic as regards elastic modulus but in opposite direction if surface viscosity was considered. This finding supports the hypothesis that sodium thiopental molecules enter the bilayer of desialated cells in a higher proportion, as compared to the normal erythrocyte, promoting a disorganization that results in a greater inner friction. The changes in the rheological parameters, triggered by sodium thiopental, could be attributed to the bilayer contribution to the membrane mechanical properties, either directly or through interaction between the bilayer and the cytoskeleton.

  11. Investigating the rheological properties of native plant latex.

    Science.gov (United States)

    Bauer, Georg; Friedrich, Christian; Gillig, Carina; Vollrath, Fritz; Speck, Thomas; Holland, Chris

    2014-01-06

    Plant latex, the source of natural rubber, has been of interest to mankind for millennia, with much of the research on its rheological (flow) properties focused towards industrial application. However, little is known regarding the rheology of the native material as produced by the plant, a key factor in determining latex's biological functions. In this study, we outline a method for rheological comparison between native latices that requires a minimum of preparatory steps. Our approach provides quantitative insights into the coagulation mechanisms of Euphorbia and Ficus latex allowing interpretation within a comparative evolutionary framework. Our findings reveal that in laboratory conditions both latices behave like non-Newtonian materials with the coagulation of Euphorbia latex being mediated by a slow evaporative process (more than 60 min), whereas Ficus appears to use additional biochemical components to increase the rate of coagulation (more than 30 min). Based on these results, we propose two different primary defensive roles for latex in these plants: the delivery of anti-herbivory compounds (Euphorbia) and rapid wound healing (Ficus).

  12. Basic physiochemical and rheological properties of detergent sclerosants.

    Science.gov (United States)

    Wong, Kaichung; Chen, Tony; Connor, David E; Behnia, Masud; Parsi, Kurosh

    2015-06-01

    To determine the basic physiochemical properties and rheological activity of detergent sclerosants. Sodium tetradecyl sulphate and polidocanol liquid and foam sclerosants were investigated in a range of concentrations (0.1-3%), liquid-plus-air fractions (1+2 to 1+8) and dilutions in water (stock solutions) or in normal saline. The embolic agent ethanol was investigated for comparison. Density was measured using a digital balance. Surface tension was measured by the Du Nuoy ring method and used to determine the critical micellar concentration. Viscosity was measured using a cone-plate rheometer for liquid and a modified parallel plate method for foam. Liquid sclerosant density decreased as the sclerosant concentration increased while foam density decreased with the increasing air fraction. The critical micellar concentration of polidocanol was 0.002% in both normal saline and water while that of sodium tetradecyl sulphate was 0.075% in normal saline and 0.200% in water. Viscosity of liquid sodium tetradecyl sulphate was lower than that of polidocanol. Foam sclerosants were at least 10,000-fold more viscous than liquid sclerosants and ethanol. All agents demonstrated a Non-Newtonian shear-thinning behaviour with a fall in viscosity at lower shear rates (<10 s(-1)). Polidocanol (but not sodium tetradecyl sulphate) foam viscosity progressively increased with increasing sclerosant concentration and liquid-plus-air fractions. Liquid and foam sclerosants and ethanol are Non-Newtonian shear thinning fluids. Foam sclerosants are significantly more viscous than liquid agents. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  13. Influence of the nanotube oxidation on the rheological and electrical properties of CNT/HDPE composites

    Energy Technology Data Exchange (ETDEWEB)

    Nobile, Maria Rossella, E-mail: mrnobile@unisa.it; Somma, Elvira; Valentino, Olga; Neitzert, Heinz-Christoph [Department of Industrial Engineering – DIIn - Università di Salerno Via Giovanni Paolo II, 132 - 84084 Fisciano (Italy); Simon, George [Department of Materials Engineering, Monash University, Clayton, Victoria 3800 (Australia)

    2016-05-18

    Rheological and electrical properties of nanocomposites based on multi-walled carbon nanotubes (MWNTs) and high density polyethylene (HDPE), prepared by melt mixing in a micro-twin screw extruder, have been investigated. The effect of MWNT concentration (0.5 and 2.5 wt %) and nanotube surface treatment (oxidative treatment in a tubular furnace at 500°C for 1 hr in a 95% nitrogen, 5% oxygen atmosphere) has been analyzed. It has been found that the sample conductivity with oxidation of the nanotubes decreases more than 2 orders of magnitude. Scanning electron microscopy showed good adhesion and dispersion of nanotubes in the matrix, independently of the surface treatment. Electrical and rheological measurements revealed that the oxidative treatment, causing some reduction of the MWNT quality, decreases the efficiency of the nanotube matrix interaction.

  14. Bioactive and rheological properties of rose hip marmalade.

    Science.gov (United States)

    Sagdic, Osman; Toker, Omer Said; Polat, Busra; Arici, Muhammet; Yilmaz, Mustafa Tahsin

    2015-10-01

    In this study, bioactive (total phenolic, antioxidant and antiradical activity) and rheological properties (steady and dynamic) of rose hip marmalade were investigated. Bioactive properties were determined in rose hip marmalade and extract. Extract had higher total phenolic content (38.5 mg GAE/g dry extract), antioxidant activity (124 mg AAE/g dry extract) and antiradical activity (49.98 %) than marmalade. Steady and dynamic rheological properties of the marmalade were determined at different temperature levels (5, 25 and 45 °C). Rose hip marmalade exhibited shear thinning behavior and Ostwald de Waele model best described flow behavior of the sample (R (2)  ≥ 0.9880) at different temperature levels. Consistency index and apparent viscosity values (η 50 ) at shear rate 50 s(-1) decreased with increase in temperature level. Viscoelastic properties were determined by oscillatory shear measurements and G' (storage modulus) values were found to be higher than G'' (loss modulus) values, indicating that the rose hip marmalade had a weak gel-like structure with solid-like behavior. G', G'', G (*) (complex modulus) and η* (complex viscosity) values decreased with increase in temperature level. Modified Cox-Merz rule was satisfactorily applied to correlate apparent and complex viscosity values of the rose hip marmalade at all temperatures studied.

  15. Evaluation of Rheological Properties of Apple Mass Based Desserts

    OpenAIRE

    Sigita Boca; Ruta Galoburda; Inta Krasnova; Dalija Seglina; Aivars Aboltins; Imants Skrupskis

    2013-01-01

    The aim of the study was to evaluate the effect of texturizers on the rheological properties of the apple mass and desserts made from various raw materials. The apple varieties - ‘Antonovka’, ‘Baltais Dzidrais’, and ‘Zarja Alatau’ harvested in Latvia, were used for the experiment. The apples were processed in a blender unpeeled for obtaining a homogenous mass. The apple mass was analyzed fresh and after storage at –18ºC. Both fresh and thawed apple mass samples with added...

  16. Rheological properties, molecular distribution, and microstructure of Fortunella margarita (Lour.) swingle polysaccharides.

    Science.gov (United States)

    Zeng, Hongliang; Zhang, Yi; Jian, Yeye; Tian, Yuting; Miao, Song; Zheng, Baodong

    2015-04-01

    Fortunella margarita polysaccharides (FMPS) are one of the main bioactive components of F. margarita. The activity is related to their rheological properties and structure. The objective of this study was to investigate the relationship between rheological properties, molecular distribution, and microstructure of crude FMPS (C-FMPS) and purified FMPS (P-FMPS). The results showed that both of solutions were shear-thinning pseudoplastic fluids with flow properties in line with the Power Law model. The pseudoplasticity of P-FMPS was stronger compared to C-FMPS. Additionally, the molecular weight and polydispersity of P-FMPS were greater, whereas the molecular radius was less compared to C-FMPS. The surface of C-FMPS was rough and dense whereas P-FMPS displayed a smooth network structure by environment scanning electron microscopy. According to confocal laser scanning microscopy, C-FMPS dispersed in the medium without connected network, whereas the network of P-FMPS was unevenly distributed in the medium and the shape was compact and smooth. The molecular distribution and microstructure of P-FMPS were attributed to the purification process while rearrangement and aggregation of polysaccharide molecules took place, which resulted in the significant difference of rheological properties between C-FMPS and P-FMPS. © 2015 Institute of Food Technologists®

  17. Interfacial rheological properties of self-assembling biopolymer microcapsules.

    Science.gov (United States)

    Xie, Kaili; de Loubens, Clément; Dubreuil, Frédéric; Gunes, Deniz Z; Jaeger, Marc; Léonetti, Marc

    2017-09-20

    Tuning the mechanical properties of microcapsules through a cost-efficient route of fabrication is still a challenge. The traditional method of layer-by-layer assembly of microcapsules allows building a tailored composite multi-layer membrane but is technically complex as it requires numerous steps. The objective of this article is to characterize the interfacial rheological properties of self-assembling biopolymer microcapsules that were obtained in one single facile step. This thorough study provides new insights into the mechanics of these weakly cohesive membranes. Firstly, suspensions of water-in-oil microcapsules were formed in microfluidic junctions by self-assembly of two oppositely charged polyelectrolytes, namely chitosan (water soluble) and phosphatidic fatty acid (oil soluble). In this way, composite membranes of tunable thickness (between 40 and 900 nm measured by AFM) were formed at water/oil interfaces in a single step by changing the composition. Secondly, microcapsules were mechanically characterized by stretching them up to break-up in an extensional flow chamber which extends the relevance and convenience of the hydrodynamic method to weakly cohesive membranes. Finally, we show that the design of microcapsules can be 'engineered' in an extensive way since they present a wealth of interfacial rheological properties in terms of elasticity, plasticity and yield stress whose magnitudes can be controlled by the composition. These behaviors are explained by the variation of the membrane thickness with the physico-chemical parameters of the process.

  18. Rheological properties of different minerals and clay soils

    Directory of Open Access Journals (Sweden)

    Dolgor Khaydapova

    2015-07-01

    Full Text Available Rheological properties of kaolinite, montmorillonite, ferralitic soil of the humid subtropics (Norfolk island, southwest of Oceania, alluvial clay soil of arid subtropics (Konyaprovince, Turkey and carbonate loess loam of Russian forest-steppe zone were determined. A parallel plate rheometer MCR-302 (Anton Paar, Austria was used in order to conduct amplitude sweep test. Rheological properties allow to assess quantitatively structural bonds and estimate structural resistance to a mechanical impact. Measurements were carried out on samples previously pounded and capillary humidified during 24 hours. In the amplitude sweep method an analyzed sample was placed between two plates. The upper plate makes oscillating motions with gradually extending amplitude. Software of the device allows to receive several rheological parameters such as elastic modulus (G’, Pa, viscosity modulus (G", Pa, linear viscoelasticity range (G’>>G”, and point of destruction of structure at which the elastic modulus becomes equal to the viscosity modulus (G’=G”- crossover. It was found out that in the elastic behavior at G '>> G " strength of structural links of kaolinite, alluvial clay soil and loess loam constituted one order of 105 Pa. Montmorillonit had a minimum strength - 104 Pa and ferrallitic soil of Norfolk island [has] - a maximum one -106 Pa. At the same time montmorillonite and ferralitic soil were characterized by the greatest plasticity. Destruction of their structure (G '= G" took place only in the cases when strain was reaching 11-12%. Destraction of the kaolinite structure happened at 5% of deformation and of the alluvial clay soil and loess loam - at 4.5%.

  19. Research on the rheological properties of a perfluoropolyether based ferrofluid

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhenkun; Yao, Jie; Li, Decai, E-mail: dcli@bjtu.edu.cn

    2017-02-15

    A perfluoropolyether based ferrofluid was prepared using co-precipitation method and the rheological properties of the ferrofluid were studied by a rotational rheometer. A series of experiments were designed to study the influence of magnetic field, shear rate and temperature on the magnetoviscous effect of the perfluoropolyether based ferrofluid. Consecutive measurements of the megnetoviscous parameter with the temperature-increasing process were made and totally different tendency of the curves was observed under a range of shear rates. The magnetic field strength influence on the observed temperature dependencies was also studied experimentally. A discussion on the different mechanisms of the influence of temperature on magnetoviscous effect is presented based on the chain model of magnetic particles and the viscosity-temperature characteristics of the base carrier liquid. - Highlights: • The rheological properties of a perfluoropolyether based ferrofluid are studied. • The influence of temperature on magnetoviscous effect is studied experimentally. • A complex relationship of the magnetoviscous effect and the temperature is shown. • Two different mechanisms of temperature influence on magnetoviscous effect are presented.

  20. THE EFFECT OF TRANSGLUTAMINASE ON THE RHEOLOGICAL PROPERTIES OF YOGURT

    Directory of Open Access Journals (Sweden)

    Iuliana Aprodu

    2011-05-01

    Full Text Available The aim of this study was to investigate the rheological characteristics of yogurts obtained from milk treated with transglutaminase prior to fermentation with Streptococus theromophilus and Lactobacillus delbrueckii subsp. Bulgaricus. A set of 36 experiments were carried out to test the influence of various enzyme concentrations ranging from 0 to 0.04%, different setting temperatures (35, 40 and 45 oC, and setting time (60, 90 and 120 min. The cross-linking of milk proteins influenced the post-acidification process as well as the stability of the yogurt samples. The enzymatic treatment of milk allowed avoiding the syneresis phenomena during yogurt storage at 4 oC; the water holding capacity during centrifugation was also improved. Concerning the rheological properties, the apparent viscosity of yogurt increased by increasing the enzyme concentration and the setting time for the entire tested domain of shear rates. The results indicate that transglutaminase catalyzed cross-linking is an effective tool for improving functional properties of yogurt.

  1. Rheology of organoclay suspension

    CSIR Research Space (South Africa)

    Hato, MJ

    2011-05-01

    Full Text Available The authors have studied the rheological properties of clay suspensions in silicone oil, where clay surfaces were modified with three different types of surfactants. Dynamic oscillation measurements showed a plateau-like behavior for all...

  2. Polyethylene/synthetic boehmite alumina nanocomposites: Structure, thermal and rheological properties

    Directory of Open Access Journals (Sweden)

    2010-05-01

    Full Text Available Synthetic boehmite alumina (BA has been incorporated up to 8 wt% in low density polyethylene (LDPE and high density polyethylene (HDPE, respectively, by melt compounding. The primary nominal particle size of these two BA grades was 40 and 60 nm, respectively. The dispersion of the BA in polyethylene (PE matrices was investigated by scanning and transmission electron microscopy techniques (SEM and TEM. The thermal (melting and crystallization, thermooxidative (oxidation induction temperature and time, and rheological behaviors of the nanocomposites were determined. It was found that BA is nanoscale dispersed in both LDPE and HDPE without any surface treatment and additional polymeric compatibilizer. BA practically did not influence the thermal (melting and crystallization and rheological properties of the parent PEs. On the other hand, BA worked as a powerful thermooxidative stabilizer for LDPE, and especially for HDPE nanocomposites.

  3. Rheological properties of salep powder-milk mixture.

    Science.gov (United States)

    Develi Işıklı, Nursel; Dönmez, Mehmet Necmi; Kozan, Nejat; Karababa, Erşan

    2015-10-01

    Rheological properties of salep-milk mixture as hot drink were evaluated using a rotational viscometer at different temperature (45, 50, 55, 60, and 65 °C) and salep concentration (0.75, 1.00, and 1.25 w/v, %). All salep-milk mixtures exhibited non-Newtonian behavior. The shear rate /shear stress data obtained from forward and backward directions were examined by common rheological models such as power law, Herschel-Bulkey, Casson and Bingham plastic models. Among the common models, the power-law model fitted the shear rate and shear stress data for 1.00 and 1.25 % salep concentration at all temperature. The Bingham plastic model described well the flow behavior of the salep-milk mixtures in 0.75 % salep concentration at all temperature. Flow behavior index (n), according to the power law and Herschel-Bulkey models decreased with an increase in salep concentration and a decrease of temperature. The consistency coefficient decreased with temperature and increased with salep concentration.

  4. Exploring properties of polyaniline-SDS dispersion: a rheological approach.

    Science.gov (United States)

    Gangopadhyay, Rupali

    2009-10-15

    The paper describes steady and dynamic rheological characterization of a system in which polyaniline (PAn) is dispersed in aqueous medium by the effect of a surfactant sodium dodecyl sulphate (SDS). During polymerization of aniline in SDS medium, large and agglomerated micelle-polymer structures are formed (supported by TEM and DLS) resulting in high viscosity of the medium. On application of steady shear micellar entanglements are ruptured and the system exhibits yield properties followed by shear thinning. From the frequency dependence of storage and loss modulii (G' and G'') it seems that the system behaves more like a viscous fluid rather than an elastic liquid. Carrying out the same experiments on another dispersion in which PAn is stabilized by dodecyl benzenesulphonic acid (DBSA), very different viscoelastic response was received. DBSA molecules become counter-ions to PAn chains and this way large and interconnected PAn-DBSA structures are formed by mutual sharing of DBSA anions and PAn chains. This system therefore, exhibits gel like properties and encounters a gel to sol transition at larger deformation. Detailed studies have established that PAn-SDS is a stabilized dispersion that resembles entangled polymeric solutions to some extent while PAn-DBSA is a partially flocculated system. Therefore, rheological response of the system is mainly governed by the mutual orientation of PAn with respect to the micelles rather than the individual properties of the components. None of these systems, however, follow the established Maxwell's model and a single relaxation time is not obtained. Rather, Rouse model of multiple relaxation times is partially applicable to PAn-SDS dispersion.

  5. Rheological properties of disperse systems based on hydrolyzed lignin and oil

    Science.gov (United States)

    Savitskaya, T. A.; Reznikov, I. V.; Shcheglov, V. A.; Tsygankova, N. G.; Telysheva, G. M.; Grinshpan, D. D.

    2012-05-01

    The rheological properties of oil dispersions of hydrophobized hydrolyzed lignin, which is an effective sorbent of oil and oil products, have been studied. It has been shown that at a lignin concentration of over 10%, free-disperse systems with Newton flow go over to coagulation thixotropic structures, demonstrating the pseudoplastic character of flow. The structural-mechanical characteristics of highly filled (lignin content of 40-45%) dispersions have been determined and the concentration region of existence of an oil-saturated sorbent in the form of a solid product easily removed from the water surface has been established.

  6. EFFECTS OF PROPERTIES POLYMERIC ADDITIVES IN RHEOLOGIC AND DRILLING FLUIDS

    Directory of Open Access Journals (Sweden)

    Danielly Vieira de Lucena

    2014-03-01

    Full Text Available The influence of carboxymethylcellulose, CMC (filtrate reducer and xanthan gum (viscosifier in plastic and apparent viscosity at yield strength and the volume of filtrate in the composition of drilling fluids based on water was investigated based on statistical design. Five formulations consist of a range of concentrations used commercially were utilized in the design of the experiment. The formulations were prepared in accordance with company standards Petrobras. Regression models were calculated and correlated with the properties of the compositions. The relevance and validation of the models were confirmed by statistical analysis. The design can be applied to statistically optimize the mud properties considering the addition of CMC and xanthan gum, and to provide a better understanding of the influence of additives on the properties of polymer-based fluid system water. From the study it was observed that the values of the rheological properties vary with the concentration of additives, increasing with increasing concentration of the same, and that the concentration of the additives caused a decline of parameter values filtration.

  7. Optimization of the functional characteristics, pasting and rheological properties of pearl millet-based composite flour

    Directory of Open Access Journals (Sweden)

    Olugbenga Olufemi Awolu

    2017-02-01

    Full Text Available Optimisation of composite flour comprising pearl millet, kidney beans and tigernut with xanthan gum was evaluated for rheological evaluations. The functional properties of the composite flour were optimized using optimal design of response surface methodology. The optimum blends, defined as blends with overall best functional characteristics were run 3 (75.956% pearl millet, 17.692% kidney beans, 6.352% tigernut flours, run 7 (85.000% pearl millet, 10.000% kidney beans, 5.000% tigernut flours and run 13 (75.000% pearl millet, 20.000% kidney beans, 5.000% tigernut flours. The pasting characteristics and rheological evaluation of the optimized blends were further evaluated in rapid visco units (RVU. Run 7 had the overall best pasting characteristics; peak viscosity (462 RVU, trough (442 RVU, breakdown viscosity (20 RVU, final viscosity (975 RVU, setback (533 RVU, peak time (5.47 min and pasting temperature (89.60 °C. These values were found to be better than several composite flours consisting mixture of wheat and non-wheat crops. In addition, the rheological characteristics (measured by Mixolab showed that run 7 is the best in terms of dough stability, swelling, water absorption and shelf stability. Composite flour with 85% pearl millet flour in addition to kidney beans and tigernut flours could therefore serve as a viable alternative to 100% wheat flour in bread production.

  8. Rheological and morphological properties of graphene-epoxy nanocomposites

    Science.gov (United States)

    Nobile, Maria Rossella; Raimondo, Marialuigia; Lafdi, Khalid; Guadagno, Liberata

    2016-05-01

    In this paper the rheological and morphological properties of an epoxy resin filled with graphene-based nanoparticles have been investigated. Two samples of partially exfoliated graphite (pEG) and carboxylated partially exfoliated graphite (CpEG), differing essentially for the content of carboxylated groups, are used. The percentage of exfoliated graphite is slightly different for the two samples: 56% for pEG and and 60% for CpEG. Exfoliated graphite is prepared using traditional acid intercalation followed by a sudden treatment at high temperature (900°C). The epoxy matrix is prepared by mixing a tetrafunctional precursor with a reactive diluent which produces a significant decrease in the viscosity of the epoxy precursor so that the dispersion step of nanofillers in the matrix can easily occur. The hardener agent, the 4,4-diaminodiphenyl sulfone (DDS), is added at a stoichiometric concentration with respect to all the epoxy rings. The inclusion of the pEG and CpEG samples in the formulated epoxy mixture significantly modifies the rheological behaviour of the mixture itself. The epoxy mixture, indeed, shows a Newtonian behavior; on the contrary the complex viscosity of the nanocomposites clearly shows a shear thinning behavior at 3 wt % of pEG content and at 0.75 wt% of CpEG content. The increase in complex viscosity with the increasing of pEG and CpEG content is mostly caused by a dramatic increase in the storage modulus of the nanocomposites. All the graphene-based epoxy mixtures are cured by a two-stage curing cycles: a first isothermal stage is carried out at the lower temperature of 125°C for 1 hour and, then, a second isothermal stage at the higher temperature of 200°C for 3 hours. The different morphology shown by the two pEG and CpEG samples is consistent with the difference in the percentage of exfoliation degree and well correlates with the rheological behavior of investigated graphene-epoxy nanocomposites.

  9. The effect of sweeteners and milk type on the rheological properties ...

    African Journals Online (AJOL)

    Administrator

    The aim of the study was, to determine effects of sweeteners and milk type on the rheological and sensorial properties of reduced ... Key words: Rheology, artifical sweeteners, low-calorie, power-law model, salep drink. INTRODUCTION ... to several adverse health effects including cardiovascular diseases, diabetes and ...

  10. Physical and rheological properties of Titanium Dioxide modified asphalt

    Science.gov (United States)

    Buhari, Rosnawati; Ezree Abdullah, Mohd; Khairul Ahmad, Mohd; Chong, Ai Ling; Haini, Rosli; Khatijah Abu Bakar, Siti

    2018-03-01

    Titanium Dioxide (TiO2) has been known as a useful photocatalytic material that is attributed to the several characteristics includes high photocatalytic activity compared with other metal oxide photocatalysts, compatible with traditional construction materials without changing any original performance. This study investigates the physical and rheological properties of modified asphalt with TiO2. Five samples of asphalt with different concentration of TiO2 were studied, namely asphalt 2%, 4%, 6% 8% and 10% TiO2. The tests includes are penetration, softening point, ductility, rotational viscosity and dynamic shear rheometer (DSR) test. From the results of this study, it is noted that addition of TiO2 has significant effect on the physical properties of asphalt. The viscosity tests revealed that asphalt 10% TiO2 has good workability among with reducing approximately 15°C compared to base asphalt. Based on the results from DSR measurements, asphalt 10% TiO2 has reduced temperature susceptibility and increase stiffness and elastic behaviour in comparison to base asphalt. As a result, TiO2 can be considered to be an additive to modify the properties of asphalt.

  11. Physical, rheological, functional and film properties of a novel emulsifier: Frost grape polysaccharide (FGP) from Vitis riparia Michx

    Science.gov (United States)

    A novel emulsifier, Frost grape polysaccharide (FGP), isolated from natural exudate of the species Vitis riparia Michx, was physically and rheologically characterized. The determination of the physical, structural, thermodynamic, emulsification, film, and rheological properties of FGP provide essent...

  12. Gelatins as rock analogs: A systematic study of their rheological and physical properties

    Science.gov (United States)

    Di Giuseppe, E.; Funiciello, F.; Corbi, F.; Ranalli, G.; Mojoli, G.

    2009-08-01

    In a laboratory model the behavior of the selected analog material must be properly scaled to nature. Here, we systematically investigate both rheological and physical properties of a wide range of gelatins as functions of temperature, composition, concentration, ageing and applied strain rate. Results show that gelatins' behavior changes gradually from purely elastic to visco-elasto-brittle to purely viscous (nonlinear) rheology going from the gel- to the sol-state. The rheological variability of gelatins appears promising for the potential use of these analog materials to simulate crustal and lithospheric rheological behavior. In particular, we found that pig skin 2.5 wt.% at 10 °C has the required rheological properties for a suitable experimental set-up to model crustal deformation.

  13. Changes in rheological properties of Edam-type cheese during ripening

    Directory of Open Access Journals (Sweden)

    Ivi Jõudu

    2017-12-01

    Full Text Available Understanding the parameters affecting the rheological characteristics of cheese enables better regulation and monitoring of cheese consistency and the production of cheese with desired quality. The objectives of this research were to define the linear viscoelastic rheological properties of large scale production Edam-type cheese, to characterize the effect of ripening (from three days to 10 weeks and to determine the effect of cheese composition and cheese milk on the rheological properties of Edam-type cheese. Changes in the viscoelastic properties were more noticeable in the first four weeks of the ripening period and thereafter stabilized. Highest significant correlations for G’ and G’’ observed with the ratio of cheese moisture plus fat to protein. The compositional parameters of cheese related to rheological properties (moisture, moisture in the non-fat substance (MNFS and moisture to protein ratio significantly correlated with vat milk protein content and rennet coagulation properties.

  14. The rheological properties of tara gum (Caesalpinia spinosa).

    Science.gov (United States)

    Wu, Yanbei; Ding, Wei; Jia, Lirong; He, Qiang

    2015-02-01

    The rheological properties of tara gum, as affected by concentration, temperature, pH and the presence of salts and sucrose, were investigated by using steady and dynamic shear measurements and atomic force microscope observation. Tara gum exhibited non-Newtonian, pseudoplastic behaviour without thixotropy at tested concentrations (0.2-1.0%, w/v). Salts (CaCl2 and NaCl) led to a viscosity reduction, which was more sensitive to Ca(2+) than to Na(+). The gum had stable viscosity over a wide pH range (pH 3-11), and the influence of sucrose was concentration dependent. Increasing temperature from 20°C to 80°C decreased the gum viscosity. Frequency sweeps indicated that tara gum (1.0% w/v) behaved as a liquid at low frequency, and acted more like a gel at high frequency. With the decrease of concentration, tara gum may show a viscous property rather than an elastic one. These results are potentially useful for the application of tara gum in food processing. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Platelet morphological, functional and rheological properties attributable to addictions.

    Science.gov (United States)

    Zvetkova, Elissaveta; Antonova, Nadia; Ivanov, Ivan; Savov, Yonko; Gluhcheva, Yordanka

    2010-01-01

    Hemorheological abnormalities such as elevated whole blood viscosity, plasma viscosity, erythrocyte deformability and platelet aggregation, hematocrit and fibrinogen levels, are frequently examined as diagnostic tool and prognostic relevance in socially important hemorheological disorders. Distinct biological - morphological and functional platelet alterations, have been described in different addictions (heroin-, cocaine-, nicotine-, alcohol-, etc.). Chronic addictions could cause biochemical and conformational changes in platelets and their membranes, thus modulating platelet receptor expression, morphology (anisocytosis, giant platelets) and activation (alpha-granule release), platelet aggregation and hemorheological properties. Some of these alterations in chronic addicts - documented at cellular- and molecular level, could be easily used as a precise diagnostic tool with regard to thromboembolic complications and microcirulation injuries attributable to addictions. The present review focuses on some changes in platelet morphological, functional and rheological properties induced by chronic opiate/opioid abuse. Hypothesis is accumulated that free fatty acids (FFAs) and especially oleic acid (OA) could cause positive molecular and conformational changes in platelets of addicts with hemorheological disorders.

  16. Dynamic shear rheology of colloidal suspensions of surface-modified silica nanoparticles in PEG

    Science.gov (United States)

    Swarna; Pattanayek, Sudip Kumar; Ghosh, Anup Kumar

    2018-03-01

    The present work illustrates the effect of surface modification of silica nanoparticles (500 nm) with 3-(glycidoxypropyl)trimethoxy silane which was carried out at different reaction times. The suspensions prepared from modified and unmodified silica nanoparticles were evaluated for their shear rate-dependent viscosity and strain-frequency-dependent modulus. The linear viscoelastic moduli, viz., storage modulus and loss modulus, were compared with those of nonlinear moduli. The shear-thickened suspensions displayed strain thinning at low-frequency smaller strains and a strong strain overshoot at higher strains, characteristics of a continuous shear thickening fluids. The shear-thinned suspension, conversely, exhibited a strong elastic dominance at smaller strains, but at higher strains, its strain softened observed in the steady shear viscosity plot indicating characteristics of yielding material. Considering higher order harmonic components, the decomposed elastic and viscous stress revealed a pronounced elastic response up to 10% strain and a high viscous damping at larger strains. The current work is one of a kind in demonstrating the effect of silica surface functionalization on the linear and nonlinear viscoelasticity of suspensions showing a unique rheological fingerprint. The suspensions can thus be predicted through rheological studies for their applicability in energy absorbing and damping materials with respect to their mechanical properties.

  17. Rheological properties of polyvinylsiloxane impression materials before mixing and during setting related to handling characteristics

    Science.gov (United States)

    Lee, Hyang-Ok; Lee, In-Bog

    2012-09-01

    The purpose of this study is to determine and compare the handling and rheological properties of polyvinylsiloxane impression pastes before mixing and during setting, and to investigate the effect of its constituents on the properties of the materials. Five polyvinylsiloxane impression materials (Examixfine, Extrude, Honigum, Imprint II, and Express) were used. A flow test and a drip test were performed to determine the handling characteristics. The rheological properties of each impression material prior to mixing (shear stress, viscosity) and during setting (storage modulus G'), loss modulus G″), loss tangent tanδ) were measured with a stress-controlled rheometer at 25°C and 32°C, respectively. Inorganic filler content of each impression material was measured and observed with a SEM. The molecular weight distribution of polymer matrix was determined with a gel permeation chromatography (GPC). Express and Honigum display lower flow compared to the other materials, due to their high yield-stress values. Examixfine exhibits the greatest flow. All materials display pseudoplastic behavior, excluding the Examixfine catalyst. The viscosities at low shear rate are greatest for Express and Honigum; however, under high shear conditions, the viscosities of Extrude and Honigum are the lowest. Following mixing, each material show an increase in G', finally reaching a plateau, and the tanδ rapidly decreases with time. Imprint II shows the highest final G' as well as the most rapid decrease in tanδ. Express and Imprint II present the highest filler content and rough filler surface, while Honigum shows the lowest filler content and small filler particles. Most products are composed of polymers over 30 kDa and oligomers less than 1 kDa. Each impression material possesses different rheological properties, which significantly affect the handling characteristics. The yield stress of the impression material minimizes unnecessary flow prior to and after seating. Viscoelastic

  18. Is electrical percolation in carbon-filled polymers reflected by rheological properties?

    Czech Academy of Sciences Publication Activity Database

    Münstedt, H.; Starý, Zdeněk

    2016-01-01

    Roč. 98, 19 August (2016), s. 51-60 ISSN 0032-3861 Institutional support: RVO:61389013 Keywords : electrical conductivity * rheological properties * composites Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.684, year: 2016

  19. Effect of Rheological Properties on Liquid Curtain Coating

    Science.gov (United States)

    Mohammad Karim, Alireza; Suszynski, Wieslaw; Griffith, William; Pujari, Saswati; Carvalho, Marcio; Francis, Lorraine; Dow Chemical Company Collaboration; PUC-Rio Collaboration

    2017-11-01

    Curtain coating is one of the preferred methods for high-speed precision application of single-layer and multi-layer coatings in technology. However, uniform coatings are only obtained in a certain range of operating parameters, called coating window. The two main physical mechanisms that limit successful curtain coating are liquid curtain breakup and air entrainment. The rheological properties of the liquid play an important role on these mechanisms, but the fundamental understanding of these relations is still not complete. The effect of rate-dependent shear and extensional viscosities on the stability of viscoelastic and shear thinning liquid curtains were explored by high-speed visualization. Aqueous solutions of polyethylene oxide (PEO) and polyethylene glycol (PEG) were used as viscoelastic liquids. Xanthan Gum in water and glycerol solutions with a range of compositions were used as shear thinning liquids. The critical condition was determined by examining flow rate below which curtain broke. In this work, we also analyze relative importance of rate-dependent shear and extensional viscosity on both curtain breakup and air entrainment. We would like to acknowledge the financial support from the Dow Chemical Company.

  20. Rheological properties of lactose-free dairy desserts.

    Science.gov (United States)

    Sahin, Serpil; Hamamci, Haluk; Garayev, Sultan

    2016-10-01

    People suffering from lactose intolerance cannot digest milk or lactose-containing foods. Lactose-free diet is essential for them since they do not have the ability to produce lactase to breakdown milk sugar. Physical properties of lactose-free dairy desserts will most probably be different than that of lactose containing ones because of lactose hydrolysis. In this study, it was aimed to analyze the rheological and textural behaviors of different lactose-free dessert formulations containing different gum types and different waxy maize starch and sucrose concentrations. Waxy maize starch was used at concentrations of 0.032 g·mL -1 , 0.040 g·mL -1 , and 0.048 g·mL -1 In addition to waxy maize starch, guar gum, gum arabic, or κ-carrageenan at two different concentrations (1.0% w/w and 0.5% w/w) was added. Sucrose was added at concentrations of 0.14 g·mL -1 and 0.10 g·mL -1 in lactose-free desserts. Power law model was found to be suitable to explain the flow behavior of desserts. The storage and loss modulus of lactose-free desserts were higher than that of lactose-containing desserts. The κ-Carrageenan was found to be the most effective gum for structure build-up. © The Author(s) 2016.

  1. Rheological and microstructural properties of the chia seed polysaccharide.

    Science.gov (United States)

    Timilsena, Yakindra Prasad; Adhikari, Raju; Kasapis, Stefan; Adhikari, Benu

    2015-11-01

    Chia seed polysaccharide (CSP) was extracted from chia (Salvia hispanica) seeds, and its rheological and microstructural properties in aqueous solutions were studied. CSP solution exhibited Newtonian and shear thinning flow patterns depending on shear rate when the concentration was ≤0.06% (w/v). CSP solutions at concentrations >0.06% (w/v) exhibited strong shear thinning behaviour within the shear rate tested (0.001-300s(-1)). The transition from dilute to semi-dilute regime occurred at a critical concentration (C*) of 0.03gdL(-1). The intrinsic viscosity was high (∼16dLg(-1)) and concentration dependence of zero shear viscosity in the semi-dilute regime followed η0∝C(2.7) relationship. The storage modulus (G') was higher than the loss modulus (G″) at all experimental frequencies and their frequency dependence was negligible at all tested concentrations. Apparent shear viscosity was smaller than dynamic complex viscosity at equivalent values of deformation and G' varied with the square of concentration indicating a gel-like behaviour in CSP solutions within 0.02-3.0% (w/v) concentrations. Controlled acid hydrolysis of purified CSP yielded various low molecular fractions with fairly uniform polydispersity giving a Mark-Houwink-Sakurada relationship of intrinsic viscosity equaling to 1.52×10(-4) (molecular weight)(0.803) (dLg(-1)). Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Chitosan/titanium dioxide nanocomposite coatings: Rheological behavior and surface application to cellulosic paper.

    Science.gov (United States)

    Tang, Yanjun; Hu, Xiulan; Zhang, Xinqi; Guo, Daliang; Zhang, Junhua; Kong, Fangong

    2016-10-20

    Incorporation of nanofillers into a polymeric matrix has received much attention as a route to reinforced polymer nanocomposites. In the present work, an environmentally friendly chitosan (CTS)/titanium dioxide (TiO2) nanocomposite coating was designed/prepared and subsequently employed for imparting antibacterium and improved mechanical properties to cellulosic paper via surface coating. Effect of TiO2 nanoparticle loadings on the rheological behavior of nanocomposite coatings was investigated. Surface application of CTS/TiO2 nanocomposite coatings to cellulosic paper was performed, and the antibacterial activity and mechanical properties of surface-coated cellulosic paper were examined. Results showed that the increased TiO2 nanoparticle loadings decreased the viscosity and dynamic viscoelasticity of the as-prepared coatings, and improved the antibacterial activity and mechanical properties of surface-coated cellulosic paper. The optimum loading of TiO2 nanoparticles was identified at 10%. This work suggested that CTS/TiO2 nanocomposite coatings may have the potential to be used as a promising antibacterial protective coating for paper packaging. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Rheological properties of strawberry fruit coating with methylcellulose

    Directory of Open Access Journals (Sweden)

    Z Nadim

    2016-04-01

    Full Text Available Introduction: The maintenance of the quality of fresh products is still a major challenge for the consumers. The most important quality attributes contributing to the marketability of fresh fruit include appearance, color, texture, flavor, nutritional value and microbial safety. Strawberry fruits should be firm but not crunchy. Decreased quality during postharvest handling is most often associated with water loss and decay. The postharvest life of strawberries can be extended by coating technique combined with refrigeration. Application of edible coatings is a conventional method to increase shelf life and maintain fruit quality. Edible coatings can provide an alternative to enlarge fresh fruits’ postharvest life. In this study, the effects of application of methyl cellulose edible coatings and storage time on some mechanical properties, including: the yield stress, yield strain, energy of rupture and modulus of elasticity and also, the viscoelastic behavior of the strawberry fruit was investigated. Materials and Methods: MC (Methocel, Dow Chemical Company, Midland, MI coating was prepared by solubilizing MC powder (3.0 g per 100 mL in a water–ethyl alcohol mixture (2:1 at 75ºC under the high speedmixer (900 rpm for 15 min. Coatings were used directly on the fruit surface. The physical and mechanical characteristics of fruits were analyzed on 2, 5, 8 and 11 days of storage. The puncture test and relaxation test were done using a texture analyzer (Zwick/Roell Model BT1_FR0.5TH.D14, Zwick GmbH Co., Ulm, Germany; using Xforce HP model of loadcell with capacity of 500 N, by 2 mv/v characteristic. General Maxwell model is widely used to analyze experimental results of the stress tests applied for relaxation. The obtained model coefficients were determined and evaluated from relaxation stress curves. Residues were determined using the sequential model. Usually, multicomponent models can properly describe the actual behavior of agricultural

  4. Effects of main parameters on rheological properties of oil-coal slurry

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yong-gang; Hao Li-fang; Xiong Chu-an; Sun Xiu-ying [China University of Mining & Technology, Beijing (China). School of Chemical and Environmental Engineering

    2006-09-15

    Oil-coal slurry prepared in coal direct liquefaction is a dispersed solid-liquid suspension system. In this paper, some factors such as solvent properties, solid concentrations and temperatures, which affect viscosity change of oil-coal slurry, were studied. The viscosity of coal slurry was measured using rotary viscometer, and the rheological properties have been investigated. The viscosity and rheological curves were plotted and regressed, respectively. The results show that the coal slurry behaves a pseudoplastic and thixotropic property. The rheological type of coal slurry was ascertained and its rheological equations were educed. The oil-coal slurry changes to non-Newtonian fluid from Newtonian fluid with the increasing of solid concentration. 10 refs., 5 figs., 3 tabs.

  5. AN EXPERIMENTAL STUDY ON THE RHEOLOGICAL PROPERTIES OF CONDITIONED MUNICIPAL ACTIVATED SLUDGE

    Directory of Open Access Journals (Sweden)

    SALAM K. AL-DAWERY

    2017-01-01

    Full Text Available This research work was focused on the rheological characteristics of conditioned fresh activated sludge using TA rheometer HR-2. The effect of cationic polyelectrolyte conditioner has been investigated for floc size, surface properties and yield stress at different pH values in a comparative fashion. Our approach was to reveal the effect of polymer on the municipal activated sludge with high organic contents up to 80%. The results indicated an improvement of 50% in settling properties by addition polyelectrolyte up to 4 mg/g solid/l. Rheological data analysis showed that responses of shear stress - shear rate were found to be closest to Bingham model and gave almost similar and smaller k values of average 6.2×10-3. The results of shear creep indicated that all sludge samples have less rigid structures with no reconstruction behavior. The optical analyses of the samples indicated that the floc sizes were increased with successive addition of polyelectrolyte. The increase of floc sizes caused large stresses especially for solution with pH=9. As the flocculation accorded despite the negative zeta potential, this phenomenon can be referred to that interparticles hydrogen bridging was governing flocculation rather than charge neutralization. Also, during the experiment, bacterial growth showed an adaption despite the conditioning with polyelectrolyte.

  6. Numerical study of jumps formed in free-surface flows down an incline : influence of the fluid rheology

    Science.gov (United States)

    Naaim, Mohamed; Faug, Thierry

    2017-04-01

    The discontinuities in height and velocity, namely jumps, formed in free-surface flows are important processes in geophysics, for instance when they are formed during the interaction of avalanche-flows with protection structures. The present study investigates steady state jumps formed in free-surface flows with the help of numerical simulations based on depth-averaged equations. A control constant mass discharge is supplied to an incline. By imposing a difference in basal friction between a upper part of the chute bottom and a lower part of the chute bottom, a supercritical flow is produced upstream while a subcritical flow appears downstream. The transition between both gives birth to a jump located at the transition between the two portions of the chute with different basal friction. Different constitutive equations are tested (laminar, turbulent, local granular rheology, Voellmy, Herschel Bulkley), thus allowing us to quantify the influence of the fluid rheology on the jump properties : position, geometry and size.

  7. Effect of various supplementary cementitious materials on rheological properties of self-consolidating concrete

    OpenAIRE

    Saleh Ahari, Reza; Erdem, Tahir Kemal; Ramyar, Kambiz

    2015-01-01

    In design of self-consolidating concrete (SCC) for a given application, the mixture's rheological parameters should be adjusted to achieve a given profile of yield stress and plastic viscosity. Supplementary cementitious materials (SCM) can be useful for this adjustment in addition to their other advantages. In this study, the rheological properties of 57 SCC mixtures with various SCM were investigated for a constant slump flow value. For this aim, various amounts of silica fume (SF), metakao...

  8. Rheological Properties of Cemented Tailing Backfill and the Construction of a Prediction Model

    OpenAIRE

    Lang, Liu; Song, KI-IL; Lao, Dezheng; Kwon, Tae-Hyuk

    2015-01-01

    Workability is a key performance criterion for mining cemented tailing backfill, which should be defined in terms of rheological parameters such as yield stress and plastic viscosity. Cemented tailing backfill is basically composed of mill tailings, Portland cement, or blended cement with supplementary cement material (fly ash and blast furnace slag) and water, among others, and it is important to characterize relationships between paste components and rheological properties to optimize the w...

  9. Effects of Momordica charantia L. on the Blood Rheological Properties in Diabetic Patients

    OpenAIRE

    França, Eduardo Luzía; Ribeiro, Elton Brito; Scherer, Edson Fredulin; Cantarini, Déborah Giovanna; Pessôa, Rafael Souza; França, Fernando Luzía; Honorio-França, Adenilda Cristina

    2014-01-01

    An evaluation of the rheological properties and the effects of Momordica. charantia L. (M. charantia) nanoparticles and polyethylene glycol (PEG) microspheres adsorbed with M. charantia nanoparticles on the blood of hyperglycemic patients is presented. Blood samples were collected according to glycemic status: normoglycemic (N = 56) and hyperglycemic (N = 26). General and hematological characteristics were determined. Blood rheological parameters were determined at room temperature and under ...

  10. Nonlinear Surface Dilatational Rheology and Foaming Behavior of Protein and Protein Fibrillar Aggregates in the Presence of Natural Surfactant.

    Science.gov (United States)

    Wan, Zhili; Yang, Xiaoquan; Sagis, Leonard M C

    2016-04-19

    The surface and foaming properties of native soy glycinin (11S) and its heat-induced fibrillar aggregates, in the presence of natural surfactant steviol glycoside (STE), were investigated and compared at pH 7.0 to determine the impact of protein structure modification on protein-surfactant interfacial interactions. The adsorption at, and nonlinear dilatational rheological behavior of, the air-water interface were studied by combining drop shape analysis tensiometry, ellipsometry, and large-amplitude oscillatory dilatational rheology. Lissajous plots of surface pressure versus deformation were used to analyze the surface rheological response in terms of interfacial microstructure. The heat treatment generates a mixture of long fibrils and unconverted peptides. The presence of small peptides in 11S fibril samples resulted in a faster adsorption kinetics than that of native 11S. The addition of STE affected the adsorption of 11S significantly, whereas no apparent effect on the adsorption of the 11S fibril-peptide system was observed. The rheological response of interfaces stabilized by 11S-STE mixtures also differed significantly from the response for 11S fibril-peptide-STE mixtures. For 11S, the STE reduces the degree of strain hardening in extension and increases strain hardening in compression, suggesting the interfacial structure may change from a surface gel to a mixed phase of protein patches and STE domains. The foams generated from the mixtures displayed comparable foam stability to that of pure 11S. For 11S fibril-peptide mixtures STE only significantly affects the response in extension, where the degree of strain softening is decreased compared to the pure fibril-peptide system. The foam stability of the fibril-peptide system was significantly reduced by STE. These findings indicate that fibrillization of globular proteins could be a potential strategy to modify the complex surface and foaming behaviors of protein-surfactant mixtures.

  11. Rheological properties of micro-/nanofibrillated cellulose suspensions: wall-slip and shear banding phenomena.

    Science.gov (United States)

    Nechyporchuk, Oleksandr; Belgacem, Mohamed Naceur; Pignon, Frédéric

    2014-11-04

    The rheological properties of enzymatically hydrolyzed and TEMPO-oxidized microfibrillated/nanofibrillated cellulose (MFC/NFC) aqueous suspensions were investigated in oscillation and steady-flow modes and were compared with the morphology of the studied materials. The flow instabilities, which introduce an error in the rheological measurements, were discovered during flow measurements. A wall-slip (interfacial slippage on the edge of geometry tools and suspension) was detected at low shear rates for two types of NFC suspensions while applying cone-plate geometry. A roughening of the tool surfaces was performed to overcome the aforementioned problem. Applying to TEMPO-oxidized NFC, a stronger suspension response was detected at low shear rates with higher values of measured shear stress. However, a shear banding (localization of shear within a sample volume) became more pronounced. The use of serrated tools for enzymatically hydrolyzed NFC produced lower shear stress at the moderate shear rates, which was influenced by water release from the suspension. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Modeling and experimental investigation of rheological properties of injectable poly(lactide ethylene oxide fumarate)/hydroxyapatite nanocomposites.

    Science.gov (United States)

    Sarvestani, Alireza S; Jabbari, Esmaiel

    2006-05-01

    Injectable multiphasic polymer/ceramic composites are attractive as bioresorbable scaffolds for bone regeneration because they can be cross-linked in situ and are osteoconductive. The injectability of the composite depends on the nanoparticle content and the energetic interactions at the polymer/particle interface. The objective of this research was to determine experimentally the rheological properties of the PLEOF/apatite composite as an injectable biomaterial and to compare the viscoelastic response with the predictions of a linear elastic dumbbell model. A degradable in situ cross-linkable terpolymer based on low molecular weight poly(L-lactide) and poly(ethylene oxide) linked by unsaturated fumarate groups is synthesized. The poly(L-lactide-co-ethylene oxide-co-fumarate) (PLEOF) terpolymer interacts with the surface of the apatite nanoparticles by polar interactions and hydrogen bonding. A kinetic model is developed that takes into account the adsorption/desorption of polymer chains to/from the nanoparticle surface. Rheological properties of the aqueous dispersion of PLEOF terpolymer reinforced with nanosized hydroxyapatite (HA) particles are investigated using mechanical rheometry. To this end, we performed a series of rheological experiments on un-cross-linked PLEOF reinforced with different volume fractions of HA nanoparticles. The results demonstrate that the observed nonlinear viscoelasticity at higher shear rates is controlled by the energetic interactions between the polymer chains and dispersed particle aggregates and by the rate of the adsorption/desorption of the chains to/from the surface of the nanoparticles.

  13. Rheological properties of nanofiltered Athabasca bitumen and Maya crude oil

    Czech Academy of Sciences Publication Activity Database

    Hasan, M.D.A.; Fulem, Michal; Bazyleva, A.; Shaw, J.M.

    2009-01-01

    Roč. 23, - (2009), s. 5012-5021 ISSN 0887-0624 Institutional research plan: CEZ:AV0Z10100521 Keywords : viscosity * rheology * Athabasca bitumen * Maya crude oil * phase behavior * asphaltenes * nanofiltration Subject RIV: JJ - Other Materials Impact factor: 2.319, year: 2009

  14. Tentative hierarchization of the influence of milk properties and technological practices on rheological properties of Abondance cheese.

    Science.gov (United States)

    Tessier, Laurent; Bugaud, Christophe; Buchin, Solange

    2003-11-01

    An attempt at classifying the influence of different characteristics of milk and cheesemaking on the rheological properties of Abondance cheese is presented. Abondance is a traditional farmhouse French hard cheese with protected denomination of origin (PDO). Thirty-nine cheeses made from unpasteurized cows' milk were sampled. Spline partial least squares regression was used to relate milk properties and cheesemaking practices to rheological properties of the six-month-old cheeses. These properties were the deformability modulus and the strain and stress at fracture measured by compression. Milk properties and technological practices had overall the same degree of relationship with the rheological properties investigated: plasminogen-derived activity in milk and mineral-protein equilibrium, on the one hand, and brining and resting, on the other hand. However, acidification kinetics and 1-d pH, which result from both milk properties and technological practices, showed the strongest relationships with rheological characteristics. Factors that were most appropriate for modelling Abondance rheological properties are discussed.

  15. Physicochemical, pasting, rheological, thermal and morphological properties of horse chestnut starch.

    Science.gov (United States)

    Rafiq, Syed Insha; Jan, Kulsum; Singh, Sukhcharn; Saxena, D C

    2015-09-01

    Indian Horse chestnuts contain high content of starch which can be explored to be used in various applications in food industry as encapsulating agent, stabilizer, binder, thickener, gelling agents and many more. Horse chest nut is locally available and can be a boon for food industry if the inherent properties are explored. Hence, horse chest nut starch can be a better option for the replacement of conventional starches to meet the industrial demand of starch. Physicochemical, pasting, rheological, thermal and morphological properties of starch isolated from Indian Horse chestnut (HCN) were determined. Amylose content was found to be 26.10 %. Peak viscosity obtained from RVA profile was 4110 cP. Hardness, cohesiveness, adhesiveness and gumminess were determined by Texture Profile Analyser. Particle size analysis showed a typical Uni modal size distribution profile with particle distribution ranging from 7.52 to 27.44 μm. The shape of starch granules varied from round, irregular, oval, and elliptical with smooth surface. X- ray diffraction revealed that HCN starch showed a typical C-type pattern with characteristic peaks at 5.7, 15.0, 17.3 and 22.3°. The transition temperatures (To, Tp, and Tc) and enthalpy of gelatinization (ΔH) values were 53.35, 58.81, 63.57 °C and 8.76 J/g, respectively. The rheological properties were determined in terms of variation of storage modulus (G (/)), loss modulus (G (//)) and loss factor (tan δ) at different temperatures. Peak G (/), peak G (//) and peak tan δ values were observed as 10,400 Pa, 1,710 Pa, and 0.164, respectively.

  16. Effects of advera® warm mix additive on the rheological properties ...

    African Journals Online (AJOL)

    The performance of asphalt pavement is mainly governed by the properties of the binder. Many asphalt pavement distress are pronounced to be related to the rheological properties of asphalt binder. The oxidation changes the structure and composition of asphalt binder resulting stiffer and brittle of asphalt. This paper ...

  17. Green Polymers in Personal Care Products: Rheological Properties of Tamarind Seed Polysaccharide

    Directory of Open Access Journals (Sweden)

    Alessandra Semenzato

    2014-12-01

    Full Text Available Tamarind seed polysaccharide (TSP is a xyloglucan of vegetable origin, recently proposed for the cosmetic and pharmaceutical market as a “green” alternative to hyaluronic acid. In this study, TSP water dispersions, at different concentrations, were characterized by means of rheological measurements, both in continuous and oscillatory flow conditions. The results were compared with those of hyaluronic acid of two different molecular weights. The results pointed out the close rheological behaviors between TSP and hyaluronic acid with comparable molecular weight. Afterwards, the structural features of binary and ternary polysaccharide associations prepared with TSP, hyaluronic acid (very high MW and dehydropolysaccharide gum, a modified xanthan gum, with high stabilizing properties, were investigated. The rheological properties were significantly affected by the polysaccharide ratios in the mixture, suggesting that the combination of TSP with other polymers can lead to a modulation of the texture and functional properties of cosmetics.

  18. Effect of pulsed electric field on the rheological and colour properties of soy milk.

    Science.gov (United States)

    Xiang, Bob Y; Simpson, Marian V; Ngadi, Michael O; Simpson, Benjamin K

    2011-12-01

    The effects of pulsed electric field (PEF) treatments on rheological and colour properties of soy milk were evaluated. Flow behaviour, viscosity and rheological parameters of PEF-treated soy milk were monitored using a controlled stress rheometer. For PEF treatments, electric field intensity of 18, 20 and 22 kV cm(-1) and number of pulses of 25, 50, 75 and 100 were used. For the measurements of rheological properties of soy milk shear rates between 0 and 200 s(-1) was used. The rheological behaviour of control and the PEF-treated soy milk were described using a power law model. The PEF treatments affected the rheological properties of soy milk. Apparent viscosity of soy milk increased from 6.62 to 7.46 (10(-3) Pa s) with increase in electric field intensity from 18 to 22 kV cm(-1) and increase in the number of pulses from 0 to 100. The consistency index (K) of soy milk also changed with PEF treatments. Lightness (L*), red/greenness (a*) and yellowness/blueness (b*) of soy milk were affected by PEF treatments.

  19. Modifying the rheological properties of melter feed for the Hanford Waste Vitrification Plant

    International Nuclear Information System (INIS)

    Blair, H.T.; McMakin, A.H.

    1986-03-01

    Selected high-level nuclear wastes from the Hanford Site may be vitrified in the future Hanford Waste Vitrification Plant (HWVP) by Rockwell Hanford Company, the contractor responsible for reprocessing and waste management at the Hanford Site. The Pacific Northwest Laboratory (PNL), is responsible for providing technical support for the HWVP. In this capacity, PNL performed rheological evaluations of simulated HWVP feed in order to determine which processing factors could be modified to best optimize the vitrification process. To accomplish this goal, a simulated HWVP feed was first created and characterized. Researchers then evaluated how the chemical and physical form of the glass-forming additives affected the rheological properties and melting behavior of melter feed prepared with the simulated HWVP feed. The effects of adding formic acid to the waste were also evaluated. Finally, the maximum melter feed concentration with acceptable rheological properties was determined

  20. RHEOLOGICAL PROPERTIES OF RAPESEED OIL AND HYDRAULIC OIL

    Directory of Open Access Journals (Sweden)

    IOANA STANCIU

    2012-06-01

    Full Text Available This article presents the rheological behavior of refined rapeseed oil and hydraulic oil. Apparent viscosity of both oils was determined at temperatures between 40 and 90°C and shear rates ranging from 3.3 to 120 s-1. The aim of the study was to find a polynomial dependence of oil viscosity on temperature and shear rate. The modified Andrade equation was used. Constants A, B, C and correlation coefficient were determined by correlating a characteristic polynomial equation of each curve.

  1. Effect of Oxidative Enzymes on Bulk Rheological Properties of Wheat Flour Doughs

    NARCIS (Netherlands)

    Dunnewind, B.; Vliet, van T.; Orsel, R.

    2002-01-01

    The use of enzymes such as peroxidases or glucose oxidase instead of chemical oxidants is a very interesting option for improving breadmaking performance of doughs. In this study the effect of such enzymes on bulk rheological properties of dough was quantified and their influence on the polymer

  2. Effect of oxidative enzymes on bulk rheological properties of wheat flour doughs

    NARCIS (Netherlands)

    Dunnewind, B.; Vliet, T. van; Orsel, R.

    2002-01-01

    The use of enzymes such as peroxidases or glucose oxidase instead of chemical oxidants is a very interesting option for improving breadmaking performance of doughs. In this study the effect of such enzymes on bulk rheological properties of dough was quantified and their influence on the polymer

  3. Rheological Properties of Extreme Pressure Greases Measured Using a Process Control Rheometer

    DEFF Research Database (Denmark)

    Glasscock, Julie; Smith, Robin S.

    2012-01-01

    A new process control rheometer (PCR) designed for use in industrial process flows has been used to measure the rheological properties of three extreme-pressure greases. The rheometer is a robust yet sensitive instrument designed to operate in an industrial processing environment in either in...

  4. Structure and rheological properties of acid-induced egg white protein gels

    NARCIS (Netherlands)

    Weijers, M.; Velde, F. van de; Stijnman, A.; Pijpekamp, A. van de; Visschers, R.W.

    2006-01-01

    This study compares the rheological properties of acid-induced gels prepared of industrial spray-dried egg white proteins (EWP) with the acid-induced gels prepared of ovalbumin (OA) and whey protein isolate (WPI). Also we aimed to form transparent gels of EWP by means of the cold-gelation process.

  5. The role of mixing temperature on microstructure and rheological properties of butter blends

    DEFF Research Database (Denmark)

    Buldo, Patrizia; Wiking, Lars

    2012-01-01

    The present study demonstrated that the rheological properties of butter blends can be modified by the applied mixing temperature. Blends were prepared by mixing 10 or 25% of rapeseed oil (RO) with butter, at three different temperatures (13, 18 and 23 °C). Afterwards the blends were stored at 5 ...

  6. The effect of measuring procedure on the apparent rheological properties of self-compacting concrete

    DEFF Research Database (Denmark)

    Geiker, Mette Rica; Bradl, M.; Thrane, L.N.

    2002-01-01

    Torque versus time during testing of the rheological properties of fresh concrete has been investigated. The testing was performed in a BML viscometer and on a self-compacting concrete (w/c = 0.45, 70% rapid hardening Portland cement, 3% silica fume, 27% fly ash, third generation superplasticizer...

  7. Effect of storage time and temperature on the rheological and microstructural properties of gluten

    NARCIS (Netherlands)

    Nicolas, Y.; Smit, R.J.M.; van Aalst, H.; Esselink, F.J.; Weegels, P.L.; Agterof, W.G.M.

    2003-01-01

    To investigate the effects of frozen storage on the rheological and microstructural properties of gluten, two model systems were investigated: System A, gluten and water; System B, gluten, water, and NaCl. The storage time was varied from 1 to 16 weeks and the storage temperature was varied from -5

  8. Influence of the dosing process on the rheological and microstructural properties of a bakery product

    NARCIS (Netherlands)

    Baixauli, R.; Sanz, T.; Salvador, A.; Fisman, S.M.

    2007-01-01

    This study examined the effect of the use of an automatic dosing unit on the rheological, microstructural, and textural properties of an aerated batter for preparing a bakery product. Two cases were studied: in one the batter was dosed manually into the paper cups and in the other the batter was

  9. Relations between rheological properties, saliva-induced structure breakdown and sensory texture attributes of custards

    NARCIS (Netherlands)

    Janssen, A.M.; Terpstra, M.E.J.; Wijk, R.A.de; Prinz, J.F.

    2007-01-01

    The relevance of initial rheological properties and mechanical and enzymatic structure breakdown in determining selected sensory texture attributes of custards was studied. The so-called structure breakdown cell was used to characterize saliva-induced breakdown, i.e., by monitoring digestion of

  10. Cytokine profile in psoriatic arthritis: search for relationships with inflammation and blood rheological properties

    Directory of Open Access Journals (Sweden)

    Tat'yana Viktorovna Korotaeva

    2011-01-01

    Conclusion. The enhanced clinical and laboratory activity of PSA is attended by the systemic activation of immunological mediators of inflammation and neoangiogenesis and by impaired blood rheological properties, which supports the interaction of these factors in the immunopathogenesis of the diseases.

  11. Fat droplet characteristics affect rheological, tribological and sensory properties of food gels

    NARCIS (Netherlands)

    Liu, K.; Stieger, M.A.; Linden, van der E.; Velde, van de F.

    2015-01-01

    This work aims to investigate the effect of fat droplet characteristics in emulsion-filled gels on their dynamic rheological, tribological and microstructure properties during breakdown, and their sensory perceptions. Fat droplet characteristics investigated were the interaction of the fat droplet

  12. Rheology Effects on Predicted Fiber Orientation and Elastic Properties in Large Scale Polymer Composite Additive Manufacturing

    Directory of Open Access Journals (Sweden)

    Zhaogui Wang

    2018-02-01

    Full Text Available Short fiber-reinforced polymers have recently been introduced to large-scale additive manufacturing to improve the mechanical performances of printed-parts. As the short fiber polymer composite is extruded and deposited on a moving platform, velocity gradients within the melt orientate the suspended fibers, and the final orientation directly affects material properties in the solidified extrudate. This paper numerically evaluates melt rheology effects on predicted fiber orientation and elastic properties of printed-composites in three steps. First, the steady-state isothermal axisymmetric nozzle melt flow is computed, which includes the prediction of die swell just outside the nozzle exit. Simulations are performed with ANSYS-Polyflow, where we consider the effect of various rheology models on the computed outcomes. Here, we include Newtonian, generalized Newtonian, and viscoelastic rheology models to represent the melt flow. Fiber orientation is computed using Advani–Tucker fiber orientation tensors. Finally, elastic properties in the extrudate are evaluated based from predicted fiber orientation distributions. Calculations show that the Phan–Thien–Tanner (PTT model yields the lowest fiber principal alignment among considered rheology models. Furthermore, the cross section averaged elastic properties indicate a strong transversely isotropic behavior in these composites, where generalized Newtonian models yield higher principal Young’s modulus, while the viscoelastic fluid models result in higher shear moduli.

  13. Rheological properties of biscuit dough from different cultivars, and relationship to baking characteristics

    DEFF Research Database (Denmark)

    Pedersen, L.; Kaack, K.; Bergsøe, M.N.

    2004-01-01

    Rheological properties of semi-sweet biscuit doughs from eight wheat cultivars were studied, and related to the dimensional changes of biscuits after cutting and baking. The tested cultivars were selected in order to represent a wide diversity in biscuit baking performance, and were grown with low...

  14. Synthesis and Rheological Properties of an Associative Star Polymer in Aqueous Solutions

    DEFF Research Database (Denmark)

    Hietala, Sami; Mononen, Pekka; Strandman, Satu

    2007-01-01

    Rheological properties of aqueous solutions and hydrogels fonned by an amphiphiIic star block copolymer poly(acrylic acid)-blockpolystyrene (PAAS4-b-PS6)4. were investigated as a function of the polymer concentration (Cp), temperature, and added saIt concentration. The water-soluble polymer...

  15. Solid state polymerization: its action on thermal and rheological properties of PET/PC reactive blends

    Directory of Open Access Journals (Sweden)

    Luis C. Mendes

    2013-01-01

    Full Text Available The solid state polymerization (SSP of PET/PC reactive extrusion blends - with and without cobalt catalyst - at different polymer ratios was studied. Thermal and rheological evaluations were performed. DSC results showed changes in the PET's Tg, Tch, Tm and Xc.. The melt flow rate (MFR decreased for PET and the blends. The intrinsic viscosity increased. The variation in calorimetric and rheological properties might be attributed to the PET's chain extension reactions - esterification and transesterification. These reactions led to an increase in the PET's molar mass, consequently shifting the PET's Tg to lower temperature and PET's crystallization, besides reducing the blend miscibility and flowability.

  16. Effects of ripening on rheological properties of avocado pulp (Persea americana mill. Cv. Hass)

    Science.gov (United States)

    Osorio, F.; Roman, A.; Ortiz, J.

    2015-04-01

    Avocado (Persea americana Mill) Hass variety is the most planted in Chile with a greater trade prospect. The aim of this study was to investigate the effect of maturity on rheological properties of Chilean Avocado Hass pulp. Fresh unripe avocados were washed and peeled, cut and stored at 3 different times; a portion was treated at 5°C and the other was treated at 20°C until it reached 2 lb puncture pressure. During maturation changes would develop due to temperature and time, with internal cellular structure changes. Preliminary results of the rheological characteristics of avocado puree show a Bingham plastic behavior.

  17. Rheological Properties of Silica Nanoparticles in Brine and Brine-Surfactant Systems

    Science.gov (United States)

    Pales, Ashley; Kinsey, Erin; Li, Chunyan; Mu, Linlin; Bai, Lingyun; Clifford, Heather; Darnault, Christophe

    2016-04-01

    Rheological Properties of Silica Nanoparticles in Brine and Brine-Surfactant Systems Ashley R. Pales, Erin Kinsey, Chunyan Li, Linlin Mu, Lingyun Bai, Heather Clifford, and Christophe J. G. Darnault Department of Environmental Engineering and Earth Sciences, Laboratory of Hydrogeoscience and Biological Engineering, L.G. Rich Environmental Laboratory, Clemson University, Clemson, SC, USA Nanofluids are suspensions of nanometer sized particles in any fluid base, where the nanoparticles effect the properties of the fluid base. Commonly, nanofluids are water based, however, other bases such as ethylene-glycol, glycerol, and propylene-glycol, have been researched to understand the rheological properties of the nanofluids. This work aims to understand the fundamental rheological properties of silica nanoparticles in brine based and brine-surfactant based nanofluids with temperature variations. This was done by using variable weight percent of silica nanoparticles from 0.001% to 0.1%. Five percent brine was used to create the brine based nanofluids; and 5% brine with 2CMC of Tween 20 nonionic surfactant (Sigma-Aldrich) was used to create the brine-surfactant nanofluid. Rheological behaviors, such as shear rate, shear stress, and viscosity, were compared between these nanofluids at 20C and at 60C across the varied nanoparticle wt%. The goal of this work is to provide a fundamental basis for future applied testing for enhanced oil recovery. It is hypothesized that the addition of surfactant will have a positive impact on nanofluid properties that will be useful for enhance oil recovery. Differences have been observed in preliminary data analysis of the rheological properties between these two nanofluids indicating that the surfactant is having the hypothesized effect.

  18. Controlling polypropylene rheological properties by promoting organic peroxide during extrusion with improved properties for automotive applications

    Science.gov (United States)

    Herlambang, Bayu; Sandytama

    2017-05-01

    Excellent stability and processability of Controlled-Rheology Polypropylene (CRPP) was mandatory parameters especially for automotive application. Selected organic peroxide which was used to control the rheology of PP should perform good stability in physical properties due to pre-process of compounding for automotive application. The common organic peroxide that widely used is 2,5-dimethyl-2,5-di-tert-butylperoxyhexane (DHBP). However, the problems that usually encountered are Melt Flow Index (MFI) stability, initial color, and the odor which come from decomposition process. Research and Development (RND) team of PT Chandra Asri Petrochemical, Tbk (CAP) did the study to change the type of organic peroxide to 3,6,9-triethyl-3,6,9,-trimethyl-l,4,7-triperoxonane (TETMTPA) which was intended to improve these inferiorities when using DHBP. The results indicate better MFT stability, better initial color, and less odor when using TETMTPA than DHBP. This superiority is very applicable particularly for automotive application. Detailed analysis about volatile decomposition product from both peroxide indicated CRPP with TETMTPA has lower volatile compound which result lower odor level than CRPP with DHBP.

  19. Rheological and electrical properties of hybrid nanocomposites of epoxy resins filled with graphite nanoplatelets and carbon black.

    Science.gov (United States)

    Truong, Quang-Trung; Lee, Seon-Suk; Lee, Dai-Soo

    2011-02-01

    Graphite nanoplatelets (GNP) were prepared by microwave irradiation of natural graphites intercalated with ferric chloride in nitromethane (GIC). Intercalated structure of GIC was confirmed by X-ray diffraction patterns. SEM images of GIC after microwave irradiation showed the exfoliation of GIC, the formation of GNPs. Hybrid nanocomposites of bisphenol-A type epoxy resins filled with GNP and a conductive carbon black (CB) were prepared and rheological and electrical properties of the nanocomposites were investigated. Viscosity and electrical surface resistivity of the nanocomposites showed minima at certain mixtures of GNP and CB in the epoxy resins.

  20. Analysis of the Magnetic Field Influence on the Rheological Properties of Healthy Persons Blood

    Directory of Open Access Journals (Sweden)

    Anna Marcinkowska-Gapinska

    2013-01-01

    Full Text Available The influence of magnetic field on whole blood rheological properties remains a weakly known phenomenon. An in vitro analysis of the magnetic field influence on the rheological properties of healthy persons blood is presented in this work. The study was performed on blood samples taken from 25 healthy nonsmoking persons and included comparative analysis of the results of both the standard rotary method (flow curve measurement and the oscillatory method known also as the mechanical dynamic analysis, performed before and after exposition of blood samples to magnetic field. The principle of the oscillatory technique lies in determining the amplitude and phase of the oscillations of the studied sample subjected to action of a harmonic force of controlled amplitude and frequency. The flow curve measurement involved determining the shear rate dependence of blood viscosity. The viscoelastic properties of the blood samples were analyzed in terms of complex blood viscosity. All the measurements have been performed by means of the Contraves LS40 rheometer. The data obtained from the flow curve measurements complemented by hematocrit and plasma viscosity measurements have been analyzed using the rheological model of Quemada. No significant changes of the studied rheological parameters have been found.

  1. Rheological Properties of Nanoparticle Silica-Surfactant Stabilized Crude Oil Emulsions: Influence of Temperature, Nanoparticle Concentration and Water Volume Fraction"

    Science.gov (United States)

    Kinsey, Erin; Pales, Ashley; Li, Chunyan; Mu, Linlin; Bai, Lingyun; Clifford, Heather; Darnault, Christophe

    2016-04-01

    Oil in water emulsions occur during oil extraction due to the presence of water, naturally-occurring surface-active agents and mechanical mixing in pipelines or from oil spillage. Emulsions present difficulties for use of oil in fuel and their rheological properties are important to treat environmental impacts of spills. The objective of this study is to assess the rheological characteristics of oil in water emulsions stabilized by 5% NaCl brine, Tween 20 surfactant and silica nanoparticles to gain knowledge about the behavior of oil flow in pipelines and characterize them for environmental applications. Rheological behaviors such as shear rate, shear stress, and viscosity of Prudhoe Bay crude oil emulsions were analyzed with varying percent of water volume fractions (12.5, 25 and 50%), varying weight percent of silica nanoparticles (0.001, 0.01 and 0.1 weight %), with and without 2 CMC Tween 20 nonionic surfactant. Emulsions with varying water volume fractions were analyzed at 20, 40 and 60 degrees Celsius. Flow curve analysis of the emulsions was performed using an Anton-Paar rheometer. Preliminary findings indicate that increased temperature and increasing the concentration of nanoparticles both produced lower shear stress and that the addition of surfactant decreased the viscosity and shear stress of the emulsions.

  2. Comparative Effects of MMT Clay Modified with Two Different Cationic Surfactants on the Thermal and Rheological Properties of Polypropylene Nanocomposites

    Directory of Open Access Journals (Sweden)

    Meshal Al-Samhan

    2017-01-01

    Full Text Available Polypropylene montmorillonite (MMT nanocomposites were prepared by melt blending using two different organoclays modified with imidazolium and alkylammonium surfactants. The imidazolium and ammonium modified organoclays were characterized by the FTIR and SEM analysis. The effect of organic clay (MMT on the physical properties of polypropylene was evaluated, thermal and rheological properties with different filler weight percentage. Differential scanning calorimetric results showed that imidazolium modified clay (IMMT exhibits low melting temperature compared to the ammonium modified clay (AMMT. The crystallinity analysis showed that crystallization improved in all nanocomposites irrespective of surface modification; the thermogravimetric analysis showed that the imidazolium modified polymer composites are more thermally stable than conventional ammonium modified composites. The Transmission Electron Microscopy (TEM analyses indicated that the PP-IMMT composites displayed exfoliated morphologies compared with the intercalated structure in PP-AMMT, and the rheological analysis at 180°C showed an enhancement in the viscoelastic properties as the clay concentration increases. The melt viscosity, crossover modulus, and relaxation times were comparable for both the surface modified composites with two different cations. The imidazolium based surfactant was found to be an effective organic modification for MMT to prepare thermally stable PP/MMT nanocomposites.

  3. Solid Character of Membrane Ceramides: A Surface Rheology Study of Their Mixtures with Sphingomyelin

    Science.gov (United States)

    Catapano, Elisa R.; Arriaga, Laura R.; Espinosa, Gabriel; Monroy, Francisco; Langevin, Dominique; López-Montero, Iván

    2011-01-01

    The compression and shear viscoelasticities of egg-ceramide and its mixtures with sphingomyelin were investigated using oscillatory surface rheology performed on Langmuir monolayers. We found high values for the compression and shear moduli for ceramide, compatible with a solid-state membrane, and extremely high surface viscosities when compared to typical fluid lipids. A fluidlike rheological behavior was found for sphingomyelin. Lateral mobilities, measured from particle tracking experiments, were correlated with the monolayer viscosities through the usual hydrodynamic relationships. In conclusion, ceramide increases the solid character of sphingomyelin-based membranes and decreases their fluidity, thus drastically decreasing the lateral mobilities of embedded objects. This mechanical behavior may involve important physiological consequences in biological membranes containing ceramides. PMID:22261061

  4. Influence of hydroxypropylmethyl cellulose-sodium laurylsulfate interaction on rheological properties of the solution

    Directory of Open Access Journals (Sweden)

    Šaletić Jelena V.

    2004-01-01

    Full Text Available Interactions between the polymers and surfactants in solution have widely been investigated because of their scientific and technological importance. These interactions can be utilized to modify the physicochemical properties of system in many food products, pharmaceutical formulations, personal care products, paints, pesticides, etc. Interaction between nonionic polymer - hydroxypropylmethyl cellulose (HPMC and anionic surfactant - sodium laurylsulfate (SDS in solution has been investigated in this paper by rheological measurements. Rheological measurements are performed by rotational viscometer at 20°C and changes of rheological characteristics of HPMC solutions (0.5-1.5% with increasing SDS concentrations (0-4.0% were determined. The results of these investigations showed that viscosity of the solution is dependant on HPMC-SDS interaction. At particular SDS concentration viscosity increases, reach maximum and after that decreases until reach constant value. From the viscosity changes the characteristic concentrations of SDS, critical aggregation concentration (cac and polymer saturation point (psp, were determined. These concentrations are in linear relationships with HPMC concentrations. Rheological properties of the solution are strong influenced by HPMC-SDS interaction and exhibits more or less pronounced pseudoplastic behavior, which changes to Newtonian one after the psp has been reached.

  5. Rheological Properties with Temperature Response Characteristics and a Mechanism of Solid-Free Polymer Drilling Fluid at Low Temperatures

    Directory of Open Access Journals (Sweden)

    Sheng Wang

    2016-12-01

    Full Text Available The rheological properties of drilling fluid have important effects during drilling in natural gas hydrate at low temperatures. The present study was performed using theoretical analysis. Experiments and micro-analyses were carried out to determine the rheological properties with temperature response characteristics and the mechanism involved in solid-free polymer drilling fluid (SFPDF at low temperatures when drilling in permafrost with natural gas hydrates (NGH. The curves of shear stress with the shear rates of three kinds of polymer drilling fluids, Semen Lepidii natural vegetable gum, polyacrylamide, and xanthan gum, were drawn. Then, statistical and related analyses of test data were performed using Matlab ver. 8.0. Through regression analysis, the Herschel–Bulkley model was used to characterize the rheological characteristics of SFPDF. On this basis, the laws regarding the rheological properties of the three kinds of SFPDF under changing temperatures were analyzed and rheological properties with temperature response state equations were established. Next, the findings of previous studies on rheological properties with temperature response characteristics of the SFPDF were reviewed. Finally, the rheological properties with temperature response mechanisms were assessed using scanning electron microscopy and infrared spectrum analysis.

  6. Rheological properties of poly(vinyl alcohol) (PVA) derived composite membranes for fuel cells

    International Nuclear Information System (INIS)

    Remiš, T

    2017-01-01

    Rheological properties of new anhydrous proton conducting membrane based on PVA, tetraethyl orthosilicate (TEOS),sulfosuccinic acid (SSA), titanium dioxide (TiO 2 )was examined at various stoichiometric ratios. SSA was used as sulfonating agents to form a crosslinked structure and as proton source, whereas TEO Sand TiO 2 were utilized to improve the thermal and mechanical properties of the membrane. In order to verify that all the substances were immobilized into the matrix, the membranes were analysed by means of FT-IR. The rheological, mechanical and thermal properties of the membranes were investigated using rheometer ARES G2 and thermogravimetic analyser (TGA).The analysis of mixed PVA solutions exhibited a unique behaviour of viscosity with increased crosslink density. The dynamic storage modulus G´ of dried composite membranes shows better mechanical resistance and increased tolerance to pressure applied during membrane electrode assembly (MEA). (paper)

  7. Rheological properties of poly(vinyl alcohol) (PVA) derived composite membranes for fuel cells

    Science.gov (United States)

    Remiš, T.

    2017-01-01

    Rheological properties of new anhydrous proton conducting membrane based on PVA, tetraethyl orthosilicate (TEOS),sulfosuccinic acid (SSA), titanium dioxide (TiO2)was examined at various stoichiometric ratios. SSA was used as sulfonating agents to form a crosslinked structure and as proton source, whereas TEO Sand TiO2were utilized to improve the thermal and mechanical properties of the membrane. In order to verify that all the substances were immobilized into the matrix, the membranes were analysed by means of FT-IR. The rheological, mechanical and thermal properties of the membranes were investigated using rheometer ARES G2 and thermogravimetic analyser (TGA).The analysis of mixed PVA solutions exhibited a unique behaviour of viscosity with increased crosslink density. The dynamic storage modulus G´ of dried composite membranes shows better mechanical resistance and increased tolerance to pressure applied during membrane electrode assembly (MEA).

  8. Study of irradiation effect of wheat flour on microbiological properties and on rheology of obtained dough

    International Nuclear Information System (INIS)

    Salem, Senda

    2008-01-01

    The purpose of this work is to study the effect of the irradiation by gamma rays in 1, 2, and 3 kGy on the microbiological and physico-chemical properties of the wheat flour, and on dough rheology. The rheological properties, studied by a compression-relaxation test in greased conditions are estimated by an analysis of variance approach and repeatability studies. Results show that irradiation has no effect on relaxation properties of dough. On the other hand we registered an increase of the falling number. Bread making essay shows that a dose lower than 2 kGy increased the bread volume. Reduction of the microbial load according to the dose of irradiation is also observed. (Author)

  9. Importance of physical vs. chemical interactions in surface shear rheology

    NARCIS (Netherlands)

    Wierenga, P.A.; Kosters, H.; Egmond, M.R.; Voragen, A.G.J.; Jongh, H.H.J. de

    2006-01-01

    The stability of adsorbed protein layers against deformation has in literature been attributed to the formation of a continuous gel-like network. This hypothesis is mostly based on measurements of the increase of the surface shear elasticity with time. For several proteins this increase has been

  10. Rheological Characteristics of Cement Grout and its Effect on Mechanical Properties of a Rock Fracture

    Science.gov (United States)

    Liu, Quansheng; Lei, Guangfeng; Peng, Xingxin; Lu, Chaobo; Wei, Lai

    2018-02-01

    Grouting reinforcement, which has an obvious strengthening effect on fractured rock mass, has been widely used in various fields in geotechnical engineering. The rheological properties of grout will greatly affect its diffusion radius in rock fractures, and the water-cement ratio is an important factor in determining the grouting flow patterns. The relationship between shear stress and shear rate which could reflect the grout rheological properties, the effects of water-cement ratio, and temperature on the rheological properties of grouting was studied in the laboratory. Besides, a new method for producing fractured rock specimens was proposed and solved the problem of producing natural fractured rock specimens. To investigate the influences of grouting on mechanical properties of a rock fracture, the fractured rock specimens made using the new method were reinforced by grouting on the independent designed grouting platform, and then normal and tangential mechanical tests were carried out on fractured rock specimens. The results showed that the mechanical properties of fractured rock mass are significantly improved by grouting, the peak shear strength and residual strength of rock fractures are greatly improved, and the resistance to deformation is enhanced after grouting. Normal forces affect the tangential behavior of the rock fracture, and the tangential stress strength increases with normal forces. The strength and stability of fractured rock mass are increased by grouting reinforcement.

  11. Cooling of a channeled lava flow with non-Newtonian rheology: crust formation and surface radiance

    Directory of Open Access Journals (Sweden)

    Stefano Santini

    2011-12-01

    Full Text Available We present here the results from dynamical and thermal models that describe a channeled lava flow as it cools by radiation. In particular, the effects of power-law rheology and of the presence of bends in the flow are considered, as well as the formation of surface crust and lava tubes. On the basis of the thermal models, we analyze the assumptions implicit in the currently used formulae for evaluation of lava flow rates from satellite thermal imagery. Assuming a steady flow down an inclined rectangular channel, we solve numerically the equation of motion by the finite-volume method and a classical iterative solution. Our results show that the use of power-law rheology results in relevant differences in the average velocity and volume flow rate with respect to Newtonian rheology. Crust formation is strongly influenced by power-law rheology; in particular, the growth rate and the velocity profile inside the channel are strongly modified. In addition, channel curvature affects the flow dynamics and surface morphology. The size and shape of surface solid plates are controlled by competition between the shear stress and the crust yield strength: the degree of crust cover of the channel is studied as a function of the curvature. Simple formulae are currently used to relate the lava flow rate to the energy radiated by the lava flow as inferred from satellite thermal imagery. Such formulae are based on a specific model, and consequently, their validity is subject to the model assumptions. An analysis of these assumptions reveals that the current use of such formulae is not consistent with the model.

  12. Rheological and electrical properties used to investigate the coagulation process during sludge treatment.

    Science.gov (United States)

    Mortadi, A; El Melouky, A; Chahid, E; Nasrellah, H; Bakasse, M; Zradba, A; Cherkaoui, O; El Moznine, R

    2018-01-01

    Analyses of rheological properties and electrical conductivity (σ dc ) at direct current have been employed in order to investigate the effects of calcium oxide on the coagulation process during sludge treatment in the textile industry. In this context, rheological and electrical measurements were performed on five samples - one that contained raw sludge and the other four that were prepared from the raw sludge and different amounts of calcium oxide: 2, 3, 4, 5% (w/w). Rheological behavior of these samples was analyzed using the Herschel-Bulkley modified model. The influence of calcium oxide content on the rheological parameters such as infinite viscosity, the yield stress, the consistency coefficient, and the consistency index, are presented and discussed. The impact of the calcium oxide content on pH and conductivity were also examined. Similar behaviors have been seen in the evolution of conductivity and infinite viscosity as a function of the calcium oxide content. These latter characteristics were modeled by an equation using two power laws. This equation was able to fit very well the evolution of electrical conductivity and also the viscosity versus the percentage of calcium oxide to predict the optimal amount of calcium oxide (3%) to achieve the coagulation step during sludge treatment.

  13. In situ measurement of the rheological properties and agglomeration on cementitious pastes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae Hong [School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan 44919 (Korea, Republic of); Yim, Hong Jae, E-mail: yimhj@knu.ac.kr [Department of Construction and Disaster Prevention Engineering, Kyungpook National University, 2559 Gyeongsang-daero, Sangju, Gyeongsangbuk-do 742-711 (Korea, Republic of); Ferron, Raissa Douglas [Department of Civil, Architectural and Environmental Engineering, University of Texas at Austin, 301 East Dean Keeton Street, C1748, Austin, Texas 78712 (United States)

    2016-07-15

    Various factors influence the rheology of cementitious pastes, with the most important being the mixing protocol, mixture proportions, and mixture composition. This study investigated the influence of ground-granulated blast-furnace slag, on the rheological behavior of cementitious pastes. In tandem with the rheological measurements, fresh state microstructural measurements were conducted using three different techniques: A coupled stroboscope-rheometer, a coupled laser backscattering-rheometer, and a conventional laser diffraction technique. Laser diffraction and the coupled stroboscope-rheometer were not good measures of the in situ state of flocculation of a sample. Rather, only the laser backscattering technique allowed for in situ measurement on a highly concentrated suspension (cementitious paste). Using the coupled laser backscattering-rheometer technique, a link between the particle system and rheological behavior was determined through a modeling approach that takes into account agglomeration properties. A higher degree of agglomeration was seen in the ordinary Portland cement paste than pastes containing the slag and this was related to the degree of capillary pressure in the paste systems.

  14. Optimization Of Rheological Properties In The Formulation Of An Ointment Base From Natural Ingredients

    Directory of Open Access Journals (Sweden)

    R. K. Tsatsop

    2017-09-01

    Full Text Available The purpose of this study was to optimize the formulation of ointment base by using statistical mixture design. Screening of hard thickeners Palm Stearin Beef Tallow and Beeswax was done to choose the best hard thickener or combination of hard thickeners whose nature and proportions would give the best semi-solid and consistent ointment with desired rheological properties Spreadability viscosity hardness. Contour plots of each response were depicted based on the equation given by the statistical-fitted models. The optimum area for the ointment base properties were located and the combination BeeswaxPalm stearinBeef Tallow was chosen. Other optimization was done to check the contribution of different factors Hard Thickener Soft Thickener and Lubricant on the rheological properties and their correlation. A strong inverse correlation was found to exist between the spreadability and the viscosity of the ointment base 91. A multi-response optimization was done to obtain a combined optimum proportion of ingredients that gave us 5 HT 84ST and 11 L. It can be concluded that the ointment base obtained with optimal rheological and drug release properties can be used for cosmetic and pharmacological applications. The plant extracts can be incorporated in this matrix for herbal ointments.

  15. Effect of Maltodextrins on the Rheological Properties of Potato Starch Pastes and Gels

    Directory of Open Access Journals (Sweden)

    Lesław Juszczak

    2013-01-01

    Full Text Available The study examines the effects of maltodextrins saccharified to various degrees on some rheological properties of potato starch dispersions. Pasting characteristics, flow curves, and mechanical spectra were determined for native potato starch and for its blends with potato maltodextrins having dextrose equivalents (DE of 10.5, 18.4, and 26.5. The results showed that medium-saccharified maltodextrin (DE = 18.4 gave the strongest effect, manifesting itself as a considerable reduction in the viscosity at pasting, a decrease in apparent viscosity during flow, and a decrease in the storage and loss moduli. Addition of high-(DE = 26.5 or low-(DE = 10.5 saccharified maltodextrins had a markedly smaller effect on the rheological properties of starch. The differences in the effects produced by the maltodextrins are closely connected to the degree of polymerisation of the maltooligosaccharides in the systems.

  16. Infuence of gamma radiation on the rheological and functional properties of bread wheats

    International Nuclear Information System (INIS)

    Paredes-Lopez, O.; Covarrubias-Alvarez, M.M.

    1984-01-01

    The effects of gamma irradiation on some biochemical, rheological and functional properties of bread wheats were studied. Two wheat cultivars were selected to represent medium-strong and weak dough mixing strengths. Falling number values were severely depressed at doses of 500 and 1000 krad. Rheological dough properties, as assessed with the mixograph and farinograph, were also investigated. Radiation at medium doses produced an increase in the farinograph water absorption for both wheats. Radiation decreased the amount of bound water as compared to the control sample. For the medium-strong wheat low levels of radiation produced bread with volumes and overall bread quality equal to or slightly better than those of the control flour, whereas for the weak wheat an improvement of the baking performance was obtained at all the low doses of radiation. However, the overall bread quality of both wheats was highly reduced at medium doses of radiation. (author)

  17. Studying The Rheological Properties of Xanthan Cellulose Gum-Dioxide Titanium Nano-Composites

    Directory of Open Access Journals (Sweden)

    Abdulazeez O. Mousa Al-Ogaili

    2017-02-01

    Full Text Available In this paper, we investigated the rheological properties of xanthan cellulose gum(Xn dissolves in distilled water for different concentrations (0.1 , 0.2, …, 0.8% g/mL before and after adding (0.25 g of (TiO2 for each concentration. The rheological properties such as shear viscosity have been practically measured, but relative viscosity, specific viscosity, reduced viscosity and viscosity average molecular weight have been calculated, all the viscosities depend on density and concentration. The results show that adding (TiO2 led to increase the values of all types of viscosities before and after adding(TiO2.

  18. The influence of blend ratio on the morphology, mechanical, thermal, and rheological properties of PP/LDPE blends

    CSIR Research Space (South Africa)

    Mofokeng, TG

    2016-10-01

    Full Text Available This paper reports on how the blend ratio and morphology influence the mechanical, thermal, thermomechanical, and rheological properties of poly(propylene) (PP)/low density polyethylene (LDPE) blends. The blend morphology is composed of the major...

  19. Influence of boehmite nanoparticle loading on the mechanical, thermal, and rheological properties of biodegradable polylactide/ poly(e-caprolactone) blends

    CSIR Research Space (South Africa)

    Agwuncha, SC

    2015-01-01

    Full Text Available -1 Macromolecular Materials and Engineering Vol. 300(1), 31-47 Influence of Boehmite Nanoparticle Loading on the Mechanical, Thermal, and Rheological Properties of Biodegradable Polylactide/Poly(e-caprolactone) Blendsa Stephen C. Agwuncha, Suprakas Sinha...

  20. Study of polyacrylamide-surfactant system on the water–oil interface properties and rheological properties for EOR

    Directory of Open Access Journals (Sweden)

    S.Z. Mahdavi

    2017-12-01

    Full Text Available Nowadays, due to the remarkable oil reduction in oil fields, enhanced oil recovery (EOR techniques have been considered by a large number of scientists and company. Situ oil extraction is normally done by these techniques with high efficiency. In this particular study, five different surface active agents (surfactant, two kinds of oil with various API, two kinds of sulfonated polyacrylamide, two different electrolyte solutions with various TDS and two distinctive alcohols were tested and evaluated. An optimal formulation in terms of the properties and quantity of materials has to be used in order to enhance oil recovery, achieved by investigation of surface tension and the phase behavior of mentioned substances. Rheological behavior of polymer flooding and surfactant was studied. Employing this formulation, the maximum micro emulsion of oil in water occurred. Due to the synergy between surfactant and alcohol (as a co-surfactant, relatively lower amounts of surfactants were used which led to the dip in the cost of operation, and ultimately the efficiency of operation improved.

  1. Physicochemical, rheological and functional properties of fats and oils in relation to cookie quality: a review

    OpenAIRE

    Devi, Amita; Khatkar, B. S.

    2016-01-01

    Sincere efforts of researchers are underway to understand the functionality of different fats and oils in relation to cookie quality. The quality of cookie primarily relies upon the functionality of fats and oils in cookie system which ultimately is combined result of their physical, chemical, and rheological properties. Effects of some major fats and oils such as butter, bakery fat, hydrogenated fat, lard, margarine, palm oil, sunflower oil, coconut oil, and soybean oil on the physical and s...

  2. SOLAR ACTIVITY AND PECULIARITIES OF THE RHEOLOGICAL PROPERTIES OF THE BLOOD IN PATIENTS WITH ANGINA PECTORIS

    Directory of Open Access Journals (Sweden)

    T.N. Afanasjeva

    2008-03-01

    Full Text Available The peculiarities of the rheological properties of the blood are studied in patients with non-stable angina pectohs in different perbds of solar activity. It has been established, that in high solar activity hemorheological disorders are characterized by increase of blood viscosity and compensatory decrease oferythrocyte aggregation and increase of their deformation. In low solar activity less perceptible hyperviscositywas accompanied by significant increase oferythrocyte aggregation and decrease of their deformity capacity.

  3. Interfacial rheological properties and conformational aspects of soy glycinin at the air/water interface

    NARCIS (Netherlands)

    Martin, A.H.; Bos, M.A.; Vliet, T. van

    2002-01-01

    Interfacial (rheological) properties of soy glycinin were studied at different pH. At acidic and high alkaline pH glycinin (11S form, Mw ∼ 350 kDa) dissociates into smaller subunits, the so called 3S form (Mw ∼ 44 kDa) and 7S form (Mw ∼ 175 kDa). This dissociation behaviour is expected to affect the

  4. Physical, mechanical and rheological properties of polymers: test facilities and experiences

    International Nuclear Information System (INIS)

    Zahid Abdullah

    2005-01-01

    The laboratories in polymer pilot plant of BTPS, MINT TECH-PARK well equipped with various polymer testing facilities. The determination of physical, mechanical and rheological properties of polymers are very important not only for research purpose but also for characterizations of polymer products from industries. This paper illustrates the polymer testing facilities available at polymer pilot plant of BTPS. The discussion includes the list of equipment, applications, customers, experience and problem faced during the daily operation. (Author)

  5. Rheological Properties of Cemented Tailing Backfill and the Construction of a Prediction Model

    Directory of Open Access Journals (Sweden)

    Liu Lang

    2015-04-01

    Full Text Available Workability is a key performance criterion for mining cemented tailing backfill, which should be defined in terms of rheological parameters such as yield stress and plastic viscosity. Cemented tailing backfill is basically composed of mill tailings, Portland cement, or blended cement with supplementary cement material (fly ash and blast furnace slag and water, among others, and it is important to characterize relationships between paste components and rheological properties to optimize the workability of cemented tailing backfill. This study proposes a combined model for predicting rheological parameters of cemented tailing backfill based on a principal component analysis (PCA and a back-propagation (BP neural network. By analyzing experimental data on mix proportions and rheological parameters of cemented tailing backfill to determine the nonlinear relationships between rheological parameters (i.e., yield stress and viscosity and mix proportions (i.e., solid concentrations, the tailing/cement ratio, the specific weight, and the slump, the study constructs a prediction model. The advantages of the combined model were as follows: First, through the PCA, original multiple variables were represented by two principal components (PCs, thereby leading to a 50% decrease in input parameters in the BP neural network model, which covered 98.634% of the original data. Second, in comparison to conventional BP neural network models, the proposed model featured a simpler network architecture, a faster training speed, and more satisfactory prediction performance. According to the test results, any error between estimated and expected output values from the combined prediction model based on the PCA and the BP neural network was within 5%, reflecting a remarkable improvement over results for BP neural network models with no PCA.

  6. Rheological Properties of Cemented Tailing Backfill and the Construction of a Prediction Model

    Science.gov (United States)

    Lang, Liu; Song, KI-IL; Lao, Dezheng; Kwon, Tae-Hyuk

    2015-01-01

    Workability is a key performance criterion for mining cemented tailing backfill, which should be defined in terms of rheological parameters such as yield stress and plastic viscosity. Cemented tailing backfill is basically composed of mill tailings, Portland cement, or blended cement with supplementary cement material (fly ash and blast furnace slag) and water, among others, and it is important to characterize relationships between paste components and rheological properties to optimize the workability of cemented tailing backfill. This study proposes a combined model for predicting rheological parameters of cemented tailing backfill based on a principal component analysis (PCA) and a back-propagation (BP) neural network. By analyzing experimental data on mix proportions and rheological parameters of cemented tailing backfill to determine the nonlinear relationships between rheological parameters (i.e., yield stress and viscosity) and mix proportions (i.e., solid concentrations, the tailing/cement ratio, the specific weight, and the slump), the study constructs a prediction model. The advantages of the combined model were as follows: First, through the PCA, original multiple variables were represented by two principal components (PCs), thereby leading to a 50% decrease in input parameters in the BP neural network model, which covered 98.634% of the original data. Second, in comparison to conventional BP neural network models, the proposed model featured a simpler network architecture, a faster training speed, and more satisfactory prediction performance. According to the test results, any error between estimated and expected output values from the combined prediction model based on the PCA and the BP neural network was within 5%, reflecting a remarkable improvement over results for BP neural network models with no PCA.

  7. Comparison of rheological properties of graphene / carbon nanotube hydrogenated oil based biodegradable drilling fluid

    Science.gov (United States)

    Chai, Y. H.; Yusup, S.; Chok, V. S.; Irawan, S.; Singh, J. D. B. S.; Chin, B. L. F.

    2017-06-01

    An experimental investigation has been carried out to investigate the rheological properties of graphene / carbon nanotube hydrogenated oil based biodegradable drilling fluid at different nanoparticle loadings. The rheological behaviours of interest in this investigation are the viscosity and shear stresses of two different nanofluids respectively. The limiting parameters in this study are 25 ppm, 50 ppm and 100 ppm weight concentration at operating temperature ranging from 30°C to 50°C. Both nanofluids are subjected to shear rate ranging from 0 - 140 s-1 for comparison of rheological behaviours. Both samples’ viscosity reduces to base fluid’s viscosity value at higher shear rate with carbon nanotube-hydrogenated oil yielding higher viscosity compared to graphene-hydrogenated oil for all nanoparticle loadings at lower shear rate. Shear stress analysis also shows similar results with carbon nanotube based samples showing higher stress between the two at all particle loadings. Both samples show Newtonian behaviour that is similar to base fluid even at higher particle loadings. Analysis revealed both nanofluids yields close to zero yield stress even with the presence of graphene or carbon nanotube particles. The significance of this study shows that addition of low nanomaterials for enhancement of drilling fluids can improve its thermophysical properties without compromising the quality of drilling fluids such as viscosity and shear stress properties.

  8. Rheological properties of flowable resin composites and pit and fissure sealants.

    Science.gov (United States)

    Beun, Sébastien; Bailly, Christian; Devaux, Jacques; Leloup, Gaëtane

    2008-04-01

    The purpose of this research was to determine the viscoelastic properties of commercially available flowable resin composites and resin-based pit and fissure sealants. The weight percentage of filler particles and the morphology of the filler particles were also investigated. Eight flowable resin composites (Admira Flow, Filtek Flow, FlowLine, Grandio Flow, Point-4 Flowable, Revolution Formula 2, Tetric Flow and X-Flow) and four pit and fissure sealants (Clinpro, Delton FS+, Estiseal F and Guardian Seal) were tested. Rheological measurements were performed using a dynamic oscillation rheometer. The filler weight content was determined by thermogravimetric analysis (TGA) and the morphology of the particles was investigated by scanning-electron microscopy (SEM). Flowable resin composites are non-Newtonian, shear-thinning materials. As the shear rate increased, the complex viscosity decreased drastically. They all showed elasticity even at the lowest frequencies. They also all showed thixotropy. Pit and fissure sealants are non-Newtonian, very low-viscosity fluids. No correlation was found between the rheological properties and the filler weight content or the particles' shape. Huge differences are observed in the viscosity and flow characteristics of flowable resin composites that can have a potential influence on their clinical behavior during handling and thus on their clinical indications. Pit and fissure sealants show very different rheological properties from one another.

  9. Selected Rheological Properties of RS3/4 Type Resistant Starch

    Directory of Open Access Journals (Sweden)

    Kapelko-Żeberska Małgorzata

    2017-12-01

    Full Text Available This study was aimed at determining the effect of acetylation degree and crosslinking of retrograded starch with adipic acid on selected rheological properties of prepared pastes and gels. The esterification of retrograded starch allowed obtaining preparations with various degrees of substitution with residues of acetic (0.7–11.2 g/100 g and adipic acids (0.1–0.3 g/100 g. Acetylation and crosslinking caused a decrease in amylose content of the preparations (3–21 g/100 g. Solubility of the preparations in water, in a wide range of variability, was increasing along with an increasing degree of acetylation and with a decreasing degree of crosslinking (19–100 g/100 g. Values of most of the rheological coefficients determined based on the flow curves of the prepared pastes and mechanical spectra of gels (3.5rheological properties upon the effect of double modification were not the sum of changes proceeding as a result of single modifications. Instead, interaction of both factors was observed. The conducted modifications enable modelling the properties of produced preparations.

  10. Assessing gelling properties of chia (Salvia hispanica L.) flour through rheological characterization.

    Science.gov (United States)

    Ramos, Susana; Fradinho, Patrícia; Mata, Paulina; Raymundo, Anabela

    2017-04-01

    Chia (Salvia hispanica L.) seeds are considered a promising ingredient for the development of functional products owing to their high nutritional value: 343 g kg -1 lipids, 251 g kg -1 protein and 226 g kg -1 fibre. Considering chia's technological capacities, mainly the ability to swell when absorbing water and gel-forming properties, its addition to a food matrix can affect texture and rheological behaviour, acting as a texturing and stabilizing agent. The aim of the present work was to assess the gelling properties of chia flour through the rheological characterization of 100, 130 and 150 g kg -1 chia flour gels. According to the mechanical spectra, all gels presented weak gel-like structures, as G' was always less than a decade higher than G″, but higher chia flour concentrations showed a considerable increase in viscoelastic moduli. The gels had relatively low maturation times, almost instantaneous for lower concentrations, but the cooling rate affected the dynamics of formation of the gel structure. Based on texture and rheological properties, gels with 130 g kg -1 of chia flour processed at 90 °C for 30 min showed the most suitable characteristics for use in the development of new food applications. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  11. Rheological properties of concentrated alumina slurries: influence of ph and dispersant agent

    International Nuclear Information System (INIS)

    Ewais, E.M.M.

    2004-01-01

    The relationship between the ph, the electrolyte concentrations and the rheological properties of high concentrated alumina slurries in aqueous medium is of great importance because it is considered to be the key to control the stability of the slurries from flocculation. Zeta potential of alumina slurries with and without Duramax C (dispersant agent) as a function of ph was studied. Two ph around the zero point of charge of alumina slurries were selected for the investigation of rheological properties. The rheological properties of aqueous alumina slurries with respect to different parameters, e.g.: viscosity, elastic modulus (storage modulus G) and viscous modulus (loss modulus G), were investigated. Viscosity measurements of the slurries as a function of Duramax C content at both ph 8.4 and 9.4) were used to determine the state of slurries. Three states of slurries, termed flocculated, partially de flocculated and fully de flocculated, were selected for further investigation. The viscosity of the three slurries at both ph as a function of shear rate was determined. Fully de flocculated slurry shows Newtonian behavior at all shear rates at both tested ph compared by the partial de flocculated and flocculated system. Results of investigation of G and G at ph of 9.4 as a function of applied stress explored the critical stress

  12. Surface Rheology and Adsorption Kinetics Reveal the Relative Amphiphilicity, Interfacial Activity, and Stability of Human Exchangeable Apolipoproteins☆

    Science.gov (United States)

    Bolanos-Garcia, Victor Martin; Renault, Anne; Beaufils, Sylvie

    2008-01-01

    Exchangeable apolipoproteins are located in the surface of lipoprotein particles and regulate lipid metabolism through direct protein-protein and protein-lipid interactions. These proteins are characterized by the presence of tandem repeats of amphiphatic α-helix segments and a high surface activity in monolayers and lipoprotein surfaces. A noteworthy aspect in the description of the function of exchangeable apolipoproteins is the requirement of a quantitative account of the relation between their physicochemical and structural characteristics and changes in the mesoscopic system parameters such as the maximum surface pressure and relative stability at interfaces. To comply with this demand, we set out to establish the relations among α-helix amphiphilicity, surface concentration, and surface rheology of apolipoproteins ApoA-I, ApoA-II, ApoC-I, ApoC-II, and ApoC-III adsorbed at the air-water interface. Our studies render further insights into the interfacial properties of exchangeable apolipoproteins, including the kinetics of their adsorption and the physical properties of the interfacial layer. PMID:17993480

  13. Researches on thermal and rheological properties of cream- and vegetable spread

    Directory of Open Access Journals (Sweden)

    A. N. Ostrikov

    2016-01-01

    Full Text Available Researches of thermal and rheological properties of cream- and vegetable spread are necessary for the scientific substantiation of their obtaining process, namely mixing and crystallization processes. As the object of research, we chose a cream- and vegetable spread, with the following composition: peanut butter 10%; wheat germ oil 10%; linseed oil 20%; butter 59.8%; emulsifier 0.2%. With the data obtained in the course of research of the rheological properties of cream- and vegetable spread, one can subsequently generate recommendations for optimization of technological modes of production. In particular, one can solve problems of intensification of hydro-mechanical and thermal processes by carrying them out at such a temperature and speed when the maximum preservation of the produced product structure will be achieved. Determination of thermal characteristics was carried out in the apparatus for the study of thermal and rheological properties of viscoelastic liquids Coesfeld RT-1394H. Rheological researches of cream- and vegetable spread were carried out on a series of viscometers SV-10 and PB-8m. The graphs of spread dynamic viscosity dependence on the temperature, and the dependence of the effective viscosity of the spread and vegetable oils on the shear rate were built according to experimental data. The data obtained is rational to choose the equipment for processing and production of cream- and vegetable spread, to simulate processes taking place in the production process, to solve problems of intensification of thermal and hydro-mechanical processes reasonably, by conducting the production process at temperatures that do not cause the destruction of the product structure.

  14. INFLUENCE OF STORING AND TEMPERATURE ON RHEOLOGIC AND THERMOPHYSICAL PROPERTIES OF WHISKY SAMPLES

    Directory of Open Access Journals (Sweden)

    Peter Hlavac

    2013-09-01

    Full Text Available Temperature and storing time can be included between the most significant parameters that influence physical properties of food. This article deals with selected rheologic and thermophysical properties of alcohol drink whisky. Our research was oriented on measuring of rheologic and thermophysical characteristics of whisky. There were measured two types of whisky Grant s and Jim Beam from two different producers, both samples had 40 percent of alcohol content. During the experiments were analyzed rheologic parameters as dynamic viscosity, kinematic viscosity and fluidity and thermophysical parameters as thermal conductivity, thermal diffusivity and volume specific heat. Selected parameters were measured in temperature range 5 to 27 C. Measurements were done on whisky samples in different days during the storage. Measuring of dynamic viscosity was performed by digital rotational viscometer Anton Paar. Principle of measuring is based on dependency of sample resistance against the probe rotation. Density of whisky samples was determined by pycnometric method. Average density at given temperature along with dynamic viscosity value was used at calculation of kinematic viscosity and fluidity was also determined. Measuring of thermophysical parameters was performed by instrument Isomet 2104 Measurement by Isomet is based on analysis of the temperature response of the measured sample to heat flow impulses. Relations of rheologic and thermophysical parameters to the temperature were made and influence of storing time was discussed. From obtained results is clear that dynamic and kinematic viscosity is decreasing exponentially with temperature and fluidity has increasing exponential progress. We found out that both whisky samples had at the beginning and after one week of storage very similar values of rheologic parameters. Very small difference in rheologic parameters of whisky samples was found after two weeks of storing. Values of dynamic and kinematic

  15. Rheological and thermophysical properties of ultra-stable kerosene-based Fe3O4/Graphene nanofluids for energy conservation

    International Nuclear Information System (INIS)

    Askari, S.; Lotfi, R.; Rashidi, A.M.; Koolivand, H.; Koolivand-Salooki, M.

    2016-01-01

    Highlights: • Graphene-Fe 3 O 4 nanoparticles coated by oleic acid were synthesized. • Ultra-stable kerosene based nanofluid was produced from Graphene-Fe 3 O 4 nanohybrid. • Rheological and thermal properties of nanofluids were investigated. • Significant enhancement in thermal characteristics of nanofluid was observed. - Abstract: This research deals with a novel synthesis method for preparation of Fe 3 O 4 decorated Graphene and its application as a kerosene-based nanofluid with the purpose of heat transfer enhancement. In order to stabilize the Graphene-Fe 3 O 4 nanoparticles, oleic acid was grafted on the surface of nanoparticles by chemisorption. Synthesized nanohybrid was characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), Dynamic light scattering (DLS) and UV–Vis spectrophotometer. The nanofluid remains stable for more than five months without any sedimentation. Moreover, rheological and thermal properties of nanofluids were measured. Viscosity increment, especially in low concentrations of nanoparticles was negligible enough for industrial applications and density enhancement is completely negligible even in high concentrations. The thermal conductivity was improved 31% at 50 °C, compared to the base fluid. In order to examine convective heat transfer enhancement, an experimental setup was designed and measurements were examined in Reynolds numbers between 2166 and 4553. The maximum heat transfer enhancement was 66% at Reynolds number of 4553 and 0.3 wt.% of nanoparticle. Increase in particles loading and Reynolds number causes convective heat transfer coefficient to improve.

  16. Melt rheological properties of natural fiber-reinforced polypropylene

    Science.gov (United States)

    Jarrod J. Schemenauer; Tim A. Osswald; Anand R. Sanadi; Daniel F. Caulfield

    2000-01-01

    The melt viscosities and mechanical properties of 3 different natural fiber-polypropylene composites were investigated. Coir (coconut), jute, and kenaf fibers were compounded with polypropylene at 30% by weight content. A capillary rheometer was used to evaluate melt viscosity. The power-law model parameters are reported over a shear rate range between 100 to 1000 s–1...

  17. The Bioadhesive and Rheological properties of some fluconazole gels

    African Journals Online (AJOL)

    The results obtained indicate that high viscosity grade sodium carboxymethylcellulose (HV NaCMC) at 1.0 - 2% w/w concentration levels gave bioadhesive gels with viscoelastic properties which are affected by type and concentration of dye added to the formulation either as excipient or to assist in the determination of MTR.

  18. Rheological properties and tunable thermoplasticity of phenolic rich fraction of pyrolysis bio-oil.

    Science.gov (United States)

    Sahaf, Amir; Laborie, Marie-Pierre G; Englund, Karl; Garcia-Perez, Manuel; McDonald, Armando G

    2013-04-08

    In this work we report on the preparation, characterization, and properties of a thermally treated lignin-derived, phenolic-rich fraction (PRF) of wood pyrolysis bio-oil obtained by ethyl acetate extraction. The PRF was characterized for viscoelastic and rheological behavior using dynamic mechanical analysis (DMA) and cone and plate rheology. A unique thermoplastic behavior was evidenced. Heat-treated PRFs acquire high modulus but show low temperatures of thermal flow which can be systematically manipulated through the thermal pretreatment. Loss of volatiles, changes in molecular weight, and glass transition temperature (Tg) were investigated using thermogravimetric analysis (TGA), mass spectrometry (MS), and differential scanning calorimetry (DSC), respectively. Underlying mechanisms for the thermal and rheological behavior are discussed with regard to interactions between pyrolytic lignin nanoparticles present in the system and the role of volatile materials on determining the properties of the material resembling in several aspects to colloidal suspension systems. Low thermal flow temperatures and reversible thermal effects can be attributed to association of pyrolytic lignin particles due to intermolecular interactions that are easily ruptured at higher temperatures. The thermoplastic behavior of PRF and its low Tg is of particular interest, as it gives opportunities for application of this fraction in several melt processing and adhesive technologies.

  19. Optimization of the Formulation of Prebiotic Milk Chocolate Based on Rheological Properties

    Directory of Open Access Journals (Sweden)

    Hannaneh Farzanmehr

    2009-01-01

    Full Text Available Rheological properties are very important parameters in the production of products with high-quality and desirable texture. So far, many attempts to produce low-calorie milk chocolate have not succeeded. Therefore, the present study aims to evaluate the effects of sugar substitutes on rheological characteristics of prebiotic milk chocolate using Simplex-lattice mixture design. For doing this, a prebiotic compound (inulin with two bulking agents (polydextrose and maltodextrin at different levels (0–100 % along with sucralose were used. Fifteen formulations covering the entire range of a triangular simplex were examined in order to find the optimum levels. All chocolates showed thixotropic and shear thinning behaviour and among the evaluated mathematical models, Casson model showed the best fitting for predicting rheological properties. According to our findings, chocolate formulations containing high levels of sugar substitutes (where a single component predominated had higher moisture content, Casson viscosity and yield stress than others, including the control. In contrast, the lowest moisture content, Casson viscosity and yield stress were observed at medium levels. Therefore, the optimum values for substitution of sucrose and production of a low-calorie prebiotic milk chocolate are 8–28 % and 67–86 % for inulin, 0–19 % and 31–69 % for polydextrose and 0–47 % for maltodextrin, respectively.

  20. Mechanical, Rheological and Thermal Properties of Polystyrene/1-Octadecanol Modified Carbon Nanotubes Nanocomposites

    KAUST Repository

    Amr, Issam Thaher

    2014-09-04

    The results of the studies on the functionalization of multi-walled carbon nanotubes (MWCNT) with 1-octadecanol and its usage as reinforcing filler in the bulk polymerization of styrene are reported in this article. Both unmodified and modified CNTs were utilized in different loadings, however, without any initiator. The resulting composites were characterized by using mechanical testing, differential scanning calorimetry, thermogravimetric analysis and melt rheology. The tensile tests show the addition of 0.5wt% of CNT-C18 results in 19.5% increment of Young\\'s modulus. The DSC study shows a decrease in T-g values of prepared PS/CNT nanocomposite. The rheological study was conducted at 190 degrees C and shows that addition of pure CNT increased the viscoelastic behavior of the PS matrices, while the CNT-C18 act as plasticizer. Thermogravimetric analysis shows that the incorporation of CNT into PS enhanced the thermal properties significantly.

  1. Effect of high hydrostatic pressure on rheological and thermophysical properties of murtilla (Ugni molinae Turcz) berries.

    Science.gov (United States)

    Lemus-Mondaca, Roberto; Ah-Hen, Kong; Vega-Gálvez, Antonio; Zura-Bravo, Liliana

    2016-06-01

    Effects of high hydrostatic pressure (HHP) on rheological and thermophysical properties of murtilla berries were evaluated after pressure treatments for 5 min between 100 and 500 MPa. Differential scanning calorimetry was employed to measure specific heat capacity. HHP caused a significant decrease in specific heat and density, while thermal diffusivity did not changed significantly. Thermal conductivity showed a slight increase upon HHP treatment. Apparent viscosity increased significantly above 200 MPa HHP treatment. Apparent viscosity of treated samples between 200 and 400 MPa did not differ significantly and the increase was significant at 500 MPa. Herschel-Bulkley, Bingham and Ostwald de Waele models were used to describe the rheological behaviour of murtilla purée, and Ostwald de Waele model gave the best fit for the experimental data.

  2. Effect of β-cyclodextrin on Rheological Properties of some Viscosity Modifiers.

    Science.gov (United States)

    Rao, G Chandra Sekhara; Ramadevi, K; Sirisha, K

    2014-01-01

    Cyclodextrins are a group of novel excipients, extensively used in the present pharmaceutical industry. Sometimes they show significant interactions with other conventional additives used in the formulation of dosage forms. The effect of β-cyclodextrin on the rheological properties of aqueous solutions of some selected viscosity modifiers was studied in the present work. β-cyclodextrin showed two different types of effects on the rheology of the selected polymers. In case of natural polymers like xanthan gum and guar gum, enhanced apparent viscosity was found and in case of semi-synthetic polymers like sodium carboxymethyl cellulose and methyl cellulose, reduction in apparent viscosity was found. β-cyclodextrin was included at 0.5, 1 and 2% w/v concentrations into the polymeric solutions. These findings are useful in the adjustment of concentrations of viscosity modifiers during the formulation of physically stable disperse systems.

  3. Rheological properties of poly (vinylpiyrrolidone) as a function of average molecular weight and its applications

    DEFF Research Database (Denmark)

    Marani, Debora; Sudireddy, Bhaskar Reddy; Kiebach, Ragnar

    of formulations for pharmaceutics, food, personal care, or coatings, paintings, and printing applications. It is also widely used as organic additive, i.e. dispersant for ceramics. Regardless of the application, the control over the polymer behavior in solution is required for an efficient optimization...... of the formulation. Specifically, understanding the rheological properties is of paramount interest. Among the different factors that influence the rheological behavior, viscosity average molecular weight of the polymer is the most relevant. In this work, PVP polymers with various molecular weights have been....... The MHS equation relates the intrinsic viscosity [η] of a polymer in a given solvent at fixed temperature to the molecular weight. The adopted method also enables for the evaluation of the two MHS equation parameters (a and K), and of the polydispersity correction factor (qMHS). The intrinsic viscosity...

  4. Atomic force microscopy for the examination of single cell rheology.

    Science.gov (United States)

    Okajima, Takaharu

    2012-11-01

    Rheological properties of living cells play important roles in regulating their various biological functions. Therefore, measuring cell rheology is crucial for not only elucidating the relationship between the cell mechanics and functions, but also mechanical diagnosis of single cells. Atomic force microscopy (AFM) is becoming a useful technique for single cell diagnosis because it allows us to measure the rheological properties of adherent cells at any region on the surface without any modifications. In this review, we summarize AFM techniques for examining single cell rheology in frequency and time domains. Recent applications of AFM for investigating the statistical analysis of single cell rheology in comparison to other micro-rheological techniques are reviewed, and we discuss what specificity and universality of cell rheology are extracted using AFM.

  5. Equilibrium paths analysis of materials with rheological properties by using the chaos theory

    Science.gov (United States)

    Bednarek, Paweł; Rządkowski, Jan

    2018-01-01

    The numerical equilibrium path analysis of the material with random rheological properties by using standard procedures and specialist computer programs was not successful. The proper solution for the analysed heuristic model of the material was obtained on the base of chaos theory elements and neural networks. The paper deals with mathematical reasons of used computer programs and also are elaborated the properties of the attractor used in analysis. There are presented results of conducted numerical analysis both in a numerical and in graphical form for the used procedures.

  6. Rheological and textural properties of cracker dough with addition of pea dietary fiber

    Directory of Open Access Journals (Sweden)

    Dokić Ljubica

    2015-01-01

    Full Text Available Consumers are becoming aware of health benefits of dietary fiber intake. In past years, the development of products containing different fiber is increasing. The aim of this research was to look into the effect of addition pea fiber to dough for crackers. Rheological and textural properties were evaluated. In order to develop dough in which wheat flour was partly substituted with pea fiber, it was necessary to increase water content. The addition of 5% and 10% of pea fiber affected intramolecular linkages of gluten and lowered elastic properties of the dough. Dough with addition of 30% of fiber was brittle, grainy and impossible to process.

  7. Rheological Properties of Rubber Compounds with Finely Divided Carbon Additives

    Science.gov (United States)

    Shashok, Zh. S.; Prokopchuk, N. R.; Vishnevskii, K. V.; Krauklis, A. V.; Borisevich, K. O.; Borisevich, I. O.

    2018-01-01

    A study has been made of the influence of three different nanomaterials: of the starting material, and also of those functionalized by amine and oxygen-containing groups, on the properties of elastomer compositions based on rubbers for special purposes. As the elastomer matrix, use was made in one case of a rubber compound based on BNKS-18 butadiene-nitrile rubber and in the other, of a combination of two grades of butadiene-nitrile rubber (BNKS-18 + BNKS-28 in a 50:50 ratio), which differed by the amount of the bound nitrile of acrylic acid. To determine the degree of interaction between the additives and the elastomer matrix, the authors carried out multiple tests of the rubber compounds. The indices of plastoelastic properties of the rubber compounds and the qualitative characteristics of distribution of the filler (elastic modulus at small deformation amplitudes and the shear modulus under large deformation) and the difference in these indices (complex dynamic modulus) alike have been determined.

  8. The Rheological Properties of Fluid Denture-Base Resins,

    Science.gov (United States)

    1977-03-17

    Prosthet Dent, 24:662—668, 1970. 4. Mirza, F. D.: Dimensional stability of acrylic resin dentures . J Prosthet Dent, 11:848—857, 1961. 5. Winkler, S...SC) . 3 i~~ C I P I E N T S C A r A L O G NUM~~~ .~ - 5. T Y P E O F RE PO N T & PER(OO COV EREQ Rheo logical Properties of Fluid Denture ...resins; pour resins and denture resins. c_fl; \\ 10. A~~~T P A C T (Continue on revere. eid~ if n.c.saary end Identity by block number) Li.. The pour

  9. Rheological properties of concentrated solutions of carboxymethyl starch

    Directory of Open Access Journals (Sweden)

    Stojanović Željko

    2003-01-01

    Full Text Available Carboxymethyl starch was synthesized by the esterification of starch with monochloroacetic acid in ethanol as a reaction medium. Three samples of carboxymethyl starch having different degrees of substitution were prepared. The influence of temperature on the viscosity of concentrated carboxymethyl starch solutions, as well as the dynamic-mechanical properties of the concentrated solutions were investigated. The activation energy of viscous flow was determined and it was found that it decreased with increasing degree of substitution. The results of the dynamic-mechanical measurements showed that solutions of starch and carboxymethyl starches with higher degrees of substitution behave as gels. Values of the storage modulus in the rubbery plateau were used to calculate the molar masses between two points of physical crosslinking, the density of crosslinking and the distance between two points of crosslinking.

  10. Evolution of rheological properties of nuclear bituminized waste products, towards an ageing/viscosity law

    International Nuclear Information System (INIS)

    Mouazen, M.

    2011-01-01

    This work is a contribution to the understanding of rheological properties of bitumen and their evolution under gamma irradiation. The prediction of swelling ratio is necessary to evaluate the state of the containers, particularly during the reversibility phase of the storage. The objective of this work is thus to establish the rheological data its evolution under irradiation in order to predict the container swelling with time. After the rheological and thermal characterization of pure bitumen, a series of extrusion trials has been carried out. The state of dispersion essentially depends on the ratio N/Q (screw speed to feed rate). Extreme values of N/Q show the highest yield stress, indicating an improved dispersion state. The industrial bitumen compound exhibits the highest viscosity compared to model compounds, which limits bubble migration. Finally, the effect of gamma irradiation on pure bitumen and compounds behaviour has been studied. External and structural modifications have been evidenced. A theoretical model based on Krieger-Dougherty equation has been developed and shows a good agreement with experimental data. (author)

  11. Physicochemical, rheological, thermal, and bread making properties of flour obtained from irradiated wheat

    International Nuclear Information System (INIS)

    Singer, Carolina Sobral

    2006-01-01

    Most of the methods that are nowadays used for food preservation derive from old times. Besides these methods, new non-thermal methods have been developed in order to improve food quality during its processing. Irradiation technology has a great contribution potential to improve preservation, storage and distribution of foods. Several studies from international literature have reported the efficiency of irradiation process on microbiological control of grains and their products. Due to the low technological quality of national wheat, Brazil depends on its import. Wheat is the main ingredient of bread which is one of the most important products of Brazilian people's diet. The objective of this work was to study the effect of ionizing radiation on wheat on physicochemical, rheological, and thermal properties of flour produced from this wheat, and consequently, its performance on bread making. All experiments were conducted on laboratory scale. Wheat was submitted to irradiation on different doses (0.0; 0.5; 1.0 and 2.0 kGy) and flour produced underwent physicochemical, rheological, thermal and microbiological analyses. Flour bread making performance was measured through quality of bread. None of the physicochemical, rheological or thermal parameters was influenced by irradiation, with the exception of Falling Number, which decreased significantly with the increase of irradiation dose, indicating the effect of irradiation on wheat starch, and consequently on dough's gelatinization. Bread quality parameters did also not show significant differences, and sensory analysis showed that bread produced from irradiated and non irradiated wheat did not present perceivable flavor. (author)

  12. The effect of alternative sweeteners on batter rheology and cake properties.

    Science.gov (United States)

    Psimouli, Vasso; Oreopoulou, Vassiliki

    2012-01-15

    The aim of this research was to investigate whether certain polyols (mannitol, maltitol, sorbitol, lactitol), fructose, oligofructose and polydextrose can replace sugar (by an equal amount of each substitute) in cake formulations. The rheological behaviour of the cake batter and the physical characteristics of the cakes containing sugar substitutes were compared with the respective attributes of the control cake. Differential scanning calorimetry was used to investigate the effect of sugar substitutes on starch gelatinisation. Furthermore sensorial characteristics were evaluated by instrumental measurements and sensory evaluation. The correlation of the batter characteristics with the textural attributes of the final product was also attempted. The best results were obtained by using oligofructose, lactitol or maltitol as sugar replacers, which exhibited similar behaviour to sucrose in terms of batter rheology and increased starch gelatinisation temperature. Fructose and mannitol led to cakes of poor quality characteristics, as was demonstrated by instrumental measurements and sensory evaluation. Batter rheological behaviour as well as the ability of sugar substitutes to increase starch gelatinisation temperature proved to be controlling factors of the textural properties and volume of the cakes. The sensory evaluation indicated that overall acceptance followed closely the scores of tenderness and taste. Copyright © 2011 Society of Chemical Industry.

  13. Evaluation of rheological and thermic properties of neat and modified asphalt with a waste of LDPE

    Directory of Open Access Journals (Sweden)

    William Andrés Castro López

    2016-01-01

    Full Text Available Context: The asphalt technology and modified asphalt mixtures has been widely used and studied, worldwide. Adding polymers to asphalt modifies mechanical, chemical and rheological properties, trying to improve behavior of the mixtures subjected to different environmental and load conditions. The paper report results from rheological and thermal characterization on conventional 60-70 asphalt cement and 60-70 asphalt cement modified by introducing a waste of low density polyethylene (LDPE. Method: Modification of the asphalt was performed by wet way in a proportion of LDPE/CA=5% with respect to the mass. Rheological (using DSR, Thermogravimetry (TGA and Differential Scanning Calorimetry (DSC techniques were performed. Results and Conclusions: The modified asphalt develops a remarkable increase in stiffness and improvement of the performance grade at high temperatures of service. Additionally, the modified asphalt is more resistant to oxidation and aging processes due to heat. However, the asphalt modified showed a decrease in crack resistance at low and intermediate temperatures of service.

  14. Effect of Carboxymethylation on the Rheological Properties of Hyaluronan.

    Science.gov (United States)

    Wendling, Rian J; Christensen, Amanda M; Quast, Arthur D; Atzet, Sarah K; Mann, Brenda K

    2016-01-01

    Chemical modifications made to hyaluronan to enable covalent crosslinking to form a hydrogel or to attach other molecules may alter the physical properties as well, which have physiological importance. Here we created carboxymethyl hyaluronan (CMHA) with varied degree of modification and investigated the effect on the viscosity of CMHA solutions. Viscosity decreased initially as modification increased, with a minimum viscosity for about 30-40% modification. This was followed by an increase in viscosity around 45-50% modification. The pH of the solution had a variable effect on viscosity, depending on the degree of carboxymethyl modification and buffer. The presence of phosphates in the buffer led to decreased viscosity. We also compared large-scale production lots of CMHA to lab-scale and found that large-scale required extended reaction times to achieve the same degree of modification. Finally, thiolated CMHA was disulfide crosslinked to create hydrogels with increased viscosity and shear-thinning aspects compared to CMHA solutions.

  15. Interaction of gliding motion of bacteria with rheological properties of the slime.

    Science.gov (United States)

    Asghar, Z; Ali, N; Sajid, M

    2017-08-01

    Bacteria which do not have organelles of motility, such as flagella, adopt gliding as a mode of locomotion. In gliding motility bacterium moves under its own power by secreting a layer of slime on the substrate. The exact mechanism by which a glider achieves motility is yet in controversy but there are evidences which support the wave-like undulation on the surface of the organism, as a possible mechanism of motility. Based on this observation, a model of undulating sheet over a layer of slime is examined as a possible model of the gliding motion of a bacterium. Three different non-Newtonian constitutive equations namely, finite extendable nonlinear elastic-peterline (FENE-P), Simplified Phan-Thien-Tanner (SPTT) and Rabinowitsch equations are used to capture the rheological properties of the slime. It is found that the governing equation describing the fluid mechanics of the model under lubrication approximation is same for all the considered three constitutive equations. In fact, it involves a single non-Newtonian parameter which assumes different values for each of the considered constitutive relations. This differential equation is solved using both perturbation and semi-analytic procedure. The perturbation solution is exploited to get an estimate of the speed of the glider for different values of the non-Newtonian parameter. The solution obtained via semi-analytic procedure is used to investigate the important features of the flow field in the layer of the slime beneath the glider when the glider is held fixed. The expression of forces generated by the organism and power required for propulsion are also derived based on the perturbation analysis. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Rheological Properties of Natural Subduction Zone Interface: Insights from "Digital" Griggs Experiments

    Science.gov (United States)

    Ioannidi, P. I.; Le Pourhiet, L.; Moreno, M.; Agard, P.; Oncken, O.; Angiboust, S.

    2017-12-01

    The physical nature of plate locking and its relation to surface deformation patterns at different time scales (e.g. GPS displacements during the seismic cycle) can be better understood by determining the rheological parameters of the subduction interface. However, since direct rheological measurements are not possible, finite element modelling helps to determine the effective rheological parameters of the subduction interface. We used the open source finite element code pTatin to create 2D models, starting with a homogeneous medium representing shearing at the subduction interface. We tested several boundary conditions that mimic simple shear and opted for the one that best describes the Grigg's type simple shear experiments. After examining different parameters, such as shearing velocity, temperature and viscosity, we added complexity to the geometry by including a second phase. This arises from field observations, where shear zone outcrops are often composites of multiple phases: stronger crustal blocks embedded within a sedimentary and/or serpentinized matrix have been reported for several exhumed subduction zones. We implemented a simplified model to simulate simple shearing of a two-phase medium in order to quantify the effect of heterogeneous rheology on stress and strain localization. Preliminary results show different strength in the models depending on the block-to-matrix ratio. We applied our method to outcrop scale block-in-matrix geometries and by sampling at different depths along exhumed former subduction interfaces, we expect to be able to provide effective friction and viscosity of a natural interface. In a next step, these effective parameters will be used as input into seismic cycle deformation models in an attempt to assess the possible signature of field geometries on the slip behaviour of the plate interface.

  17. The field-dependent rheological properties of magnetorheological fluids featuring plate-like iron particles

    Directory of Open Access Journals (Sweden)

    Seung-Bok eChoi

    2014-10-01

    Full Text Available This study is concerned with an investigation of the plate-like iron particles based MR suspensions under the application of magnetic fields to ascertain the influence of particle size in the rheological performance. A novel synthesis route to prepare magnetorheological fluid (MRF using two different sizes of plate-like iron particles is described in detail. Two different kinds of MRF are then prepared and their rheological properties are presented and discussed extensively. Steady shear flow and small amplitude dynamic oscillatory measurements are carried out in the presence of magnetic field. This experimental study reveals and highlights the importance of exploiting some parameters such as magnetic field strength, effect of particle size, magneto-viscous and visco-elastic properties of the suspending fluid. The magnetization of the fluids is also performed to explain the effect of particle size in the magnetic field which is directly correlated with the yield stress. In the absence of magnetic field, the properties of fluid are isotropic and upon the application of magnetic field the magnetized particles form a strong-chain like structures in the field direction which promotes the appearance of yield stress. This material is known as smart material whose properties amend from liquid to solid immediately after applying the magnetic field. It is found from this work that the large size particle based MRF exhibits high yield stress and strong chain structuration under the applying magnetic field.

  18. Laser Speckle Rheology for evaluating the viscoelastic properties of hydrogel scaffolds

    Science.gov (United States)

    Hajjarian, Zeinab; Nia, Hadi Tavakoli; Ahn, Shawn; Grodzinsky, Alan J.; Jain, Rakesh K.; Nadkarni, Seemantini K.

    2016-01-01

    Natural and synthetic hydrogel scaffolds exhibit distinct viscoelastic properties at various length scales and deformation rates. Laser Speckle Rheology (LSR) offers a novel, non-contact optical approach for evaluating the frequency-dependent viscoelastic properties of hydrogels. In LSR, a coherent laser beam illuminates the specimen and a high-speed camera acquires the time-varying speckle images. Cross-correlation analysis of frames returns the speckle intensity autocorrelation function, g2(t), from which the frequency-dependent viscoelastic modulus, G*(ω), is deduced. Here, we establish the capability of LSR for evaluating the viscoelastic properties of hydrogels over a large range of moduli, using conventional mechanical rheometry and atomic force microscopy (AFM)-based indentation as reference-standards. Results demonstrate a strong correlation between |G*(ω)| values measured by LSR and mechanical rheometry (r = 0.95, p  0.08) over a large range (47 Pa – 36 kPa). In addition, |G*(ω)| values measured by LSR correlate well with indentation moduli, E, reported by AFM (r = 0.92, p rheology and micro-indentation in assessing hydrogel viscoelastic properties at multiple frequencies and small length-scales. PMID:27905494

  19. Effect of rheological properties of dissolved cellulose/microfibrillated cellulose blend suspensions on film forming.

    Science.gov (United States)

    Saarikoski, Eve; Rissanen, Marja; Seppälä, Jukka

    2015-03-30

    Enzymatically treated cellulose was dissolved in a NaOH/ZnO solvent system and mixed together with microfibrillated cellulose (MFC) in order to find the threshold in which MFC fibers form a percolation network within the dissolved cellulose solution and in order to improve the properties of regenerated cellulose films. In the aqueous state, correlations between the rheological properties of dissolved cellulose/MFC blend suspensions and MFC fiber concentrations were investigated and rationalized. In addition, rheological properties of diluted MFC suspensions were characterized and a correlation with NaOH concentration was found, thus partly explaining the flow properties of dissolved cellulose/MFC blend suspensions. Finally, based on results from Dynamic Mechanical Analysis (DMA), MFC addition had strengthening/plasticizing effect on regenerated cellulose films if low concentrations of MFC, below the percolation threshold (5.5-6 wt%, corresponding to 0.16-0.18 wt% of MFC in the blend suspensions), were used. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Buckwheat and Millet Affect Thermal, Rheological, and Gelling Properties of Wheat Flour.

    Science.gov (United States)

    Wu, Kao; Gan, Renyou; Dai, Shuhong; Cai, Yi-Zhong; Corke, Harold; Zhu, Fan

    2016-03-01

    Buckwheat (BF) and millet (MF) are recommended as healthy foods due to their unique chemical composition and health benefits. This study investigated the thermal and rheological properties of BF-WF (wheat flour) and MF-WF flour blends at various ratios (0:100 to 100:0). Increasing BF or MF concentration led to higher cold paste viscosity and setback viscosity of pasting properties gel adhesiveness, storage modulus (G') and loss modulus (G″) of dynamic oscillatory rheology, and yield stress (σ0 ) of flow curve of WF. BF and MF addition decreased peak viscosity and breakdown of pasting, gel hardness, swelling volume, and consistency coefficient (K) of flow curve of WF. Thermal properties of the blends appeared additive of that of individual flour. Nonadditive effects were observed for some property changes in the mixtures, and indicated interactions between flour components. This may provide a physicochemical basis for using BF and MF in formulating novel healthy products. © 2016 Institute of Food Technologists®

  1. Effect of cream fermentation on microbiological, physicochemical and rheological properties of L. helveticus-butter.

    Science.gov (United States)

    Ewe, Joo-Ann; Loo, Su-Yi

    2016-06-15

    The primary objective of this study was to evaluate the physicochemical and rheological properties of butter produced by Lactobacillus helveticus fermented cream. The incorporation of putative probiotic - the L. helveticus, to ferment cream prior to butter production was anticipated to alter the nutritional composition of butter. Changes in crude macronutrients and the resultant modification relating to textural properties of butter induced upon metabolic activities of L. helveticus in cream were focused in this research. Fermented butter (LH-butter) was produced by churning the cream that was fermented by lactobacilli at 37 °C for 24 h. Physicochemical analysis, proximate analysis and rheology properties of LH-butter were compared with butter produced using unfermented cream (control). LH-butter showed a significantly (Pbutter in which LH-butter contained higher health beneficial unsaturated fatty acids than the control and thus rendered the product softer. Its enrichment with probiotics could thus further enhance its functional property. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Research of rheological and physico-mechanical properties of decorative concrete

    Directory of Open Access Journals (Sweden)

    Сергей Григорьевич Гузий

    2016-09-01

    Full Text Available The results of experimental researches of rheological and physico-mechanical properties of geocement-based decorative concrete are shown. The optimum composition of the material is defined. It is determined that introduction of the ground limestone in the concrete increases the stabilization time of process viscosity and additives Murasan BWA 21 contributes to the preservation of the geometric dimensions of the samples in the process of pulling out. Bending strength and frost resistance with a significant decrease in water absorption are increased after microwave drying.

  3. Using Micromechanical Resonators to Measure Rheological Properties and Alcohol Content of Model Solutions and Commercial Beverages

    Directory of Open Access Journals (Sweden)

    Bart W. Hoogenboom

    2012-05-01

    Full Text Available Micromechanic resonators provide a small-volume and potentially high-throughput method to determine rheological properties of fluids. Here we explore the accuracy in measuring mass density and viscosity of ethanol-water and glycerol-water model solutions, using a simple and easily implemented model to deduce the hydrodynamic effects on resonating cantilevers of various length-to-width aspect ratios. We next show that these measurements can be extended to determine the alcohol percentage of both model solutions and commercial beverages such as beer, wine and liquor. This demonstrates how micromechanical resonators can be used for quality control of every-day drinks.

  4. FRESH AND RHEOLOGICAL PROPERTIES OF 3D PRINTING BIO- CEMENT-BASED MATERIALS

    OpenAIRE

    Rubio, M; Sonebi, M; Amziane, S

    2017-01-01

    International audience; The aim of this study is to investigate the effect of different mix composition on fresh and rheological properties of a bio-printable mortar. Different binders were tested such as fly ash (FA), silica fume (SF), and used with CEMI and sand for a water/binder ratio of 0.50. Then, superplasticizer (SP) and natural flax fibres 15 mm (FL) were used in the investigation at varying percentage for a given binder. Two viscosity modifying agents were also tested. Adding flax f...

  5. Effects of colloidal nanosilica on the rheological properties of epoxy resins filled with organoclay.

    Science.gov (United States)

    Nguyen, Dinh Huong; Song, Gwang Seok; Lee, Dai Soo

    2011-05-01

    The rheological properties of epoxy resins filled with organoclay and colloidal nanosilica were investigated by employing a parallel plate rheometer in flow mode at 25 degrees C. Shear thickening and shear thinning behaviors were observed in the epoxy resins filled with a mixture of organoclay and colloidal nanosilica. Minima were observed in the relaxation time of the systems consisting of epoxy resins filled with organoclay and colloidal silica as the content of colloidal nanosilica was increased. It seems that the colloidal nanosilica increased the mobility of the filled epoxy resins and reduced the interactions between the silicate layers in the systems.

  6. Effect of microdrops deformation on electrical and rheological properties of magnetic fluid emulsion

    International Nuclear Information System (INIS)

    Zakinyan, Arthur R.; Dikansky, Yuri I.

    2017-01-01

    The magnetic fluid emulsions with low interfacial tension have been studied experimentally. The shape deformation of the dispersed phase microdrops under the action of comparatively weak magnetic field has been observed. The effect of microdrops deformation on the macroscopic properties of the emulsion has been investigated. The anisotropic character of emulsion properties in the presence of external magnetic field has been demonstrated. The emulsion dielectric permeability has been measured as a function of the magnetic field strength, the emulsion concentration, and the angle between electrical and magnetic fields. The influence of the droplets deformation under the magnetic field on the rheological behavior of the emulsion has been observed. The obtained results have been analyzed and discussed. - Highlights: • The dispersed phase drops of emulsion studied can be deformed by magnetic field. • The emulsion becomes anisotropic under the action of external field. • The emulsion electrical properties depends on magnetic field strength and direction. • The emulsion rheological behavior can be controlled by external magnetic field.

  7. Physicochemical, rheological and functional properties of fats and oils in relation to cookie quality: a review.

    Science.gov (United States)

    Devi, Amita; Khatkar, B S

    2016-10-01

    Sincere efforts of researchers are underway to understand the functionality of different fats and oils in relation to cookie quality. The quality of cookie primarily relies upon the functionality of fats and oils in cookie system which ultimately is combined result of their physical, chemical, and rheological properties. Effects of some major fats and oils such as butter, bakery fat, hydrogenated fat, lard, margarine, palm oil, sunflower oil, coconut oil, and soybean oil on the physical and sensory characteristics of cookie have been studied. Previous studies reported that fats and oils had radical contribution in cookie quality and most authors agree on the fact that different fats and oils affect the cookie quality to different extent. Furthermore, it was observed by many researchers that with oils, dough was softer and cookie spread was higher as compared with that of fats. It is important to understand the molecular basis of the difference in technological changes in cookies properties with different fats and oils. This review focuses on the current knowledge of quality determining physical, chemical, thermal, microstructural, and functional properties of fats and oils in relation to cookie dough rheology and cookie quality.

  8. Rheological properties and sensory characteristics of set-type soy yogurt.

    Science.gov (United States)

    Donkor, Osaana N; Henriksson, A; Vasiljevic, T; Shah, N P

    2007-11-28

    The study examined chemical composition and rheological and sensory properties of probiotic soy yogurt during 28 day storage at 4 degrees C. Soymilk supplemented with 2% (w/v) inulin or 1% (w/v) each of raffinose and glucose was used as a base for soy yogurt manufacture. Viability of probiotic organisms and their metabolic activity measured as production of organic acids and aldehyde content responsible for beany flavor, as well as rheological and sensory properties of soy yogurt, were examined. Inulin or raffinose/glucose supplementation in soymilk increased the bacterial population by one log cycle and the amount of lactic acid. Probiotic bacteria metabolized more aldehyde than yogurt culture and substantially reduced the beaniness in soy yogurt as determined by sensory evaluation. The probiotic soy yogurts showed more viscous and pseudoplastic properties than the control soy yogurts, but the sensory evaluation results showed preference for the control soy yogurts which were slightly less viscous. Control soy yogurt provided better mouth feel than probiotic soy yogurts.

  9. Functional and rheological properties of amaranth albumins extracted from two Mexican varieties.

    Science.gov (United States)

    Silva-Sánchez, C; González-Castañeda, J; de León-Rodríguez, A; Barba de la Rosa, A P

    2004-01-01

    The functional and rheological properties of amaranth albumins isolates extracted from two new Mexican varieties were determined. Functional properties tested were protein solubility, foaming, water and oil absorption capacities, emulsifying activity, and emulsion stability. The maximum solubility values for both amaranth albumins were found above pH 6 and values were compared to the solubility of egg albumins. Albumins from amaranth showed excellent foaming capacity and foaming stability at pH 5, suggesting that this protein could be used as whipping agents as egg albumins, also the water and oil absorption capacities reached their maximum values at acidic pH, suggesting that amaranth albumins could be appropriate in preparation of acidic foods. The rheological test based on farinograms and alveograms showed that wheat flour supplemented with 1% amaranth albumins improves the dough properties due to higher mixing stability and the bread had better crumb characteristics. In addition of the known high nutritional values of amaranth albumins, our results indicate the high potential for use of these proteins as an ingredient in food preparations.

  10. Dynamic rheological properties of viscoelastic magnetic fluids in uniform magnetic fields

    International Nuclear Information System (INIS)

    Yamaguchi, Hiroshi; Niu Xiaodong; Ye Xiaojiang; Li Mingjun; Iwamoto, Yuhiro

    2012-01-01

    The dynamic rheological properties of viscoelastic magnetic fluids in externally applied uniform magnetic fields are investigated by a laboratory-made cone-plate rheometer in this study. In particular, the effects of the magnetic field on the viscoelastic properties (the complex dynamic modulus) of the viscoelastic magnetic fluids are studied. In the investigation, three viscoelastic magnetic fluids are made by mixing a magnetic fluid and a viscoelastic fluid with different mass ratios. As a supplementation to the experimental investigation, a theoretical analysis is also presented. The present study shows that the viscosity and elasticity of the viscoelastic magnetic fluids are significantly influenced by the magnetic field and the concentrations of the magnetic particles in the test fluids. Theoretical analysis qualitatively explains the present findings. - Highlights: ► The dynamic rheological properties of the viscoelastic magnetic fluids in uniform magnetic fields are investigated. ► Both the magnetic field strength and the concentration of the magnetic particles in the fluids have significant effects on the viscosity and elasticity of the viscoelastic magnetic fluids. ► Theoretical prediction and analysis qualitatively explains the present findings.

  11. Performances of screen-printing silver thick films: Rheology, morphology, mechanical and electronic properties

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Jung-Shiun; Liang, Jau-En; Yi, Han-Liou [Department of Chemical Engineering, National Chung Cheng University, Chia Yi 621, Taiwan, ROC (China); Chen, Shu-Hua [China Steel Corporation, Kaohsiung City 806, Taiwan, ROC (China); Hua, Chi-Chung, E-mail: chmcch@ccu.edu.tw [Department of Chemical Engineering, National Chung Cheng University, Chia Yi 621, Taiwan, ROC (China)

    2016-06-15

    Numerous recent applications with inorganic solar cells and energy storage electrodes make use of silver pastes through processes like screen-printing to fabricate fine conductive lines for electron conducting purpose. To date, however, there have been few studies that systematically revealed the properties of the silver paste in relation to the mechanical and electronic performances of screen-printing thick films. In this work, the rheological properties of a series of model silver pastes made of silver powders of varying size (0.9, 1.3, and 1.5 μm) and shape (irregular and spherical) were explored, and the results were systematically correlated with the morphological feature (scanning electron microscopy, SEM) and mechanical (peeling test) and electronic (transmission line method, TLM) performances of screen-printing dried or sintered thick films. We provided evidence of generally intimate correlations between the powder dispersion state in silver pastes—which is shown to be well captured by the rheological protocols employed herein—and the performances of screen-printing thick films. Overall, this study suggests the powder dispersion state and the associated phase behavior of a paste sample can significantly impact not only the morphological and electronic but also mechanical performances of screen-printing thick films, and, in future perspectives, a proper combination of silver powders of different sizes and even shapes could help reconcile quality and stability of an optimum silver paste. - Highlights: • Powder dispersion correlates well with screen-printing thick film performances. • Rheological fingerprints can be utilized to fathom the powder dispersion state. • Good polymer-powder interactions in the paste ensure good powder dispersion. • Time-dependent gel-like viscoelastic features are found with optimum silver pastes. • The size and shape of functional powder affect the dispersion and film performances.

  12. Effect of Cationic Surface Modification on the Rheological Behavior and Microstructure of Nanocrystalline Cellulose

    Directory of Open Access Journals (Sweden)

    Yanjun Tang

    2018-03-01

    Full Text Available In the present work, the microstructure and rheological behavior of nanocrystalline cellulose (NCC and cationically modified NCC (CNCC were comparatively studied. The resultant CNCC generally showed improved dispersion and higher thermal stability in comparison to the un-modified NCC. The rheological behavior demonstrated that the viscosity of the NCC suspension substantially decreased with the increasing shear rate (0.01–100 s−1, showing the typical characteristics of a pseudoplastic fluid. In contrast, the CNCC suspensions displayed a typical three-region behavior, regardless of changes in pH, temperature, and concentration. Moreover, the CNCC suspensions exhibited higher shear stress and viscosity at a given shear rate (0.01–100 s−1 than the NCC suspension. Meanwhile, the dynamic viscoelasticity measurements revealed that the CNCC suspensions possessed a higher elastic (G′ and loss modulus (G″ than NCC suspensions over the whole frequency range (0.1–500 rad·s−1, providing evidence that the surface cationization of NCC makes it prone to behave as a gel-like structure.

  13. New insight into rheology and flow properties of complex fluids with Doppler optical coherence tomography

    Science.gov (United States)

    Haavisto, Sanna; Koponen, Antti I.; Salmela, Juha

    2014-01-01

    Flow properties of complex fluids such as colloidal suspensions, polymer solutions, fiber suspensions and blood have a vital function in many technological applications and biological systems. Yet, the basic knowledge on their properties is inadequate for many practical purposes. One important reason for this has been the lack of effective experimental methods that would allow detailed study of the flow behavior of especially opaque multi-phase fluids. Optical Coherence Tomography (OCT) is an emerging technique capable of simultaneous measurement of the internal structure and motion of most opaque materials, with resolution in the micrometer scale and measurement frequency up to 100 kHz. This mini-review will examine the recent results on the use of Doppler-OCT in the context of flows and rheological properties of complex fluids outside biomedical field. PMID:24904920

  14. New insight into rheology and flow properties of complex fluids with Doppler optical coherence tomography.

    Science.gov (United States)

    Haavisto, Sanna; Koponen, Antti I; Salmela, Juha

    2014-01-01

    Flow properties of complex fluids such as colloidal suspensions, polymer solutions, fiber suspensions and blood have a vital function in many technological applications and biological systems. Yet, the basic knowledge on their properties is inadequate for many practical purposes. One important reason for this has been the lack of effective experimental methods that would allow detailed study of the flow behavior of especially opaque multi-phase fluids. Optical Coherence Tomography (OCT) is an emerging technique capable of simultaneous measurement of the internal structure and motion of most opaque materials, with resolution in the micrometer scale and measurement frequency up to 100 kHz. This mini-review will examine the recent results on the use of Doppler-OCT in the context of flows and rheological properties of complex fluids outside biomedical field.

  15. Study of Rheological Properties of Bituminous Binders in Middle and High Temperatures

    Directory of Open Access Journals (Sweden)

    Remišová Eva

    2016-05-01

    Full Text Available The bitumen binders in road pavements are exposed traffic loading effect at different climatic conditions. A resistance to these stresses depends on bitumen properties as well. The paper presents rheological properties (G*, δ, ν* determined and compared for four bituminous binders (unmodified and polymer modified bitumen at temperature 46 – 60 (80 °C and dynamic viscosity at temperature 130 – 190 °C (Brookfield viscometer. On the basis of viscosity results it is possible to set optimal production and compaction temperatures. Elastic and viscous behavior of binder in the middle temperature is determined in rheometers. The higher value of complex modulus, the stiffer bitumen binder is able to resist deformation. The greater content of elastic components (e.g. polymer in bitumen varies mainly elastic-viscous properties of primary bitumen.

  16. The effects of concentration and heating-cooling rate on rheological properties of Plantago lanceolata seed mucilage

    DEFF Research Database (Denmark)

    Hesarinejad, Mohammad Ali; Sami Jokandan, Maryam; Mohammadifar, Mohammad Amin

    2017-01-01

    In this study, the effect of concentration (0.5, 1, 1.5 and 2%) and heating-cooling rate (1, 5 and 10 °C min−1) on the rheological properties of Plantago lanceolata seed mucilage (PLSM) solutions were investigated. It was observed that the gum dispersions exhibited viscoelastic properties under t...

  17. PLA/Bio-PE blends: effect of the Bio-PE content on the crystallinity rheological properties

    International Nuclear Information System (INIS)

    Araujo, Aylanna P.M. de; Agrawal, Pankaj; Cavalcanti, Shirley N.; Alves, Amanda M.; Melo, Tomas J.A. de; Brito, Gustavo F.

    2014-01-01

    The aim of this work is to evaluate the effect of the Bio-PE content on the crystallinity and rheological properties of PLA/Bio-PE blend. The blends containing 05 and 15% of Bio-PE were prepared by extrusion followed by injection molding and characterized by X-Ray Diffraction (XRD) and rheological properties at low and high shear rates. XRD results indicated that the PLA present low crystallinity and this behavior was not changed with the addition of Bio-PE, regardless of Bio-PE content. Rheological properties results indicated that at low shear rates the viscosity of the PLA/Bio-PE increased with the increase in the Bio-PE content while at high shear rates the viscosities where almost similar, which may be ascribed to the orientation of Bio-PE particles in the flow direction or by the viscous dissipation. (author)

  18. Rheology, Mechanical Properties, and Thermal Stability of Maleated Polyethylene Filled with Nanoclays

    Directory of Open Access Journals (Sweden)

    Abdulhadi A. Al-Juhani

    2015-01-01

    Full Text Available Maleated polyethylene (MAPE was used in this study as a model matrix for hosting hydrophobic nanoclay (C15A and hydrophilic nanoclay (C30B, to investigate the effect of nanoclay loading on the bulk properties of the composites. Composites were prepared by melt-blending technique, with varying the loading from 0 to 9 wt.%. Tensile, oxidative TGA, and FE-SEM tests were employed for both C15A-filled polymer and C30B-filled polymer, which confirmed that C15A had better dispersion and was much superior to C30B for enhancing the mechanical properties and thermal stability of MAPE. Consequently, XRD and melt rheology tests were performed for C15A-filled polymer only. XRD confirmed the formation of nanocomposite structure, which could be the main reason for the significant increase in the thermal stability and viscosity. For example, compared to the neat polymer, the degradation temperature at the 20% mass loss was increased by 72°C after the addition of 5 wt.% C15A. Based on rheological analysis, the percolation threshold was around 3 wt.% loading of C15A. Fitting the viscosity data to the Cross model suggested that increasing C15A loading had a strong effect for increasing the shear thinning index and relaxation time of the nanocomposites.

  19. The physico-chemical properties of chia seed polysaccharide and its microgel dispersion rheology.

    Science.gov (United States)

    Goh, Kelvin Kim Tha; Matia-Merino, Lara; Chiang, Jie Hong; Quek, Ruisong; Soh, Stephanie Jun Bing; Lentle, Roger G

    2016-09-20

    The polysaccharide gel layer surrounding hydrated chia seeds was extracted using water and isolated by ethanol precipitation. The freeze-dried sample consisted of ∼95% non-starch polysaccharides (35% w/w neutral soluble fraction and 65% w/w negatively charged insoluble fraction). The soluble polysaccharide fraction has molar mass, root-mean square radius and intrinsic viscosity of ∼5×10(5)g/mol, 39nm and 719mL/g, respectively. The whole polysaccharide (included soluble and insoluble fractions) when dispersed in water showed presence of irregular shape, fibrous microgel particles with an average size (D4,3) of ∼700μm. Rheological measurements indicated a 'weak' viscoelastic gel and strong shear dependent properties even at low concentration (0.05% w/w). The viscosity of the dispersion was fairly resistant to variations in temperatures (20-80°C), pH (4-12), ionic strengths (0.01-0.5M NaCl) and cation types (MgCl2, CaCl2, NaCl and KCl). The swollen microgel particles dispersed in soluble polysaccharide continuous phase provided complex and potentially useful rheological properties in food systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Sugar Profile, Mineral Content, and Rheological and Thermal Properties of an Isomerized Sweet Potato Starch Syrup

    Science.gov (United States)

    Dominque, Brunson; Gichuhi, Peter N.; Rangari, Vijay; Bovell-Benjamin, Adelia C.

    2013-01-01

    Currently, corn is used to produce more than 85% of the world's high fructose syrup (HFS). There is a search for alternative HFS substrates because of increased food demand and shrinking economies, especially in the developing world. The sweet potato is a feasible, alternative raw material. This study isomerized a high glucose sweet potato starch syrup (SPSS) and determined its sugar profile, mineral content, and rheological and thermal properties. Rheological and thermal properties were measured using a rheometer and DSC, respectively. Sweet potato starch was hydrolyzed to syrup with a mean fructose content of 7.6 ± 0.4%. The SPSS had significantly higher (P syrups. During 70 days of storage, the SPSS acted as a non-Newtonian, shear-thinning liquid in which the viscosity decreased as shear stress increased. Water loss temperature of the SPSS continually decreased during storage, while pancake and ginger syrups' peak water loss temperature decreased initially and then increased. Further and more detailed studies should be designed to further enhance the fructose content of the syrup and observe its stability beyond 70 days. The SPSS has the potential to be used in human food systems in space and on Earth. PMID:26904593

  1. Particle stability in dilute fermented dairy drinks: formation of fluid gel and impact on rheological properties.

    Science.gov (United States)

    Kiani, H; Mousavi, M E; Mousavi, Z E

    2010-12-01

    Fluid gels are known to be very shear-thinning materials with yield stress. In this study, the rheological properties of gellan and gellan-pectin fluid gels in fermented dairy drinks were evaluated using viscometric measurements. Both gellan- and gellan-pectin-containing solutions showed the rheological properties of fluid gels resulting in stabilization of particles; but no evidence of a fluid gel was observed for those with pectin alone and those with no hydrocolloid content. Unlike pectin, gellan gum was capable of creating significant values of yield stress and accordingly stabilized colloidal particles and extrinsic added solid particles in the fermented dairy drink. However, pectin improved the stability in combination with gellan. The origin of fluid gel formation was assumed to be both permanent interactions occurring between gellan and proteins, forming hairy particle gels and transient interactions between the particle gels. The significance of yield stress values for particle stability was demonstrated and two methods, including a noteworthy infinite apparent viscosity method and a conventional Bingham approach, were employed to calculate the values of yield stress. Both the methods showed a good application potential due to their simplicity, reasonable results and also wide availability of the instrument applied.

  2. Influence of high power ultrasound on rheological and foaming properties of model ice-cream mixtures

    Directory of Open Access Journals (Sweden)

    Verica Batur

    2010-03-01

    Full Text Available This paper presents research of the high power ultrasound effect on rheological and foaming properties of ice cream model mixtures. Ice cream model mixtures are prepared according to specific recipes, and afterward undergone through different homogenization techniques: mechanical mixing, ultrasound treatment and combination of mechanical and ultrasound treatment. Specific diameter (12.7 mm of ultrasound probe tip has been used for ultrasound treatment that lasted 5 minutes at 100 percent amplitude. Rheological parameters have been determined using rotational rheometer and expressed as flow index, consistency coefficient and apparent viscosity. From the results it can be concluded that all model mixtures have non-newtonian, dilatant type behavior. The highest viscosities have been observed for model mixtures that were homogenizes with mechanical mixing, and significantly lower values of viscosity have been observed for ultrasound treated ones. Foaming properties are expressed as percentage of increase in foam volume, foam stability index and minimal viscosity. It has been determined that ice cream model mixtures treated only with ultrasound had minimal increase in foam volume, while the highest increase in foam volume has been observed for ice cream mixture that has been treated in combination with mechanical and ultrasound treatment. Also, ice cream mixtures having higher amount of proteins in composition had shown higher foam stability. It has been determined that optimal treatment time is 10 minutes.

  3. Predicting Pumpability and Shootability of Crushed Aggregate Wet-Mix Shotcrete Based on Rheological Properties

    Directory of Open Access Journals (Sweden)

    Kyong-Ku Yun

    2016-01-01

    Full Text Available This study aims to estimate the pumpability and shootability of wet-mix shotcrete (WMS made with crushed aggregates and various admixtures such as silica fume, fly ash, ground granulated blast furnace slag (GGBFS, metakaolin, and steel fiber based on rheological properties. The IBB rheometer was employed as an apparatus to measure the rheological properties of freshly mixed shotcrete such as flow resistance and torque viscosity. Results have shown that the use of silica fume and metakaolin led to satisfactory pumpability, whereas mixtures with fly ash and steel fiber failed to meet the pumping criteria at normal pump pressure. The build-up thickness, an indicator to represent shotcrete shootability, was predicted to vary between 68 and 218 mm, demonstrating that the use of admixtures resulted in a wide spectrum of shootability. In particular, the use of metakaolin was found to substantially increase the predicted build-up thickness only with a small replacement. The findings of this study are expected to be used as an easy-to-use guideline for estimating pumpability and shootability of WMS when no compliance testing data is available.

  4. Effects of Waste Plastic on the Physical and Rheological Properties of Bitumen

    Science.gov (United States)

    Ezree Abdullah, Mohd; Asyiqin Ahmad, Nurul; Putra Jaya, Ramadhansyah; Hassan, Norhidayah Abdul; Yaacob, Haryati; Rosli Hainin, Mohd

    2017-05-01

    Plastic disposal is one of the major problems for developing countries like Malaysia, at the same time Malaysia needs a large network of roads for its smooth economic and social development. The limited source of bitumen needs a deep thinking to ensure fast road construction. Therefore, the use of plastic waste in road construction not only can help to protect environment but also able to help the road construction industry. The aims of this research are to study the effects of waste plastic on rheological properties of bitumen. Modified bitumen was prepared by using blending techniques. Bitumen was heated and plastic waste was slowly added. Rheological properties of bitumen were performance by penetration, softening point, viscosity and direct shear rheometer test. The results showed that when content of plastic waste increase, the penetration value, softening point and viscosity of bitumen also increase. Generally, plastic waste improves the performance of bitumen when it was added into bitumen. It can be said that the usage helps to improve the performance of the road pavement which also reduces the rutting effect.

  5. Rheological properties of rice-blackgram batter while replacing white rice with brown rice.

    Science.gov (United States)

    Manickavasagan, Annamalai; Al-Marhubi, Insaaf Mohd; Dev, Satyanarayan

    2014-06-01

    Rice-blackgram batter is a raw material for many traditional convenience foods in Asia. Reformulation of traditional convenience food by replacing white rice with whole rice (brown rice) is a novel method to reduce the consumption of refined grain and increase the intake of whole grain in our diet. In this study, rheological properties of rice-blackgram batter was investigated while replacing white rice with brown rice at five levels (T1--0% replacement (control), T2--25% replacement, T3--50% replacement, T4--75% replacement, and T5--100% replacement). The shear stress versus shear rate plot indicates that the rice-blackgram batter exhibited non-Newtonian fluid behavior (shear thinning property) even after 100% replacement of white rice with brown rice. The rheological characteristics of rice-blackgram batters fitted reasonably well in Cassan (r2 = 0.8521-0.9856) and power law (r2 = 0.8042-0.9823) models. Brown rice replacement at all levels did not affect the flow behavior index, yield stress, consistency coefficient, and apparent viscosity of batter at 25 degrees C. However, at higher temperature, the viscosity was greater for T4 and T5 (no difference between them) than T1, T2, and T3 (no difference between them) batters. Further research is required to determine the sensory attributes and acceptability of the cooked products with brown rice-blended batter.

  6. Rheological and microstructural properties of beef sausage batter formulated with fish fillet mince.

    Science.gov (United States)

    Hashemi, Ala; Jafarpour, Ali

    2016-01-01

    Rheological properties and microstructure of beef meat sausage batter, incorporated with different percentages of fish fillet mince (5 %, 20 %, 35 % and 50 %), were investigated and compared to the control (0 % fish). By increasing the proportion of fish fillet mince to the sausage formula up to 35 % and 50 %, hardness was increased by 40 % and 16 %, respectively, (P  0.05). In terms of temperature sweep test, storage modulus (G') of control sample faced a substantial slop from 10 °C to 58 °C, corresponding to the lowest magnitude of G' at its gelling point (~58°), but completed at around 70 °C, as same as the other treatments. Whereas the gelling point of batter sample with 50 % fish mince remained at nearly 42 °C, which was remarkably lowest among all treatments, indicating the better gel formation process. SEM micrographs revealed a previous orderly set gel before heating in all treatments whereas after heating up to 90 °C gel matrices became denser with more obvious granular pattern and aggregated structure, specifically in sample with 50 % fish mince. In conclusion, addition of fish mince up to 50 % into beef sausage formula, positively interacted in gel formation process, without diminishing its rheological properties.

  7. Rheological, thermo-mechanical, and baking properties of wheat-millet flour blends.

    Science.gov (United States)

    Aprodu, Iuliana; Banu, Iuliana

    2015-07-01

    Millet has long been known as a good source of fiber and antioxidants, but only lately started to be exploited by food scientists and food industry as a consequence of increased consumer awareness. In this study, doughs and breads were produced using millet flour in different ratios (10, 20, 30, 40, and 50%) to white, dark, and whole wheat flour. The flour blends were evaluated in terms of rheological and thermo-mechanical properties. Fundamental rheological measurements revealed that the viscosity of the flour formulations increases with wheat flour-extraction rate and decreases with the addition of millet flour. Doughs behavior during mixing, overmixing, pasting, and gelling was established using the Mixolab device. The results of this bread-making process simulation indicate that dough properties become critical for the flour blends with millet levels higher than 30%. The breads were evaluated for volume, texture, and crumb-grain characteristics. The baking test and sensory evaluation results indicated that substitution levels of up to 30% millet flour could be used in composite bread flour. High levels of millet flour (40 and 50%) negatively influenced the loaf volume, crumb texture, and taste. © The Author(s) 2014.

  8. Rapid heating of Alaska pollock and chicken breast myofibrillar proteins as affecting gel rheological properties.

    Science.gov (United States)

    Liu, Wenjie; Stevenson, Clint D; Lanier, Tyre C

    2013-07-01

    Surimi seafoods (fish/poikilotherm protein) in the U.S.A. are typically cooked rapidly to 90+°C, while comminuted products made from land animals (meat/homeotherm protein) are purposely cooked much more slowly, and to lower endpoint temperatures (near 70 °C). We studied heating rate (0.5, 25, or 90 °C/min) and endpoint temperature (45 to 90 °C) effects on rheological properties (fracture, small strain) of washed myofibril gels derived from fish (Alaska pollock) compared with chicken breast at a common pH (6.75). This was contrasted with published data on gelation kinetics of chicken myosin over the same temperature range. Heating rate had no effect on fracture properties of fish gels but slow heating did yield somewhat stronger, but not more deformable, chicken gels. Maximum gel strength by rapid heating could be achieved within 5 min holding after less than 1 min heating time. Dynamic testing by small strain revealed poor correspondence of the present data to that published for gelling response of chicken breast myosin in the same temperature range. The common practice of reporting small-strain rheological parameters measured at the endpoint temperature was also shown to be misleading, since upon cooling, there was much less difference in rigidity between rapidly and slowly heated gels for either species. © 2013 Institute of Food Technologists®

  9. Probiotic Bacillus spp. in Soy-Curd: Nutritional, Rheological, Sensory, and Antioxidant Properties.

    Science.gov (United States)

    Shobharani, P; Prakash, Maya; Halami, Prakash M

    2015-10-01

    The focus of this study was to coculture probiotic Bacillus spp. with dairy starter cultures namely, Streptococcus thermophilus and Lactobacillus bulgaricus for enhanced nutritional properties of soy-curd. Subsequently, rheological, sensory, and antioxidant properties of soy-curd along with mineral as well as fatty acid composition were analyzed. Data revealed an increase in the cell viability of probiotic Bacillus spp. on coculturing rather than as mono-culture. Proximate analysis showed higher nutritional value along with increased trace elements. UFA/SFA ratio, rheology, and sensory properties of probiotic soy-curd were in the acceptable range. Probiotic soy-curd showed higher antioxidant activity as measured by the ability to scavenge free radicals. No significant difference in the overall quality within the probiotic products was observed. However, B. flexus MCC2427 cocultured product displayed slightly better attributes than other samples. In general, the results suggest that soy-curd can be a suitable carrier for probiotic Bacillus spp. and the enhanced nutritional and antioxidant properties could be of additional advantage to combat malnutrition problem. In order to supply consumers with intriguing probiotic products for improving health benefits, several criteria including technological and functional properties should be considered as a quality control measures. Further, a meaningful level of probiotics has to be viable to exhibit beneficial effect. Hence, present work has been carried out to improve the quality of soy-curd by supplementation of probiotic Bacillus spp. These Bacillus spp. are well characterized native probiotic cultures with potential functional attributes including antimicrobial, antioxidant, anticholesterol activity (Shobharani and Halami 2014). Hence, the application of these cultures will encourage for development of food product with wider health benefits. © 2015 Institute of Food Technologists®

  10. Rheological and mechanical properties of polyamide 6 modified by electron-beam initiated mediation process

    International Nuclear Information System (INIS)

    Shin, Boo Young; Kim, Jae Hong

    2015-01-01

    Polyamide (PA6) has been modified by electron-beam initiated mediator process to improve drawbacks of PA6. Glycidyl methacrylate (GMA) was chosen as a reactive mediator for modification process of PA6. The mixture of the PA6 and GMA was prepared by using a twin-screw extruder, and then the mixture was exposed to electron-beam irradiation at various doses at room temperature. The modified PA6 were characterized by observing rheological and mechanical properties and compared virgin PA6. Thermal properties, water absorption, and gel fraction were also investigated. Tight gel was not found even when PA6 was irradiated at 200 kGy. Complex viscosity and storage modulus of PA6 were remarkably increased by electron-beam irradiation with medium of GMA. Maximum increase in complex viscosity was 75 times higher than virgin PA6 at 0.1 rad/s when it was irradiated at 200 kGy with the GMA. Mechanical properties were also improved without scarifying of processability. The reaction mechanisms for the mediation process with the reactive mediator of GMA were estimated to elucidate the cause of significantly enhanced rheological and mechanical properties without loss of thermoplasticity. - Highlights: • PA6 was modified by the electron-beam initiated mediation process. • Maximum increase in complex viscosity of modified PA6 was 75 times higher than virgin PA6 at 0.1 rad/s. • Mechanical properties were improved without scarifying of processability. • The GMA as a mediator played a key role in the electron-beam initiated mediation process

  11. Thermal, tensile and rheological properties of low density polyethylene (LDPE) processed irradiated by gamma-ray

    International Nuclear Information System (INIS)

    Ferreto, Helio F.R.; Oliveira, Ana C.F. de; Parra, Duclerc F.; Lugao, Ademar B.

    2013-01-01

    The aim of this paper is to investigate structural changes of low density polyethylene (LDPE) modified by ionizing radiation (gamma rays). The gamma radiation process for modification of commercial polymers is a widely applied technique to promote new physical-chemical and mechanical properties. Gamma irradiation originates free radicals which can induce chain scission or recombination, providing its annihilation, branching or crosslinking. The samples were prepare in hydraulic press in temperature 180 deg C after was irradiated with gamma source of 60 Co at doses of 5, 10, 20, 50 or 100 kGy at a dose rate of 5 kGy/h in inert atmosphere. The changes in molecular structure of LDPE, after gamma irradiations were evaluated using thermogravimetric analysis (TGA) and tensile machine and oscillatory rheology. The results showed the variations of the properties depending on the dose at each atmosphere. (author)

  12. Effect of whey and casein protein hydrolysates on rheological, textural and sensory properties of cookies.

    Science.gov (United States)

    Gani, Adil; Broadway, A A; Ahmad, Mudasir; Ashwar, Bilal Ahmad; Wani, Ali Abas; Wani, Sajad Mohd; Masoodi, F A; Khatkar, Bupinder Singh

    2015-09-01

    Milk proteins were hydrolyzed by papain and their effect on the rheological, textural and sensory properties of cookies were investigated. Water absorption (%) decreased significantly as the amount of milk protein concentrates and hydrolysates increased up to a level of 15 % in the wheat flour. Dough extensibility decreased with inrease in parental proteins and their hydrolysates in wheat flour, significantly. Similarly, the pasting properties also varied significantly in direct proportion to the quantity added in the wheat flour. The colour difference (ΔE) of cookies supplemented with milk protein concentrates and hydrolysates were significantly higher than cookies prepared from control. Physical and sensory characteristics of cookies at 5 % level of supplementation were found to be acceptable. Also the scores assigned by the judges for texture and colour were in good agreement with the measurements derived from the physical tests.

  13. Mechanical and rheological properties of the bionanocomposites of biope/organoclay vermiculite

    International Nuclear Information System (INIS)

    Hanken, R.B.L.; Agrawal, P.; Oliveira, A.D.B.; Melo, T. J. A.

    2014-01-01

    Bionanocomposites of green polyethylene with organic vermiculite were prepared by melt intercalation method. Rheological and mechanical properties of these bionanocomposites were studied. The clay was treated with a quaternary ammonium salt, characterized by infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The results showed the incorporation of salt in clay. The bionanocomposites were then prepared by extrusion followed by injection, in amounts of 0.5 to 5 phr of clay in the final compound. Subsequently, the samples were characterized by: capillary rheometer and mechanical tests (tensile and impact). Capillary rheometer results showed that the presence of organic vermiculite in the green polyethylene decreased viscosity of the systems. The mechanical properties of bionanocomposites showed an increased elastic modulus and reduced impact resistance. (author)

  14. Rheological properties of biscuit dough from different cultivars, and relationship to baking characteristics

    DEFF Research Database (Denmark)

    Pedersen, L.; Kaack, K.; Bergsøe, M.N.

    2004-01-01

    Rheological properties of semi-sweet biscuit doughs from eight wheat cultivars were studied, and related to the dimensional changes of biscuits after cutting and baking. The tested cultivars were selected in order to represent a wide diversity in biscuit baking performance, and were grown with low...... use of N-fertiliser in three successive years. A standard recipe for semi-sweet biscuit dough was used, and the amount of water added was adjusted to the water absorption capacity. The theological properties of the dough were characterised by creep recovery and oscillation. The fundamental methods...... recovery parameters. Sedimentation value was the only physiochernical flour characteristic with considerable influence on the model. Validation of the partial least squares-model including all samples from the 3 years gave only a weak correlation (r = 0.58), whereas when each single year was evaluated...

  15. Changes in Saliva Rheological Properties and Mucin Glycosylation in Dry Mouth.

    Science.gov (United States)

    Chaudhury, N M A; Shirlaw, P; Pramanik, R; Carpenter, G H; Proctor, G B

    2015-12-01

    Saliva is vital for the maintenance of normal oral physiology and mucosal health. The loss of salivary function can have far-reaching consequences, as observed with dry mouth, which is associated with increased orodental disease, speech impairment, dysphagia, and a significant negative effect on quality of life. The timely diagnosis of oral dryness is vital for the management of orodental disease and any associated often-undiagnosed systemic disease (e.g., Sjögren syndrome). Our aim was to investigate differences in mucin glycoproteins and saliva rheological properties between sufferers and nonsufferers of dry mouth in order to understand the relationship between saliva composition, rheological properties, and dryness perception and provide additional potential diagnostic markers. All patients exhibited objective and subjective oral dryness, irrespective of etiology. Over half of the patients (n = 20, 58.8%) had a saliva secretion rate above the gland dysfunction cutoff of 0.1 mL/min. Mucin (MUC5B and MUC7) concentrations were generally similar or higher in patients. Despite the abundance of these moisture-retaining proteins, patients exhibited reduced mucosal hydration (wetness) and significantly lower saliva spinnbarkeit (stringiness), suggesting a loss of the lubricating and retention/adhesion properties of saliva, which, at least partially, are associated with mucin glycoproteins. Over 90% of patients with dry mouth (DMPs) consistently had unstimulated whole mouth saliva (UWMS) spinnbarkeit below the proposed normal cutoff (10 mm). Further analysis of mucins revealed the reduced glycosylation of mucins in DMPs compared to healthy controls. Our data indicate that UWMS mucin concentrations are not reduced in dry mouth but that the mucin structure (glycosylation) is altered. UWMS from DMPs had reduced spinnbarkeit, the assessment of which, in conjunction with sialometry, could improve sensitivity for the diagnosis of dry mouth. Additionally, it may be useful to

  16. Intraluminal mapping of tissue viscoelastic properties using laser speckle rheology catheter (Conference Presentation)

    Science.gov (United States)

    Wang, Jing; Hosoda, Masaki; Tshikudi, Diane M.; Nadkarni, Seemantini K.

    2016-03-01

    A number of disease conditions including coronary atherosclerosis, peripheral artery disease and gastro-intestinal malignancies are associated with alterations in tissue mechanical properties. Laser speckle rheology (LSR) has been demonstrated to provide important information on tissue mechanical properties by analyzing the time scale of temporal speckle intensity fluctuations, which serves as an index of tissue viscoelasticity. In order to measure the mechanical properties of luminal organs in vivo, LSR must be conducted via a miniature endoscope or catheter. Here we demonstrate the capability of an omni-directional LSR catheter to quantify tissue mechanical properties over the entire luminal circumference without the need for rotational motion. Retracting the catheter using a motor-drive assembly enables the reconstruction of cylindrical maps of tissue mechanical properties. The performance of the LSR catheter is tested using a luminal phantom with mechanical moduli that vary in both circumferential and longitudinal directions. 2D cylindrical maps of phantom viscoelastic properties are reconstructed over four quadrants of the coronary circumference simultaneously during catheter pullback. The reconstructed cylindrical maps of the decorrelation time constants easily distinguish the different gel components of the phantom with different viscoelastic moduli. The average values of decorrelation times calculated for each gel component of the phantom show a strong correspondence with the viscoelastic moduli measured via standard mechanical rheometry. These results highlight the capability for cylindrical mapping of tissue viscoelastic properties using LSR in luminal organs using a miniature catheter, thus opening the opportunity for improved diagnosis of several disease conditions.

  17. Rheological Properties of Commercially Available Hyaluronic Acid Products in the United States for the Treatment of Osteoarthritis Knee Pain

    Directory of Open Access Journals (Sweden)

    Mathew Nicholls

    2018-01-01

    Full Text Available Objective: The inconsistent results within the current literature regarding the efficacy of intra-articular-hyaluronic acid (IA-HA for the treatment of knee osteoarthritis (OA have been suggested to be due to intrinsic differences between individual HA products. The purpose of this investigation is to define the rheological differences between currently available HA products in the United States at the time of this study for the treatment of knee OA, which will help elaborate on the appropriateness of classifying HA products as a class opposed to as individual agents. Methods: The rheological parameters for Euflexxa, Orthovisc, Supartz, Monovisc, Synvisc, Synvisc-One, Gel-One, and Hyalgan were obtained with a TA AR 2000 EX Rheometer with a cone-plate geometry (40-mm plate diameter and a 2° cone angle at room temperature. Results: The bulk rheological parameters of the different products suggest molecular structures traversing the range of dilute solution (Hyalgan, Supartz, semidilute solution (Euflexxa, Orthovisc, entangled solutions (Monovisc, Synvisc, Synvisc-One, and even gel-like (Gel-One behavior. Conclusions: Due to the differences in rheological properties between IA-HA products, the universal assessment of these products as a class may not be appropriate. Instead, it may be more appropriate to assess each product individually. Future research should aim to link these differences in rheological properties to the differences in clinical efficacy seen across these IA-HA products.

  18. Rheological Properties of Commercially Available Hyaluronic Acid Products in the United States for the Treatment of Osteoarthritis Knee Pain.

    Science.gov (United States)

    Nicholls, Mathew; Manjoo, Ajay; Shaw, Peter; Niazi, Faizan; Rosen, Jeffrey

    2018-01-01

    The inconsistent results within the current literature regarding the efficacy of intra-articular-hyaluronic acid (IA-HA) for the treatment of knee osteoarthritis (OA) have been suggested to be due to intrinsic differences between individual HA products. The purpose of this investigation is to define the rheological differences between currently available HA products in the United States at the time of this study for the treatment of knee OA, which will help elaborate on the appropriateness of classifying HA products as a class opposed to as individual agents. The rheological parameters for Euflexxa, Orthovisc, Supartz, Monovisc, Synvisc, Synvisc-One, Gel-One, and Hyalgan were obtained with a TA AR 2000 EX Rheometer with a cone-plate geometry (40-mm plate diameter and a 2° cone angle) at room temperature. The bulk rheological parameters of the different products suggest molecular structures traversing the range of dilute solution (Hyalgan, Supartz), semidilute solution (Euflexxa, Orthovisc), entangled solutions (Monovisc, Synvisc, Synvisc-One), and even gel-like (Gel-One) behavior. Due to the differences in rheological properties between IA-HA products, the universal assessment of these products as a class may not be appropriate. Instead, it may be more appropriate to assess each product individually. Future research should aim to link these differences in rheological properties to the differences in clinical efficacy seen across these IA-HA products.

  19. Relation between ultrasonic properties, rheology and baking quality for bread doughs of widely differing formulation.

    Science.gov (United States)

    Peressini, Donatella; Braunstein, Dobrila; Page, John H; Strybulevych, Anatoliy; Lagazio, Corrado; Scanlon, Martin G

    2017-06-01

    The objective was to evaluate whether an ultrasonic reflectance technique has predictive capacity for breadmaking performance of doughs made under a wide range of formulation conditions. Two flours of contrasting dough strength augmented with different levels of ingredients (inulin, oil, emulsifier or salt) were used to produce different bread doughs with a wide range of properties. Breadmaking performance was evaluated by conventional large-strain rheological tests on the dough and by assessment of loaf quality. The ultrasound tests were performed with a broadband reflectance technique in the frequency range of 0.3-6 MHz. Principal component analysis showed that ultrasonic attenuation and phase velocity at frequencies between 0.3 and 3 MHz are good predictors for rheological and bread scoring characteristics. Ultrasonic parameters had predictive capacity for breadmaking performance for a wide range of dough formulations. Lower frequency attenuation coefficients correlated well with conventional quality indices of both the dough and the bread. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  20. Effects of Momordica charantia L. on the blood rheological properties in diabetic patients.

    Science.gov (United States)

    França, Eduardo Luzía; Ribeiro, Elton Brito; Scherer, Edson Fredulin; Cantarini, Déborah Giovanna; Pessôa, Rafael Souza; França, Fernando Luzía; Honorio-França, Adenilda Cristina

    2014-01-01

    An evaluation of the rheological properties and the effects of Momordica. charantia L. (M. charantia) nanoparticles and polyethylene glycol (PEG) microspheres adsorbed with M. charantia nanoparticles on the blood of hyperglycemic patients is presented. Blood samples were collected according to glycemic status: normoglycemic (N = 56) and hyperglycemic (N = 26). General and hematological characteristics were determined. Blood rheological parameters were determined at room temperature and under a temperature scan. We determined the effects on whole blood viscosity of treatment with an extract of M. charantia, PEG, or PEG microspheres adsorbed with plant extract. The viscosity of the blood of hyperglycemic patients is greater than that of normoglycemic patients. Nanoparticles of M. charantia extracts lowered blood viscosity at equivalent rates in normo- and hyperglycemic individuals. PEG microspheres did not reduce blood viscosity in hyperglycemic individuals. However, PEG microspheres adsorbed with nanofraction extracts of M. charantia reduced blood viscosity. These data suggest that the effects of diabetes on the viscosity of the blood should be considered. The use of a nanoparticles extract of M. charantia and its adsorption on PEG microspheres may represent an alternative for the control and treatment of blood disorders in diabetic patients.

  1. Effect of cellulose nanocrystals (CNCs) on crystallinity, mechanical and rheological properties of polypropylene/CNCs nanocomposites

    Science.gov (United States)

    Bagheriasl, D.; Carreau, P. J.; Dubois, C.; Riedl, B.

    2015-05-01

    Rheological and mechanical properties of polypropylene (PP)/CNCs nanocomposites were compared with those of nanocomposites containing poly(ethylene-co-vinyl alcohol) as a compatibilizer. The nanocomposites were prepared by a Brabender internal mixer at CNC contents of 5 wt%. The compression molded nanocomposite dog-bones and disks were characterized regarding their tensile and dynamic rheological behavior, respectively. The complex viscosity of the nanocomposites samples containing the compatibilizer were increased, slightly, compared to the non-compatibilized nanocomposite samples. Moreover, an overshoot in the transient start-up viscosity of the compatibilized nanocomposite was observed. The Young modulus of the nanocomposite samples containing the compatibilizer were increased up to ca. 37% compared to the neat PP. The elongation at break was decreased in all PP/CNC nanocomposite samples, but less for the nanocomposite samples containing the compatibilizer. The crystalline content of the PP in the nanocomposites and also the crystallization temperature were increased after compatibilization. These results could be ascribed to the efficiency of the poly(ethylene-co-vinyl alcohol) as a compatibilizer that favors a better dispersion and wetting of the hydrophilic CNCs within the hydrophobic PP.

  2. Investigation of Rheological Properties of Blended Cement Pastes Using Rotational Viscometer and Dynamic Shear Rheometer

    Directory of Open Access Journals (Sweden)

    Yoo Jae Kim

    2018-01-01

    Full Text Available To successfully process concrete, it is necessary to predict and control its flow behavior. However, the workability of concrete is not completely measured or specified by current standard tests. Furthermore, it is only with a clear picture of cement hydration and setting that full prediction and control of concrete performance can be generalized. In order to investigate the rheological properties of blended cement pastes, a rotational viscometer (RV was used to determine the flow characteristics of ordinary and blended pastes to provide assurance that it can be pumped and handled. Additionally, a dynamic shear rheometer (DSR was used to characterize both the viscous and elastic components of pastes. Ordinary Portland cement paste and blended pastes (slag, fly ash, and silica fume were investigated in this study. The stress and strain of the blended specimens were measured by the DSR, which characterizes both viscous and elastic behaviors by measuring the complex shear modulus (the ratio of total shear stress to total shear strain and phase angle (an indicator of the relative amounts of recoverable and nonrecoverable deformation of materials. Cement pastes generally exhibit different rheological behaviors with respect to age, mineral admixture type, and cement replacement level.

  3. Rheological, pasting, thermal and retrogradation properties of octenyl succinic anhydride modified potato starch

    Directory of Open Access Journals (Sweden)

    Chuin WON

    Full Text Available Abstract The objective of the present study was to investigate the rheological, pasting, and thermal properties of octenyl succinic anhydrate (OSA-modified potato starch. Potato starch was modified using different concentrations of OSA (0, 1, 3, and 5%, v/v. The degree of substitution (DS for the OSA-modified starch ranged from 0.0012 to 0.0055. The amylose leaching values of native and OSA-modified potato starch with different DS levels were in the range of 47.09-87.32%. The gel strength values of the OSA-modified starch were lower than those of native potato starch. Rapid Visco Analyzer data showed that peak, hot pasting, final and setback viscosities of the native starch decreased after OSA modification. Dynamic shear rheological tests, conducted at 4 °C, indicated that OSA-modified potato starch had weak gel-like behavior with the storage moduli (G' higher than the loss moduli (G” over most of the frequency ranges (0.63-63.8 rad·s-1.

  4. Microstructural evolution and rheological properties of AA6063 alloy produced by semisolid processing (SIMA and MHD)

    International Nuclear Information System (INIS)

    Bustos, O.; Leiva, R.; Sanchez, C.; Ordonez, S.; Carvajal, L.; Mannheim, R.

    2007-01-01

    In this work the rheological behaviour and the microstructural evolution of alloy AA6063 submitted to two different processing routes were studied: cold deformation and partial fusion (SIMA process) and magneto hydrodynamic stirring during its solidification (MHD process). The microstructural evolution during the isothermal holding was studied to verify if the Ost wald ripening mechanisms, classic growth and coalescence, are applicable to alloys made by these processing routes. The rheological properties were evaluated using a compression rheometer with parallel plates and digital capture of position and time data. Compression tests were made in short cylinders extracted from ingots that showed: a dendritic microstructure typical of as cast material, a typical microstructure of cold deformed material and a microstructure of materials obtained by MHD process. It was found that a globular microstructure has a typical behaviour of a fluid when being formed in semisolid state, contrary to the behaviour of the as cast dendritic microstructure. In addition, the mechanisms that operate in the microstructural evolution during the isothermal holdings were verified, through metallographic analysis. (Author) 29 refs

  5. Rheological, mechanical and membrane penetration properties of novel dual drug systems for percutaneous delivery.

    Science.gov (United States)

    Woolfson, A D; Malcolm, R K; Campbell, K; Jones, D S; Russell, J A

    2000-07-03

    In this study it has been demonstrated that mixtures of two solid drugs, ibuprofen and methyl nicotinate, with different but complementary pharmacological activities and which exist as a single liquid phase over a wide composition range at skin temperature, can be formulated as o/w emulsions without the use of an additional hydrophobic carrier. These novel dual drug systems provided significantly enhanced in vitro penetration rates through a model lipophilic barrier membrane compared to conventional individual formulations of each active. Thus, for ibuprofen, drug penetration flux enhancements of three- and 10-fold were observed when compared to an aqueous ibuprofen suspension and a commercial alcohol-based ibuprofen formulation, respectively. Methyl nicotinate penetration rates were shown to be similar for aqueous gels and emulsified systems. Mechanisms explaining these observations are proposed. Novel dual drug formulations of ibuprofen and methyl nicotinate, formulated within the liquid range at skin temperature, were investigated by oscillatory rheology and texture profile analysis, demonstrating the effects of drug and viscosity enhancer concentrations, and disperse phase type upon the rheological, mechanical and drug penetration properties of these systems.

  6. Effects of Momordica charantia L. on the Blood Rheological Properties in Diabetic Patients

    Science.gov (United States)

    França, Eduardo Luzía; Ribeiro, Elton Brito; Scherer, Edson Fredulin; Cantarini, Déborah Giovanna; Pessôa, Rafael Souza; França, Fernando Luzía; Honorio-França, Adenilda Cristina

    2014-01-01

    An evaluation of the rheological properties and the effects of Momordica. charantia L. (M. charantia) nanoparticles and polyethylene glycol (PEG) microspheres adsorbed with M. charantia nanoparticles on the blood of hyperglycemic patients is presented. Blood samples were collected according to glycemic status: normoglycemic (N = 56) and hyperglycemic (N = 26). General and hematological characteristics were determined. Blood rheological parameters were determined at room temperature and under a temperature scan. We determined the effects on whole blood viscosity of treatment with an extract of M. charantia, PEG, or PEG microspheres adsorbed with plant extract. The viscosity of the blood of hyperglycemic patients is greater than that of normoglycemic patients. Nanoparticles of M. charantia extracts lowered blood viscosity at equivalent rates in normo- and hyperglycemic individuals. PEG microspheres did not reduce blood viscosity in hyperglycemic individuals. However, PEG microspheres adsorbed with nanofraction extracts of M. charantia reduced blood viscosity. These data suggest that the effects of diabetes on the viscosity of the blood should be considered. The use of a nanoparticles extract of M. charantia and its adsorption on PEG microspheres may represent an alternative for the control and treatment of blood disorders in diabetic patients. PMID:24672797

  7. Effects of Momordica charantia L. on the Blood Rheological Properties in Diabetic Patients

    Directory of Open Access Journals (Sweden)

    Eduardo Luzía França

    2014-01-01

    Full Text Available An evaluation of the rheological properties and the effects of Momordica. charantia L. (M. charantia nanoparticles and polyethylene glycol (PEG microspheres adsorbed with M. charantia nanoparticles on the blood of hyperglycemic patients is presented. Blood samples were collected according to glycemic status: normoglycemic (N=56 and hyperglycemic (N=26. General and hematological characteristics were determined. Blood rheological parameters were determined at room temperature and under a temperature scan. We determined the effects on whole blood viscosity of treatment with an extract of M. charantia, PEG, or PEG microspheres adsorbed with plant extract. The viscosity of the blood of hyperglycemic patients is greater than that of normoglycemic patients. Nanoparticles of M. charantia extracts lowered blood viscosity at equivalent rates in normo- and hyperglycemic individuals. PEG microspheres did not reduce blood viscosity in hyperglycemic individuals. However, PEG microspheres adsorbed with nanofraction extracts of M. charantia reduced blood viscosity. These data suggest that the effects of diabetes on the viscosity of the blood should be considered. The use of a nanoparticles extract of M. charantia and its adsorption on PEG microspheres may represent an alternative for the control and treatment of blood disorders in diabetic patients.

  8. Design of a dual nanostructured lipid carrier formulation based on physicochemical, rheological, and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Vitorino, Carla [University of Coimbra, Centro de Estudos Farmaceuticos (CEF), Faculty of Pharmacy (Portugal); Alves, Luis; Antunes, Filipe E. [University of Coimbra, Department of Chemistry (Portugal); Sousa, Joao J. [University of Coimbra, Centro de Estudos Farmaceuticos (CEF), Faculty of Pharmacy (Portugal); Pais, Alberto A. C. C., E-mail: pais@qui.uc.pt [University of Coimbra, Department of Chemistry (Portugal)

    2013-10-15

    The synergy between nanostructured lipid carriers (NLC) and chemical penetration enhancers provides the basis for a promising strategy to effectively deliver drugs through the skin. In the present work, focus is given to the study of the interaction of limonene, ethanol, and Carbopol Ultrez{sup Registered-Sign} 10NF, as the gelling agent, with a co-encapsulating NLC dispersion, containing both olanzapine and simvastatin. The analysis is based on rheological, mechanical, and physicochemical properties. The nanoparticle size ranged from 130 to 400 nm, depending on the system considered. The inclusion of carbopol resulted in a considerable increase in the NLC particle size, which was attributed to carbomer bridging nanoparticles, resulting in some particle aggregation. Rheological measurements indicated that the viscosity of the neat carbopol hydrogel was reduced by the enhancers and to a higher extent by the presence of NLC. A more apolar medium can be pointed out as a general explanation, while a polymer/nanoparticle hydrophobic interaction coupled with surfactant/polymer H-bonding provides the rationale for the NLC effect. The inclusion of enhancers and a carbomer largely contributed to the physicochemical stability of the NLC formulation, as revealed by the low transmission profiles and more negative zeta potential values.

  9. Protein conformational transitions at the liquid-gas interface as studied by dilational surface rheology.

    Science.gov (United States)

    Noskov, Boris A

    2014-04-01

    Experimental results on the dynamic dilational surface elasticity of protein solutions are analyzed and compared. Short reviews of the protein behavior at the liquid-gas interface and the dilational surface rheology precede the main sections of this work. The kinetic dependencies of the surface elasticity differ strongly for the solutions of globular and non-globular proteins. In the latter case these dependencies are similar to those for solutions of non-ionic amphiphilic polymers and have local maxima corresponding to the formation of the distal region of the surface layer (type I). In the former case the dynamic surface elasticity is much higher (>60 mN/m) and the kinetic dependencies are monotonical and similar to the data for aqueous dispersions of solid nanoparticles (type II). The addition of strong denaturants to solutions of bovine serum albumin and β-lactoglobulin results in an abrupt transition from the type II to type I dependencies if the denaturant concentration exceeds a certain critical value. These results give a strong argument in favor of the preservation of the protein globular structure in the course of adsorption without any denaturants. The addition of cationic surfactants also can lead to the non-monotonical kinetic dependencies of the dynamic surface elasticity indicating destruction of the protein tertiary and secondary structures. The addition of anionic surfactants gives similar results only for the protein solutions of high ionic strength. The influence of cationic surfactants on the local maxima of the kinetic dependencies of the dynamic surface elasticity for solutions of a non-globular protein (β-casein) differs from the influence of anionic surfactants due to the heterogeneity of the charge distribution along the protein chain. In this case one can use small admixtures of ionic surfactants as probes of the adsorption mechanism. The effect of polyelectrolytes on the kinetic dependencies of the dynamic surface elasticity of protein

  10. Examination of the rheological properties of stirred joghurt during the long-term storage by using dynamic oscillation method

    Directory of Open Access Journals (Sweden)

    Milica Vilušić

    2003-07-01

    Full Text Available In this work the rheological properties of stirred yoghurt during the longterm storage at 4 and 8°C were investigated. The optimal quantity of additives, in order to increase dry matter content (whole milk powder and whey protein-lactalbumin, was preliminary determined and the fermentation was performed. During 42 days, i.e., 1st, 7th, 14th, 21st, 28th, 35th and 42nd day of storage of stirred yoghurt, in refrigerator at 4 and 8°C, the changes of pH value, acidity and rheological properties by using of dynamic oscillation method were observed. Results of this work indicated that an addition of whole milk powder and whey protein have an influence on rheological properties of stirred yoghurt. The long-term storage of stirred yoghurt and the results of dynamic oscilations showed permanently higher G’storage (elasticity modulus, where elastic properties of viscoelastic products dominate, in comparison with the G” loss (viscosity modulus. Increased moduls of elasticy and viscosity, as function of time, permanently occurs at pH value 4.00 and lower, as an indication of alteration of long casein chains in the coagulum structure. Different temperatures of storage had no influence on changes of rheological properties of examinated types of stirred yoghur. The relation of above mentioned moduls of elasticy and viscosity kept the same increasing tendency.

  11. Some Mineral Physics Observations Pertinent to the Rheological Properties of Super-Earths

    Science.gov (United States)

    Karato, S.

    2010-12-01

    Both orbital and thermal evolution of recently discovered super-Earths (terrestrial planets whit mass exceeding that of Earth) depends critically on the rheological properties of their mantle. Although direct experimental studies on rheological properties are unavailable under the conditions equivalent to the deep mantles of these planets (~1 TPa and ~5000 K), a review of key materials science observations suggests that the deep mantle of these planets have much lower viscosity than most of the shallower regions of these planets. The key observations are: (i) phase transformations likely occur under these conditions including the B1 to B2 transition in MgO (1) and the dissociation of MgSiO3 into two oxides (MgO and SiO2) (2), (ii) the systematics in high-temperature creep show that materials with NaCl (B1) structures have much smaller viscosity than other oxides compared at the same normalized conditions (3), and (iii) diffusion coefficients in most of materials have a minimum at certain pressure and above that pressure it increases with pressure (due to mechanism transition) (4). In addition, a review of existing studies also shows that the ionic solids with B2 (CsCl) structure have larger diffusion coefficients than their B1 counter parts. Furthermore, if metallization transition occurs in any of these materials, delocalized electrons will further weaken the material. All of these observations or concepts suggest that even though the viscosity of a planet (below the asthenosphere) increases with depth in the relatively shallow regions, viscosity likely starts to decrease with depth below some critical depth (>~2000 km). The inferred low viscosity of super-Earths implies a large tidal dissipation and relatively rapid orbital evolution. Also such a rheological properties likely promote a layered mantle convection that enhances a weak deep mantle and retards the thermal evolution. 1. A. R. Oganov, M. J. Gillan, G. D. Price, Journal of Chemical Physics 118, 10174

  12. Some Qualitative and Rheological Properties of Virgin Olive Oil- Apple Vinegar Salad Dressing Stabilized With Xanthan Gum.

    Science.gov (United States)

    Abedinzadeh, Solmaz; Torbati, Mohammadali; Azadmard-Damirchi, Sodeif

    2016-12-01

    Purpose: Lipid oxidation and rheological properties are the main qualitative parameters determined in food emulsions. Salad dressings are food emulsions important in our daily diet, but conventional salad dressings have high amounts of cholesterol and saturated fatty acids because of egg yolk in their formulations. There are many studies on the modification of salad dressing formulations to replace egg yolk and saturated fats. The present study describes new formulation of salad dressing with olive oil and apple vinegar to produce a functional food product. Methods: This study investigated the qualitative properties, oxidative stability, rheological behavior and microstructure of the salad dressing without egg yolk. Oil-in-water emulsions were prepared with virgin olive oil and apple vinegar stabilized with various percentages of xanthan (T1: 0.25%, T2: 0.5%. T3: 0.75%). Samples were stored at refrigerator for 90 days and experiments were performed at production day and during storage. Results: The obtained results showed that peroxide value was increased for all samples during storage, but it was at an acceptable level. Fatty acid changes were not significant during storage. Droplet size was reduced by increasing xanthan gum. T2 had the best rheological properties during storage. Generally, T2 and T3 had higher scores and were more acceptable in organoleptic assay. Conclusion: Obtained results showed that T 2 had suitable qualitative and rheological properties and can be a proper egg yolk free salad dressing to introduce to the market.

  13. Some Qualitative and Rheological Properties of Virgin Olive Oil- Apple Vinegar Salad Dressing Stabilized With Xanthan Gum

    Directory of Open Access Journals (Sweden)

    Solmaz Abedinzadeh

    2016-12-01

    Full Text Available Purpose: Lipid oxidation and rheological properties are the main qualitative parameters determined in food emulsions. Salad dressings are food emulsions important in our daily diet, but conventional salad dressings have high amounts of cholesterol and saturated fatty acids because of egg yolk in their formulations. There are many studies on the modification of salad dressing formulations to replace egg yolk and saturated fats. The present study describes new formulation of salad dressing with olive oil and apple vinegar to produce a functional food product. Methods: This study investigated the qualitative properties, oxidative stability, rheological behavior and microstructure of the salad dressing without egg yolk. Oil-in-water emulsions were prepared with virgin olive oil and apple vinegar stabilized with various percentages of xanthan (T1: 0.25%, T2: 0.5%. T3: 0.75%. Samples were stored at refrigerator for 90 days and experiments were performed at production day and during storage. Results: The obtained results showed that peroxide value was increased for all samples during storage, but it was at an acceptable level. Fatty acid changes were not significant during storage. Droplet size was reduced by increasing xanthan gum. T2 had the best rheological properties during storage. Generally, T2 and T3 had higher scores and were more acceptable in organoleptic assay. Conclusion: Obtained results showed that T2 had suitable qualitative and rheological properties and can be a proper egg yolk free salad dressing to introduce to the market.

  14. Effect of smectite clays storage in their rheological properties; Efeito do armazenamento de argilas esmectiticas nas suas propriedades reologicas

    Energy Technology Data Exchange (ETDEWEB)

    Silva, I.A. da; Sousa, F.K.A. de; Neves, G. de A.; Ferreira, H.C., E-mail: isabelle_albuquerquecg@hotmail.com, E-mail: kegalves@gmail.com, E-mail: gelmires.neves@ufcg.edu.br, E-mail: heber.ferreira@ufcg.edu.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil); Ferreira, H.S., E-mail: hsivini@terra.com.br [Universidade Federal Rural de Pernambuco (UFRPE), Recife, PE (Brazil). Departamento de Educacao; Ferreira, H.S., E-mail: heber@ct.ufpb.br [Universidade Federal da Paraiba (UFPB), Joao Pessoa (Brazil). Departamento de Engenharia de Materiais

    2017-01-15

    This work investigates the storage influence of natural and industrial smectite clays in their rheological properties, since the salt metathesis reaction that occurs following treatment of polycationic clays with Na{sub 2} CO{sub 3} is reversible. The phenomena involved in this reaction are not yet fully known and previous studies show improvement in some properties. The rheological properties were determined in sodium-clays in 1995 and polycationic clays added with sodium carbonate (Na{sub 2} CO{sub 3} ) in 2015. Physical, chemical and mineralogical characterizations of the samples were performed using the following techniques: particle size analysis by laser diffraction, chemical composition by X-ray fluorescence, X-ray diffraction and thermal analysis (DTA and TGA). The rheology of dispersions was determined by the apparent viscosity, plastic viscosity and filtrate volume, which were later considered the oil industry standards only as a benchmark. The results showed that the storage conditions, humidity and particle size of the samples resulted in improvements in their rheological properties over the years, indicating the non-reversibility of the reaction of cation exchange, which is important in their validity after manufacturing. (author)

  15. Rheological and thermo-mechanical properties of poly(lactic acid)/lignin-coated cellulose nanocrystal composites

    Science.gov (United States)

    Anju Gupta; William Simmons; Gregory T. Schueneman; Donald Hylton; Eric A. Mintz

    2017-01-01

    Improving the processability and physical properties of sustainable biobased polymers and biobased fillers is essential to preserve its biodegradability and make them suitable for different end user applications. Herein, we report the use of spray-dried lignin-coated cellulose nanocrystals (L-CNCs), a biobased filler, to modify the rheological and thermos-mechanical...

  16. Effect of in situ exopolysaccharide production on physicochemical, rheological, sensory, and microstructural properties of the yogurt drink ayran: an optimization study based on fermentation kinetics.

    Science.gov (United States)

    Yilmaz, M T; Dertli, E; Toker, O S; Tatlisu, N B; Sagdic, O; Arici, M

    2015-03-01

    Exopolysaccharide (EPS)-producing starter cultures are preferred for the manufacture of fermented milk products to improve rheological and technological properties. However, no clear correlation exists between EPS production and the rheological and technological properties of fermented milk products such as the yogurt drink ayran. In this study, 4 different strain conditions (EPS- and EPS+ Streptococcus thermophilus strains) were tested as a function of incubation temperature (32, 37, or 42°C) and time (2, 3, or 4 h) to determine the effect of culture type and in situ EPS production on physicochemical, rheological, sensory, and microstructural properties of ayran. Furthermore, we assessed the effect of fermentation conditions on amounts of EPS production by different EPS-producing strains during ayran production. A multifactorial design of response surface methodology was used to model linear, interaction, and quadratic effects of these variables on steady shear rheological properties of ayran samples and in situ EPS production levels. The physicochemical and microbiological characteristics of ayran samples altered depending on incubation conditions and strain selection. Steady shear tests showed that ayran samples inoculated with EPS+ strains exhibited pseudoplastic flow behavior. Production of ayran with EPS- strain (control sample) resulted in the lowest apparent viscosity values (η50), whereas those produced with the combination of 2 EPS+ strains yielded ayran with notably increased η50 values. We concluded that incubation time was the variable with the greatest effect on η50, consistency coefficient (K), and flow behavior index (n) values. In situ EPS production was also affected by these conditions during ayran fermentation in which strain-specific metabolism conditions were found to be the most important factor for EPS production. In addition, these findings correlated the amount of in situ EPS produced with the rheological properties of ayran. Scanning

  17. Effect of selected Hofmeister salts on textural and rheological properties of nonfat cheese.

    Science.gov (United States)

    Stankey, J A; Johnson, M E; Lucey, J A

    2011-09-01

    Three Hofmeister salts (HS; sodium sulfate, sodium thiocyanate, and sodium chloride) were evaluated for their effect on the textural and rheological properties of nonfat cheese. Nonfat cheese, made by direct acidification, were sliced into discs (diameter=50 mm, thickness=2 mm) and incubated with agitation (6 h at 22°C) in 50 mL of a synthetic Cheddar cheese aqueous phase buffer (pH 5.4). The 3 HS were added at 5 concentrations (0.1, 0.25, 0.5, 0.75, and 1.0 M) to the buffer. Post-incubation, cheese slices were air dried and equilibrated in air-tight bags for 18 h at 5°C before analysis. Small amplitude oscillatory rheology properties, including the dynamic moduli and loss tangent, were measured during heating from 5 to 85°C. Hardness was determined by texture profile analysis. Acid-base buffering was performed to observe changes in the indigenous insoluble (colloidal) calcium phosphate (CCP). Moisture content decreased with increasing HS concentration. Cheeses incubated in high concentrations of SCN(-) softened earlier (i.e., loss tangent=1) compared with other HS treatments. Higher melting temperature values were observed for cheeses incubated in high concentrations of SO(4)(2-). Hardness decreased in cheeses incubated in buffers with high concentrations of SCN(-). The indigenous CCP profile of nonfat cheese was not greatly affected by incubation in Cl(-) or SCN(-), whereas buffers with high concentrations of SO(4)(2-) reduced the acid-base buffering contributed by CCP. The use of high concentrations (1.0M) of SCN(-) for incubation of cheeses resulted in a softer protein matrix at high temperatures due to the chaotropic effect of SCN(-), which weakened hydrophobic interactions between CN. Cheese samples incubated in 1.0M SO(4)(2-) buffers exhibited a stiffer protein matrix at high temperatures due to the kosmotropic effect of SO(4)(2-), which helped to strengthen hydrophobic interactions in the proteins during the heating step. This study showed that HS

  18. Thermal and Rheological Properties of Polypropylene/Organoclay/Poly(ethylene-co-octene) Nanocomposites

    Science.gov (United States)

    Sun, Tongchen; Dong, Xia; Du, Kai; Meng, Kun; Han, Charles C.; Wang, Ke; Fu, Qiang

    2007-03-01

    Poly(ethylene-co-octene) (PEOc) is added to polypropylene/organoclay(organic modified montmorillonite-OMMT) nanocomposites which are prepared by a co-rotating twin-screw extruder to improve the properties of these materials. These ternary materials are investigated in details with the combination of XRD, TGA and rheology measurements. The onset and 5% loss temperatures have increased with clay content increasing and reached to a plateau when clay composition is 2% or higher. The degradation temperatures of the ternary nanocomposites are higher than binary nanocomposites. Storage modulus of these two systems show a pseudo-solid like behavior in low frequency region when clay content is 2% or higher. But ternary nanocomposite is more stable and relaxation slower than binary composites. All results indicated that PEOc plays an important role for thermal stability and structure stability of these nanocomposites.

  19. Influence of cementitious additions on rheological and mechanical properties of reactive powder concretes

    Science.gov (United States)

    Zenati, A.; Arroudj, K.; Lanez, M.; Oudjit, M. N.

    2009-11-01

    Following needs of concrete market and the economic and ecological needs, several researchers, all over the world, studied the beneficial effect which the incorporation of the mineral additions in Portland cement industry can bring. It was shown that the incorporation of local mineral additions can decrease the consumption of crushing energy of cements, and reduce the CO2 emission. Siliceous additions, moreover their physical role of filling, play a chemical role pozzolanic. They contribute to improving concrete performances and thus their durability. The abundance of dunes sand and blast furnace slag in Algeria led us to study their effect like cementitious additions. The objective of this paper is to study the effect of the incorporation of dunes sand and slag, finely ground on rheological and mechanical properties of reactive powder concretes containing ternary binders.

  20. Pasting, rheological, and retrogradation properties of low-amylose rice starch with date syrup.

    Science.gov (United States)

    Mohamed, Ibrahim O; Babucurr, Jobe

    2017-09-01

    Effects of date syrup on pasting, rheological, and retrogradation properties of low-amylose rice starch were investigated using three levels of date syrup (starch:syrup 1:1, 1:2, or 1:3). Measurements were carried out using HR-2 Discovery Rheometer equipped with a pasting cell and parallel plate geometry. The pasting measurements showed that the peak viscosity of the control is significantly higher than the samples with date syrup (p syrup levels. Addition of date syrup increases the solid-like behavior of the gel in reverse order with increased date syrup levels. Low-amylose starch gel used in this study showed minor changes in elastic modulus (G') during one week cold storage indicting that low-amylose rice starch is resistant to retrogradation. Addition of date syrup slightly resulted in increased retrogradation compared to the control.

  1. Effect of acid treated carbon nanotubes on mechanical, rheological and thermal properties of polystyrene nanocomposites

    KAUST Repository

    Amr, Issam Thaher

    2011-09-01

    In this work, multiwall carbon nanotubes (CNT) were functionalized by acid treatment and characterized using Fourier Transform Infrared Spectroscopy (FTIR) and thermogravimetric analysis (TGA). Polystyrene/CNT composites of both the untreated and acid treated carbon nanotubes were prepared by thermal bulk polymerization without any initiator at different loadings of CNT. The tensile tests showed that the addition of 0.5 wt.% of acid treated CNT results in 22% increase in Young\\'s modulus. The DSC measurements showed a decrease in glass transition temperature (Tg) of PS in the composites. The rheological studies at 190 °C showed that the addition of untreated CNT increases the viscoelastic behavior of the PS matrix, while the acid treated CNT acts as plasticizer. Thermogravimetric analysis indicated that the incorporation of CNT into PS enhanced the thermal properties of the matrix polymer. © 2011 Elsevier Ltd. All rights reserved.

  2. Solid state characterization and rheological properties of native and modified Bambara groundnut (Vigna subterranean starches

    Directory of Open Access Journals (Sweden)

    Michael Odeniyi

    2017-09-01

    Full Text Available This study was designed to determine the suitability of native, pregelatinized and carboxymethylated Vigna subterranean (Bambara nut starches for pharmaceutical applications, through their characterization by means of physicochemical, rheological, thermal, morphological and instrumental spectroscopic methods. The native starch was extracted from Bambara nut, after which it was used to prepare both pregelatinized and carboxymethylated forms. Microscopy revealed increased in granular size on modification. Both pregelatinized and carboxymethylated Bambara starches had better flow properties and swellability compared to the native starch. Native Bambara starch had greater tendency to retrogradation, was more sensitive to heat and heat change, these were alleviated by both pregelatinization and carboxymethylation. DSC confirmed that carboxymethylated Bambara starch was the most thermally stable starch. Presence of functional groups and crystallinity were established by FTIR and XRD, respectively. Native and modified Bambara starches can be used as locally and readily available alternative excipients in pharmaceutical formulations.

  3. Physical, microbiological and rheological properties of probiotic yogurt supplemented with grape extract.

    Science.gov (United States)

    Felix da Silva, Denise; Junior, Nelson Nunes Tenório; Gomes, Raquel Guttierres; Dos Santos Pozza, Magali Soares; Britten, Michel; Matumoto-Pintro, Paula Toshimi

    2017-05-01

    In this study, yogurt was supplemented with 1.5 and 3.0 g L -1 of grape extract, inoculated culture containing Streptococcus thermophilus , Lactobacillus bulgaricus , Lactobacillus acidophilus and Bifidobacterium bb12 bifidum , fermented and stored at 4 °C. Acid production, microbial growth, gel strength, syneresis, rheological and sensory properties were studied. An increase in grape extract concentration extended fermentation time. Bacterial strains were found in at least 109 CFU100 g -1 of yogurt showing the possibility of probiotic yogurt production with grape extract. Gel strength decreased with increasing concentration of grape extract while syneresis increased. The addition of grape extract changed the dilatant behavior to a pseudoplastic behavior, decreased yield stress, whereas k values increased. Sensory attributes (color, flavor, taste, texture and appearance) didn't differ significantly.

  4. Modification of the rheological properties of screen printing ceramic paints containing gold

    Science.gov (United States)

    Izak, P.; Mastalska-Poplawska, J.; Lis, J.; Stempkowska, A.

    2017-01-01

    This work presents the results of modification of rheological properties of screen printing paints containing gold. 15 wt% glossy gold paste and 15 wt% glossy liquid gold were used as modifiers containing gold. The study showed that the gold paint for screen printing can be obtained by evaporation of the 15 wt% liquid gold and the golden luster. The compaction process of liquid gold by evaporation is slow and easy to perform in industrial conditions. The second way to adapt the 15 wt% gold ceramic paint for screen printing application depended on adding the aniseed oil and the pine oil. The course of the flow curve of the gold paste without modification indicates that it is shear thinning and shows the desired effect of thixotropy, and even anti-thixotropy, at low shear rates (paste converts itself from the non-rheostable to the rheostable liquid.

  5. Rheological properties of purified illite clays in glycerol/water suspensions

    Science.gov (United States)

    Dusenkova, I.; Malers, J.; Berzina-Cimdina, L.

    2015-04-01

    There are many studies about rheological properties of clay-water suspensions, but no published investigations about clay-glycerol suspensions. In this work apparent viscosity of previously purified illite containing clay fraction acids and other non-clay minerals were almost totally removed by centrifugation. All obtained suspensions behaved as shear-thinning fluids with multiple times higher viscosity than pure glycerol/water solutions. Reduction of clay fraction concentration by 5% decreased the apparent viscosity of 50% glycerol/water suspensions approximately 5 times. There was basically no difference in apparent viscosity between all four 50% glycerol/water suspensions, but in 90% glycerol/water suspensions samples from Iecava deposit showed slightly higher apparent viscosity, which could be affected by the particle size distribution.

  6. Characterization of wami tilapia (Oreochromis urolepis hornorum) skin gelatin: microbiological, rheological and structural properties.

    Science.gov (United States)

    Alfaro, Alexandre Da Trindade; Fonseca, Gustavo Graciano; Balbinot, Evellin; Prentice, Carlos

    2014-07-01

    Gelatin was extracted from the skin of tilapia (Oreochromis urolepis hornorum) and its microbiological, rheological and structural properties were characterized. The tilapia skin gelatin presented typical molecular weight distribution of type I collagen with contents of imino acids (proline + hydroxyproline) of 21.67%. Gel strength and viscosity values were 221 ± 5.68 g and 5.98 ± 0.34 cP, respectively, with the maturation time of 18 ± 1 h, and both parameters increased with the maturation time. Melting and gelling points of 25 degrees C and 21 degrees C, respectively, were obtained for tilapia skin gelatin. The gelatin presented microbiological standards in accordance with the Brazilian Legislation.

  7. The effect of structural properties on rheological behaviour of starches in binary dimethyl sulfoxide-water solutions.

    Directory of Open Access Journals (Sweden)

    Anna Ptaszek

    Full Text Available This research study analysed the rheological properties of potato amylose and potato amylopectin in binary solutions of the following water and dimethyl sulfoxide concentrations: 90% DMSO (1, 80% DMSO (2 and 50% DMSO (3, with preparation methodology involving the dissolution at the temperature of 98°C. The studies of dynamic light scattering on the biopolymer coils and the determination of main relaxation times of the solutions were carried out. For the amylose solutions, the fast relaxation phenomena are predominant. The results of the quality tests of the hysteresis loop showed, that the amylose solutions in the solvents (1 and (2 are rheologically stable and shear-thickened. The amylose solutions in solvents (3 reveal oscillatory alterations of viscosity in the time. Amylopectin solutions are characterized by 80% share of slow relaxation phenomena, very low diffusion coefficients and hydrodynamic radii in the range of 2000 nm. The amylopectin solutions are rheologically unstable.

  8. The effect of structural properties on rheological behaviour of starches in binary dimethyl sulfoxide-water solutions

    Science.gov (United States)

    Ptaszek, Paweł; Dziubiński, Marek; Grzesik, N. Mirosław; Liszka-Skoczylas, Marta

    2017-01-01

    This research study analysed the rheological properties of potato amylose and potato amylopectin in binary solutions of the following water and dimethyl sulfoxide concentrations: 90% DMSO (1), 80% DMSO (2) and 50% DMSO (3), with preparation methodology involving the dissolution at the temperature of 98°C. The studies of dynamic light scattering on the biopolymer coils and the determination of main relaxation times of the solutions were carried out. For the amylose solutions, the fast relaxation phenomena are predominant. The results of the quality tests of the hysteresis loop showed, that the amylose solutions in the solvents (1) and (2) are rheologically stable and shear-thickened. The amylose solutions in solvents (3) reveal oscillatory alterations of viscosity in the time. Amylopectin solutions are characterized by 80% share of slow relaxation phenomena, very low diffusion coefficients and hydrodynamic radii in the range of 2000 nm. The amylopectin solutions are rheologically unstable. PMID:28152071

  9. Rheological and thermophysical properties of carragenan and β-lactoglobulin model systems treated with high hydrostatic pressure

    Directory of Open Access Journals (Sweden)

    Edita Juraga

    2006-03-01

    Full Text Available The aim of this paper is to examine the influence of high hydrostatic pressure treatment on the rheological and thermophisical properties of β-lactoglobulin and carragenan model systems. Suspensions of β-lactoglobulin were treated with a high hydrostatic pressure in a range of 300 to 600 MPa. Holding period was 5 and 10 minutes.Measurements were performed using rotational viscosimeter Rheometric Scientific RM-180 at 20 oC. The rheological parameters were determined by the Ostwald de Waele law. The results of the investigation have shown that all investigated systems are non-Newtonian – pseudoplastic. All samples treated with high hydrostatic pressure have changed rheological characteristics. The extent of protein denaturation was proportional to the intensity of applied pressure and holding time. The phase transition temperatures were determined by differential thermal analysis (DTA. High pressure treatment caused depression of freezing point and melting point, respectively. Carragenan acts as a crioprotectant.

  10. Nutritional, functional and rheological properties of processed sorghum and ragi grains

    Directory of Open Access Journals (Sweden)

    Himadri Mahajan

    2015-12-01

    Full Text Available This study was undertaken to determine the effect of different treatments such as roasting, puffing and germination of white sorghum, red sorghum and ragi grains on physicochemical, antioxidant, protein, amylose, bulk density, colour index and rheological properties of respective flour. In case of ragi, after roasting treatment, total phenolic content (TPC content for flour was increased from 0.331 ± 0.001 to 0.373 ± 0.004 mg of gallic acid equivalents per gram of dry sample. However, total flavonoids content was also increased slightly after different processing treatments. The rheological properties of respective flour were studied using Chopin Mixolab, where wheat flour dough profile acts as a reference to study the effect of different treatments. Dough elasticity which is expressed by the values of amplitude (Nm was found to be low in case of untreated flour as compared to wheat flour dough. Elasticity values of untreated flour such as white sorghum, red sorghum and ragi were 0.02, 0.00 and 0.06 Nm, respectively. Whereas, after processing treatments, values of elasticity for roasted flour dough of white sorghum, puffed flour dough of red sorghum and roasted flour dough of ragi increased to 0.36, 0.11 and 0.15 Nm, respectively, as compared to wheat flour dough of 0.10 Nm. The results found that roasted ragi flour had higher rate of starch gelatinization, lower starch retrogradation, high antioxidant and amylose contents which were found to be prospective ingredients in whole wheat flour in various baked and fermented food applications.

  11. Features of the rheological properties of dough with sunflower and cedar flour

    Directory of Open Access Journals (Sweden)

    V. A. Gaysina

    2016-01-01

    Full Text Available Promising directions of development of assortment of flour confectionery products are currently creating new combinations, more extraordinary and interesting, the reduction in calories, increase the nutritional value, development of formulations of functional products. As enriching additives in the manufacture of pastry products can be used flour sunflower flour and cedar. Sunflower meal – one of the possible sources of increase of food value. The only raw material component of this product are sunflower seeds that have passed the purification from impurities and shell of the particles, with the subsequent removal of oil from them and grinding. In this torment, to the maximum extent maintained all the valuable biological active substances and vitamins. Sunflower flour is a complex product: it is good recommendation system of proteins, fats, carbohydrates, including fiber, vitamins, phospholipids and mineral substances. Cedar flour is characterized by high protein content (up to 48 % is well balanced in amino acids resultant composition contains b vitamins, food fibers, micro - and macroelements, necessary for life of the human body. Cedar flour has a good functional and technological properties In this paper we study the effect of cedar flour and sunflower meal on the rheological characteristics of dough. Effect of formulation components on the rheological properties of the test is evaluated in terms of water absorption of the flour, the duration of doughing, degree of its dilution and stability when mixing. It was found that the addition of 17% sunflower meal increases the viscosity of the dough and has a strengthening effect on the structure of the dough. Adding cedar flour in the amount of 20% caused the decrease in viscosity and getting more flexible dough.

  12. Effect of gluten, egg and soy proteins on the rheological and thermo-mechanical properties of wholegrain rice flour.

    Science.gov (United States)

    Pătraşcu, Livia; Banu, Iuliana; Vasilean, Ina; Aprodu, Iuliana

    2017-03-01

    The effect of protein addition on the rheological, thermo-mechanical and baking properties of wholegrain rice flour was investigated. Gluten, powdered eggs and soy protein concentrate were first analyzed in terms of rheological properties, alone and in admixture with rice flour. The temperature ramp tests showed clear differences in the rheological behavior of the batters supplemented with different proteins. The highest thermal stability was observed in case of soy protein samples. Frequency sweep tests indicated significant improvements of the rheological properties of rice flour supplemented with 15% gluten or soy proteins. The thermo-mechanical tests showed that, due to the high fat contents and low level of free water, the dough samples containing powdered eggs exhibited the highest stability. Addition of gluten resulted in a significant decrease of the dough development time, whereas samples with powdered eggs and soy proteins were more difficult to hydrate. The incorporation of proteins into the rice flour-based dough formulations significantly affected starch behavior by decreasing the peak consistency values. Concerning the quality of the rice flour-based breads, soy protein addition resulted in lighter crumb color and increased texture attributes, samples with gluten had better resilience and adhesiveness, whereas breads with egg protein were less brittle.

  13. Chemical and rheological properties of exopolysaccharides produced by four isolates of rhizobia.

    Science.gov (United States)

    Moretto, Cristiane; Castellane, Tereza Cristina Luque; Lopes, Erica Mendes; Omori, Wellington Pine; Sacco, Laís Postai; Lemos, Eliana Gertrudes de Macedo

    2015-11-01

    The rheological, physicochemical properties, emulsification and stability of exopolysaccharides (EPSs) from four rhizobia isolates (LBMP-C01, LBMP-C02, LBMP-C03 and LBMP-C04) were studied. The EPS yields of isolates under these experimental conditions were in the range of 1.5-6.63gL(-1). The LBMP-C04 isolate, which presented the highest EPS production (6.63gL(-1)), was isolated from Arachis pintoi and was identified as a Rhizobium sp. strain that could be explored as a possible potential source for the production of extracellular heteropolysaccharides. All polymers showed a pseudoplastic non-Newtonian fluid behavior or shear thinning property in aqueous solutions. Among the four EPS tested against hydrocarbons, EPS LBMP-C01 was found to be more effective against hexane, olive and soybean oils (89.94%, 82.75% and 81.15%, respectively). Importantly, we found that changes in pH (2-11) and salinity (0-30%) influenced the emulsification of diesel oil by the EPSs. EPSLBMP-C04 presented optimal emulsification capacity at pH 10 (E24=53%) and 30% salinity (E24=27%). These findings contribute to the understanding of the influence of the chemical composition, physical properties and biotechnology applications of rhizobial EPS solutions their bioemulsifying properties. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Effect of Process Parameters of Mixing on Physicomechanical and Rheological Properties of Rubber Compound

    Directory of Open Access Journals (Sweden)

    M. Shiva

    2008-12-01

    Full Text Available In this research work with the aid of Tagouchi experimental design and rawing of interaction curves with Minitab software, the best rotor speed and dump temperature of mixing for physico-mechanical and rheological properties of the rubber compound with three mixing steps was obtained. Moreover by plotting the mean curves in Excel worksheet, the dependency of properties on rotor speed, dump temperature and mixing energy were analyzed. The Results showed that dispersion was improved with increasing rotor speed and dump temperature at the lower total time. The best dispersion occurred at the highest dump temperature and the rotor speed in the second stage. We attributed better dispersion to lower filler-filler interaction, because of the mixing process performed at higher temperatures when we used higher rotor speeds at higher dump temperatures. Effect of rotor speed and dump temperature on tension properties were negligible. However, the higher dump temperature had negative effect on tear resistance, whereas, the high rotor speed had positive effect. The same results were observed for die swell while the governed mechanism on these properties was studied as well.

  15. The effect of gum tragacanth on the rheological properties of salep based ice cream mix.

    Science.gov (United States)

    Kurt, Abdullah; Cengiz, Alime; Kahyaoglu, Talip

    2016-06-05

    The influence of concentration (0-0.5%, w/w) of gum tragacanth (GT) on thixotropy, dynamic, and creep-recovery rheological properties of ice cream mixes prepared with milk or water based were investigated. These properties were used to evaluate the viscoelastic behavior and internal structure of ice cream network. The textural properties of ice cream were also evaluated. Thixotropy values of samples were reduced by increasing GT concentration. The dynamic and creep-recovery analyses exhibited that GT addition increased both ice cream elastic and viscous behaviors. The increasing of Burger's model parameters with GT concentration indicated higher resistance network to the stress and more elastic behavior of samples. The applying of Cox-Merz rule is possible by using shift factor (α). GT also led to an increase in Young's modulus and the stickiness of ice creams. The obtained results highlighted the possible application of GT as a valuable member to promote structural properties of ice cream. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. The effect of binders on the rheological properties and the microstructure formation of lithium-ion battery anode slurries

    Science.gov (United States)

    Lim, Sanghyuk; Kim, Sunhyung; Ahn, Kyung Hyun; Lee, Seung Jong

    2015-12-01

    There have been many efforts to enhance the performance and the stability of Li-ion battery. It is crucial to develop a new material as well as to understand the mechanism of microstructure formation of the electrode in order to enhance the performance of the battery. In this study, the effect of sodium carboxymethyl cellulose (CMC) and styrene butadiene rubber (SBR) on the microstructure formation as well as on the rheological properties in the aqueous anode slurries is investigated. The graphite particles aggregate with each other due to their hydrophobicity and form a gel structure in an aqueous slurry. Both CMC and SBR induce the dispersion of the graphite particles by adsorbing onto the graphite surface. In the graphite/CMC/SBR slurry, the SBR can affect the dispersion of the graphite particles at low CMC concentration, while the microstructure is not changed regardless of added SBR at high CMC concentration because the SBR cannot adsorb on the graphite surface due to the presence of CMC. The microstructure of the slurry is also confirmed by the cryo-SEM images. Understanding the role of the binders on the microstructure formation will be helpful for the effective design of the battery slurries.

  17. Interparticle Forces and Rheology of Cement Based Suspensions

    Science.gov (United States)

    Lowke, D.

    Rheological properties of cement based suspensions are affected by the surface properties of the particles, the properties of the solvent and the adsorbed polymers. To understand the interaction between these parameters and the rheology of cement based suspensions the surface forces of the colloidal powder particles were considered. Three surface forces are taken into consideration - the attractive van der Waals forces, the repulsive double layer forces and the polymer induced steric forces. A theoretical basis for the evaluation of these forces in cement based suspension is given. Within the experimental program the superplasticizer adsorption was determined for cement and ground limestone suspensions. Rheological measurements were performed with these suspensions to determine yield stress and thixotropy. The results indicate a strong correlation between polymer adsorption, rheological properties of the suspensions and evaluated forces.

  18. Shear rheology of mixed protein adsorption layers vs their structure studied by surface force measurements.

    Science.gov (United States)

    Danov, Krassimir D; Kralchevsky, Peter A; Radulova, Gergana M; Basheva, Elka S; Stoyanov, Simeon D; Pelan, Eddie G

    2015-08-01

    The hydrophobins are proteins that form the most rigid adsorption layers at liquid interfaces in comparison with all other investigated proteins. The mixing of hydrophobin HFBII with other conventional proteins is expected to reduce the surface shear elasticity and viscosity, E(sh) and η(sh), proportional to the fraction of the conventional protein. However, the experiments show that the effect of mixing can be rather different depending on the nature of the additive. If the additive is a globular protein, like β-lactoglobulin and ovalbumin, the surface rigidity is preserved, and even enhanced. The experiments with separate foam films indicate that this is due to the formation of a bilayer structure at the air/water interface. The more hydrophobic HFBII forms the upper layer adjacent to the air phase, whereas the conventional globular protein forms the lower layer that faces the water phase. Thus, the elastic network formed by the adsorbed hydrophobin remains intact, and even reinforced by the adjacent layer of globular protein. In contrast, the addition of the disordered protein β-casein leads to softening of the HFBII adsorption layer. Similar (an even stronger) effect is produced by the nonionic surfactant Tween 20. This can be explained with the penetration of the hydrophobic tails of β-casein and Tween 20 between the HFBII molecules at the interface, which breaks the integrity of the hydrophobin interfacial elastic network. The analyzed experimental data for the surface shear rheology of various protein adsorption layers comply with a viscoelastic thixotropic model, which allows one to determine E(sh) and η(sh) from the measured storage and loss moduli, G' and G″. The results could contribute for quantitative characterization and deeper understanding of the factors that control the surface rigidity of protein adsorption layers with potential application for the creation of stable foams and emulsions with fine bubbles or droplets. Copyright © 2014

  19. Chemical, morphological, rheological and thermal properties of Solanum lycocarpum phosphorylated starches

    Directory of Open Access Journals (Sweden)

    Diego Palmiro Ramirez Ascheri

    2014-08-01

    Full Text Available The increasing need for starches with specific characteristics makes it important to study unconventional starches and their modifications in order to meet consumer demands. The aim of this work was to study physicochemical characteristics of native starch and phosphate starch of S. lycocarpum. Native starch was phosphated with sodium tripolyphosphate (5-11% added with stirring. Chemical composition, morphology, density, binding ability to cold water, swelling power and solubility index, turbidity and syneresis, rheological and calorimetric properties were determined. Phosphorus was not detected in the native sample, but the phosphating process produced modified starches with phosphorus contents of 0.015, 0.092 and 0.397%, with the capacity of absorbing more water, either cold or hot. Rheological data showed the strong influence of phosphorus content on viscosity of phosphate starch, with lower pasting temperature and peak viscosity higher than those of native starch. Enthalpy was negatively correlated with the phosphorus content, requiring 9.7; 8.5; 8.1 and 6.4 kJ g-1 of energy for the transition from the amorphous to the crystalline state for the starch granules with phosphorus contents of 0; 0.015; 0.092 and 0.397%, respectively. Cluster analysis and principal component analysis showed that starches with 0.015 and 0.092% phosphorus have similar characteristics and are different from the others. Our results show that the characteristics of phosphate modified S. lycocarpum starch have optimal conditions to meet the demands of raw materials, which require greater consistency in stickiness, combined with low rates of retrogradation and syneresis.

  20. Investigation into the Microstructure, Texture and Rheological Properties of Chocolate Ganache.

    Science.gov (United States)

    McGill, Jade; Hartel, Rich W

    2018-03-01

    Ganache is a mixture of chocolate and dairy. Although a popular confection, little is known about how it functions as a system. Objectives were to (1) determine if dairy fats and cocoa butter mix in ganache, (2) characterize ganache microstructure, and how structure affects texture and rheology, and (3) identify how changes in chocolate composition alter ganache. Textural analysis, differential scanning calorimetry, stress sweep tests, and microscopy were used to examine ganache formulations that varied in dairy source (cream or butter) or in solid fat content (SFC), composition or type of chocolate. Melting temperatures for all ganache formulations were lower than for chocolate, indicating that cream milk fat globules rupture during processing, and mix with cocoa butter. Altering the SFC of chocolate affected ganache hardness, spreadability, melting enthalpy, and resistance to deformation. Chocolate systems made with constant fat content and greater amounts of defatted cocoa powder relative to sugar or nonfat milk powder yielded ganache that was harder, less spreadable, and more resistant to deformation. Ganache made with commercially produced dark, milk, and white chocolates behaved similarly to model chocolate systems. Ganache attributes are affected by chocolate crystalline fat content in addition to particle phase volume-greater levels of cocoa powder, which is mostly insoluble, strengthens ganache structure, producing a firmer product, whereas greater levels of milk powder and sugar, which dissolve in the aqueous cream component, produce a softer ganache. Understanding how ganache functions as a system and how differences in chocolate composition affect its textural and rheological properties may allow for greater control over the desired characteristics of the final product. For example, this research shows how changing cocoa content of the chocolate affects ganache, which is useful when developing formulations involving chocolates with different cocoa

  1. Rheological behaviour and physical properties of controlled-release gluten-based bioplastics.

    Science.gov (United States)

    Gómez-Martínez, D; Partal, P; Martínez, I; Gallegos, C

    2009-03-01

    Bioplastics based on glycerol, water and wheat gluten have been manufactured in order to determine the effect that mechanical processing and further thermal treatments exert on different thermo-mechanical properties of the biomaterials obtained. An "active agent", KCl was incorporated in these matrices to develop controlled-release formulations. Oscillatory shear, dynamic mechanical thermal analysis (DMTA), diffusion and water absorption tests were carried out in order to study the influence of the above-mentioned treatments on the physico-chemical characteristics and rheological behaviour of these bioplastic samples. Wheat gluten protein-based bioplastics studied in this work present a high ability for thermosetting modification, due to protein denaturation, which may favour the development of a wide variety of biomaterials. Bioplastic hygroscopic properties depend on plasticizer nature and processing procedure, and may be a key factor for industrial applications where water absorption is required. On the other hand, high water absorption and slow KCl release from bioplastic samples (both of them suitable properties in agricultural applications) may be obtained by adding citric acid to a given formulation, at selected processing conditions.

  2. Physicochemical and Rheological Properties of a Dairy Dessert, Enriched with Chickpea Flour

    Directory of Open Access Journals (Sweden)

    Victoria Guadalupe Aguilar-Raymundo

    2018-02-01

    Full Text Available Dairy desserts are complex mixtures and matrices including main components such as milk, sugar, starch, hydrocolloids, colorants and flavors, with a proteinaceous structure; they are widely consumed and present a semisolid consistency. In this work, the physicochemical and rheological properties of a dairy dessert with the addition of chickpea flour (raw and cooked, at four concentrations were studied to determine the effect of the flour. The results indicated that luminosity (L*: 62.75–83.29, pH (6.35–7.11 and acidity (1.56–3.56 changed with the type of flour. The flow properties of the custards exhibited a non-Newtonian behavior that was well fitted by three flow models. The studied custard systems were stored for twelve days at 4 °C. The physicochemical and flow properties of the custards changed notably as a function of flour addition and storage time. From all samples, only four were analyzed with oscillatory tests, showing their mechanical spectra with elastic behavior. The dessert texture was also measured, founding that those formulated with Blanco Noroeste chickpea flour exhibited the highest values of hardness (0.356–0.391 Newton (N through the twelve days. It can be concluded that those custard systems with the highest content of flour presented a very good response as a potential new dairy product.

  3. Intrinsic viscosity and rheological properties of natural and substituted guar gums in seawater.

    Science.gov (United States)

    Wang, Shibin; He, Le; Guo, Jianchun; Zhao, Jinzhou; Tang, Hongbiao

    2015-05-01

    The intrinsic viscosity and rheological properties of guar gum (GG), hydroxypropyl guar (HPG) and carboxymethyl guar (CMG) in seawater and the effects of shear rate, concentration, temperature and pH on these properties were investigated. An intrinsic viscosity-increasing effect was observed with GG and HPG in seawater (SW) compared to deionized water (DW), whereas the intrinsic viscosity of CMG in seawater was much lower than that in DW due to a screening effect that reduced the repulsion between the polymer chains. Regardless of the functional groups, all sample solutions was well characterized by a modified Cross model that exhibited the transition from Newtonian to pseudoplastic in the low shear rate range at the concentrations of interest to industries, and their viscosity increased with the increase in their concentration but decreased with the increase in temperature. In contrast to nonionic GG or HPG, anionic CMG had a slightly decreased viscosity property in SW, exhibiting polyelectrolyte viscosity behavior. The α value in the zero-shear rate viscosity vs. concentration power-law equation for the samples gave the order of CMG>HPG>GG while the SW solution of CMG had the lowest viscous flow activation energy and exhibited a strong pH-dependent viscosity by a different shear rate. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. The Field-Dependent Rheological Properties of Magnetorheological Grease Based on Carbonyl-Iron-Particles

    Science.gov (United States)

    Mohamad, N.; Mazlan, S. A.; Ubaidillah; Choi, Seung-Bok; Nordin, M. F. M.

    2016-09-01

    This paper presents dynamic viscoelastic properties of magnetorheological (MR) grease under variation of magnetic fields and magnetic particle fractions. The tests to discern the field-dependent properties are undertaken using both rotational and oscillatory shear rheometers. As a first step, the MR grease is developed by dispersing the carbonyl iron (CI) particles into grease medium with a mechanical stirrer. Experimental data are obtained by changing the magnetic field from 0 to 0.7 T at room temperature of 25 °C. It is found that a strong Payne effect limits the linear viscoelastic region of MR grease at strains above 0.1%. The results exhibit a high dynamic yield stress which is equivalent to Bingham plastic rheological model, and show relatively good MR effect at high shear rate of 2000 s-1. In addition, high dispersion of the magnetic particles and good thermal properties are proven. The results presented in this work directly indicate that MR grease is a smart material candidate that could be widely applicable to various fields including vibration control.

  5. PyFLOWGO: An open-source platform for simulation of channelized lava thermo-rheological properties

    Science.gov (United States)

    Chevrel, Magdalena Oryaëlle; Labroquère, Jérémie; Harris, Andrew J. L.; Rowland, Scott K.

    2018-02-01

    Lava flow advance can be modeled through tracking the evolution of the thermo-rheological properties of a control volume of lava as it cools and crystallizes. An example of such a model was conceived by Harris and Rowland (2001) who developed a 1-D model, FLOWGO, in which the velocity of a control volume flowing down a channel depends on rheological properties computed following the thermal path estimated via a heat balance box model. We provide here an updated version of FLOWGO written in Python that is an open-source, modern and flexible language. Our software, named PyFLOWGO, allows selection of heat fluxes and rheological models of the user's choice to simulate the thermo-rheological evolution of the lava control volume. We describe its architecture which offers more flexibility while reducing the risk of making error when changing models in comparison to the previous FLOWGO version. Three cases are tested using actual data from channel-fed lava flow systems and results are discussed in terms of model validation and convergence. PyFLOWGO is open-source and packaged in a Python library to be imported and reused in any Python program (https://github.com/pyflowgo/pyflowgo)

  6. Influence of binder system and temperature on rheological properties of water atomized 316L powder injection moulding feedstocks

    Directory of Open Access Journals (Sweden)

    Uğur GÖKMEN

    2016-02-01

    Full Text Available In order to obtain a proper powder injection molding the rheological behavior of feedstocks should be known. To determine the binder effect on the rheological behavior of 316L stainless steel powders feedstock two different feedstock were prepared. In the current experiments water atomized 316L stainless steel powders (-20 µm were used. Two types of binders, one of which is mainly paraffin wax can be dissolved in heptane and the other Polietilenglikol (PEG based and can be dissolved in water, were used. Polypropylene was used as binder and steric acid was used as lubricant for both binder systems as skeleton binder. Dry binder system were mixed for 30 min in a three dimensional Turbola. Capillary rheometer was used to characterize the rheological properties of feed stocks at 150-200 °C and a pressures of 0.165-2.069 MPa. Powder loading capacity of PEG and PW based feed stocks were found to be %55 and %61 respectively. The lowest viscosity of PEG and PW based feed stocks were found to be 304.707 Pa.s and 48.857 Pa.s respectively.Keywords: PIM, Binder, Rheological properties

  7. The effect of sweeteners and milk type on the rheological properties ...

    African Journals Online (AJOL)

    In addition to sugar, three different sweeteners; aspartame, saccharine and cyclamate as well as three different milk types; full-fat, low-fat and non-fat; were used for sample preparation. The rheological characterization of samples was described by powerlaw model. Rheological data revealed that salep samples showed ...

  8. The effect of diesters and lauric acid on rheological properties of air/water interfaces stabilized by oligofructose lauric acid monoesters.

    Science.gov (United States)

    van Kempen, Silvia E H J; Schols, Henk A; van der Linden, Erik; Sagis, Leonard M C

    2013-08-14

    In this study, the rheological properties of interfaces stabilized by oligofructose fatty acid esters were elucidated. First, the properties of interfaces stabilized by monoesters (ME), diesters (DE), lauric acid (LA), oligofructose (OF), and mixtures of ME with DE, LA, or OF were studied. Second, the properties of interfaces stabilized by the crude product (CP) containing ME, DE, LA, and OF were studied. The dependency of the dilatational modulus on frequency and deformation amplitude indicated the possible formation of a soft glass phase for ME, and a viscous interface for DE. When ME and DE were mixed at a ratio of 0.8/0.2, the experimental results suggest that the interfacial structure consists of islands of a glass phase formed by ME, dispersed in a 2D viscous phase of DE. CP stabilized interfaces, where the ratio ME/DE was higher, lead to a different rheological response. The ratio ME/DE plays an important role in the surface properties of the CP. This may have significant consequences for applications in macroscopic systems such as foams.

  9. Rheological and interfacial properties at the equilibrium of almond gum tree exudate (Prunus dulcis) in comparison with gum arabic.

    Science.gov (United States)

    Mahfoudhi, Nesrine; Sessa, Mariarenata; Ferrari, Giovanna; Hamdi, Salem; Donsi, Francesco

    2016-06-01

    Almond gum contains an arabinogalactan-type polysaccharide, which plays an important role in defining its interfacial and rheological properties. In this study, rheological and interfacial properties of almond gum and gum arabic aqueous dispersions were comparatively investigated. The interfacial tension of almond gum and gum arabic aqueous dispersions was measured using the pendant drop method in hexadecane. The asymptotic interfacial tension values for almond gum were significantly lower than the corresponding values measured for gum arabic, especially at high concentration. Rheological properties were characterized by steady and oscillatory tests using a coaxial geometry. Almond gum flow curves exhibited a shear thinning non-Newtonian behavior with a tendency to a Newtonian plateau at low shear rate, while gum arabic flow curves exhibited such behavior only at high shear rate. The influence of temperature (5-50  ℃) on the flow curves was studied at 4% (m/m) gum concentration and the Newtonian viscosities at infinite and at zero shear rate, for gum arabic and almond gum, respectively, were accurately fitted by an Arrhenius-type equation. The dynamic properties of the two gum dispersions were also studied. Both gum dispersions exhibited viscoelastic properties, with the viscous component being predominant in a wider range of concentrations for almond gum, while for gum arabic the elastic component being higher than the elastic one especially at higher concentrations.The rheological and interfacial tension properties of almond gum suggest that it may represent a possible substitute of gum arabic in different food applications. © The Author(s) 2015.

  10. Effect of extraction process on composition, oxidative stability and rheological properties of purslane seed oil.

    Science.gov (United States)

    Delfan-Hosseini, Sasan; Nayebzadeh, Kooshan; Mirmoghtadaie, Leila; Kavosi, Maryam; Hosseini, Seyede Marzieh

    2017-05-01

    Purslane seed oil could be considered as potential nutritious oil due to its desirable fatty acid composition and other biological active compounds. In this study the effect of three extraction procedure including solvent extraction, cold pressing and microwave pretreatment (MW) followed by cold pressing on oil yield, physicochemical properties, oxidative stability and rheological behaviors of oil was investigated. Solvent extracted oil had the highest extraction yield (72.31%). Pretreatment by microwave before cold press extraction resulted in an increase in extraction yield, total phenolic compound (TPC) and antioxidant activity. Cold press extracted oil had the lowest oxidative stability (4.64h). This property was greatly enhanced by microwave irradiation, so that the longest oxidative stability was found in MW-cold press extracted oil with 9.67h. Furthermore, all extracted oils demonstrated Newtonian flow behaviors. MW-cold press extracted oil had the greatest apparent viscosity and highest sensitivity to temperature changes (E a =29.18kJ/mol -1 ). Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Electrical conductivity, thermal conductivity, and rheological properties of graphene oxide-based nanofluids

    Science.gov (United States)

    Hadadian, Mahboobeh; Goharshadi, Elaheh K.; Youssefi, Abbas

    2014-12-01

    Highly stable graphene oxide (GO)-based nanofluids were simply prepared by dispersing graphite oxide with the average crystallite size of 20 nm, in polar base fluids without using any surfactant. Electrical conductivity, thermal conductivity, and rheological properties of the nanofluids were measured at different mass fractions and various temperatures. An enormous enhancement, 25,678 %, in electrical conductivity of distilled water was observed by loading 0.0006 mass fraction of GO at 25 °C. GO-ethylene glycol nanofluids exhibited a non-Newtonian shear-thinning behavior followed by a shear-independent region. This shear-thinning behavior became more pronounced at higher GO concentrations. The maximum ratio of the viscosity of nanofluid to that of the ethylene glycol as a base fluid was 3.4 for the mass fraction of 0.005 of GO at 20 °C under shear rate of 27.5 s-1. Thermal conductivity enhancement of 30 % was obtained for GO-ethylene glycol nanofluid for mass fraction of 0.07. The measurement of the transport properties of this new kind of nanofluid showed that it could provide an ideal fluid for heat transfer and electronic applications.

  12. Rheological properties, gelling behavior and texture characteristics of polysaccharide from Enteromorpha prolifera.

    Science.gov (United States)

    Qiao, Leke; Li, Yinping; Chi, Yongzhou; Ji, Yinglu; Gao, Yan; Hwang, Hueymin; Aker, Winfred G; Wang, Peng

    2016-01-20

    Polysaccharide from Enteromorpha prolifera (PE) which is the most common green algae is gradually becoming an attractive candidate with novel functions by virtue of its unique chemical and physicochemical properties. The infrared spectrum (FT-IR) of PE confirmed that it is a distinctive, sulfated heteropolysaccharide. Dynamic rheology was systematically conducted to investigate the effect of concentration, temperature, pH, and electrolytes on PE. The flow behavior testing verified its pseudoplastic character. A closed hysteresis loop was obtained when the PE concentration reached 10 g/L. For the phase angel (tanδ) was always less than 1, the solid-like behavior of PE is also found at 10-14 g/L PE in the linear viscoelastic region (LVR). Furthermore, study on its potential gelling behavior showed that 16 g/L PE could form a gel and had well textural properties. The unique functional groups and characteristics of PE provided the possibility to apply into food industry. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Rheological properties of N-[(2-hydroxyl)-propyl-3-trimethyl ammonium] chitosan chloride.

    Science.gov (United States)

    Wang, Beibei; Qiao, Congde; Gao, Xinyue; Yang, Xiaodeng; Li, Yan; Li, Tianduo

    2017-09-01

    N-[(2-hydroxyl)-propyl-3-trimethyl ammonium] chitosan chloride (HTCC) was synthesized using 1-allyl-3-methylimidazole chloride (AmimCl) as a homogeneous green reaction media. The effects of polymer concentration, temperature, cation valence, anion type and concentration of inorganic salt, and degree of substitution (DS) on the rheological properties of HTCC were investigated. The apparent viscosity indicated that HTCC solution was a typical pseudoplastic fluid, which could be described by Ostwald de Waele and Cross-empirical models. The viscoelastic properties showed the formation of gel-like structures. Temperature showed slight effect on the apparent viscosity of HTCC solution, while the DS of HTCC showed remarkable effect on the apparent viscosity. At a low shear rate, the apparent viscosities of HTCC solution increased firstly with an increase of c NaCl from 0 to 40mmol/L, and then decreased with further increasing c NaCl to 60mmol/L. At a high shear rate, the opposite trends were observed. The variation of HTCC molecular construction under different inorganic salt conditions was confirmed by scanning electron microscopy, meanwhile, the variation mechanism was proposed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. INVESTIGATION OF EFFECTS TO THE RHEOLOGICAL PROPERTIES OF ADDITIVE MATERIALS WHICH ARE USED ON CEMENT ENJECTIONS

    Directory of Open Access Journals (Sweden)

    Özcan TAN

    2004-02-01

    Full Text Available In this study the rheological properties of the injection mixtures containing various proportions of bentonite (B, fly ash (UK and silica fume (SD were investigated. L16 orthogonal array with three parameters and four levels was selected using Taguchi Design of Experiment Method. In the preparation of the injection mixtures the percentages of bentonite, fly ash and silica fume (by weight of solid used were 0 %, 0.5 %, 1 %, 3 %, 10 %, 20 %, 30 %, 40 %, and 0 %, 5 %, 10 %, 20 %, respectively. For the prepared injection mixtures the sedimentation and Marsh funnel experiments were performed. The experiments were carried out water to solid ratios (W/S of 1.25 and the experimental results were evaluated separately using Taguchi method. As a result of the evaluations; the most effective parameter on the flowing time (viscosity and the amount of sedimentation was determined as the silica fume. For the investigated properties of the injection mixtures the optimum mixing ratios were determined with the Taguchi method and for these ratios the confirmation experiments were performed.

  15. Effect of size reduction on colour, hydration and rheological properties of wheat bran

    Directory of Open Access Journals (Sweden)

    Oluwatoyin Oladayo ONIPE

    Full Text Available Abstract The aim of this study was to determine the effect of size reduction of wheat bran (WB on water holding capacity (WHC, water retention capacity (WRC, swelling capacity (SC; rheological and colour properties. Coarse WB exhibited the highest mean values for WHC (6.49 g/g, WRC (5.76 g/g, SC (7.67 g/g and OHC (4.23 g/g, while these values were significantly reduced in fine WB. Size reduction increased lightness of WB as indicated by high L* values (62.65 to 75.80, Hue angle of 74.63 and whiteness index value of 81.42. Increasing WB additions increased water absorption of dough from 63 to 70.2%, while dough stability decreased from 12.5 min to 6.80 min. As coarse WB addition increased from 1 to 15 g extensibility decreased from 419 BU to 283 BU (highest level of addition. A negative correlation (r2 = –0.992 was found between farinograph water absorption and all extensograph indices measured; implying that an increase in water absorption of dough led to a significant decrease in extensibility, maximum resistance and energy recorded for the dough. WB can be used as potential additive in foods like bread/ doughnut with the aim of optimizing their quality parameters such as nutritional and textural properties.

  16. Discrete Element Method Modeling of the Rheological Properties of Coke/Pitch Mixtures

    Directory of Open Access Journals (Sweden)

    Behzad Majidi

    2016-05-01

    Full Text Available Rheological properties of pitch and pitch/coke mixtures at temperatures around 150 °C are of great interest for the carbon anode manufacturing process in the aluminum industry. In the present work, a cohesive viscoelastic contact model based on Burger’s model is developed using the discrete element method (DEM on the YADE, the open-source DEM software. A dynamic shear rheometer (DSR is used to measure the viscoelastic properties of pitch at 150 °C. The experimental data obtained is then used to estimate the Burger’s model parameters and calibrate the DEM model. The DSR tests were then simulated by a three-dimensional model. Very good agreement was observed between the experimental data and simulation results. Coke aggregates were modeled by overlapping spheres in the DEM model. Coke/pitch mixtures were numerically created by adding 5, 10, 20, and 30 percent of coke aggregates of the size range of 0.297–0.595 mm (−30 + 50 mesh to pitch. Adding up to 30% of coke aggregates to pitch can increase its complex shear modulus at 60 Hz from 273 Pa to 1557 Pa. Results also showed that adding coke particles increases both storage and loss moduli, while it does not have a meaningful effect on the phase angle of pitch.

  17. Incorporation mode effect of Nano-silica on the rheological and mechanical properties of cementitious pastes and cement mortars

    Science.gov (United States)

    Safi, B.; Aknouche, H.; Mechakra, H.; Aboutaleb, D.; Bouali, K.

    2018-04-01

    Previous research indicates that the inclusion of nanosilica (NS) modifies the properties of the fresh and hardened state, compared to the traditional mineral additions. NS decreases the setting times of the cement mortar compared to silica fume (SF) and reduce of required water while improving the cohesion of the mixtures in the fresh state. Some authors estimate that the appropriate percentage of Nano-silica should be small (1 to 5% by weight) because of difficulties caused by agglomeration to particles during mixing, while others indicate that 10% by weight, if adjustments are made to the formulation to avoid an excess of self-drying and micro cracks that could impede strength. For this purpose, the present work aim to see the effect of the introduction mode of the nanosilica on the rheological and physic mechanical properties of cement mortars. In this study, NS was used either powdered with cement or in solution with the superplasticizer (Superplasticizer doped in nanosilica). Results show that the use of nanosilica powder (replacing cement on the one hand) has a negative influence on the rheological parameters and the rheological behavior of cementitious pastes. However, the introduction of nanosilica in solution in the superplasticizer (SP) was significantly improved the rheological parameters and the rheological behavior of cementitious pastes. Indeed, more the dosage of NS-doped SP increases more the shear stress and viscosities of the cementitious pastes become more fluid and manageable. A significant reduction of shear stress and plastic viscosity were observed that due to the increase in superplasticizer. A dosage of 1.5% NS-doped SP gave adequate fluidity and the shear rate was lower.

  18. Surface properties of beached plastics.

    Science.gov (United States)

    Fotopoulou, Kalliopi N; Karapanagioti, Hrissi K

    2015-07-01

    Studying plastic characteristics in the marine environment is important to better understand interaction between plastics and the environment. In the present study, high-density polyethylene (HDPE), polyethylene terephalate (PET), and polyvinyl chloride (PVC) samples were collected from the coastal environment in order to study their surface properties. Surface properties such as surface functional groups, surface topography, point of zero charge, and color change are important factors that change during degradation. Eroded HDPE demonstrated an altered surface topography and color and new functional groups. Eroded PET surface was uneven, yellow, and occasionally, colonized by microbes. A decrease in Fourier transform infrared (FTIR) peaks was observed for eroded PET suggesting that degradation had occurred. For eroded PVC, its surface became more lamellar and a new FTIR peak was observed. These surface properties were obtained due to degradation and could be used to explain the interaction between plastics, microbes, and pollutants.

  19. Investigating the rheological properties of crumb rubber modified bitumen and its correlation with temperature susceptibility

    Directory of Open Access Journals (Sweden)

    Nuha Salim Mashaan

    2013-02-01

    Full Text Available There is substantial evidence on the advantages of using crumb rubber in enhancing conventional bitumen properties, gaining environmental protection and boosting industrial-economical benefits. Thus, the use of this ingenious additive in bitumen modification through sustainable technology is highly advocated.The main objective of this research is to investigate the effects of different blending conditions (of time and temperature and various crumb rubber contents on the properties of bitumen binders. Testing was conducted using the Dynamic shear rheometer (DSR test and softening point test. The results showed that differing crumb rubber contents and blending temperature have significant effects on modified binder properties whereas the blending time showed an insignificant effect. Higher blending temperature and crumb rubber content were found to influence the interaction of bitumen-rubber blends and also increased the swelling rate of rubber particles, resulting in an increase in complex shear modulus (G*, storage modulus (G', loss modulus (G" and softening point as well as a decrease in phase angle (δ. Thus, the modified bitumen became less susceptible to deformation after stress removals. The study also presented a considerable relationship between rheological parameters (G*, G', G' and δ and softening point in terms of predicting physical-mechanical properties regardless of blending conditions. Thus, in terms of elasticity for the softening point data, the storage modulus and phase angle were found to be good indicators of binder elasticity. When softening point is made available, a prediction about binder ability to recover its original shape after stress removals can be done.

  20. Investigating the rheological properties of crumb rubber modified bitumen and its correlation with temperature susceptibility

    Directory of Open Access Journals (Sweden)

    Nuha Salim Mashaan

    2012-01-01

    Full Text Available There is substantial evidence on the advantages of using crumb rubber in enhancing conventional bitumen properties, gaining environmental protection and boosting industrial-economical benefits. Thus, the use of this ingenious additive in bitumen modification through sustainable technology is highly advocated.The main objective of this research is to investigate the effects of different blending conditions (of time and temperature and various crumb rubber contents on the properties of bitumen binders. Testing was conducted using the Dynamic shear rheometer (DSR test and softening point test. The results showed that differing crumb rubber contents and blending temperature have significant effects on modified binder properties whereas the blending time showed an insignificant effect. Higher blending temperature and crumb rubber content were found to influence the interaction of bitumen-rubber blends and also increased the swelling rate of rubber particles, resulting in an increase in complex shear modulus (G*, storage modulus (G', loss modulus (G" and softening point as well as a decrease in phase angle (δ. Thus, the modified bitumen became less susceptible to deformation after stress removals. The study also presented a considerable relationship between rheological parameters (G*, G', G' and δ and softening point in terms of predicting physical-mechanical properties regardless of blending conditions. Thus, in terms of elasticity for the softening point data, the storage modulus and phase angle were found to be good indicators of binder elasticity. When softening point is made available, a prediction about binder ability to recover its original shape after stress removals can be done.

  1. Influence of transglutaminase treatment on the physicochemical, rheological, and melting properties of ice cream prepared from goat milk

    Directory of Open Access Journals (Sweden)

    Hatice Şanlidere Aloğlu

    2018-01-01

    Full Text Available This study was conducted to evaluate the effects of the transglutaminase enzyme on the physicochemical characteristics, overrun, melting resistance, rheological and sensorial properties of ice cream made from goat’s milk. Different enzyme units (0.5, 1, 2, and 4 U/g milk protein and treatment times (20 min and 60 min were applied to determine the optimum process conditions. Treatment of the transglutaminase in the ice cream mix significantly affected the rheological and melting properties of the ice cream samples. The samples prepared with higher enzyme units and enzyme-treatment times showed higher melting resistance, consistency index, and viscoelastic modulus (G’ than the ice cream mix. The correlation coefficient between melting resistance and viscoelastic modulus was found to be high (0.76. The apparent viscosity of all samples decreased with increasing the shear rate, indicating that all samples exhibited non-Newtonian shear thinning flow behavior. The sensory, overrun, and physicochemical properties of samples were not affected by the enzyme treatment. This study showed that treatment times and enzyme units are essential factors in the processing of the transglutaminase enzyme for improving the rheological and melting properties of ice cream mixes. Another significant result was that desired melting resistance could be achieved for ice cream with lower stabilizer and fat content.

  2. Mechanical and electro-rheological properties of electrospun poly(vinyl alcohol) nanofibre mats filled with carbon black nanoparticles

    International Nuclear Information System (INIS)

    Chuangchote, Surawut; Sirivat, Anuvat; Supaphol, Pitt

    2007-01-01

    The present contribution reports, for the first time, the mechanical and electro-rheological properties of electrospun poly(vinyl alcohol) (PVA) nanofibre mats with or without the incorporation of carbon black (CB) nanoparticles. The effects of sonication and the addition of CB on morphological appearance, average diameter of the as-spun fibre mats, and that of the individual fibres, were thoroughly investigated. Incorporation of CB (1-10% based on the weight of PVA) in 10% w/v PVA solution did not affect the morphology and average diameter of the obtained fibres (∼160 nm), but it affected both the mechanical and the electro-rheological properties of the as-spun PVA/CB fibre mats, in which the mats became more rigid with the addition and increasing amount of CB

  3. The effects of concentration and heating-cooling rate on rheological properties of Plantago lanceolata seed mucilage.

    Science.gov (United States)

    Hesarinejad, Mohammad Ali; Sami Jokandan, Maryam; Mohammadifar, Mohammad Amin; Koocheki, Arash; Razavi, Seyed Mohammad Ali; Ale, Marcel Tutor; Attar, Farnaz Rezaiyan

    2017-10-17

    In this study, the effect of concentration (0.5, 1, 1.5 and 2%) and heating-cooling rate (1, 5 and 10°Cmin -1 ) on the rheological properties of Plantago lanceolata seed mucilage (PLSM) solutions were investigated. It was observed that the gum dispersions exhibited viscoelastic properties under the given conditions. Mechanical spectra of PLSM were classified as weak gels based on the frequency sweep, complex viscosity (η*) and tan δ results. All variables had significant impacts on the rheological parameters. Chemical and monosaccharide compositions were also determined to provide more structural information. The results revealed that PLSM had high total sugar content (87.35%), and it is likely an arabinoxylomannan-type polysaccharide. Copyright © 2017. Published by Elsevier B.V.

  4. Structural Features of Alkaline Extracted Polysaccharide from the Seeds of Plantago asiatica L. and Its Rheological Properties

    Directory of Open Access Journals (Sweden)

    Jun-Yi Yin

    2016-09-01

    Full Text Available Polysaccharide from the seeds of Plantago asiatica L. has many bioactivities, but few papers report on the structural and rheological characteristics of the alkaline extract. The alkaline extracted polysaccharide was prepared from seeds of P. asiatica L. and named herein as alkaline extracted polysaccharide from seeds of P. asiatica L. (PLAP. Its structural and rheological properties were characterized by monosaccharide composition, methylation, GC-MS and rheometry. PLAP, as an acidic arabinoxylan, was mainly composed of 1,2,4-linked Xylp and 1,3,4-linked Xylp residues. PLAP solution showed pseudoplastic behavior, and weak gelling properties at high concentration. Sodium and especially calcium ions played a significant role in increasing the apparent viscosity and gel strength.

  5. Oxidizing gel formulation for nuclear decontamination: rheological and acidic properties of the organic matrix and its ozonolysis

    International Nuclear Information System (INIS)

    Rouy, E.

    2003-10-01

    An acidic and oxidizing gel was formulated with a purely organic matrix, xanthan gum, at low concentrations (1 to 2 wt %). This polymer gel was investigated in various media (aqueous, acidic and ceric) by means of rheology: shear thinning behaviour, thixotropy, yield stress... Evidences of unexpected rheological properties in highly concentrated media show that xanthan is quite convenient for industrial projection of this type of gel on metallic walls in nuclear plants, notwithstanding its time-limited resistance to oxidation (about a few hours). Complexation mechanisms between ceric species and polar sites of the polymer led us to characterise acidic properties of our xanthan sample by potentiometric titration and 1 H NMR techniques. The matrix was finally treated by ozonolysis to suppress organic residues, as required to handle nuclear wastes. In acidic medium, ozonolysis of the gel was achieved successfully while in acidic and ceric medium this process showed limited efficiency, needing further investigation to be clarified. (author)

  6. Rheological properties and physical stability of ecological emulsions stabilized by a surfactant derived from cocoa oil and high pressure homogenization

    OpenAIRE

    Trujillo-Cayado, L. A.; Natera, A.; García, M. C.; Muñoz, J.; Alfaro, M. C.

    2015-01-01

    The goal of this work was to investigate the influence of the emulsification method on the rheological properties, droplet size distribution and physical stability of O/W green emulsions formulated with an eco-friendly surfactant derived from cocoa oil. The methodology used can be applied to other emulsions. Polyoxyethylene glycerol esters are non-ionic surfactants obtained from a renewable source which fulfill the environmental and toxicological requirements to be used as eco-fri...

  7. Effects of reducing fat content on the proteolytic and rheological properties of Cheddar-like caprine milk cheese

    Science.gov (United States)

    High-moisture Cheddar-like cheeses made from caprine milk containing 3.6, 2.0, 1.0, and 0.1-0.5% fat were manufactured and their proteolytic and rheological properties compared after 1, 3, and 6 mo of aging at 4 deg C. The full-fat (FF), reduced fat (RF), low-fat (LF), and non-fat (NF) cheeses conta...

  8. Surface properties of HMX crystal

    Science.gov (United States)

    Yee, R. Y.; Adicoff, A.; Dibble, E. J.

    1980-01-01

    The surface properties of Beta-HMX crystals were studied. The surface energies of three principal crystal faces were obtained by measuring contact angles with several reference liquids. The surface energies and polarity of the three crystal faces are found to be different.

  9. The effect of spherical nanoparticles on rheological properties of bi-dispersed magnetorheological fluids

    Science.gov (United States)

    Kannappan, K. Thiruppathi; Laherisheth, Zarana; Parekh, Kinnari; Upadhyay, R. V.

    2015-06-01

    In the present investigation, the rheological properties of bi-dispersed magnetorheological (MR) fluid based on Fe3O4 nanosphere and microsphere of iron particles are experimentally investigated. The MR fluid is prepared by substituting nanosphere of 40nm Fe3O4 particles in MR fluids having microsphere iron particles (7-8 μm). Three different weight fractions (0%, 1% and 3%) of nanosphere-microsphere MR fluids are synthesized. In the absence of the magnetic field, substitution of magnetic nanosphere decreases the viscosity lower than without substituted sample at high as well as low shear rate. Upon the application of the magnetic field, the particles align along the direction of the field, which promotes the yield stress. Here too the yield stress value decreases with magnetic nanosphere substitution. This behaviour is explain based on the inter-particle interaction as well as formation of nanosphere cloud around the magnetic microsphere, which effectively reduces the viscosity and works as weak point when chains are formed. Variation of dynamic yield stress with magnetic field is explained using microscopic model. In any event such fluid does not sediment and is not abrasive so it could be useful if not too high yield stress is needed.

  10. Effect of d-allulose on rheological properties of chicken breast sausage.

    Science.gov (United States)

    Hadipernata, M; Ogawa, M; Hayakawa, S

    2016-09-01

    d-Allulose (Alu), a rare sugar, was applied to chicken breast sausage as a sucrose (Suc) substitute. The ratio (w/w) of Alu to Suc in sugar that was added to the sausage batter was 0/1 (A0S1), 3/7 (A3S7), 7/3 (A7S3), and 1/0 (A1S0). The total amount of Suc used was 2.5% of the weight of minced chicken breast meat. Substituting Suc with Alu did not affect water content, cooking loss, breaking stress, breaking strain, and modulus of elasticity of chicken breast sausage, but a 100% substitution with Alu caused a 10% decrease in viscosity and a 31% decrease in expressible water. A significant difference appeared in the rheological properties of elasticity, viscosity, and water-holding capacity of chicken breast sausage frozen-stored (-20°C) for 90 d. Particularly, the modulus of elasticity for A1S0 chicken breast sausage was 19% higher than that of the control A0S1 chicken breast sausage, suggesting that Alu appreciably reduced the deterioration in elasticity that is caused by long-term frozen storage of sausage. The quality improvement of frozen-stored chicken breast sausage demonstrates the feasibility and benefits of the application of Alu to frozen foods. © 2016 Poultry Science Association Inc.

  11. Stability of Oligosaccharides Derived from Lactose and Lactulose regarding Rheological and Thermal Properties

    Directory of Open Access Journals (Sweden)

    Sara López-Sanz

    2018-01-01

    Full Text Available Prebiotic carbohydrates derived from lactulose (OsLu are appealing ingredients that provide beneficial effects following their fermentation by the gut microbiota; however, more investigation is needed to evaluate their technological properties and applicability as a functional food ingredient in the market. In this paper, a comparative study on the rheological and thermal behavior of OsLu and a commercial mixture of galactooligosaccharides (GOS was carried out. In both cases, there was a strong influence of temperature and shear rate on viscosity. Viscosity of OsLu was higher than that of commercial GOS and variations and rheopexy cycles were also higher for OsLu. The exponential increase of viscosity associated with the structural changes took place later in OsLu than in commercial GOS, suggesting more stability to the shear over time in the former. More stability of OsLu was also observed in the study of the effect of temperature on viscosity. In addition, the thermal study indicated different behavior of both prebiotics under the assayed conditions, showing that OsLu have lower values of glass transition temperature (Tg than commercial GOS and that commercial GOS are more sensible against humidity. The results here obtained provide important information on the treatment and storage conditions of these prebiotic ingredients during the elaboration of functional foods.

  12. Textural, Rheological and Sensory Properties and Oxidative Stability of Nut Spreads—A Review

    Directory of Open Access Journals (Sweden)

    Hasanah Mohd Ghazali

    2013-02-01

    Full Text Available Tree nuts are rich in macro and micronutrients, phytochemicals, tocopherols and phenolic compounds. The development of nut spreads would potentially increase the food uses of nuts and introduce consumers with a healthier, non-animal breakfast snack food. Nut spreads are spreadable products made from nuts that are ground into paste. Roasting and milling (particle size reduction are two important stages for the production of nut spreads that affected the textural, rheological characteristic and overall quality of the nut spread. Textural, color, and flavor properties of nut spreads play a major role in consumer appeal, buying decisions and eventual consumption. Stability of nut spreads is influenced by its particle size. Proper combination of ingredients (nut paste, sweetener, vegetable oil and protein sources is also required to ensure a stable nut spread product is produced. Most of the nut spreads behaved like a non-Newtonian pseudo-plastic fluid under yield stress which help the producers how to start pumping and stirring of the nut spreads. Similar to other high oil content products, nut spreads are susceptible to autoxidation. Their oxidation can be controlled by application of antioxidants, using processing techniques that minimize tocopherol and other natural antioxidant losses.

  13. Control of rheological and structural properties cement stone at the nanomodification

    Directory of Open Access Journals (Sweden)

    Chernishov Evgeny Mihalovich

    2016-12-01

    Full Text Available The efficiency of the use of nanotechnology solutions specially grown nanoparticles to regulate the rheological properties, the kinetics of setting and hardening of the modified cement stone. Modification of the cement stone structure was carried out using the synthesized authors complex nanomodifier (CNA on the basis of SiO2 nanopar-ticles and superplasticizer GLENIUM®ACE 30 based on polycarboxylate. The originality of the author's approach is the method of synthesis and the method of administration of complex nanomodifier based on SiO2. CNA was prepared in an aqueous medium, which is then used both as a cement mixing water system. It was found that the use of the synthesized CNA reduces the viscosity of the cement paste is 1.5 times, extends the setting time, provides in the first days of hardening strength increase by 4.5 times in comparison with the unmodified system. It is important that the optimum dosage of CNA is only 0.01% by weight of cement. Achieved effects are associated with the manifestation of the role of structure particles embryos substrate for crystallization centers tumors zoning.

  14. Effects of oligosaccharides on pasting, thermal and rheological properties of sweet potato starch.

    Science.gov (United States)

    Zhou, Da-Nian; Zhang, Bao; Chen, Bo; Chen, Han-Qing

    2017-09-01

    Effects of sucrose, raffinose and stachyose on pasting, thermal, and rheological properties of sweet potato starch (SPS) were investigated. The results indicated that pasting temperature of SPS increased with increasing sugar concentration in the order of stachyose>raffinose>sucrose. Addition of sugars significantly decreased the peak, trough, and final viscosities as well as setback value. The gelatinization temperatures of SPS-sugar mixtures markedly increased with increasing sugar concentration in the order of stachyose>raffinose=sucrose, gelatinization enthalpy also increased when sugar was added at high concentration compared with native starch. The addition of sugars increased the yield stress and consistency coefficient of SPS-sugar mixed pastes. The SPS-sugar mixed pastes exhibited a pseudoplastic and shear-thinning behavior under yield stress condition. Moreover, storage moduli (G') of SPS-sugar mixed pastes decreased with addition of sugars. This study also showed that addition of sugars promoted liquid-like characteristics of SPS-sugar mixed pastes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Textural, Rheological and Sensory Properties and Oxidative Stability of Nut Spreads—A Review

    Science.gov (United States)

    Shakerardekani, Ahmad; Karim, Roselina; Ghazali, Hasanah Mohd; Chin, Nyuk Ling

    2013-01-01

    Tree nuts are rich in macro and micronutrients, phytochemicals, tocopherols and phenolic compounds. The development of nut spreads would potentially increase the food uses of nuts and introduce consumers with a healthier, non-animal breakfast snack food. Nut spreads are spreadable products made from nuts that are ground into paste. Roasting and milling (particle size reduction) are two important stages for the production of nut spreads that affected the textural, rheological characteristic and overall quality of the nut spread. Textural, color, and flavor properties of nut spreads play a major role in consumer appeal, buying decisions and eventual consumption. Stability of nut spreads is influenced by its particle size. Proper combination of ingredients (nut paste, sweetener, vegetable oil and protein sources) is also required to ensure a stable nut spread product is produced. Most of the nut spreads behaved like a non-Newtonian pseudo-plastic fluid under yield stress which help the producers how to start pumping and stirring of the nut spreads. Similar to other high oil content products, nut spreads are susceptible to autoxidation. Their oxidation can be controlled by application of antioxidants, using processing techniques that minimize tocopherol and other natural antioxidant losses. PMID:23429239

  16. Rheological Properties and Electrospinnability of High-Amylose Starch in Formic Acid.

    Science.gov (United States)

    Lancuški, Anica; Vasilyev, Gleb; Putaux, Jean-Luc; Zussman, Eyal

    2015-08-10

    Starch derivatives, such as starch-esters, are commonly used as alternatives to pure starch due to their enhanced mechanical properties. However, simple and efficient processing routes are still being sought out. In the present article, we report on a straightforward method for electrospinning high-amylose starch-formate nanofibers from 17 wt % aqueous formic acid (FA) dispersions. The diameter of the electrospun starch-formate fibers ranged from 80 to 300 nm. The electrospinnability window between starch gelatinization and phase separation was determined using optical microscopy and rheological studies. This window was shown to strongly depend on the water content in the FA dispersions. While pure FA rapidly gelatinized starch, yielding solutions suitable for electrospinning within a few hours at room temperature, the presence of water (80 and 90 vol % FA) significantly delayed gelatinization and dissolution, which deteriorated fiber quality. A complete destabilization of the electrospinning process was observed in 70 vol % FA dispersions. Optical micrographs showed that FA induced a disruption of starch granule with a loss of crystallinity confirmed by X-ray diffraction. As a result, starch fiber mats exhibited a higher elongation at break when compared to brittle starch films.

  17. Effect of sugars and salts on rheological properties of Balangu seed (Lallemantia royleana) gum.

    Science.gov (United States)

    Salehi, Fakhreddin; Kashaninejad, Mahdi; Behshad, Vahid

    2014-06-01

    The effect of different sugars (sucrose, glucose, fructose, and lactose) and salts (NaCl and CaCl2) at various concentrations on rheological properties of Balangu seed gum (BSG, 1% w/w) was investigated. The apparent viscosity was influenced by the sugars and salts concentration and shear rate. Synergistic interaction between BSG gum and sugars improved the viscosity of solutions, whereas addition of salts decreased viscosity of gum solutions. The Power law and Herschel-Bulkley models were fitted to shear stress-shear rate data to obtain the consistency coefficient (K) and flow behavior index (n) for BSG solutions. Power law model well described non-Newtonian pseudoplastic behavior of BSG. Both K and n were sensitive to sugars and salts concentration. Highest values (0.45-0.49) of flow behavior index were observed for glucose at all concentrations. Addition of sucrose, fructose, lactose and salts to BSG led to more pseudoplastic solutions, whereas glucose decreased pseudoplasticity of solutions. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Influence of time addition of superplasticizers on the rheological properties of fresh cement pastes

    International Nuclear Information System (INIS)

    Aiad, Ismail

    2003-01-01

    It is well known that the fluidity and the fluidity loss of fresh cement pastes are affected by the kind and the time of addition of organic admixtures. The influence of the time addition of two chemical admixtures, namely, melamine formaldehyde sulfonate (MFS) and naphthalene formaldehyde sulfonate (NFS), on the rheological properties of ordinary Portland and sulfate-resisting cement pastes through the first 120 min of hydration was investigated. The admixture addition was delayed by 0, 5, 10, 15, 20, and 25 min. Shear stress and apparent viscosity of the cement pastes were determined at different shear rates (3-146 s -1 ) and hydration times of 30, 60, 90, and 120 min. The concentration of Ca 2+ and the combined water content of the cement pastes were determined after 120 min. Yield stress and plastic viscosity values were also determined by using the Bingham model. The results show that an increase in the addition time of the admixture reduces the shear stress, the yield stress, and the plastic viscosity of the cement pastes at the early ages (15 min) as well as at later early ages (120 min). The optimum delaying time of admixture addition is found to be 10-15 min. This time does not depend on the cement and superplasticizer type

  19. Determination of rheological properties of fresh concrete and similar materials in a vibration rheometer

    Directory of Open Access Journals (Sweden)

    Sandra Juradin

    2012-02-01

    Full Text Available A vibration rheometer has been developed for the purpose of determining the viscosity coefficient and the yield value of fresh concrete under vibration. The main parts of the apparatus, a test specimen and a vibration source form a unitary oscillatory system whose parameters can be measured with sufficient precision. Two types of fine grained reference material have been prepared and examined; one with a high coefficient of viscosity and the other with a high yield value. The rheological properties of reference materials have been determined in a capillary tube viscometer. Since there is no analytical solution to the flow in the vibration rheometer, the constants of the vibration rheometer have been determined by experiment, for each position of the apparatus piston within the measuring range. The parameters of the flow depend on the maximum acceleration of the vibration source. An increase in acceleration causes an increase in the yield value as well as a reduction in the plastic viscosity coefficient of the material specimen. A testing of fresh mortar has been carried out as well. The obtained results have been compared with the impact on reference materials, which makes the results of our research applicable to fresh vibrated concrete.

  20. Effects of WMA Additive on the Rheological Properties of Asphalt Binder and High Temperature Performance Grade

    Directory of Open Access Journals (Sweden)

    Jiupeng Zhang

    2015-01-01

    Full Text Available Sasobit additives with different dosages were added into 70# and 90# virgin asphalt binders to prepare WMA binders. The rheological properties, including G∗ and δ, were measured by using DSR at the temperature ranging from 46°C to 70°C, and the effects of temperature, additive dosage and aging on G∗/sin⁡δ, critical temperature, and H-T PG were investigated. The results indicate that WMA additive improves G∗ but reduces δ, and the improvement on 70# virgin binder is more significant. G∗/sin⁡δ exponentially decreases with the increasing temperature but linearly increases with the increasing additive dosage. Aging effect weakens the interaction between binder and additive but significantly increases the binder’s viscosity; that is why G∗/sin⁡δ is higher after short-term aging. In addition, the critical temperature increases with the increasing additive dosage, and the additive dosage should be more than 3% and 5% to improve H-T PG by one grade for 70# and 90# virgin binder, respectively.

  1. Optimization of the rheological properties of epoxy resins for glass and carbon reinforced plastics

    Science.gov (United States)

    Phyo Maung, Pyi; Malysheva, G.; Romanova, I.

    2016-10-01

    Vacuum assisted resin transfer moulding (VARTM) offers advantages such as simplicity, low cost of consumables, and the ability to carry out the impregnation process and curing without using expensive equipment and tooling. In the VARTM process, rheological properties of resin have a critical impact on the impregnation and curing process. In this article, the experimental results of viscosity are presented, including the glass transition temperature, and the tensile and bending strength of the epoxy binders with the amine hardener, which depend on the quantity of its active solvent composition. The active solvent used is diethylene glycol. It shows that for an increase in the content of the active solvent, a reduction in the viscosity and a reduction of the glass transition temperature and strength occurs. The optimum composition of the binder is selected by using the Pareto optimization criteria and the Cayley - Smorodinskaya method. By using the epoxy binder, the active solvent should not exceed 10-15% by weight. This approach helps to optimize the amount of active solvent added to the epoxy resins for the criterion of viscosity, strength, and heat resistance.

  2. Chemical, Sensorial and Rheological Properties of a New Organic Rice Bran Beverage

    Directory of Open Access Journals (Sweden)

    Gerson Luis FACCIN

    2009-09-01

    Full Text Available Rice bran is a solid residue from rice polishing that is used in animal nutrition and rice oil production. Cultivation conditions with agro-toxics, lipids instability, and tendency for mycotoxin contamination restrict its application in human nutrition. Therefore, organic agriculture is an alternative to use the properties of rice bran. Rice bran beverage is a new cereal product from organic rice. This work presents the preliminary results of the chemical and rheological studies of a bath pasteurized rice bran beverage. Compared with integral defatted milk, soy extracts, and brown rice low-fat milk, the rice bran beverage studied in this work presents itself as an important source of minerals and unsaturated lipids. All essential amino acids were found in this product. Glutamic and aspartic acids were predominant. Bath pasteurization at boiling water temperature for 15 and 30 min was adequate for microbiological safety. Refrigeration storage for 20 days, evaluated by pH and acidity variations, was ideal for assessment of the beverage conservation time. The beverage viscosity was of the Newtonian standard behavior, and its viscosity during storage was not a good parameter to evaluate shelf life. Sensory preference tests showed positive perspectives for this new beverage.

  3. Effect of glass fibers on rheology, thermal and mechanical properties of recycled PET

    Czech Academy of Sciences Publication Activity Database

    Kráčalík, M.; Pospíšil, L.; Šlouf, Miroslav; Mikešová, Jana; Sikora, Antonín; Fortelný, Ivan; Šimoník, J.

    2008-01-01

    Roč. 29, č. 8 (2008), s. 915-921 ISSN 0272-8397 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyethyleneterephthalate * recycling * rheology Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.054, year: 2008

  4. Antimicrobial, Rheological, and Thermal Properties of Plasticized Polylactide Films Incorporated with Essential Oils to Inhibit Staphylococcus aureus and Campylobacter jejuni.

    Science.gov (United States)

    Ahmed, Jasim; Hiremath, Nikhil; Jacob, Harsha

    2016-02-01

    Polylactide (PLA) is the most mature biobased and biodegradable polymer. Due to its inherent brittleness, the polymer cannot be used as a packaging material without plasticizer. An attempt was made to develop antimicrobial plasticized PLA film by incorporating polyethylene glycol (PEG) and 3 essential oils (EO), namely cinnamon, garlic, and clove by solvent casting method. Physical, thermal, and rheological properties of those films were evaluated for practical applications whereas the antimicrobial properties were tested against Staphylococcus aureus and Campylobacter jejuni-pathogens related to poultry industry. Both PEG and EOs led to the formation of flexible PLA/PEG/EO films with significant drop in the glass transition temperature (Tg ), and mechanical property. Time-temperature superposition (TTS) principle was employed to melt rheology of EO-based films at selected temperature, and rheological moduli superimposed well in an extended frequency range. Among EOs, cinnamon and clove oil-based films (PLA/PEG/CIN and PLA/PEG/CLO) exhibited a complete zone of inhibition against C. jejuni at the maximum concentration (1.6 mL per 2 g PLA/PEG blend) whereas the garlic oil-based film (PLA/PEG/GAR) had the lowest activity. © 2016 Institute of Food Technologists®

  5. Green Polymers in Personal Care Products: Rheological Properties of Tamarind Seed Polysaccharide

    OpenAIRE

    Semenzato, Alessandra; Costantini, Alessia; Baratto, Giovanni

    2014-01-01

    Tamarind seed polysaccharide (TSP) is a xyloglucan of vegetable origin, recently proposed for the cosmetic and pharmaceutical market as a “green” alternative to hyaluronic acid. In this study, TSP water dispersions, at different concentrations, were characterized by means of rheological measurements, both in continuous and oscillatory flow conditions. The results were compared with those of hyaluronic acid of two different molecular weights. The results pointed out the close rheological behav...

  6. Investigation of Mechanical Properties of Magneto-Rheological Ethylene Propylene Diene Monomer and Natural Rubber Type Synthetic Rubbers for Both Isotropic and Anisotropic Situations

    Directory of Open Access Journals (Sweden)

    Uğur Mazlum

    2015-12-01

    Full Text Available Magneto-rheological (MR materials are in a smart material class that has the rheological properties to be quickly and reversibly controlled with the external magnetic field applications. Considering the technological developments the rubber-like smart materials has had a more functional usage area with magneto- rheological effect. This study investigates the axial mechanical properties of magneto-rheological Ethylene Propylene Diene Monomer (EPDM and Natural Rubber (NR type synthetic rubbers for isotropic and anisotropic situations. Also, these composite materials were built by means of hot press systems as either isotropic or anisotropic using magnetic field application after addition of ferromagnetic powders. The influence of magnetic field was investigated. In this study, NR rubber was found to be more susceptible in terms of smart material properties unlike EPDM synthetic rubber.

  7. Effect of Magnetic Hysteresis of the Solid Phase on the Rheological Properties of Mr Fluids

    Science.gov (United States)

    de Vicente, J.; Durán, J. D. G.; Delgado, A. V.; González-Caballero, F.; Bossis, G.

    An experimental investigation is described concerning the effect of the existence of a remanent magnetization of the dispersed particles on the rheological properties of magnetorheological fluids (MRF). Two MRF's were used: (1) solid phase: cobalt ferrite particles + silica gel (1.5% w/w) liquid phase: silicone oil (viscosity 20 mPa.s) and (2) solid phase: carbonyl iron + silica gel; liquid phase; silicone oil. The cobalt ferrite particles were synthetized as monodisperse colloidal spheres with an average diameter of 850 nm. The dependence of the dimensionless shear stress (τ*/φ) vs. Mason number (Mn) fails to scale when a ``magnetorheological hysteresis procedure'' is followed, specially for the higher volume fractions used (~ 7.5%). The yield stress (τy) is first estimated from successive rheograms obtained decreasing the external field (H0) values for different φ. A more precise determination can be done by applying a stress ramp in the oscillatory regime. The critical stress amplitude (τc) needed to exceed the viscoelastic linear region (VLR) is obtained. It is found that both τy and τc strongly depend on the magnetic history of the sample. As expected, the previous results were not obtained in a classical MRF of carbonyl iron particles since they do not present magnetic hysteresis. We conclude that cobalt ferrite suspensions are an other kind of MRF which works at low fields (0 - 17.8 kA/m) with the opposite effect: decrease of the yield stress with the field. This property can be improved using particles with stronger remanent magnetization.

  8. Investigation of Cure Reaction, Rheology, Volume Shrinkage and Thermomechanical Properties of Nano-TiO2 Filled Epoxy/DDS Composites

    Directory of Open Access Journals (Sweden)

    Jyotishkumar Parameswaranpillai

    2013-01-01

    Full Text Available The cure reaction, rheology, volume shrinkage, and thermomechanical behavior of epoxy-TiO2 nanocomposites based on diglycidyl ether of bisphenol A cured with 4,4′-diaminodiphenylsulfone have been investigated. The FTIR results show that, at the initial curing stage, TiO2 acts as a catalyst and facilitates the curing. The catalytic effect of TiO2 was further confirmed by the decrease in maximum exothermal peak temperature (DSC results; however, it was also found that the addition of TiO2 decreases the overall degree of cure, as evidenced by lower total heat of reaction of the cured composites compared to neat epoxy. The importance of cure rheology in the microstructure formation during curing was explored by using rheometry. From the PVT studies, it was found that TiO2 decreases the volume shrinkage behavior of the epoxy matrix. The mechanical properties of the cured epoxy composites, such as tensile strength, tensile modulus, flexural strength, flexural modulus, impact strength, and fracture toughness of the polymer composites, were examined. The nanocomposites exhibited good improvement in dimensional, thermal, and mechanical properties with respect to neat cross-linked epoxy system. FESEM micrographs of fractured surfaces were examined to understand the toughening mechanism.

  9. High-water-content mouldable polyvinyl alcohol-borax hydrogels reinforced by well-dispersed cellulose nanoparticles: dynamic rheological properties and hydrogel formation mechanism.

    Science.gov (United States)

    Han, Jingquan; Lei, Tingzhou; Wu, Qinglin

    2014-02-15

    Cellulose nanoparticle (CNP) reinforced polyvinyl alcohol-borax (PB) hydrogels were produced via a facile approach in an aqueous system. The effects of particle size, aspect ratio, crystal structure, and surface charge of CNPs on the rheological properties of the composite hydrogels were investigated. The rheological measurements confirmed the incorporation of well-dispersed CNPs to PB system significantly enhanced the viscoelasticity and stiffness of hydrogels. The obtained free-standing, high elasticity and mouldable hydrogels exhibited self-recovery under continuous step strain and thermo-reversibility under temperature sweep. With the addition of cellulose I nanofibers, a 19-fold increase in the high-frequency plateau of storage modulus was obtained compared with that of the pure PB. CNPs acted as multifunctional crosslinking agents and nanofillers to physically and chemically bridge the 3D network hydrogel. The plausible mechanism for the multi-complexation between CNPs, polyvinyl alcohol and borax was proposed to understand the relationship between the 3D network and hydrogel properties. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. THE STUDY OF RHEOLOGICAL AND SORPTION PROPERTIES OF PECTINESTERASE SOLUTIONS FROM THE LEAVES OF SORBARIA SORBIFOLIA

    Directory of Open Access Journals (Sweden)

    S. L. Adjiahmetova

    2017-01-01

    Full Text Available Currently, searching for new sources of raw materials of biologically active substances of plant origin is very important. Widespread distribution, relatively easy isolation and high physiological activity have made the practical use of pectins attractive. That is why nowadays an intensive study of the relationship between the structure and physico-chemical properties of pectin polysaccharides is being carried out, and the studies of the sorption and complexing pectin properties are also being expanded.The aim of the work was to study rheological properties of aqueous solutions of pectin substances obtained from the leaves of Sorbaria sorbifolia (L..Materials and methods. Secretion of polysaccharides from the leaves of Sorbaria sorbifolia was carried out fraction by fraction on the basis of N. K. Kochetkov and M. Sinner’s method. We evaluated the adsorption capacity basing on the experimental data. From the literature data it follows that the adsorption process can be described by Freundlich’s or Langmuir’s equation. The applicability of the particular equation depends on the nature of the adsorbent and the concentration of the adsorbate.Results and discussion. In the course of the work polysaccharides were isolated from the leaves of Sorbaria sorbifolia and some of their physico-chemical properties were studied. The average molar mass of pectic substances was determined as 32923. The influence of the pH medium on the viscosity of solutions of pectin substances was studied and it was found out that a distinct minimum viscosity is observed at pH 5.2. In such an environment the molecules of pectic substances are electrically neutral and the polyelectrolyte is in the isoelectric state. The obtained data show that the maximal binding of Pb2 + ions by pectin leaves of Sorbaria sorbifolia within 50 minutes is 60.0%.Conclusion. The determination of the average molar mass and the isoelectric point makes it possible to specify the possibility of

  11. Rheological and functional properties of composite sweet potato - wheat dough as affected by transglutaminase and ascorbic acid.

    Science.gov (United States)

    Ndayishimiye, Jean Bernard; Huang, Wei-Ning; Wang, Feng; Chen, Yong-Zheng; Letsididi, Rebaone; Rayas-Duarte, Patricia; Ndahetuye, Jean Baptiste; Tang, Xiao-Juan

    2016-02-01

    Effect of transglutaminase (TGM) and ascorbic acid (AA) on composite sweet potato - wheat dough functional and rheological properties was studied. Partial substitution of wheat flour with sweet potato flour at the level of 20 % significantly (P ≤ 0.05) reduced glutenin, gliadin, dough stability, protein weakening, storage modulus (G') and viscous modulus (G″). Mixolab revealed that both TGM and AA treated dough had stability and protein weakening closed to wheat dough (control), with TGM treated dough having the highest values. TGM Introduced new cross-link bonds as shown by the change of amino acid concentration, leading to an increase in storage modulus (G') and viscous modulus (G″), with G' being higher at all levels of TGM concentration. The opposite was observed for composite dough treated with AA as measured by controlled - stress rheometer. TGM treatment increased glutenin and gliadin content. Compared with the control, dough treated with AA exhibited high molecular weight of polymers than TGM treated dough. The results indicate that the TGM and AA modification of the mixolab and dynamic rheological characteristics (G' and G″) dependent on the changes of GMP, glutenin, gliadin and protein weakening in the composite dough. TGM and AA treatment could improve functional and rheological properties of sweet potato - wheat dough to levels that might be achieved with normal wheat bread. However, it's extremely important to optimize the concentrations of both additives to obtain the optimum response.

  12. Effect of cellulose nanocrystals (CNC) on rheological and mechanical properties and crystallization behavior of PLA/CNC nanocomposites.

    Science.gov (United States)

    Kamal, Musa R; Khoshkava, Vahid

    2015-06-05

    In earlier work, we reported that spray freeze drying of cellulose nanocrystals (CNC) yields porous agglomerate structures. On the other hand, the conventional spray dried CNC (CNCSD) and the freeze dried CNC (CNCFD) produce compact solid structures with very low porosity. As it is rather difficult to obtain direct microscopic evidence of the quality of dispersion of CNC in polymer nanocomposites, it was shown that supporting evidence of the quality and influence of dispersion in a polypropylene (PP)/CNC nanocomposite could be obtained by studying the rheological behavior, mechanical properties and crystallization characteristics of PP/CNC nanocomposites. In an effort to produce a sustainable, fully biosourced, biodegradable nanocomposite, this manuscript presents the results of a study of the rheological, mechanical and crystallization behavior of PLA/CNCSFD nanocomposites obtained by melt processing. The results are analyzed to determine CNC network formation, rheological percolation threshold concentrations, mechanical properties in the rubbery and glassy states, and the effect of CNCSFD on crystalline nucleation and crystallization rates of PLA. These results suggest that the porosity and network structure of CNCSFD agglomerates contribute significantly to good dispersion of CNC in the PLA matrix. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Study of the rheological properties of water and Martian soil simulant mixtures for engineering applications on the red planet

    Science.gov (United States)

    Taylor, Lewis; Alberini, Federico; Sullo, Antonio; Meyer, Marit E.; Alexiadis, Alessio

    2018-03-01

    The rheological properties of mixtures of water and the Martian soil simulant JSC-Mars-1A are investigated by preparing and testing samples at various solids concentrations. The results indicate that the dispersion is viscoelastic and, at small timescales (∼0.1 s), reacts to sudden strain as an elastic solid. At longer timescales the dispersion behaves like a Bingham fluid and exhibits a yield stress. Hysteresis loops show that rapid step-changes (2 s duration) of shear-rate result in thixotropic behaviour, but slower changes (>10 s duration) can result in rheopexy. These observations are explained with the breakdown and recovery of the packing structure under stress. The rheological information is used to generate practical tools, such as the system curve and the Moody chart that can be used for designing piping systems, and calculating pump sizes and pressure requirements.

  14. Physical, Rheological, Functional, and Film Properties of a Novel Emulsifier: Frost Grape Polysaccharide from Vitis riparia Michx.

    Science.gov (United States)

    Hay, William T; Vaughn, Steven F; Byars, Jeffrey A; Selling, Gordon W; Holthaus, Derek M; Price, Neil P J

    2017-10-04

    A novel emulsifier, Frost grape polysaccharide (FGP), isolated from natural exudate of the species Vitis riparia Michx, was physically and rheologically characterized. The determination of the physical, structural, thermodynamic, emulsification, film, and rheological properties of FGP provide essential details for the commercial adoption of this novel plant polysaccharide. FGP is capable of producing exceptionally stable emulsions when compared with the industrially ubiquitous gum arabic (GA). The FGP isolate contained a negligible amount of nitrogen (0.03%), indicating that it does not contain an associated glycoprotein, unlike GA. Solutions of FGP have a high degree of thermostability, displaying no loss in viscosity with temperature cycling and no thermal degradation when held at 90 °C. FGP is an excellent film former, producing high tensile strength films which remain intact at temperatures up to 200 °C. This work identified a number of potential food and pharmaceutical applications where FGP is significantly superior to GA.

  15. Rheological properties of oil-in-water emulsions prepared with oil and protein isolates from sesame (Sesamum Indicum

    Directory of Open Access Journals (Sweden)

    David Ramirez BREWER

    2016-01-01

    Full Text Available In this study, food emulsions of oil in water from sesame (Sesamum indicum protein isolates and their oil were formulated and standardised. The effect of the concentrations of sesame (Sesamum indicum protein isolates and base oil and the speed of the emulsification process for the food emulsion stability was studied. The protein isolates were achieved from the defatted sesame flour (DSF, obtaining a percentage of 80% ± 0.05% of protein. Emulsions were formulated through a factorial design 23. The rheological behaviour of sesame (Sesamum indicum protein isolates-stabilised emulsions and microstructural composition were investigated. Stable emulsions with suitable rheological properties and microstructure were formulated at a concentration of 10% sesame oil and different concentrations of protein isolates, between 1.5% and 2.5%, with the best droplet distribution characteristics being shown for the 2.5% sesame protein isolates. The emulsions showed a non-Newtonian fluid behaviour, adjusting the Sisko model.

  16. Effect of carbon black on electrical and rheological properties of graphite nanoplatelets/poly(ethylene-butyl acrylate composites

    Directory of Open Access Journals (Sweden)

    H. Oxfall

    2015-01-01

    Full Text Available The effect of adding carbon black on the electrical and rheological properties of graphite nanoplatelets/poly(ethylene-butyl acrylate copolymer composites produced via melt or solution mixing was studied. By adding a small amount of low- or high-structured carbon black to the nanocomposite, the electrical percolation threshold decreased and the final conductivity (at higher filler contents increased. The effect on the percolation threshold was significantly stronger in case of the high-structured carbon black where replacing 10 wt% of the total filler content with carbon black instead of graphite nanoplatelets reduced the electrical percolation threshold from 6.9 to 4.6 vol%. Finally, the solution mixing process was found to be more efficient leading to a lower percolation threshold. For the composites containing high-structured carbon black, graphite nanoplatelets and their hybrids there was a quite reasonable correlation between the electrical and rheological percolation thresholds.

  17. Influence of partially demineralized milk proteins on rheological properties and microstructure of acid gels.

    Science.gov (United States)

    Meletharayil, G H; Patel, H A; Metzger, L E; Marella, C; Huppertz, T

    2018-03-01

    Innovative clean label processes employed in the manufacture of acid gels are targeted to modify the structure of proteins that contribute to rheological properties. In the present study, CO 2 -treated milk protein concentrate powder with 80% protein in dry matter (TMPC80) was mixed with nonfat dry milk (NDM) in different ratios for the manufacture of acid gels. Dispersions of NDM and TMPC80 that provided 100, 90, 70, and 40% of protein from NDM were reconstituted to 4.0% (wt/wt) protein and 12.0% (wt/wt) total solids. Dispersions were adjusted to pH 6.5, followed by heat treatment at 90°C for 10 min. Glucono-δ-lactone was added and samples were incubated at 30°C, reaching pH 4.5 ± 0.05 after 4 h of incubation. Glucono-δ-lactone levels were adjusted to compensate for the lower buffering capacity of samples with higher proportions of TMPC80, which is attributable to the depletion of buffering minerals from both the serum and micellar phase during preparation of TMPC80. Sodium dodecyl sulfate-PAGE analysis indicated a higher amount of caseins in the supernatant of unheated suspensions with increasing proportions of CO 2 -treated TMPC80, attributable to the partial disruption of casein micelles in TMPC80. Heat treatment reduced the level of whey proteins in the supernatant due to the heat-induced association of whey proteins with casein micelles, the extent of which was larger in samples containing more micellar casein (i.e., samples with a lower proportion of TMPC80). Particle size analysis showed only small differences between nonheated and heated dispersions. Gelation pH increased from ˜5.1 to ˜5.3, and the storage modulus of the gels at pH 4.5 increased from ˜300 to ˜420 Pa when the proportion of protein contributed by TMPC80 increased from 0 to 60%. Water-holding capacity also increased and gel porosity decreased with increasing proportion of protein contributed by TMPC80. The observed gel properties were in line with microstructural observations by

  18. Investigation of the rheological properties and die swell of polylactic acid/nanoclay composites in a capillary rheometer

    Science.gov (United States)

    Dangtungee, R.; Petcharoen, K.; Pinijsattawong, K.; Siengchin, S.

    2012-01-01

    The purpose of this research was to investigate the rheological behavior and extrudate swell of polylactic acid (PLA) filled with a nanoclay. The effects of the amount of nanoclay and surface treatment were studied by a capillary rheometer. The dispersion of the nanoclay was inspected by using the scanning electron microscopy. Generally, PLA/nanoclay composites exhibited a pseudoplastic rheological behavior as the shear stress and die swell increased with increasing shear rate. However, the shear viscosity decreased. The die swell also increased with increasing shear stress. The elongation viscosity decreased with increasing elongation rate. The incorporation of nanoclay decreased the shear stress and shear viscosity to a lesser degree than the elongation viscosity.

  19. Influence of hydrodynamic cavitation on the rheological properties and microstructure of formulated Greek-style yogurts.

    Science.gov (United States)

    Meletharayil, G H; Metzger, L E; Patel, Hasmukh A

    2016-11-01

    cavitation that can influence final textural properties of the product, make this technology promising for large-scale industrial application. Overall, the current set of experiments employed in the manufacture of GSY, which included the use of TMPC as a protein source in conjunction with hydrodynamic cavitation, could help achieve comparable titratable acidity values, rheological properties, and microstructure to that of a commercial strained Greek yogurt. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  20. Effect of the gamma radiation on the chemical, rheological, baker and microbiological properties in wheat flour

    International Nuclear Information System (INIS)

    Agundez A, Z.; Fernandez R, M.V.; Arce C, M.E.; Cruz Z, E.; Chernov, V.; Barboza F, M.

    2002-01-01

    The gamma radiation has been used in several places of the World as a sterilization method, preservation and pasteurization of foodstuffs, effect which is achieved due to diminishing or elimination of the microorganisms, reaching every time more acceptance, moreover eliminates the uses of toxic and carcinogenic substances, of general use, but at the present, being in the process of being totally prohibited, due to the higher risk in the human health. In this work the related results with the effects of the gamma radiation are presented, coming from a 60 Co source, in commercial wheat flour exposed to a dose of 1.0 KGy. The used dose is that allowed according to the NOM-033-SSA1-1993 standard. It was determined that the chemical characteristics of humidity, protein and ashes were not affected by radiation. The rheological properties neither suffer severe effects as consequence of radiation; the pharynographic and alveographic parameters were lightly affected by the treatment. Significant changes were detected in the percentage of water absorption and in the tolerance index to mixing. However a diminish of 10% in the development time and an increase of 13% in the stability was observed, for the irradiated samples respect to the those samples not irradiated. In relation to the alveograph parameters it was only detected a diminish of 7% in the force parameter (w) without changes in the tenacity/blowing up index ratio (P/L). The fall number diminish 11% indicating a small diminution in viscosity. The bakering properties do not turn out modified by the irradiation treatment finding a specific weight of 4.6 and 4.5 (cm 3 /g) for the control and irradiated samples, respectively. In the mesophyll analysis it was found a diminish of 96% from the original charge in control samples, observing a diminution of 74 and 25% in yeasts and mushrooms respectively. Microbiologically it was determined absence of total coliforms bacteria and faecal coliforms in the control samples and of

  1. Molecular Rheology of Complex Fluids

    DEFF Research Database (Denmark)

    Huang, Qian; Rasmussen, Henrik Koblitz

    The processing of polymer materials is highly governed by its rheology, and influences the properties of the final product. For example, a recurring problem is instability in extrusion that leads to imperfect plastic parts. The ability to predict and control the rheological behavior of polymer...... flow is the dominant type of deformation. The polymer molecules experience a significant amount of chain orientation and stretching during these processes. Shear rheology measured by conventional shear rheometers is good at describing chain orientation, whereas extensional rheology gives a good way...... of inducing chain stretching. Accurate and reliable stress–strain measurements of extensional flow play a crucial role in the understanding of non–linear rheological properties of polymers. However, the non–linear extensional rheology has not been extensively studied. It is known that the rheology of polymer...

  2. Effect of pulsed electric field and pasteurisation treatments on the rheological properties of mango nectar (Mangifera indica

    Directory of Open Access Journals (Sweden)

    S. S. Manjunatha

    2015-01-01

    Full Text Available The rheological behaviour of pulsed electric field (PEF processed and thermally pasteurised mango nectar (Mangifera indica was evaluated using controlled stress rheometer. The mango nectar was subjected to pulsed electric field (PEF as well as thermal processing. The rheological parameter shear stress was measured up to the shear rate of 750 s-1 using co-axial cylinder attachment at wide range of temperatures from 10 to 70 °C. The investigation showed that pulsed electric field (PEF processed and thermally pasteurised mango nectar behaved like a pseudo plastic (shear thinning fluid and obeyed Herschel-Bulkley model (0.9780 0.893, p < 0.05 and flow activation energy (Ea was significantly (p < 0.05 affected by processing conditions. The results indicated that the pulsed electric field (PEF and thermal processing condition has affected the rheological properties of mango nectar. The combined equation relating to shear stress (τ with temperature and shear rate of mango nectar was established.

  3. Rheological properties of grouts with viscosity modifying agents as diutan gum and welan gum incorporating pulverised fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed Sonebia [Queen' s University Belfast, Belfast (United Kingdom). School of Planning, Architecture and Civil Engineering

    2006-09-15

    This investigation was undertaken to evaluate the influence of the dosage of the second generation of viscosity modifying agent (diutan gum) on fluidity and rheological parameters of cement-based materials grout compared to welan gum. All grouts were made with 0.40 water-to-binder ratio (W/B). The fresh properties of control grouts made without any viscosity modifying agent (VMA) and with superplasticizer (SP) were compared to those of grouts made with 0.02, 0.04, 0.06 and 0.08% diutan gum by mass of binder. Similar mixes made with welan gum were compared to those containing diutan gums. The effect of admixtures on fluidity and rheological parameters are discussed in this paper. The effect of the replacement of cement by pulverised fly ash (PFA) was also investigated. Grouts with replacements of PFA of 5, 13 and 20% by mass were used with the same W/B. Similar control grouts and mixes incorporated different dosages of PFA made with welan gum were made in order to compare the fluidity and the rheological parameters to the previous grouts made with diutan gum.

  4. Effect of cellulose nanocrystals (CNC) particle morphology on dispersion and rheological and mechanical properties of polypropylene/CNC nanocomposites.

    Science.gov (United States)

    Khoshkava, Vahid; Kamal, Musa R

    2014-06-11

    Polypropylene (PP) nanocomposites containing spray-dried cellulose nanocrystals (CNC), freeze-dried CNC, and spray-freeze-dried CNC (CNCSFD) were prepared via melt mixing in an internal batch mixer. Polarized light, scanning electron, and atomic force microscopy showed significantly better dispersion of CNCSFD in PP/CNC nanocomposites compared with the spray-dried and freeze-dried CNCs. Rheological measurements, including linear and nonlinear viscoelastic tests, were performed on PP/CNC samples. The microscopy results were supported by small-amplitude oscillatory shear tests, which showed substantial rises in the magnitudes of key rheological parameters of PP samples containing CNCSFD. Steady-shear results revealed a strong shear thinning behavior of PP samples containing CNCSFD. Moreover, PP melts containing CNCSFD exhibited a yield stress. The magnitude of the yield stress and the degree of shear thinning behavior increased with CNCSFD concentration. It was found that CNCSFD agglomerates with a weblike structure were more effective in modifying the rheological properties. This effect was attributed to better dispersion of the agglomerates with the weblike structure. Dynamic mechanical analysis showed considerable improvement in the modulus of samples containing CNCSFD agglomerates. The percolation mechanical model with modified volume percolation threshold and filler network strength values and the Halpin-Kardos model were used to fit the experimental results.

  5. Effect of modification with 1,4-α-glucan branching enzyme on the rheological properties of cassava starch.

    Science.gov (United States)

    Li, Yadi; Li, Caiming; Gu, Zhengbiao; Hong, Yan; Cheng, Li; Li, Zhaofeng

    2017-10-01

    Steady and dynamic shear measurements were used to investigate the rheological properties of cassava starches modified using the 1,4-α-glucan branching enzyme (GBE) from Geobacillus thermoglucosidans STB02. GBE treatment lowered the hysteresis loop areas, the activation energy (E a ) values and the parameters in rheological models of cassava starch pastes. Moreover, GBE treatment increased its storage (G') and loss (G″) moduli, and decreased their tan δ (ratio of G″/G') values and frequency-dependencies. Scanning electron microscopic studies showed the selective and particular attack of GBE on starch granules, and X-ray diffraction analyses showed that GBE treatment produces significant structural changes in amylose and amylopectin. These changes demonstrate that GBE modification produces cassava starch with a more structured network and improved stability towards mechanical processing. Differential scanning calorimetric analysis and temperature sweeps indicated greater resistance to granule rupture, higher gel rigidity, and a large decrease in the rate of initial conformational ordering with increasing GBE treatment time. Pronounced changes in rheological parameters revealed that GBE modification enhances the stability of cassava starch and its applicability in the food processing industry. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Influence of calcium fortification on physical and rheological properties of sucrose-free prebiotic milk chocolates containing inulin and maltitol.

    Science.gov (United States)

    Konar, Nevzat; Poyrazoglu, Ender Sinan; Artik, Nevzat

    2015-04-01

    In the present study, chocolates were investigated that had been prepared according to the composition specified as a result of this previous work (9.00 % w/w inulin and 34.0 % w/w maltitol) Certain physical (particle size distribution [PSD], brightness, chroma, water activity and hardness) and rheological features of the samples resulting from the addition of calcium carbonate in different quantities (300, 450, 600, 750 and 900 mg calcium carbonate to 100 mg milk chocolate) were studied. Both the Herschel-Bulkley and Casson models were used to investigate the rheological findings. It was determined by comparing certain rheological (rate index, Casson yield stress and Casson viscosity) and physical (chroma and hardness) parameters that samples containing 409.5 mg calcium (nearly 41.0 % of the RDA of calcium) per 100 g chocolate did not show significant differences from samples from the control group. Furthermore, these calcium-containing samples were shown to exhibit positive differences in other physical properties (brightness and water activity) that could be noteworthy and significant with respect to visual quality and shelf life.

  7. Rheological property of mafic schist and geological interpretation to the subduction dynamics

    Science.gov (United States)

    Okazaki, K.; Hirth, G.

    2013-12-01

    To understand the spatial and temporal distribution of deformation (e.g., underplating and exhumation of metamorphic rocks) and earthquakes in subduction zones, it is important to constrain the rheological properties of metamorphic rocks (i.e., altered oceanic crust and sediments), and how they evolve during metamorphic reactions following hydration, carbonation and dehydration of the down-going slab. Metamorphism of oceanic crust has stimulated hypotheses on the relationship between intra-slab earthquakes and slab-wedge coupling along plate boundaries in subduction zone. While it is well known that metamorphisms have important effects on material circulation and arc volcanisms at subduction system, it remains unclear how the formation of metamorphic minerals followed by fluid release on the subduction dynamics influences rheology. Past experimental studies on mafic metamorphic rocks were mostly concentrated on phase equilibrium of mineral, thus there are very few reports on the mechanical data for these metamorphic rocks. We conducted triaxial deformation experiments on a mafic greenschist using Griggs-type solid pressure-medium apparatus installed in Brown University. Mafic schist (chlorite - amphibole - epidote - albite schist) containing calcite and quartz veins from Sambagawa metamorphic belt (Japan), which is metamorphosed at the condition of nearly the corner of mantle wedge in hot subduction (1 GPa of pressure and 520C of temperature), was used as experimental samples for typical metamorphic rocks composing oceanic crust in warm subduction zones. Constant strain rete experiments and strain rate step experiment were conducted at 1.0 GPa of confining pressure, 400 ~ 500C of temperature and 10-5 ~ 5×10-7 1/s of strain rate. At stable conditions of samples (1 GPa of confining pressure and 400 and 500C of temperature), differential stresses were higher than 1 GPa. Microstructure of recovered samples showed backing and several localized shear zones. Although

  8. The influence of thickeners on the rheological and sensory properties of cosmetic lotions

    Czech Academy of Sciences Publication Activity Database

    Morávková, Tereza; Filip, Petr

    2014-01-01

    Roč. 11, č. 6 (2014), s. 173-186 ISSN 1785-8860 R&D Projects: GA ČR GA103/09/2066 Institutional support: RVO:67985874 Keywords : cosmetic lotion * eye cream * empirical rheological model ling * sensory analysis Subject RIV: BK - Fluid Dynamics Impact factor: 0.471, year: 2013

  9. Rheological and electrical properties of polymeric nanoparticle solutions and their influence on RBC suspensions

    Czech Academy of Sciences Publication Activity Database

    Antonova, N.; Koseva, N.; Kowalczyk, A.; Říha, Pavel; Ivanov, I.

    2014-01-01

    Roč. 24, č. 3 (2014), s. 35190 ISSN 1430-6395 Institutional support: RVO:67985874 Keywords : nanoparticles and RBC suspensions * poly(acrylic acid) * rheology * electrical conductivity Subject RIV: BK - Fluid Dynamics Impact factor: 1.078, year: 2014 http://www.ar.ethz.ch/TMPPDF/24308140293.696/ApplRheol_24_35190.pdf

  10. Rheological behaviour, sensory properties and syneresis of probiotic yoghurt supplemented with various prebiotics

    DEFF Research Database (Denmark)

    Heydari, Somayeh; Amiri-Rigi, Atefeh; Ehsani, Mohammad Reza

    2017-01-01

    The main aim of this study was to investigate the effects of addition of six different prebiotic compounds (inulin, lactulose, lactitol, Hi-maize, maltodextrin and β-glucan) on syneresis, sensory attributes and rheological characteristics (elastic modulus, viscous modulus, loss tangent, complex...

  11. Effect of oil content on the rheological and textural properties of mayonnaise

    Czech Academy of Sciences Publication Activity Database

    Štern, Petr; Míková, K.; Pokorný, J.; Valentová, H.

    2007-01-01

    Roč. 46, č. 1 (2007), s. 1-8 ISSN 1336-8672 R&D Projects: GA AV ČR IAA2060404 Institutional research plan: CEZ:AV0Z20600510 Keywords : mayonnaise * oil content * rheology * sensory characteristics * texture Subject RIV: BK - Fluid Dynamics

  12. Effect of storage duration on the rheological properties of goose liquid egg products and eggshell membranes

    Czech Academy of Sciences Publication Activity Database

    Kumbár, V.; Nedomová, Š.; Trnka, Jan; Buchar, J.; Pytel, R.

    2016-01-01

    Roč. 95, č. 7 (2016), s. 1693-1701 ISSN 0032-5791 Institutional support: RVO:61388998 Keywords : egg yolk * albumen * liquid whole egg * rheology * eggshell membrane Subject RIV: BO - Biophysics Impact factor: 1.908, year: 2016 http://ps.oxfordjournals.org/

  13. The influence of thickeners on the rheological and sensory properties of cosmetic lotions

    Czech Academy of Sciences Publication Activity Database

    Morávková, Tereza; Filip, Petr

    2014-01-01

    Roč. 11, č. 6 (2014), s. 173-186 ISSN 1785-8860 R&D Projects: GA ČR GA103/09/2066 Institutional support: RVO:67985874 Keywords : cosmetic lotion * eye cream * empirical rheological modelling * sensory analysis Subject RIV: BK - Fluid Dynamics Impact factor: 0.471, year: 2013

  14. Reversible pH-Sensitive Chitosan-Based Hydrogels. Influence of Dispersion Composition on Rheological Properties and Sustained Drug Delivery

    Directory of Open Access Journals (Sweden)

    Nieves Iglesias

    2018-04-01

    Full Text Available The present work deals with the synthesis of micro-structured biomaterials based on chitosan (CTS for their applications as biocompatible carriers of drugs and bioactive compounds. Twelve dispersions were prepared by means of functional cross-linking with tricarballylic acid (TCA; they were characterized by Fourier transform infrared spectroscopy (FT-IR, modulated temperature differential scanning calorimetry (MTDSC and scanning electron microscopy (SEM, and their rheological properties were studied. To the best of the authors’ knowledge, no study has been carried out on the influence of CTS concentration, degree of cross-linking and drug loading on chitosan hydrogels for drug delivery systems (DDS and is investigated herein for the first time. The influence of dispersion composition (polymer concentration and degree of cross-linking revealed to exert a marked impact on its rheological properties, going from liquid-like to viscoelastic gels. The release profiles of a model drug, diclofenac sodium (DCNa, as well as their relationships with polymer concentration, drug loading and degree of cross-linking were evaluated. Similar to the findings on rheological properties, a wide range of release profiles was encountered. These formulations were found to display a well-controlled drug release strongly dependent on the formulation composition. Cumulative drug release under physiological conditions for 96 h ranged from 8% to 67%. For comparative purpose, Voltaren emulgel® from Novartis Pharmaceuticals was also investigated and the latter was the formulation with the highest cumulative drug release (85%. Some formulations showed similar spreadability values to the commercial hydrogel. The comparative study of three batches confirmed the reproducibility of the method, leading to systems particularly suitable for their use as drug carriers.

  15. Simultaneous Effects of Total Solids Content, Milk Base, Heat Treatment Temperature and Sample Temperature on the Rheological Properties of Plain Stirred Yogurt

    Directory of Open Access Journals (Sweden)

    Attilio Converti

    2006-01-01

    Full Text Available Response surface methodology was used to establish a relationship between total solids content, milk base, heat treatment temperature, and sample temperature, and consistency index, flow behaviour index, and apparent viscosity of plain stirred yogurts. Statistical treatments resulted in developments of mathematical models. All samples presented shear thinning fluid behaviour. The increase of the content of total solids (9.3–22.7 % and milk base heat treatment temperature (81.6–98.4 °C resulted in a significant increase in consistency index and a decrease in flow behaviour index. Increase in the sample temperature (1.6–18.4 °C caused a decrease in consistency index and increase in flow behaviour index. Apparent viscosity was directly related to the content of total solids. Rheological properties of yogurt were highly dependent on the content of total solids in milk.

  16. Influence of colloidal calcium phosphate level on the microstructure and rheological properties of rennet-induced skim milk gels

    DEFF Research Database (Denmark)

    Koutina, Glykeria; Knudsen, Jes Christian; Andersen, Ulf

    2015-01-01

    lactose, to obtain varying levels of micellar calcium and phosphorus but constant value of pH, serum and free calcium, and serum phosphorus. Bovine chymosin was added to the skim milk samples after dialysis and microstructural and rheological properties during gel formation were recorded at 30°C. Samples...... after dialysis needed approximately 30min after the addition of chymosin to form rennet gels. In addition, low micellar calcium and phosphorus values were both found to correlate with slightly less time for the gels to be formed. This information highlights the importance of CCP in the primary phase...

  17. Influence of maltodextrin dextrose equivalent value on rheological and dispersion properties of sunflower oil in water emulsions

    Directory of Open Access Journals (Sweden)

    Dokić Petar P.

    2004-01-01

    Full Text Available Effect of dextrose equivalent (DE of maltodextrin present in continuous phase on flow along with dispersion properties of sunflower oil in water emulsions has been investigated. Both, rheological and disperse characteristics of the emulsions were greatly influenced by continuous phase viscosity and thus by the DE value of maltodextrin.. The smaller DE value the greater high shear viscosity and the smaller the droplet size. Irrespective of the amount and DE value of maltodextrin used was, all the emulsions showed a pseudoplastic behaviour.

  18. Influence of hydroxyl content of binders on rheological properties of cerium-gadolinium oxide (CGO) screen printing inks

    DEFF Research Database (Denmark)

    Marani, Debora; Gadea, Christophe; Hjelm, Johan

    2015-01-01

    The influence of hydroxyl content of binders on rheological properties of screen printing inks is investigated. The actual amount of hydroxyl groups is correlated to the level of hyper-entanglement that characterizes the binders in solution. Three of the most used binders (ethyl cellulose, and two...... vinyl resins) were selected and characterized in solution via viscosimetry method. A high degree of hyper-entanglement was observed for ethyl cellulose polymers, whereas a mitigated effect characterized the two vinyl resins. Cerium-gadolinium oxides (CGO)-based inks, prepared using the selected binders...

  19. Ultrasound-assisted extraction of polysaccharides from Rhododendron aganniphum: Antioxidant activity and rheological properties.

    Science.gov (United States)

    Guo, Xiao; Shang, Xiaofei; Zhou, Xuzheng; Zhao, Baotang; Zhang, Jiyu

    2017-09-01

    In this study, we aimed to optimize the extraction of polysaccharides from the leaves of Rhododendron aganniphum and investigate its rheological properties and antioxidant activity. After optimizing the operating parameters using a Box-Behnken design (BBD), the results showed that the optimal ultrasound-assisted extraction conditions were as follows: extraction temperature, 55°C; liquid-solid ratio, 25:1; extraction time, 2.2h; and ultrasound treatment power, 200W. The optimized experimental yield of polysaccharides by ultrasound-assisted extraction (PUAE) was 9.428%, higher than that obtained by hot water extraction (PHWE) for 12h at the same liquid-solid ratio and extraction temperature. In the in vitro antioxidant activity tests, PUAE had higher positive radical scavenging activity for hydroxyl, superoxide and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals than PHWE. However, PUAE and PHWE solutions had similar intermolecular interactions in the steady-shear flow and dynamic viscoelasticity tests, resulting in similar macroscopic behaviour. With respect to the apparent viscosity, storage modulus (G') and loss modulus (G″) of PUAE were lower at the same shear rate or angular frequency. All PUAE solutions exhibited non-Newtonian shear-thinning pseudoplastic behaviour that was accurately described by the Carreau model but was better fit by the power-law model at high shear rates (≥1/s), which demonstrated that the variation in the apparent viscosity dependence was greater at higher concentrations and shear rates. The G' and G″ of the solutions increased as the experimental frequency increased from 0.05 to 500rad/s under all experimental concentrations, and the modulus crossover point decreased gradually with increasing PUAE concentration. The above results demonstrated that the ultrasound-assisted extraction methods gave a higher yield of polysaccharides from the leaves of R. aganniphum with a shorter extraction time than the hot water extraction method

  20. Biodegradable blends of poly (lactic acid) (PLA) / polyhydroxybutrate (PHB) copolymer and its effects on rheological, thermal and mechanical properties

    Science.gov (United States)

    Sood, Nitin K.

    Poly (Lactic acid) is the most important plastic derived from the renewable resources. PLA based products have extensively been used in the medical industry. However, PLA has a few disadvantages such as inherent brittleness and low toughness despite a high modulus. A focus of this experiment was to study the improvement in toughness of PLA and to study the changes in thermal and rheological properties by blending PLA with a PHB copolymer. Where, PLA and PHB copolymer were melt blended using a twin screw Brabender extruder in the ratios of 100/0, 70/30, 50/50, 30/70, 0/100. Further, the blends were injection molded into tensile bar and impact bars for mechanical testing. Rheological properties were studied using a Galaxy capillary rheometer for melt viscosities and temperature dependence indicated a shear-thinning behavior along with power law model and consistency index. Blends were characterized to study the phase model using a differential scanning calorimetric (DSC), showed two separate phases. Mechanical properties were analyzed using a Tensile and Izod impact test indicating decrease in elastic modulus with increase in toughness and elongation as the PHB copolymer content was increased in the blend.

  1. Effect of modified cassava starch on the rheological and quality properties of a dairy beverage prepared with sweet whey

    Directory of Open Access Journals (Sweden)

    Paola Catalina IMBACHÍ-NARVÁEZ

    2018-03-01

    Full Text Available Abstract The effect of sweet whey and octenyl succinic anhydride (OSA-modified cassava starch on the quality and rheological properties of fermented dairy beverages was evaluated. Sweet whey (45-65% and OSA-modified cassava starch (0.8-1.2% were added to determine an optimal fermented dairy beverage with the highest viscosity and the lowest syneresis possible. The optimal fermented dairy beverage corresponded to the addition of 40.9% sweet whey and 1.13% OSA-modified cassava starch with respect to the milk and sweet whey mixture. Moreover, the rheological and quality properties of the optimal fermented dairy beverage were compared to a commercial beverage (control during 22 days of storage. No significant differences were found in soluble solids, acidity, pH and consistency index during the time evaluated, while the syneresis of both products showed an increase during storage. OSA-modified cassava starch can be used as a stabiliser in sweet whey fermented dairy beverages because it helps improve its quality properties.

  2. RHEOLOGICAL PROPERTIES AND THE ENERGETIC VALUE OF WHEAT FLOUR SUBSTITUTED BY DIFFERENT SHARES OF WHITE AND BROWN RICE FLOUR

    Directory of Open Access Journals (Sweden)

    Nada Nikolić

    2011-09-01

    Full Text Available In order to produce dough with a lower gluten content, more enriched with rice components and satisfactory rheological properties, the rheological properties, energetic value and cake baking properties of wheat and white or brown rice flour in shares from 3 to 30% (w/w were investigated in this paper. The water absorption in wheat-rice flour mixtures was lower and decreased to 53.5% and 54.0% along with the increase of the white and the brown rice flour share, respectively, than in wheat flour, where it was 58.8%. In the dough made from rice flour, a gluten network had thinner filaments, about 2 and 1 μm in width for white and brown rice flour, respectively, compared to those in the dough from wheat flour only, where it was about 7 μm. The dough from rice flour had almost twice higher gelatinization maximum than the gelatinization maximum of the wheat flour only. The energetic values of the dough from rice flour were smaller than the energetic value of the wheat flour, for only 1.32%. Based on Cluster analysis, the white or brown rice flour share of 20% was pointed out.

  3. Determination of sorption isotherm and rheological properties of lysozyme using a high-resolution humidity scanning QCM-D technique.

    Science.gov (United States)

    Graf, Gesche; Kocherbitov, Vitaly

    2013-08-29

    The high-resolution humidity scanning QCM-D technique enables investigation of hydration of soft matter films using a quartz crystal microbalance with dissipation monitoring (QCM-D) equipped with a humidity module. Based on a continuous increase of relative humidity, properties of soft matter films can be investigated depending on the water content of the surrounding atmosphere. Determination of complete water sorption isotherms is possible via analysis of the overtone dependence of the resonance frequencies. Rheological properties are monitored via measurement of the dissipation. The glass transition can be identified from the change of viscoelastic properties of the film reflected in changes of the dissipation. A high-resolution water sorption isotherm of lysozyme was measured and compared with results from water sorption calorimetry. Analysis of the rheological behavior during hydration of lysozyme films revealed the presence of two separate sharp transitions at the water activities 0.67 and 0.91, which are connected to the glass transition. In previous works, only the existence of a broad glass transition has been reported so far. Combining the QCM-D data with Raman scattering data presented earlier, a new mechanism of isothermal glass transition in lysozyme is proposed.

  4. Influence of innovative technologies on rheological and thermophysical properties of whey proteins and guar gum model systems

    Directory of Open Access Journals (Sweden)

    Greta Krešić

    2011-03-01

    Full Text Available The aim of this study was to examine the effect of high-power ultrasound (US and highpressure processing (HP on model systems composed of whey protein concentrate (WPC and whey protein isolate (WPI with or without guar gum addition. This kind of systems can be found in food production industry so the aim was to use novel food processing technologies to be utilized as a method for products development. Aqueous suspensions (10 g kg-1 of powdered whey proteins were treated with either ultrasound or high pressure. The treatment conditions were as follows: US: frequency of 30 kHz, for 5 and 10 min; HP: pressure intensity 300-600 MPa, for 5 and 10 min. Rheological and thermophysical properties were analyzed after guar gum addition (0.5 g kg-1. Ultrasound treatment showed a significant influence on all examined properties through protein denaturation caused by cavitation and microstreaming effects. High pressure caused significant increase in viscosity and consistency coefficients of model systems with and without guar addition. Significant decrease of initial freezing and initial thawing temperature was observed in all samples. With this research the direct influence of ultrasound and high-pressure treatment on the rheological and thermophysical properties of whey protein isolate and concentrate model systems with or without guar gum was demonstrated.

  5. RHEOLOGICAL PROPERTIES OF BLOOD AT PATIENTS WITH BOWEL OBSTRUCTION OF TUMORAL GENESIS IN THE EARLY POSTOPERATIVE PERIOD

    Directory of Open Access Journals (Sweden)

    V. V. Maslyakov

    2014-01-01

    Full Text Available Introduction. Microcirculation plays an important role in early postoperative period in colorectal cancer patients. At the same time the question connected with studying of rheological properties of blood as one of microcirculation indicators in literature it studied insufficiently.Materials and methods. We studied rheological properties of blood in 30 patients operated for bowel obstruction caused by right colon cancer. 17 (56,7 % patients were male, 13 (43,3 % – female. Average age was 57 ± 3 years. Time from the moment of manifestation of the first clinical signs before admission to a hospital and the beginnings of carrying out medical and diagnostic actions was 12 ± 0,5 h. The stage of a disease was T3N0–1M0. The group of comparison consisted of 20 healthy volunteers of the same age. Changes of a rheology of blood were measured by means of the accounting of viscosity of blood, change of an index of deformation and aggregation of erythrocytes. Studying of viscosity of blood was carried out by means of the rotational viscometer at shift speeds: 200; 100; 150; 50 and 20 MPas. Measures were conducted at the time of receipt, on the first, third, fifth, seventh and tenth postoperative day.Results. In patients with bowel impassability at the time of receipt the increase in indicators of viscosity of blood is noted at all speeds of the shift, analyzed indicators increase by the third postoperative day, decrease on the seventh and are partially restored for the tenth postoperative days. Complications developed in 16,6 % of cases, in all cases – pneumonia. By comparison of the obtained laboratory data to a clinical picture it is established that complications developed on 3–5th postoperative days.

  6. Rheologic Profile, Specific Gravity, Surface Tension, and pH of Fifteen Over-the-Counter Preparations.

    Science.gov (United States)

    Al-Achi, Antoine; Baghat, Tushar; Chukwubeze, Onah; Dembla, Ishwin

    2007-01-01

    Knowledge of the physical characteristics of commercially available over-the-counter preparations can aid the compounding pharmacist in preparing medication. In this study, 15 over-the-counter products were studied with regard to their specific gravity, surface tension, pH, and rheologic profile. The specific gravities of all the products were greater than 1, with the exceptions of Nivea Lotion and rubbing alcohol, which were less than 1. The majority of the products had an acidic pH. With the exception of two products, Citrucel and Chloraseptic, all products demonstrated a surface tension value less than that of water (72.8 dynes/cm). Chloraseptic had the lowest Newtonian viscosity (1.27 cPs), whereas Vicks DayQuil had the highest (098.86 cPs). Citrucel exhibited dilatant-type flow; Suave Shampoo, herbal shampoo, Tangerine Tickle Herbal Shampoo, and Metamucil pseudoplastic flow; the remaining non-Newtonian formulations, plastic flow profiles.

  7. Rheological properties of the soft-disk model of two-dimensional foams

    DEFF Research Database (Denmark)

    Langlois, Vincent; Hutzler, Stefan; Weaire, Denis

    2008-01-01

    The soft-disk model previously developed and applied by Durian [D. J. Durian, Phys. Rev. Lett. 75, 4780 (1995)] is brought to bear on problems of foam rheology of longstanding and current interest, using two-dimensional systems. The questions at issue include the origin of the Herschel-Bulkley re......The soft-disk model previously developed and applied by Durian [D. J. Durian, Phys. Rev. Lett. 75, 4780 (1995)] is brought to bear on problems of foam rheology of longstanding and current interest, using two-dimensional systems. The questions at issue include the origin of the Herschel......-Bulkley relation, normal stress effects (dilatancy), and localization in the presence of wall drag. We show that even a model that incorporates only linear viscous effects at the local level gives rise to nonlinear (power-law) dependence of the limit stress on strain rate. With wall drag, shear localization...

  8. A Novel Method of Mechanical Oxidation of CNT for Polymer Nanocomposite Application: Evaluation of Mechanical, Dynamic Mechanical, and Rheological Properties

    Directory of Open Access Journals (Sweden)

    Priyanka Pandey

    2014-01-01

    Full Text Available A new approach of oxidation of carbon nanotubes has been used to oxidize the CNTs. A comparative aspect of the mechanical oxidation and acid oxidation process has been established. FTIR analysis and titration method have shown the higher feasibility of the mechanical oxidation method to oxidize the CNTs. Comparatively less damage to the CNTs has been observed in case of mechanically oxidized as compared to acid oxidized CNTs. The mechanical properties of the nanocomposites reinforced with the acid oxidized CNT (ACNT and mechanically oxidized CNTs (McCNT were analyzed and relatively higher properties in the nanocomposites reinforced with McCNT were noticed. The less degree of entanglement in the McCNTs was noticed as compared to ACNTs. The dynamic mechanical analysis of the nanocomposites revealed much improved load transfer capability in the McCNT reinforced composites. Further, the rheological properties of the nanocomposites revealed the higher performance of McCNT reinforced composites.

  9. Correlation between Microstructure and Rheological Properties of Broad Molecular Weight Distribution High Density Polyethylenes

    Directory of Open Access Journals (Sweden)

    Mohammad Javad Shirkavand

    2015-03-01

    Full Text Available In this article, the correlation between molecular microstructure and rheological behavior for three different grades of high density polyethylene with broad molecular weight distribution have been investigated. Structural parameters such as Mn, Mw, Mz, molecular weight distribution (MWD and branching index were characterized by high temperature Gel Permeation Chromatography (GPC test. GPC results showed that BL4 and EX3 have bigger weight average molecular weight and narrower molecular weight distribution, respectively. Furthermore,it was found from GPC results that all three HDPE has a broad MWD and EX3 has more short chain branches than two other samples. Rheological characterization was done in a Mechanical Compact Rheometer (MCR in rotational and dynamic modes at both linear and nonlinear viscoelastic region. From rheological characterization the zero shear viscosity (η0, relaxation time and relaxation time distribution, stress relaxation modulus and damping factor were obtained and by utilizing relaxation time spectrum function (h(τ, molecular weight distribution was calculated for each sample and compared with GPC results. The relationship between zero shear viscosity with molecular weight and MWD at 180 ºC obtained. After calculating molecular weight distribution function and average molecular weights using different mixing parameters (β, by choosing β=0.73, a good correlation between molecular parameters obtained from rheological data with those of GPC results was obtained. After calculating stress relaxation modulus and consequently damping factor for each sample, comparing to Doi-Edwards model, it was found that the damping function type C is an appropriate damping function type for selected polyethylenes.

  10. Properties of starch-polyglutamic acid (PGA) graft copolymer prepared by microwave irradiation - Fourier transform infrared spectroscopy (FTIR) and rheology studies

    Science.gov (United States)

    The rheological properties of waxy starch-'-polygutamic acid (PGA) graft copolymers were investigated. Grafting was confirmed by FTIR spectroscopy. The starch-PGA copolymers absorbed water and formed gels, which exhibited concentration-dependent viscoelastic solid properties. Higher starch-PGA conce...

  11. The effect of diesters and lauric acid on rheological properties of air/water interfaces stabilized by oligofructose lauric acid monoesters

    NARCIS (Netherlands)

    Kempen, van S.E.H.J.; Schols, H.A.; Linden, van der E.; Sagis, L.M.C.

    2013-01-01

    In this study, the rheological properties of interfaces stabilized by oligofructose fatty acid esters were elucidated. First, the properties of interfaces stabilized by monoesters (ME), diesters (DE), lauric acid (LA), oligofructose (OF), and mixtures of ME with DE, LA, or OF were studied. Second,

  12. A Comparison Between Rheological Properties of Intra-articular Hyaluronic Acid Preparations and Reported Human Synovial Fluid.

    Science.gov (United States)

    Nicholls, Mat; Manjoo, Ajay; Shaw, Peter; Niazi, Faizan; Rosen, Jeffrey

    2018-03-14

    This study aims to compare the properties of currently available intra-articular hyaluronate (IA-HA) products widely available in the USA to those of healthy knee synovial fluid with respect to their bulk rheological properties. We hypothesize that products would have differing rheological properties, with some more closely resembling the properties and physiological aspects of healthy joint fluid HA. We obtained reported HA product molecular weights, as well as measurements of the presence of cross-linking, zero shear rate viscosity, shear thinning ratio, and crossover frequency for the following IA-HA products available in the USA: Euflexxa ® , Orthovisc ® , Supartz ® , Monovisc ® , Synvisc ® , Synvisc-One ® , Gel-One ® , and Hyalgan ® . Differences were seen between the study products across all of the investigated parameters. Hyalgan, Supartz, Orthovisc, and Euflexxa had a linear chain structure, while Synvisc, Synvisc-One, and Monovisc were cross-linked in structure. Molecular weight, shear rates, and crossover frequencies ranged widely across tested products, with values ranging from below to above those reported for healthy knee synovial fluid HA. When compared to healthy knee parameter values reported within the current literature, observed parameters for Euflexxa and Orthovisc were typically seen to be the most similar to healthy knee synovial fluid. When comparing Euflexxa and Orthovisc directly, Euflexxa was more often similar to the properties of healthy knee synovial fluid with respect to the observed parameters of molecular structure, shear rates, and crossover frequency. Available IA-HA products vary with respect to molecular weight, presence of cross-linking, shear rate dependency of viscosity, and crossover frequency. Since IA-HA treatment for osteoarthritis aims to restore synovial fluid back to original HA property characteristics, using HA supplements resembling healthy synovial fluid is a logical approach. Our findings demonstrate that

  13. Improvement of physicochemical and rheological properties of kombucha fermented milk products by addition of transglutaminase and whey protein concentrate

    Directory of Open Access Journals (Sweden)

    Iličić Mirela D.

    2016-01-01

    Full Text Available The objective of this work was to investigate the effect of addition of transglutaminase (TG-0.02%, w/w and whey protein concentrate (WPC-0.03%, w/w, on quality of kombucha fermented milk product. Samples were prepared from pasteurized semi-skim milk (0.9%, w/w fat and kombucha inoculum (10%, v/v. The pH values were measured during the fermentation of milk (lasted until reached 4.5. Syneresis, water holding capacity and the product texture (firmness and consistency, were assessed after production. Rheological properties of kombucha fermented milk samples were measured during ten days of storage. The sample containing TG had the lowest syneresis (21 ml, the highest water holding capacity (62% and the highest textural characteristics (firmness - 23.99g, consistency - 626.54gs after production. The addition of WPC to milk improved the rheological properties, while the addition of TG improved it even to a significantly greater extent after the production and during 10 days of the storage. [Projekat Ministarstva nauke Republike Srbije, br. 46009

  14. Comparison of chemical, rheological and sensory properties of kefir produced by kefir grains and commercial kefir starter

    Directory of Open Access Journals (Sweden)

    Irena Barukčić

    2017-01-01

    Full Text Available The main objective of this study was to compare chemical, rheological and sensory characteristics of kefir produced by using kefir grains and kefir starter. The intent was also to investigate whether it is plausible to use a combined inoculum (kefir grains and starter in order to obtain a kefir with improved characteristics in terms of sensory and rheological characteristics. Kefir samples were produced at 25 °C and 35 °C by using starter culture XPL-1, kefir grains and their combinations. All of the produced kefir samples were analysed for acidity, total dry matter, ethanol content, syneresis, viscosity and were sensory evaluated by a specially trained panel. There were no significant differences considering the total dry matter, syneresis, ethanol content and acidity. Excess viscosity was observed in samples produced by starter culture at 35 °C, which was described as untypical, yoghurt like and unsatisfactory by a sensory panel. The sample produced at 25 °C by equal amounts of kefir grains and starter culture received the highest scores at sensory evaluation and showed the best potential for optimizing the further use. Further investigations need to focus on examining kefir properties during the storage period, especially regarding microbiological and sensory properties, ethanol content and texture profile.

  15. Effect of phenolic acids on the rheological properties and proteins of hard wheat flour dough and bread.

    Science.gov (United States)

    Han, Hye Min; Koh, Bong-Kyung

    2011-10-01

    The effects of different phenolic acids on the rheological properties and gluten proteins of hard wheat flour dough and bread were investigated. Caffeic, ferulic, syringic and gallic acids were each blended with hard wheat flour at a concentration of 4.44 µmol L(-1) g(-1) flour. Mixing time and tolerance were reduced with the addition of phenolic acids. The phenolic acids reduced the maximum resistance to extension (R(max)) and increased the extensibility of dough, with effects in the following order: gallic Loaf volume was most significantly decreased with the addition of caffeic acid. Extraction of sodium dodecyl sulfate-soluble high-molecular-weight proteins was increased in both mixed and fermented doughs by the addition of ferulic and caffeic acids. The order of influence of the phenolic acids on the rheological properties and protein structure of dough and bread was consistent with that of their antioxidant activity. The addition of caffeic and ferulic acids reduced R(max) and increased the extensibility of hard wheat flour dough by modifying the high-molecular-weight gluten, which resulted in decreased bread volume. Copyright © 2011 Society of Chemical Industry.

  16. An In-Depth Investigation into the Physicochemical, Thermal, Microstructural, and Rheological Properties of Petroleum and Natural Asphalts

    Directory of Open Access Journals (Sweden)

    Nader Nciri

    2016-10-01

    Full Text Available Over the last decade, unexpected and sudden pavement failures have occurred in several provinces in South Korea. Some of these failures remain unexplained, further illustrating the gaps in our knowledge about binder chemistry. To prevent premature pavement distress and enhance road performance, it is imperative to provide an adequate characterization of asphalt. For this purpose, the current research aims at inspecting the chemistry, microstructure, thermal, and physico-rheological properties of two types of asphalt, namely petroleum asphalt (PA and natural asphalt (NA. The binders were extensively investigated by using elemental analysis, thin-layer chromatography with flame ionization detection (TLC-FID, matrix-assisted laser desorption ionization time-of-fight mass spectroscopy (MALDI-TOF-MS, Fourier transform infrared spectroscopy (FT-IR, Raman spectroscopy (RS, Nuclear magnetic resonance spectroscopy (1H-NMR, ultraviolet and visible spectroscopy (UV-VIS, X-ray diffraction (XRD, scanning electron microscopy (SEM, thermogravimetric analysis (TGA, differential scanning calorimetry (DSC, penetration, softening point, ductility, and viscosity tests. The findings of this research have revealed the distinct variations between the chemical compositions, microstructures, and thermo-rheological properties of the two asphalts and provided valuable knowledge into the characteristics of the binders. Such insight has been effective in predicting the performance or distress of road pavement. This paper will, therefore, be of immediate interest to materials engineers in state highway agencies and asphalt industries.

  17. Study of the rheological properties of a fermentation broth of the fungus Beauveria bassiana in a bioreactor under different hydrodynamic conditions.

    Science.gov (United States)

    Núñez-Ramírez, Diola Marina; Medina-Torres, Luis; Valencia-López, José Javier; Calderas, Fausto; López Miranda, Javier; Medrano-Roldán, Hiram; Solís-Soto, Aquiles

    2012-11-01

    Fermentation with filamentous fungi in a bioreactor is a complex dynamic process that is affected by flow conditions and the evolution of the rheological properties of the medium. These properties are mainly affected by the biomass concentration and the morphology of the fungus. In this work, the rheological properties of a fermentation with the fungus Beauveria bassiana under different hydrodynamic conditions were studied and the rheological behavior of this broth was simulated through a mixture of carboxymethyl cellulose sodium and cellulose fibers (CMCNa-SF). The bioreactor was a 10 L CSTR tank operated at different stir velocities. Rheological results were similar at 100 and 300 rpm for both systems. However, there was a significant increase in the viscosity accompanied by a change in the consistence index, calculated according to the power law model, for both systems at 800 rpm. The systems exhibited shear-thinning behavior at all stir velocities, which was determined with the power law model. The mixing time was observed to increase as the cellulose content in the system increased and, consequently, the efficiency of mixing diminished. These results are thought to be due to the rheological and morphological similarities of the two fungal systems. These results will help in the optimization of scale-up production of these fungi.

  18. Rheological properties of silver filled polymer suspensions and their effects on printing performance: Presented at the 10th Annual European Rheology Conference, AERC 2015, April 14-17 2015, Nantes, France

    OpenAIRE

    Reinhardt, Kathrin; Eberstein, Markus; Hübner, Nancy; Saphiannikova, Marina

    2015-01-01

    Screen printing of pastes is the major structuring approach in the ceramic thick film technology by which narrow conductor, resistor and isolation layers are assembled to highly integrated sensors and microsystems. Thereby a paste is a suspension by a solvent, a polymer and an inorganic filler. Understanding the rheological properties is crucial for setting an optimal high-precision printing. Previous works have shown that the measurements of flow curves1 or the considerations of oscillation ...

  19. Correlating rheological properties and printability of collagen bioinks: the effects of riboflavin photocrosslinking and pH.

    Science.gov (United States)

    Diamantides, Nicole; Wang, Louis; Pruiksma, Tylar; Siemiatkoski, Joseph; Dugopolski, Caroline; Shortkroff, Sonya; Kennedy, Stephen; Bonassar, Lawrence J

    2017-07-05

    Collagen has shown promise as a bioink for extrusion-based bioprinting, but further development of new collagen bioink formulations is necessary to improve their printability. Screening these formulations by measuring print accuracy is a costly and time consuming process. We hypothesized that rheological properties of the bioink before, during, and/or after gelation can be used to predict printability. In this study, we investigated the effects of riboflavin photocrosslinking and pH on type I collagen bioink rheology before, during, and after gelation and directly correlated these findings to the printability of each bioink formulation. From the riboflavin crosslinking study, results showed that riboflavin crosslinking increased the storage moduli of collagen bioinks, but the degree of improvement was less pronounced at higher collagen concentrations. Dots printed with collagen bioinks with riboflavin crosslinking exhibited smaller dot footprint areas than those printed with collagen bioinks without riboflavin crosslinking. From the pH study, results showed that gelation kinetics and final gel moduli were highly pH dependent and both exhibited maxima around pH 8. The shape fidelity of printed lines was highest at pH 8-9.5. The effect of riboflavin crosslinking and pH on cell viability was assessed using bovine chondrocytes. Cell viability in collagen gels was found to decrease after blue light activated riboflavin crosslinking but was not affected by pH. Correlations between rheological parameters and printability showed that the modulus associated with the bioink immediately after extrusion and before deposition was the best predictor of bioink printability. These findings will allow for the more rapid screening of collagen bioink formulations.

  20. Vesta surface thermal properties map

    Science.gov (United States)

    Capria, Maria Teresa; Tosi, F.; De Santis, Maria Cristina; Capaccioni, F.; Ammannito, E.; Frigeri, A.; Zambon, F; Fonte, S.; Palomba, E.; Turrini, D.; Titus, T.N.; Schroder, S.E.; Toplis, M.J.; Liu, J.Y.; Combe, J.-P.; Raymond, C.A.; Russell, C.T.

    2014-01-01

    The first ever regional thermal properties map of Vesta has been derived from the temperatures retrieved by infrared data by the mission Dawn. The low average value of thermal inertia, 30 ± 10 J m−2 s−0.5 K−1, indicates a surface covered by a fine regolith. A range of thermal inertia values suggesting terrains with different physical properties has been determined. The lower thermal inertia of the regions north of the equator suggests that they are covered by an older, more processed surface. A few specific areas have higher than average thermal inertia values, indicative of a more compact material. The highest thermal inertia value has been determined on the Marcia crater, known for its pitted terrain and the presence of hydroxyl in the ejecta. Our results suggest that this type of terrain can be the result of soil compaction following the degassing of a local subsurface reservoir of volatiles.

  1. Rheological and sensory properties and aroma compounds formed during ripening of soft brined cheese made from camel milk

    DEFF Research Database (Denmark)

    Hailu, Yonas; Hansen, Egon Bech; Seifu, Eyassu

    2018-01-01

    Protein degradation, rheological properties, sensory properties and the aroma profile of soft brined cheese made from camel milk using two levels of coagulant (camel chymosin) [55 and 85 International Milk Clotting Units (IMCU) L−1] and two levels of brine (2% or 5% NaCl, w/w) were investigated...... over a ripening period of 60 d. Casein degradation in soft brined camel milk cheese significantly (p ... during ripening. However, cheese made with 85 IMCU L−1 coagulant resulted in softening of cheese texture and higher salt uptake. Using descriptive sensory analysis, the experimental cheeses were described as salty, sour and firm. The volatile aroma compounds formed in soft ripened camel milk cheese...

  2. Influence of nepheline syenite and milling time on the rheological properties of a porcelain stoneware tile slip

    Directory of Open Access Journals (Sweden)

    Jazayeri, S. H.

    2003-08-01

    Full Text Available The rheological properties of porcelain stoneware tile slips were investigated using a rotational rheometer. The first step in the study was to evaluate the rheological behaviour of a reference slip at different particle size distributions to determine the optimum conditions at which to carry out the investigation of the influence of nepheline syenite in the mix. In the second step part of the K-feldspar in the reference mix was replaced with nepheline syenite such that the mix composition contained 10 % nepheline syenite. The flow curve, yield stress and thixotropy of the slips were evaluated at different milling times in order to study the effect of particle size on the rheological behaviour. The milling times for the reference mix and for the mix with nepheline syenite which resulted in the best rheological parameters were found.

    Se han investigado las propiedades reológicas de barbotinas de porcelana dura para pavimentos usando un reómetro rotacional. El primer paso del estudio fue evaluar el comportamiento reológico de una barbotina de referencia con diferentes distribuciones de tamaño de partícula con el fin de determinar las condiciones óptimas bajo las cuales estudiar la influencia de nefelina sienita en la mezcla. En la segunda etapa, parte del feldespato potásico de la mezcla de referencia se substituyó por nefelina sienita de forma que la composición de la mezcla tuviera un 10% de neflina sienita. Se evaluaron las curvas de flujo, los puntos de fluidez y la tixotropía de las barbotinas tras diferentes tiempos de molienda con el fin de estudiar el efecto del tamaño de partícula en el comportamiento reológico. Se determinaron los tiempos de molienda en los que se alcanzaban los mejores parámetros reológicos para la mezcla de referencia y la de nefelina sienita.

  3. Rheological and gelation properties of rice starch modified with 4-alpha-glucanotransferase.

    Science.gov (United States)

    Lee, Kwang Yeon; Kim, Yong-Ro; Park, Kwan Hwa; Lee, Hyeon Gyu

    2008-04-01

    Rheological measurements were performed to characterize rice starch modified with 4-alpha-glucanotransferase (4alphaGTase) isolated from Thermus scotoductus, in terms of effects of the enzyme and starch concentration on flow behavior, gel strength, and melting and gelling kinetics of the modified rice starch. Consistency index decreased and flow behavior index increased with the level of enzyme treatment, and at high level of enzyme treatment, it demonstrated Bingham plastic behavior. As the level of enzyme decreased and the starch concentration increased, gelation time decreased and the final gel strength increased significantly. Regardless of treatment variables, all the modified starch gels melted at similar temperature.

  4. Gamma Radiation Influence on Rheological and Technological Characteristics of Wheat Flour (misr-1) and Sensory Properties of Pan Bread

    International Nuclear Information System (INIS)

    Anwar, M.M.; Asael, M.A.; El-Adly, N.A.

    2015-01-01

    This study aimed at determining the influence of gamma radiation on rheological and technological characteristics of flour extraction from irradiated wheat grains (misr-1) with 3,6 and 9 kGy, also baking quality and sensory characteristics of pan breads made from this flour. The rheological properties of wheat flour 72% extraction were determined by farinograph parameter, extensograph parameter and measured by amylo graph paramete. Gamma radiation caused increase in water absorption and decrease dough development time, and dough stability time. The decrease percentage increased by increasing dose rate and increased the dough weakness, also γ-irradiation increased the elasticity, decrease extensibility and decrease dough strength (energy), whereas γ-irradiation on wheat grains (misr-1) decrease the maximum viscosity of flour, it indicate an increase in enzymatic activity as a result of the breakdown of starch and improve the gluten index %, this fact is beneficial for bread baking purposes. So γ-irradiation increased volume loaf especially at the dose 6 kGy,and no real differences of taste, texture, appearance and odor scores for sensory evaluation of pan bread made of flour extraction from irradiated and un-irradiated wheat grains. Mean while, irradiation particularly at higher doses (6 and 9 kGy)caused difference in the color (darkness) of pan bread. Gamma irradiation increased the baking quality, and improvement volume loaf especially at the dose 6 kGy.

  5. Rheological properties of tamarind (Tamarindus indica L.) seed mucilage obtained by spray-drying as a novel source of hydrocolloid.

    Science.gov (United States)

    Alpizar-Reyes, Erik; Román-Guerrero, Angélica; Gallardo-Rivera, Raquel; Varela-Guerrero, Victor; Cruz-Olivares, Julian; Pérez-Alonso, César

    2018-02-01

    Tamarind seed mucilage (TSM) was extracted and obtained by spray drying. The power law model well described the rheological behavior of the TSM dispersions with determination coefficients R 2 higher than 0.93. According to power law model, non-Newtonian shear thinning behavior was observed at all concentrations (0.5%, 1%, 1.5% and 2%) and temperatures (25, 30, 40, and 60°C) studied. Increasing temperature decreased the viscosity and increased the flow behavior index, opposite effect was observed when increasing the concentration. The temperature effect was more pronounced at 2.0% TSM concentration with an activation energy of 20.25kJ/mol. A clear dependence of viscosity on pH was observed, as pH increased from acidic to alkaline conditions, the viscosity increased. It was found that the rheological properties of TSM were affected by the sucrose and salts and their concentrations as well due to the addition of ions (or sucrose) decreases repulsion and allows molecule expansion promoting a significant reduction in viscosity. These results suggest that TMS could be applied in the production of foods that require additives with thickening capacity. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Correlation between rheological and mechanical properties of black PE100 compounds – Effect of carbon black masterbatch

    Directory of Open Access Journals (Sweden)

    G. Pircheraghi

    2017-08-01

    Full Text Available Black PE100 compounds were prepared using a co-rotating twin screw extruder by addition of carbon black masterbatches containing 35–40 wt% carbon black and different polymer carriers to a pipe grade PE100 material with bimodal molecular weight distribution. Different properties of carbon black masterbatches and PE100 black compounds were evaluated using thermal, rheological and mechanical tests. Rheological results indicated an inverse correlation between melt flow index (MFI of masterbatch samples and storage modulus, complex viscosity and shear viscosity of black compounds, while flow instabilities of compounds were also postponed to higher shear rates. TGA indicated that masterbatch with highest value of MFI contained highest amount of low molecular weight lubricants which resulted in inhibition of strain hardening behavior in tensile test of its respective black compound unlike all other samples, reflecting possible suppressing of its long term resistance to slow crack growth. This behavior is attributable to facilitated crystallization and chain folding of longer chains in the presence of low molecular weight lubricants in this sample and consequently formation of thicker lamellas as confirmed by DSC, hence lowering density of entanglements in amorphous area and inhibition of strain hardening.

  7. Effect of Stevia (Stevia rebaudiana as a Substitute for Sugar on Physicochemical, Rheological and Sensory Properties of Dietary Saffron Syrup

    Directory of Open Access Journals (Sweden)

    Neda Hashemi

    2015-01-01

    Full Text Available In recent years production and usage of functional food and drinks is one of the public and scientist’s interest. Since carbohydrates have been recognizedas the major calorie source in many food baskets, most attention has been focused on substitution of sucrose with non-caloric sweeteners. Although both natural and synthetic sweeteners have been used in the formulation of food stuffs, deep concern is raised regarding safety aspects of synthetic ones. Stevia is a natural suitable sweetener that is currently being used as a substitute for sugar in many dietary and functional foods and drinks. In the present study the effect of using stevia sugar as a replacement for sucrose in the preparation of saffron beverages was investigated. Accordingly, saffron syrup was prepared with 5 treatments in which100%, 75%, 50%, 25% and 0% of stevia sugar replaced sucrose. Then, the physicochemical, rheological and sensory properties of saffron functional syrup were investigated. The results indicated that by increasing stevia brix level, density and viscosity increased but the syrups’ pH decreases. The best treatment was the sample containing 25% steviaand 75% sucrose that compared to other samples regarding sensory characteristics had a higher acceptance by consumer and regarding physicochemical and rheological characteristics more similar to the control sample.

  8. Effect of pre-emulsified sesame oil on physical-chemical and rheological properties of pork batters

    Directory of Open Access Journals (Sweden)

    Zhuang Li KANG

    Full Text Available Abstract Physical-chemical and rheological properties of pork batters as affected by replacing pork back-fat with pre-emulsified sesame oil were investigated. Replacement of pork back-fat with pre-emulsified sesame oil, improved L* value, moisture and protein content, hardness, cohesiveness, and chewiness, declined a* value, fat content and energy, but not affect cooking yield. When used pre-emulsified sesame oil to replace pork back-fat 50%, the sample had the highest L* value and texture. According to the results of dynamic rheological, replaced pork back-fat by pre-emulsified sesame oil increased the storage modulus (G' values at 80 °C, and formed firm gel. The result of Low-field nuclear magnetic resonance (LF-NMR shown that the batters with pre-emulsified sesame oil had higher water holding capacity than the control. Overall, the batters with pre-emulsified sesame oil enabled lowering of fat and energy contents, making the pork batter had better texture.

  9. Effect of liposomes on rheological and syringeability properties of hyaluronic acid hydrogels intended for local injection of drugs.

    Science.gov (United States)

    El Kechai, Naila; Bochot, Amélie; Huang, Nicolas; Nguyen, Yann; Ferrary, Evelyne; Agnely, Florence

    2015-06-20

    The aim of this work was to thoroughly study the effect of liposomes on the rheological and the syringeability properties of hyaluronic acid (HA) hydrogels intended for the local administration of drugs by injection. Whatever the characteristics of the liposomes added (neutral, positively or negatively charged, with a corona of polyethylene glycol chains, size), the viscosity and the elasticity of HA gels increased in a lipid concentration-dependent manner. Indeed, liposomes strengthened the network formed by HA chains due to their interactions with this polymer. The nature and the resulting effects of these interactions depended on liposome composition and concentration. The highest viscosity and elasticity were observed with liposomes covered by polyethylene glycol chains while neutral liposomes displayed the lowest effect. Despite their high viscosity at rest, all the formulations remained easily injectable through needles commonly used for local injections thanks to the shear-thinning behavior of HA gels. The present study demonstrates that rheological and syringeability tests are both necessary to elucidate the behavior of such systems during and post injection. In conclusion, HA liposomal gels appear to be a promising and versatile formulation platform for a wide range of applications in local drug delivery when an injection is required. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Rheological, mechanical and adhesive properties of surfactant-containing systems designed as a potential platform for topical drug delivery.

    Science.gov (United States)

    Carvalho, Flávia Chiva; Rocha e Silva, Hilris; da Luz, Gabriela Marielli; Barbi, Mariana da Silva; Landgraf, Daniele Silveira; Chiavacci, Leila Aparecida; Sarmento, Victor Hugo Vitorino; Gremião, Maria Palmira Daflon

    2012-04-01

    In the last few decades, nanotechnology has led to an advance in the development of topical drug delivery. Nanostructured drug delivery systems enable the compartmentalization of drugs in restricted environments, modifying the release profile and maintaining the required drug concentration for prolonged periods at the site of action and/or absorption. The development of nanostructured systems containing surfactants has evolved rapidly. Mixtures of surfactant, oil and water can self-associate to form structures, such as microemulsions and liquid crystal phases, which can be exploited as drug delivery systems because their nanostructured organization can control drug release. Therefore, the purpose of this study was to assess the potential of systems containing polyoxypropylene (5) polyoxyethylene (20) cetyl ether as surfactant, oleic acid or mineral oil as the oily phase, and water to be used as a platform in the development of topical drug delivery systems. Physicochemical characterization of the systems was performed by polarized light microscopy (PLM), small-angle X-ray scattering (SAXS), rheological tests and texture profile analysis. The ternary phase diagrams showed that combinations of surfactant/mineral oil/water and surfactant/oleic acid/water could form various thermodynamically stable structures, such as microemulsions and liquid crystals. The oily phases, oleic acid and mineral oil, changed the rheological, mechanical and adhesive properties of systems containing polyoxypropylene (5) polyoxyethylene (20) cetyl ether.

  11. An Analysis of Rheological Properties of Inconel 625 Superalloy Feedstocks Formulated with Backbone Binder Polypropylene System for Powder Injection Molding

    Directory of Open Access Journals (Sweden)

    Gökmen U.

    2017-12-01

    Full Text Available Binder formula is one of the most significant factors which has a considerable influence on powder injection molding (PIM processes. In the study, rheological behaviors and properties of different binder systems containing PIM feedstocks, Inconel 625 powder commonly used in space industry, were investigated. The feedstocks were prepared 59%-69% (volume powder loading ratios with three diversified binder systems by use of Polypropylene as backbone binder. The average particle size of the Inconel 625 powder used was 12.86 microns. Components used in the binder were mixed for 30 minutes as dry in three dimensional mixing to prepare binder systems. Rheological features of the feedstock were characterized by using a capillary rheometer. Viscosities of the feedstocks were calculated within the range of 37.996-1900 Pa.s based on the shear rate, shear stress, binder formula and temperature. “n” parameters for PIM feedstocks were determined to be less than 1. Influences of temperature on the viscosities of the feedstocks were also studied and “Ea” under various shear stresses were determined within the range of 24.41-70.89 kJ/mol.

  12. Rheological properties and mineral content of buckwheat enriched wholegrain wheat pasta

    Directory of Open Access Journals (Sweden)

    Nedeljković Nataša

    2014-01-01

    Full Text Available Light buckwheat flour (LBF was used to substitute 20% of whole wheat flour (WWF in the formulation of wholegrain wheat pasta. Wholegrain wheat pasta (WWP and buckwheat enriched wholegrain wheat pasta (BWWP were produced on an industrial scale. Substitution level of buckwheat flour (20% was based on previously conducted rheological tests on LBF/WWF blends which were performed using 10, 20 and 30% of LBF. The obtained Mixolab profiles have indicated that wheat blend containing 20% LBF expressed the most similar rheological parameters to WWF. Proximate composition, cooking quality and mineral content of BWWP were analyzed and compared with those of WWP. The substitution of WWF with LBF in the pasta formulation resulted in significantly increased (P < 0.05 contents of P, Mg, K and Zn compared to WWP in dry pasta. The reduction in mineral content of BWWP during cooking was significantly higher (P < 0.05 compared to WWP. The content of P, Mg and K were at same level in both type of pasta after cooking. The obtained results suggest that enrichment of WWP with LBF at the level of 20% did not improve the mineral content of cooked pasta, although increase in minerals was observed in dry pasta. [Projekat Ministarstva nauke Republike Srbije, br. TR31029

  13. Rheological properties of typical chernozems (Kursk oblast) under different land uses

    Science.gov (United States)

    Khaidapova, D. D.; Chestnova, V. V.; Shein, E. V.; Milanovskii, E. Yu.

    2016-08-01

    Rheological parameters of humus horizons from typical chernozems under different land use—on a virgin land (unmown steppe) and under an oak forest, long-term black fallow, and agricultural use—have been studied by the amplitude sweep method with an MCR-302 modular rheometer at water contents corresponding to swelling limit and liquid limit. From the curves of elastic and viscous moduli, the ranges of elastic and viscoelastic (plastic) behavior of soil pastes—as well as that of transition from viscoelastic to viscous behavior—have been determined. It has been shown that the rheological behavior is largely determined by the content of organic matter, which can act as a binding agent structuring the interparticle bonds and as a lubricant in the viscous-flow (plastic) state of soil pastes. Soil samples enriched with organic matter (virgin land, oak forest, forest belt) have a more plastic behavior and a higher resistance to loads. Soil samples with the lower content of organic matter (long-term fallow, plowland) are characterized by a more rigid cohesion of particles and a narrower range of load resistance. Soil pastes at the water content of liquid limit have a stronger interparticle cohesion and a more brittle behavior than at the water content of swelling limit. Methodological aspects of testing soil pastes at the constant sample thickness and the controlled normal load have been considered. For swelling soil samples, tests under controlled normal load are preferred.

  14. Effect of ball milling energy on rheological and thermal properties of amaranth flour.

    Science.gov (United States)

    Roa, Diego F; Baeza, Rosa I; Tolaba, Marcela P

    2015-12-01

    Pearled amaranth grains obtained by abrasive milling were processed by planetary ball milling to produce amaranth flours. The influence of milling energy on rheological and thermal behavior of amaranth flour dispersions and stability during 24 h storage at 4 °C were investigated based on a factorial design. The rheological behavior of flour dispersions (4 % and 8 % w/v) was determined using a rotational viscometer, while gelatinization degree was determined by differential scanning calorimetry as a measure of structural changes.The power law model was found to be suitable in expressing the relationship between shear stress and shear rate. Flour dispersions showed a pseudoplastic behavior. However this character decreased with the storage being dependent on flour concentration and milling energy. A decrease of the consistency index and an increase of the flow behavior index were observed as a result of the increasing milling energy. Gelatinization enthalpy decrease showed the loss of crystalline structure due to ball milling. Amaranth flour dispersions presented increasing stability during storage. It was observed, that the stability changed with the concentration of amaranth flours.Thus, more stable dispersions were obtained as the flour concentration increased. The highly milled sample was the most stable sample during the storage.

  15. Avaliação das propriedades reológicas do trigo armazenado Rheological properties evaluation of stored wheat

    Directory of Open Access Journals (Sweden)

    Aparecido Nivaldo Módenes

    2009-09-01

    Full Text Available Neste trabalho foi realizada uma avaliação das propriedades reológicas de trigo armazenado no período de 5 meses, objetivando dar subsídios para que as aquisições ou o uso do trigo possam ser feitos na colheita ou se necessitam de um tempo de repouso, para evolução das propriedades reológicas. Foram realizadas análises com 4 variedades de trigo Coodetec CD 104, CD 112, CD 200133 e CD 200213. O intervalo entre as análises foi de 30 dias, iniciando na colheita até 150 dias de armazenamento. Foram analisados a Alveografia (força geral do glúten, tenacidade e extensibilidade da massa, o Teor de Glúten (Glúten úmido e seco e o Número de Queda. Os resultados obtidos mostraram que, no período, não houve evolução na força do glúten e no número de queda. Pequenas variações que ocorreram nas outras análises, como tenacidade e extensibilidade, não são significativas do ponto de vista da indústria moageira. Desta forma, os resultados obtidos mostram que não existe a necessidade de retardar a aquisição e o uso do trigo na colheita em relação às propriedades reológicas, reduzindo desta forma o tempo e o custo de armazenamento.The objective of this work was to evaluate the rheological properties of 5 months of storage of wheat and investigate how the method of storage influences the use of wheat and its rheological properties. The assays were conducted with 4 variations of wheat: CoodeteC - CD 104, CD 112, CD 200133 and CD 200213. The time interval between the assays was 30 days and the storage time was up to 150 days after harvest. Alveogram parameters (general gluten force, tenacity, and extensibility of mass, the humid and dried gluten, and falling number were evaluated. The obtained results indicated that during the chosen storage period the gluten force and falling number did not change. The other assays showed small variations, for example on tenacity and extensibility, but this fact is not significant from the

  16. Microstructural and rheological properties of irradiated rice Propriedades microestrutural e reológica de arroz irradiado

    Directory of Open Access Journals (Sweden)

    Ívina Catarina de Oliveira Guimarães

    2013-06-01

    Full Text Available The culinary quality of rice directly results in its market value and consumer acceptance. Thus, the present study evaluated the effect of gamma irradiation on the properties of the polished white rice starch, as well as their characteristic pulp. Doses of 6.5 kGy and 7.5 kGy did not alter the microstructure of rice starch granules, but interfered with rheological properties when compared to the control treatment, resulting in a reduction of the maximum and final viscosity and retrogradation. Since the microstructural and rheological properties within the values associated with rice quality, it was inferred that gamma irradiation did not alter the decisive characteristics for the acceptability of this cereal.A qualidade culinária do arroz resulta diretamente em seu valor de mercado e aceitação do consumidor. Assim, no presente estudo, avaliou-se o efeito da irradiação gama sobre as propriedades do amido do arroz branco polido, bem como na sua característica de pasta. Doses de 6,5 kGy e 7,5 kGy não alteraram a microestrutura dos grânulos de amido de arroz, mas interferiram nas propriedades reológicas quando comparado ao tratamento controle, resultando na redução da viscosidade máxima e final; e retrogradação. Esse resultado pode estar correlacionado à presença de radicais livres no arroz branco polido recém-irradiado, os quais se estabilizaram ao passar quatro meses. Desde que as propriedades microestruturais e reológicas se encontrem dentro dos valores associados à qualidade do arroz, a irradiação gama não altera as características determinantes para a aceitação do cereal.

  17. The effects of heating and dilution on the rheological and physical properties of Tank 241-SY-101 waste

    International Nuclear Information System (INIS)

    Tingey, J.M.; Bredt, P.R.; Shade, E.H.

    1994-10-01

    Of the 177 high-level waste underground storage tanks at the Hanford Site, 25 have been identified as being potentially capable of generating and releasing flammable gas. Tank 241-SY-101 has exhibited periodic releases of gas, and in some cases the gas released has exceeded the lower flammable gas limit. The components of the released gas from Tank 241-SY-101 are hydrogen, nitrous oxide, nitrogen, ammonia, carbon monoxide, and methane. A mitigation strategy that may effectively reduce the retention and release of these gases and the release of flammable gases is dilution coupled with eating of the tank wastes. The purpose of this work was to determine changes in rheological and physical properties caused by heating and dilution of actual 241-SY-101 waste. In May and December 1991, following periodic gas releases, samples of the waste in Tank 241-SY-101 were obtained. Current work quantified the effects of heating coupled with NaOH dilution of a combination of waste samples from Tank 241-SY-101 characteristic of a non-convective layer. The experimental approach and results of this heating and dilution study on Tank 241-SY-101 waste samples are described in Sections 2 and 3, respectively. In Section 3.1, a discussion of the rheological properties of the waste as a function of shearing forces, volume percent dilution, and temperature is presented. In Section 3.2, the physical properties of the waste dilutions are described, including the densities of the slurry, filtered solids, and filtrate; the settling behavior; and the percent filtered solids in the composite sample and each of the composite dilutions. A brief discussion of the results and uncertainties is given is Section 3.3. The conclusions of this investigation are reported in Section 4

  18. To Study Capping or Lamination Tendency of Tablets Through Evaluation of Powder Rheological Properties and Tablet Mechanical Properties of Directly Compressible Blends.

    Science.gov (United States)

    Dudhat, Siddhi M; Kettler, Charles N; Dave, Rutesh H

    2017-05-01

    Air entrapment efficiency of the powders is one of the main factors leading to occurrence of capping or lamination tendency of tablets manufactured from the directly compressible powder blends. The purpose of the current research was to study this underlying cause leading to occurrence of capping or lamination of tablets through evaluation of powder rheological properties. Powder blends were prepared by addition of 0% w/w to 100% w/w of individual active pharmaceutical ingredient (API) [two model API: acetaminophen (APAP) and ibuprofen (IBU)] with microcrystalline cellulose without and with 0.5% w/w Magnesium Stearate as lubricant. Powder rheological properties were analyzed using FT4 Powder Rheometer for dynamic, bulk, and shear properties. Tablet mechanical properties of the respective blends were studied by determining the ability of the material to form tablet of specific strength under applied compaction pressure through tabletability profile. The results showed that powder rheometer distinguished the powder blends based on their ability to relieve entrapped air along with the distinctive flow characteristics. Powder blend prepared with increasing addition of APAP displayed low powder permeability as compared to IBU blends with better powder permeability, compressibility and flow characteristics. Also, lubrication of the APAP blends did not ease their ability to relieve air. Tabletability profiles revealed the potential occurrence of capping or lamination in tablets prepared from the powder blends with high APAP content. This study can help scientist to understand tableting performance at the early-developmental stages and can avoid occurrence capping and lamination of tablets.

  19. The rheology of a growing leaf: stress-induced changes in the mechanical properties of leaves.

    Science.gov (United States)

    Sahaf, Michal; Sharon, Eran

    2016-10-01

    We study in situ the mechanics and growth of a leaf. Young Nicotiana tabacum leaves respond to applied mechanical stress by altering both their mechanical properties and the characteristics of their growth. We observed two opposite behaviours, each with its own typical magnitude and timescale. On timescales of the order of minutes, the leaf deforms in response to applied tensile stress. During this phase we found a high correlation between the applied stress field and the local strain field throughout the leaf surface. For times over 12 hours the mechanical properties of the leaf become anisotropic, making it more resilient to deformation and restoring a nearly isotropic growth field despite the highly anisotropic load. These observations suggest that remodelling of the tissue allows the leaf to respond to mechanical perturbations by changing its properties. We discuss the relevance of the observed behaviour to the growth regulation that leads to proper leaf shape during growth. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  20. Anisotropic surface chemistry properties and adsorption behavior of silicate mineral crystals.

    Science.gov (United States)

    Xu, Longhua; Tian, Jia; Wu, Houqin; Fang, Shuai; Lu, Zhongyuan; Ma, Caifeng; Sun, Wei; Hu, Yuehua

    2018-03-07

    Anisotropic surface properties of minerals play an important role in a variety of fields. With a focus on the two most intensively investigated silicate minerals (i.e., phyllosilicate minerals and pegmatite aluminosilicate minerals), this review highlights the research on their anisotropic surface properties based on their crystal structures. Four surface features comprise the anisotropic surface chemistry of minerals: broken bonds, energy, wettability, and charge. Analysis of surface broken bond and energy anisotropy helps to explain the cleavage and growth properties of mineral crystals, and understanding surface wettability and charge anisotropy is critical to the analysis of minerals' solution behavior, such as their flotation performance and rheological properties. In a specific reaction, the anisotropic surface properties of minerals are reflected in the adsorption strengths of reagents on different mineral surfaces. Combined with the knowledge of mineral crushing and grinding, a thorough understanding of the anisotropic surface chemistry properties and the anisotropic adsorption behavior of minerals will lead to the development of effective relational models comprising their crystal structure, surface chemistry properties, and targeted reagent adsorption. Overall, such a comprehensive approach is expected to firmly establish the connection between selective cleavage of mineral crystals for desired surfaces and designing novel reagents selectively adsorbed on the mineral surfaces. As tools to characterize the anisotropic surface chemistry properties of minerals, DLVO theory, atomic force microscopy (AFM), and molecular dynamics (MD) simulations are also reviewed. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Physico-chemical, functional and rheological properties of milk protein concentrate 60 as affected by disodium phosphate addition, diafiltration and homogenization.

    Science.gov (United States)

    Meena, Ganga Sahay; Singh, Ashish Kumar; Arora, Sumit; Borad, Sanket; Sharma, Rajan; Gupta, Vijay Kumar

    2017-05-01

    Ultrafiltration and diafiltration of skim milk altered delicate salt equilibrium and composition of 5× UF retentate (5× UFR), and thus adversely affected the reconstitutional and functional properties of milk protein concentrate (MPC) powders. It might be due to interaction and aggregation of proteins during spray drying. Therefore, this study was envisaged to investigate the effect of disodium phosphate (DSP) addition, diafiltration and homogenization of retentates on physico-chemical, functional and rheological properties of MPC60 powders. Solubility of fresh control powder was significantly lower than MPC60-H powder; at par with that of MPC60-DSP and MPC60-Na-K, but remained minimum after 60 days of storage at 25 ± 1 °C. The pH (6.6) adjustment of 5× UFR with DSP, significantly enhanced the dispersability, wettability, specific surface area (SSA), heat coagulation time (HCT), emulsification capacity and stability; buffer index of MPC60-DSP powder over control. Diafiltration of 5× UFR with NaCl and KCl, significantly ( P  pseudoplastic behavior, best explained by Hershel Bulkley model. These MPC60 powders with improved functional properties can be used for the improvement of quality attributes of various food formulations.

  2. Empirical rheology and pasting properties of soft-textured durum wheat (Triticum turgidum ssp. durum) and hard-textured common wheat (T. aestivum)

    Science.gov (United States)

    Puroindoline (PIN) proteins are the molecular basis for wheat kernel texture classification and affect flour milling performance. This study aimed at investigating the effect of PINs on kernel physical characteristics and dough rheological properties of common wheat (Alpowa cv, soft wheat) and durum...

  3. Effect of polymer composition on rheological and degradation properties of temperature-responsive gelling systems composed of acyl-capped PCLA-PEG-PCLA.

    NARCIS (Netherlands)

    Petit, A.; Muller, B.; Meijboom, R.; Bruin, P.; van de Manakker, F.; Versluijs-Helder, M.; de Leede, L.G.; Doornbos, A.; Landin, M.; Hennink, W.E.; Vermonden, T.

    2013-01-01

    In this study, the ability to modulate the rheological and degradation properties of temperature-responsive gelling systems composed of acyl-capped poly(epsilon-caprolactone-co-lactide)-b-poly(ethylene glycol)-b-poly(epsilon-caprolactone-co-lactide) (PCLA-PEG-PCLA) triblock copolymers was

  4. The rheological properties of blood and the risk of cardiovascular disease in patients with obstructive sleep apnea syndrome (OSAS

    Directory of Open Access Journals (Sweden)

    Władysław Pierzchała

    2011-07-01

    Full Text Available Obstructive sleep apnea (OSA is an important public health concern, which affects around 2–4% of the population. Left untreated, it causes a decrease not only in quality of life, but also of life expectancy. Despite the fact that knowledge about the mechanisms of development of cardiovascular disease in patients with OSA is still incomplete, observations confirm a relationship between sleep disordered breathing and the rheological properties of blood. One possible consequence of an increased incidence of cardiovascular disease may be a rise in mortality in OSA patients. Continuously improved research methods are allowing for an increasingly more accurate understanding of the significance of observed changes. (Folia Histochemica et Cytobiologica 2011, Vol. 49, No. 2, 206–210

  5. Effect of Some Extrusion Variables on Rheological Properties and Physicochemical Changes of Cornmeal Extruded by Twin Screw Extruder

    Directory of Open Access Journals (Sweden)

    Chang Y.K.

    1998-01-01

    Full Text Available The effect of extrusion variables, such as barrel temperature (100 to 170ºC, feed rate (100 to 500 g/min, feed moisture (20 to 40 g/100 g wet basis, screw speed rate (from 100 to 500 rpm, and slit die rheometer configuration (0.15 and 0.30 cm height were studied using a co-rotating intermeshing twin-screw extruder coupled to a slit die rheometer on the rheological properties of yellow cornmeal. An increase in feed rate decreased WAI and WSI, but increased the viscosity values. The temperature interacts strongly with screw speed in affecting the WSI. The most important factor in starch degradation was the screw speed. Increasing the screw speed completely modifies the organised structure of starch (crystalline region.

  6. HDPE/clay hybrids: the effect of clay modified with poly(diphenyl siloxanes) on thermal and rheological properties

    Energy Technology Data Exchange (ETDEWEB)

    Monasterio, Fernanda E.; Carrera, Maria C.; Erdmann, Eleonora; Destefanis, Hugo A., E-mail: ferelenakq@gmail.co [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Buenos Aires (Argentina). Inst. de Investigaciones para la Industria Quimica; Pita, Victor J.R.R.; Dias, Marcos L. [Universidade Federal do Rio de Janeiro (IMA/UFRJ), RJ (Brazil). Inst. de Macromoleculas Profa. Eloisa Mano

    2009-07-01

    Poly(diphenyl siloxanes) (PDPhS) were synthesized in presence of organophilic clay in order to modify its nano structure. Two silane monomers were used: dimethoxydiphenylsilane and dichlorodiphenylsilane. The following characterizations were performed for all clays: XRD, FTIR and TGA/DTG. These siloxane-modified clays were more hydrophobic and had enhanced thermal stability. Solvent extraction was carried out in the siloxane-modified clays and the PDPhS soluble fraction analyzed according the molecular weight via GPC. The presence of free and grafted oligomers on clay surface was identified. The modified clays were added to HDPE by melt processing to obtain HDPE/clay hybrids which exhibited marked differences in the rheological behavior when compared with neat HDPE. (author)

  7. HDPE/clay hybrids: the effect of clay modified with poly(diphenyl siloxanes) on thermal and rheological properties

    International Nuclear Information System (INIS)

    Monasterio, Fernanda E.; Carrera, Maria C.; Erdmann, Eleonora; Destefanis, Hugo A.; Pita, Victor J.R.R.; Dias, Marcos L.

    2009-01-01

    Poly(diphenyl siloxanes) (PDPhS) were synthesized in presence of organophilic clay in order to modify its nano structure. Two silane monomers were used: dimethoxydiphenylsilane and dichlorodiphenylsilane. The following characterizations were performed for all clays: XRD, FTIR and TGA/DTG. These siloxane-modified clays were more hydrophobic and had enhanced thermal stability. Solvent extraction was carried out in the siloxane-modified clays and the PDPhS soluble fraction analyzed according the molecular weight via GPC. The presence of free and grafted oligomers on clay surface was identified. The modified clays were added to HDPE by melt processing to obtain HDPE/clay hybrids which exhibited marked differences in the rheological behavior when compared with neat HDPE. (author)

  8. Nanoparticles and nonlinear thermal radiation properties in the rheology of polymeric material

    Science.gov (United States)

    Awais, M.; Hayat, T.; Muqaddass, N.; Ali, A.; Aqsa; Awan, Saeed Ehsan

    2018-03-01

    The present analysis is related to the dynamics of polymeric liquids (Oldroyd-B model) with the presence of nanoparticles. The rheological system is considered under the application of nonlinear thermal radiations. Energy and concentration equations are presented when thermophoresis and Brownian motion effects are present. Bidirectional form of stretching is considered to interpret the three-dimensional flow dynamics of polymeric liquid. Making use of the similarity transformations, problem is reduced into ordinary differential system which is approximated by using HAM. Influence of physical parameters including Deborah number, thermophoresis and Brownian motion on velocity, temperature and mass fraction expressions are plotted and analyzed. Numerical values for local Sherwood and Nusselt numbers are presented and discussed.

  9. Rheological properties and thermal conductivity of AlN-poly(propylene glycol) suspensions

    Science.gov (United States)

    Wozniak, Maciej; Rutkowski, Pawel; Kata, Dariusz

    2016-01-01

    Nanofluids have recently attracted researches' attention as a new generation of heat-transferring fluids used in heat exchangers and for energy storage. Also aluminium nitride is commonly known for its considerable heat conductivity, as high as 320 W/(m K). Because of that, the compound might be a preferable dispersed phase of heat-transferring fluids. This presented studies are focused on nano-AlN-poly(propylene glycol) dispersions which can be applied as potential cooling fluids. The rheological response of the suspensions on shearing and their thermal conductivity in the function of solids concentration and temperature were measured and discussed. The most desired result of the studies is to produce dispersions with Newtonian-like flow at increased temperature and at higher shear rate. All the aforementioned parameters conjugated with significant thermal conductivity of such nanofluids could predispose them to be used as effective cooling media.

  10. Nanoparticles and nonlinear thermal radiation properties in the rheology of polymeric material

    Directory of Open Access Journals (Sweden)

    M. Awais

    2018-03-01

    Full Text Available The present analysis is related to the dynamics of polymeric liquids (Oldroyd-B model with the presence of nanoparticles. The rheological system is considered under the application of nonlinear thermal radiations. Energy and concentration equations are presented when thermophoresis and Brownian motion effects are present. Bidirectional form of stretching is considered to interpret the three-dimensional flow dynamics of polymeric liquid. Making use of the similarity transformations, problem is reduced into ordinary differential system which is approximated by using HAM. Influence of physical parameters including Deborah number, thermophoresis and Brownian motion on velocity, temperature and mass fraction expressions are plotted and analyzed. Numerical values for local Sherwood and Nusselt numbers are presented and discussed. Keywords: Nanoparticles, Polymeric liquid, Oldroyd-B model, Nonlinear thermal radiation

  11. Numerical Study of Natural Supercavitation Influenced by Rheological Properties of Turbulent Drag-Reducing Additives

    Directory of Open Access Journals (Sweden)

    Chen-Xing Jiang

    2014-08-01

    Full Text Available Natural supercavitations in water and turbulent drag-reducing solution were numerically simulated using unsteady Reynolds averaged Navier-Stokes (RANS scheme with mixture-multiphase model. The Cross viscosity equation was adopted to represent the fluid property of aqueous solution of drag-reducing additives. The characteristics of natural supercavity configuration and overall resistance of the navigating body were presented, respectively. The numerical simulation results indicated that, at the same cavitation number, the length and diameter of supercavity in drag-reducing solution are larger than those in water, and the drag coefficient of navigating body in solution is smaller than that in water; the surface tension plays an important role in incepting and maintaining the cavity. Turbulent drag-reducing additives have the potential in enhancement of supercavitation, drag reduction, and decrease of turbulent vortex structures. Numerical simulation results are consistent with the available experimental data.

  12. Physicochemical and Rheological Properties of Optimised Cocoyam-Based Composite Flour Comprising Cassava Starch

    Directory of Open Access Journals (Sweden)

    Awolu Olugbenga Olufemi

    2016-12-01

    Full Text Available Composite flour comprising cocoyam (Colocassia esculenta, bambara groundnut and cassava starch was produced. The proximate and minerals compositions and functional properties were optimized using optimal mixture design of response surface methodology. The antinutritional, pasting and farinograph analyses of the optimum blends were evaluated. Bambara groundnut improved protein, fibre, ash and minerals contents; cassava starch improved swelling capacity, least gelation and pasting characteristics. The optimum blends CBC1 (70% cocoyam flour, 18.33% bambara groundnut flour, 11.67% cassava starch and CBC2 (69.17% cocoyam flour, 16.67% bambara groundnut flour, 14.17% cassava starch. were comparable to wheat–based flour samples (60% wheat, 30% cocoyam, 10% bambara groundnut flours and (72% wheat, 19% cocoyam, 9% bambara groundnut flours in terms of pasting and farinograph analyses.

  13. Influence of amine-grafted multi-walled carbon nanotubes on physical and rheological properties of PMMA-based nanocomposites

    International Nuclear Information System (INIS)

    Kim, Ki-Seok; Park, Soo-Jin

    2011-01-01

    In this work, poly(methyl methacrylate) (PMMA) was grafted onto amine treated multi-walled carbon nanotubes (NH-MWNTs) and the physical and rheological properties of the NH-MWNTs-g-PMMA nanocomposites were investigated. The graft reaction of NH-MWNTs and the PMMA matrix was confirmed from the change of the N 1S peaks, including those of amine oxygen and amide oxygen, by X-ray photoelectron spectroscopy (XPS). The thermal and mechanical properties of the NH-MWNT-g-PMMA nanocomposites were enhanced by the graft reaction between NH-MWNTs and PMMA matrix. In addition, the viscosity of the nanocomposites was increased with the addition of NH-MWNTs. Storage (G') and loss modulus (G'') were significantly increased by increase in the NH-MWNT content compared to acid-treated MWNTs/PMMA nanocomposites. This increase was attributed to the strong interaction by the grafting reaction between NH-MWNTs and the PMMA matrix. - Graphical abstract: This describes the increase of mechanical properties in NH-MWNTs-g-PMMA hybrid composites with different NH-MWNT contents. Highlights: → Aminized carbon nanotubes are used as reinforcement for poly(methylmethacrylate). → Poly(methylmethacrylate) is grafted on aminized carbon nanotubes by thermal reaction. → Grafting of carbon nanotubes and polymer provide enhanced physical properties. → It was due to the strong interaction between carbon nanotubes and polymer matrix.

  14. Effect of Pre-gelatinized Wheat Starch on Physical and Rheological Properties of Shortened Cake Batter and Cake Texture

    Directory of Open Access Journals (Sweden)

    F. Ebrahimi

    2016-10-01

    Full Text Available The focus of this study was the effect of 1.5%, 3% and 4.5% pre-gelatinized wheat starch (based on the total weight of cake batter on improving the qualitative properties of shortened cake batter. Specific volume and viscosity of the shortened cake batter were measured for controls, 1.5%, 3% and 4.5% gelatinized starch; some important properties such as texture and sensory evaluation were examined. By increasing pre-gelatinized wheat starch used in the batter, a significant difference was observed in the rheological properties of the batter. Cake batter properties were found improved compared to the control samples. The sample with 3% pre-gelatinized starch had a lower viscosity than other treatments. The treatment with 4.5% pre-gelatinized starch had the lowest specific volume compared to other treatments. The overall results showed that the shortened cake with 3% pre-gelatinized starch was the best treatment in terms of texture and sensory evaluation factors.

  15. Comparison of the effects of different heat treatment processes on rheological properties of cake and bread wheat flours.

    Science.gov (United States)

    Bucsella, Blanka; Takács, Ágnes; Vizer, Viktoria; Schwendener, Urs; Tömösközi, Sándor

    2016-01-01

    Dry and hydrothermal heat treatments are efficient for modifying the technological-functional and shelf-life properties of wheat milling products. Dry heat treatment process is commonly used to enhance the volume of cakes. Hydrothermal heat treatment makes wheat flours suitable as thickener agents. In this study, cake and bread wheat flours that differed in baking properties were exposed to dry (100 °C, 12 min) and hydrothermal (95 °C, 5 min, 5-20 l/h water) heat treatments. Rheological differences caused by the treatments were investigated in a diluted slurry and in a dough matrix. Dry heat treatment resulted in enhanced dough stability. This effect was significantly higher in the cake flour than the bread flour. Altered viscosity properties of the bread flour in the slurry matrix were also observed. The characteristics of hydrothermally treated samples showed matrix dependency: their viscosity increases in the slurry and decreases in the dough matrix. These results can support us to produce flour products with specific techno-functional properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Network formation in graphene oxide composites with surface grafted PNIPAM chains in aqueous solution characterized by rheological experiments.

    Science.gov (United States)

    GhavamiNejad, Amin; Hashmi, Saud; Joh, Han-Ik; Lee, Sungho; Lee, Youn-Sik; Vatankhah-Varnoosfaderani, Mohammad; Stadler, Florian J

    2014-05-14

    Poly N-isopropyl acrylamide (PNI) radically polymerized in aqueous solution in the presence of graphene oxide (GO) can significantly change the properties of the resulting solution from a regular polymer solution to a soft solid with a GO content of only 0.176 wt% (3 wt% with respect to PNI). However, these properties require the presence of both grafting and supramolecular interactions between polymer chains and hydrophilic groups on GO (-OH, -COOH), proven by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray diffraction and spectroscopy (XRD) and Raman spectra. While very low GO-contents (below 0.05 wt%) only lead to a labile structure, which can be disassembled by shear, higher contents yield composites with solid-like characteristics. This is clearly evident from the rheological behaviour, which changes significantly at a GO content around 0.15 wt%. Intensive shearing destroys the weak network, which cannot reform quickly at lower GO-concentrations, while at intermediate concentrations, restructuring is fast. GO-contents of 0.176 wt% lead to a material behaviour, which almost perfectly recovers from small deformations (creep and creep recovery compliance almost match) but larger deformations lead to permanent damage to the sample.

  17. A Study on the Rheological and Mechanical Properties of Photo-Curable Ceramic/Polymer Composites with Different Silane Coupling Agents for SLA 3D Printing Technology

    Directory of Open Access Journals (Sweden)

    Se Yeon Song

    2018-02-01

    Full Text Available Silane coupling agents (SCAs with different organofunctional groups were coated on the surfaces of Al2O3 ceramic particles through hydrolysis and condensation reactions, and the SCA-coated Al2O3 ceramic particles were dispersed in a commercial photopolymer based on interpenetrating networks (IPNs. The organofunctional groups that have high radical reactivity and are more effective in UV curing systems are usually functional groups based on acryl, such as acryloxy groups, methacrloxy groups, and acrylamide groups, and these silane coupling agents seem to improve interfacial adhesion and dispersion stability. The coating morphology and the coating thickness distribution of SCA-coated Al2O3 ceramic particles according to the different organofunctional groups were observed by FE-TEM. The initial dispersibility and dispersion stability of the SCA-coated Al2O3/High-temp composite solutions were investigated by relaxation NMR and Turbiscan. The rheological properties of the composite solutions were investigated by viscoelastic analysis and the mechanical properties of 3D-printed objects were observed with a nanoindenter.

  18. A Study on the Rheological and Mechanical Properties of Photo-Curable Ceramic/Polymer Composites with Different Silane Coupling Agents for SLA 3D Printing Technology.

    Science.gov (United States)

    Song, Se Yeon; Park, Min Soo; Lee, Jung Woo; Yun, Ji Sun

    2018-02-07

    Silane coupling agents (SCAs) with different organofunctional groups were coated on the surfaces of Al₂O₃ ceramic particles through hydrolysis and condensation reactions, and the SCA-coated Al₂O₃ ceramic particles were dispersed in a commercial photopolymer based on interpenetrating networks (IPNs). The organofunctional groups that have high radical reactivity and are more effective in UV curing systems are usually functional groups based on acryl, such as acryloxy groups, methacrloxy groups, and acrylamide groups, and these silane coupling agents seem to improve interfacial adhesion and dispersion stability. The coating morphology and the coating thickness distribution of SCA-coated Al₂O₃ ceramic particles according to the different organofunctional groups were observed by FE-TEM. The initial dispersibility and dispersion stability of the SCA-coated Al₂O₃/High-temp composite solutions were investigated by relaxation NMR and Turbiscan. The rheological properties of the composite solutions were investigated by viscoelastic analysis and the mechanical properties of 3D-printed objects were observed with a nanoindenter.

  19. Influence of fat replacement by inulin on rheological properties, kinetics of rennet milk coagulation, and syneresis of milk gels.

    Science.gov (United States)

    Arango, O; Trujillo, A J; Castillo, M

    2013-04-01

    The objective of this study was to evaluate the effect of inulin as a fat replacer on the rheological properties, coagulation kinetics, and syneresis of milk gels. A randomized factorial design, replicated 3 times, with 3 inulin concentrations (0, 3, and 6%), 2 levels of fat (coagulation temperatures (27, 32, and 37°C) was used. The coagulation process was monitored using near-infrared spectrometry, small amplitude oscillatory rheometry, and visual coagulation indexes. The syneresis was evaluated by volumetric methods. Inulin addition increased the rates of aggregation and curd firming reactions in the casein gels. The observed effect, which was more evident on the aggregation reaction, depended on the concentration of inulin and the coagulation temperature. Addition of 6% inulin reduced the clotting time by approximately 26% and the time at which the gel reached a storage modulus equal to 30 Pa by approximately 36%. The optical parameter R'max, defined as the maximum value of change in light backscatter profile/change in time (where R' = dR/dt), was used to calculate an approximation of the temperature coefficients (Q10) for milk coagulation. Increasing fat concentration induced a consistent increase in all the optical, rheological, and visual parameters studied, although the observed trend was not statistically significant. The addition of inulin at a level of 6% produced a reduction in syneresis and increased the curd yield by approximately 30%. It was concluded that the addition of inulin affects the kinetics of milk coagulation and the cutting time and, therefore, the use of inline sensors such as near-infrared spectrometry may be necessary for optimal process control. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  20. Multiscale Modeling of the Effects of Salt and Perfume Raw Materials on the Rheological Properties of Commercial Threadlike Micellar Solutions.

    Science.gov (United States)

    Tang, Xueming; Zou, Weizhong; Koenig, Peter H; McConaughy, Shawn D; Weaver, Mike R; Eike, David M; Schmidt, Michael J; Larson, Ronald G

    2017-03-23

    We link micellar structures to their rheological properties for two surfactant body-wash formulations at various concentrations of salts and perfume raw materials (PRMs) using molecular simulations and micellar-scale modeling, as well as traditional surfactant packing arguments. The two body washes, namely, BW-1EO and BW-3EO, are composed of sodium lauryl ethylene glycol ether sulfate (SLEnS, where n is the average number of ethylene glycol repeat units), cocamidopropyl betaine (CAPB), ACCORD (which is a mixture of six PRMs), and NaCl salt. BW-3EO is an SLE3S-based body wash, whereas BW-1EO is an SLE1S-based body wash. Additional PRMs are also added into the body washes. The effects of temperature, salt, and added PRMs on micellar lengths, breakage times, end-cap free energies, and other properties are obtained from fits of the rheological data to predictions of the "Pointer Algorithm" [ Zou , W. ; Larson , R.G. J. Rheol. 2014 , 58 , 1 - 41 ], which is a simulation method based on the Cates model of micellar dynamics. Changes in these micellar properties are interpreted using the Israelachvili surfactant packing argument. From coarse-grained molecular simulations, we infer how salt modifies the micellar properties by changing the packing between the surfactant head groups, with the micellar radius remaining nearly constant. PRMs do so by partitioning to different locations within the micelles according to their octanol/water partition coefficient P OW and chemical structures, adjusting the packing of the head and/or tail groups, and by changing the micelle radius, in the case of a large hydrophobic PRM. We find that relatively hydrophilic PRMs with log P OW PRMs, with log P OW between 2 and 4, mix with the hydrophobic surfactant tails within the micellar core and slightly enhance the viscosity and micelle length, which is consistent with the packing argument. Large and very hydrophobic PRMs, with log P OW > 4, are isolated deep inside the micelle, separating

  1. Dynamic surface properties of poly(methylalkyldiallylammonium chloride) solutions

    Czech Academy of Sciences Publication Activity Database

    Novikova, A. A.; Vlasov, P. S.; Lin, S.-Y.; Sedláková, Zdeňka; Noskov, B. A.

    2017-01-01

    Roč. 80, November (2017), s. 122-127 ISSN 1876-1070 Institutional support: RVO:61389013 Keywords : polymer solutions * dynamic surface tension * dilational surface rheology Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 4.217, year: 2016

  2. Blood thixotropy in patients with sickle cell anaemia: role of haematocrit and red blood cell rheological properties.

    Directory of Open Access Journals (Sweden)

    Jens Vent-Schmidt

    Full Text Available We compared the blood thixotropic/shear-thinning properties and the red blood cells' (RBC rheological properties between a group of patients with sickle cell anaemia (SS and healthy individuals (AA. Blood thixotropy was determined by measuring blood viscosity with a capillary viscometer using a "loop" protocol: the shear rate started at 1 s-1 and increased progressively to 922 s-1 and then re-decreased to the initial shear rate. Measurements were performed at native haematocrit for the two groups and at 25% and 40% haematocrit for the AA and SS individuals, respectively. RBC deformability was determined by ektacytometry and RBC aggregation properties by laser backscatter versus time. AA at native haematocrit had higher blood thixotropic index than SS at native haematocrit and AA at 25% haematocrit. At 40% haematocrit, SS had higher blood thixotropic index than AA. While RBC deformability and aggregation were lower in SS than in AA, the strength of RBC aggregates was higher in the former population. Our results showed that 1 anaemia is the main modulator of blood thixtropy and 2 the low RBC deformability and high RBC aggregates strength cause higher blood thixotropy in SS patients than in AA individuals at 40% haematocrit, which could impact blood flow in certain vascular compartments.

  3. The Influence of Chemically Modified Potato Maltodextrins on Stability and Rheological Properties of Model Oil-in-Water Emulsions

    Directory of Open Access Journals (Sweden)

    Karolina Pycia

    2018-01-01

    Full Text Available The aim of this study was to determine the effect of the maltodextrins prepared from chemically modified starches (crosslinked, stabilized, crosslinked and stabilized on the stability and rheological properties of model oil-in-water (o/w emulsions. Based on the obtained results, it was concluded that emulsion stability depended on hydrolysates dextrose equivalent (DE value. Maltodextrin with the lowest degree of depolymerization effectively stabilized the dispersed system, and the effectiveness of this action depended on the maltodextrin type and concentration. Addition of distarch phosphate-based maltodextrin stabilized emulsion at the lowest applied concentration, and the least effective was maltodextrin prepared from acetylated starch. Emulsions stabilized by maltodextrins (DE 6 prepared from distarch phosphate and acetylated distarch adipate showed the predominance of the elastic properties over the viscous ones. Only emulsion stabilized by maltodextrin prepared from distarch phosphate (E1412 revealed the properties of strong gel. Additionally, the decrease in emulsions G′ and G″ moduli values, combined with an increase in the value of DE maltodextrins, was observed.

  4. Effect of bee pollen supplement on antimicrobial, chemical, rheological, sensorial properties and probiotic viability of fermented milk beverages

    Directory of Open Access Journals (Sweden)

    Oktay Yerlikaya

    2014-11-01

    Full Text Available In this research, effect of bee pollen supplement on antimicrobial, chemical, rheological, sensorial properties and probiotic viability of fermented milk beverages was studied. Bee pollens were added in the rate of 2.5 mg•mL-1 (B, 5 mg•mL-1 (C, 7.5 mg•mL-1 (D, 10 mg•mL-1 (E, and 20 mg•mL-1 (F. Control sample (A was not supplemented with bee pollen. Control and supplemented milk samples were fermented by a commercial ABT1 starter culture (Chr. Hansen, Hørsholm, Denmark containing Lactobacillus acidophilus La 5, Bifidobacterium animalis subs. lactis Bb 12, and Streptococcus thermophilus. While no antimicrobial impact was observed against L. monocytogenes, S. aureus, P. fluorescens, P. aeruginosa and A. hydrophilia upto 7.5 mg•mL-1 pollen addition, addition between 10 mg•mL-1 to 20 mg•mL-1 resulted in activity, and positive effect only in inhibition rates against bacteria such as S. thyphimurium and E. coli. Bee pollen supplements has shown a positive effect on probiotic viability and occurred on increase apparent viscosity, but their effect on sensorial properties was negative. Furthermore an improvement with increasing concentration of pollen addition that yielded no negative effect on physicochemical properties was detected.

  5. Activated Sludge Rheology

    DEFF Research Database (Denmark)

    Ratkovich, Nicolas Rios; Horn, Willi; Helmus, Frank

    2013-01-01

    Rheological behaviour is an important fluid property that severely impacts its flow behaviour and many aspects related to this. In the case of activated sludge, the apparent viscosity has an influence on e.g. pumping, hydrodynamics, mass transfer rates, sludge-water separation (settling and filtr...

  6. Rheology of concentrated biomass

    Science.gov (United States)

    J.R. Samaniuk; J. Wang; T.W. Root; C.T. Scott; D.J. Klingenberg

    2011-01-01

    Economic processing of lignocellulosic biomass requires handling the biomass at high solids concentration. This creates challenges because concentrated biomass behaves as a Bingham-like material with large yield stresses. Here we employ torque rheometry to measure the rheological properties of concentrated lignocellulosic biomass (corn stover). Yield stresses obtained...

  7. Evaluation of rheological behavior and sensory properties of ready to eat salad dressings submitted to irradiation

    International Nuclear Information System (INIS)

    Gallo, Juliana Maria Altavista Sagretti

    2013-01-01

    This study evaluated the rheological behavior of 11 salad dressings ready to eat, processed by gamma irradiation, at doses: 3 kGy and 5 kGy. This assessment was made by rheograms traced by measurements of viscosity and shear stress by shear rate. Mathematical parameters obtained from these measures also contributed to the conclusion of the behavior exhibited and for choosing the best mathematical model applicable to them. The measurements were performed on a Brookfield viscometer Model LVDV - III. The Neslab thermal bath was used to maintain ambient temperature during the whole analysis. This study protocol was done in two stages. In step 1, the evaluation was performed soon after the samples have been irradiated when these were close to their dates of manufacture. In phase 2 the samples were reassessed after a period of storage, near the expiration date of their validity. Simultaneously pH measurement was performed to evaluate their stability in the face of treatment and sensory analyzes of two salad dressings were studied, in order to verify the acceptance of these when submitted to irradiation. The shear-thinning behavior was confirmed for all dressings through the mathematical model, the power law, that best model apply to this, in both phases. The irradiation at the absorbed doses studied did not influence this behavior. The results of sensory evaluation indicated good acceptance of irradiated sauces for the tasters. (author)

  8. A Study on the Rheological Properties of Recycled Rubber-Modified Asphalt Mixtures

    Directory of Open Access Journals (Sweden)

    Murat Karacasu

    2015-01-01

    Full Text Available Using waste rubber in asphalt mixes has become a common practice in road construction. This paper presents the results of a study on the rheological characteristics of rubber-modified asphalt (RMA concrete under static and dynamic loading conditions. A number of static and dynamic creep tests were conducted on RMA mix specimens with different rubber sizes and contents, and a series of resonant column tests were conducted to evaluate the shear modulus and damping values. To simulate the stress-strain response of traffic-induced loading, the measurements were taken for different confining pressures and strain levels. The results of the study indicated that rubber modification increases stiffness and damping ratio, making it a very attractive material for use in road construction. However the grain size of the rubber is very important. Although RMA may cost up to 100% more than regular asphalt, the advantages it brings, such as an increased service life of the road and proper waste utilization contributing to a more sustainable infrastructure, may justify the added cost.

  9. Rheological and Mechanical Property Measurements of PMDI Foam at Elevated Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Nemer, Martin Bernard [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Thermal and Fluid Sciences; Brooks, Carlton F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Thermal and Fluid Sciences; Shelden, Bion [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Thermal and Fluid Sciences; Soehnel, Melissa Marie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Thermal and Fluid Sciences; Barringer, David Alan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Thermal and Fluid Sciences

    2014-10-01

    A study was undertaken to determine the viscosity of liquefied 20 lb/ft3 poly methylene diisocyanate (PMDI) foam and the stress required to puncture solid PMDI foam at elevated temperatures. For the rheological measurements the foam was a priori liquefied in a pressure vessel such that the volatiles were not lost in the liquefaction process. The viscosity of the liquefied PMDI foam was found to be Newtonian with a power law dependence on temperature log10(μ/Pa s) = 20.6 – 9.5 log10(T/°C) for temperatures below 170 °C. Above 170 °C, the viscosity was in the range of 0.3 Pa s which is close to the lower measurement limit (≈ 0.1 Pa s) of the pressurized rheometer. The mechanical pressure required to break through 20lb/ft3 foam was 500-800 psi at temperatures from room temperature up to 180 °C. The mechanical pressure required to break through 10 lb/ft3 was 170-300 psi at temperatures from room temperature up to 180 °C. We have not been able to cause gas to break through the 20 lb/ft3 PMDI foam at gas pressures up to 100 psi.

  10. Rheology of Supramolecular Polymers

    DEFF Research Database (Denmark)

    Shabbir, Aamir

    efficient processes or biomedical areas. Design and development of supramolecular polymers using ionic, hydrogen bonding or transition metal complexes with tailored properties requires deep understanding of dynamics both in linear and non-linear deformations. While linear rheology is important to understand...... the dynamics under equilibrium conditions, extensional rheology is relevant during the processing or in the usage of polymers utilizing supramolecular associations for example, acrylic based pressure sensitive adhesives are subjected to extensional deformations during the peeling where strain hardening......) hydrogen bonding polymers, and (b) ionic bonding polymers (hereafter termed as ionomers). We study linear and non-linear rheology fora model system of entangled pure poly(n-butyl acrylate), PnBA, homopolymer andfour poly(acrylic acid), PnBA-PAA, copolymers with varying AA side groups synthesizedvia...

  11. Effect of Extrusion on the Mechanical and Rheological Properties of a Reinforced Poly(Lactic Acid): Reprocessing and Recycling of Biobased Materials.

    Science.gov (United States)

    Peinado, Víctor; Castell, Pere; García, Lidia; Fernández, Ángel

    2015-10-19

    The aim of this research paper is to study the behaviour of a common used biopolymer (Poly(Lactic Acid) (PLA)) after several reprocesses and how two different types of additives (a melt strength enhancer and a nanoadditive) affect its mechanical and rheological properties. Systematic extraction of extrudate samples from a twin-screw compounder was done in order to study the effect in the properties of the reprocessed material. Detailed rheological tests on a capillary rheometer as well as mechanical studies on a universal tensile machine after preparation of injected specimens were carried out. Results evidenced that PLA and reinforced PLA materials can be reprocessed and recycled without a remarkable loss in their mechanical properties. Several processing restrictions and specific phenomena were identified and are explained in the present manuscript.

  12. Mathematical model of microbicidal flow dynamics and optimization of rheological properties for intra-vaginal drug delivery: Role of tissue mechanics and fluid rheology.

    Science.gov (United States)

    Anwar, Md Rajib; Camarda, Kyle V; Kieweg, Sarah L

    2015-06-25

    Topically applied microbicide gels can provide a self-administered and effective strategy to prevent sexually transmitted infections (STIs). We have investigated the interplay between vaginal tissue elasticity and the yield-stress of non-Newtonian fluids during microbicide deployment. We have developed a mathematical model of tissue deformation driven spreading of microbicidal gels based on thin film lubrication approximation and demonstrated the effect of tissue elasticity and fluid yield-stress on the spreading dynamics. Our results show that both elasticity of tissue and yield-stress rheology of gel are strong determinants of the coating behavior. An optimization framework has been demonstrated which leverages the flow dynamics of yield-stress fluid during deployment to maximize retention while reaching target coating length for a given tissue elasticity. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Rheological, functional and thermo-physical properties of ultrasound treated whey proteins with addition of sucrose or milk powder

    Directory of Open Access Journals (Sweden)

    Anet Režek Jambrak

    2011-03-01

    Full Text Available Ultrasound represents a non-thermal food processing technique and has great potential to be used in the food industry. The objective of this research was to observe ultrasound impact on physical properties of model systems prepared with whey protein isolates (WPI or whey protein concentrates (WPC with or without sucrose or milk powder addition. This kind of systems is often used in milk beverages and milk based products. Model systems with protein and milk powder or sucrose addition were treated with high power ultrasound (HPU probe of 30 kHz frequency for 5 and 10 minutes. After sonication several properties were determined and examined: solubility, emulsifying and foaming properties, rheological and thermophysical properties. Ultrasound treatment showed severe influence on all examined properties, caused by protein denaturation as a consequence of cavitation and microstreaming effects. Ultrasound treatment caused decrease in protein solubility for whey protein isolate and whey protein concentrates model systems, compared to untreated sample. There was statistically significant increase in foam volume of model systems, prepared with sucrose or milk powder and WPI after ultrasound treatment. Statistically significant decrease in emulsion activity and emulsion stability indices was observed for model systems prepared solely with isolates and concentrates. After treatment of whey protein model systems (with or without milk powder or sucrose with 30 kHz ultrasound, the changes in consistency coefficients (k were observed, but there were no significant changes in flow behaviour indices (n. After addition of milk powder or sucrose, statistically significant decrease in initial freezing and melting temperatures was observed due to the ultrasound treatment.

  14. Effect of chain extension on rheology and tensile properties of PHB and PHB-PLA blends

    Science.gov (United States)

    Bousfield, Glenn

    Poly(3-hydroxybutyrate), referred to as PHB, is a bacterially-synthesized and biodegradable polymer which is being considered as a substitute for non-biodegradable bulk polymers like polypropylene. PHB is naturally extremely isotactic and naturally has a very high degree of crystallinity, resulting in a stiff but brittle material. The stability of PHB crystals also means that the melting point of the polymer is approximately 170°C, high with respect to similar polymers. For instance, the melting point of poly(4-hydroxybutyrate) is only 53°C (Saito, Nakamura, Hiramitsu, & Doi, 1996). Above 170°C, PHB is subject to a thermomechanical degradation mechanism, meaning that the polymer cannot be melted without degrading. One possible solution to the problem of degradation is to add a chain extender to the molten polymer to increase average molecular weight to counteract the molecular weight lost to degradation. In this work, a variety of chain extenders (JoncrylRTM ADR 4368-C, pyromellitic dianhydride, hexamethylene diisocyanate, polycarbodiimide) were compounded with a random copolymer of 98 mol% 3-hydroxybutyrate and 2 mol% 3-hydroxyvalerate (referred to as PHB) in concentrations ranging from 0.25% to 4%, to determine which chain extender functionality worked best with PHB. Molecular weight change was inferred from torque monitored during compounding, and from complex viscosity determined from parallel-plate rheology. None of the chain extenders changed the rate of degradation of PHB, although Joncryl increased the complex viscosity of the polymer. PHB was also blended with Poly(L-lactic acid), referred to as PLLA in PHB/PLLA ratios of 100/0, 75/25, 50/50, 25/75 and 0/100, to determine the effect of blending on the thermal stability of PHB. Again, thermal stability was determined by monitoring torque during compounding and by measuring complex viscosity through parallel-plate rheology. Blends in which PHB was the more abundant phase, as well as the 50% PHB/50% PLA

  15. Rheological properties of reduced fat ice cream mix containing octenyl succinylated pearl millet starch.

    Science.gov (United States)

    Sharma, Monika; Singh, Ashish K; Yadav, Deep N

    2017-05-01

    The octenyl succinyl anhydride (OSA) esterified pearl millet ( Pennisetum typhoides ) starch was evaluated as fat replacer in soft serve ice cream in comparison to other fat replacers viz. inulin, whey protein concentrate-70 and commercial starch. During temperature sweep test, the yield stress and flow behaviour index of un-pasteurized ice cream mixes increased as the temperature increased from 40 to 80 °C, while the consistency index decreased. Consistency index of aged ice cream mixes containing 2% fat replacer was higher as compared to mixes with 1% level. The aged ice cream mixes exhibited non-Newtonian behaviour as flow behaviour index values were less than one. Apparent viscosity (at 50 s -1 shear rate) of control as well as ice cream mix containing 1% OSA-esterified pearl millet starch samples was 417 and 415 mPas, respectively and did not differ significantly. The overrun of the ice cream (with 5 and 7.5% fat) containing 1 and 2% of above fat replacers ranged between 29.7 and 34.3% and was significantly lower than control (40.3%). The percent melted ice cream was also low for the ice creams containing 2% of above fat replacers at 5% fat content as compared to control. However, sensory acceptability and rheological characteristics of reduced fat ice creams containing 1.0 and 2.0% OSA-esterified pearl millet starch were at par with other fat replacers under the study. Thus, OSA-esterified pearl millet starch has potential to be used as fat replacer in reduced fat ice cream.

  16. Evaluation of solution and rheological properties for hydrophobically associated polyacrylamide copolymer as a promised enhanced oil recovery candidate

    Directory of Open Access Journals (Sweden)

    A.N. El-hoshoudy

    2017-09-01

    Full Text Available Crude oil is the most critical energy source in the world, especially for transportation, provision of heat and light as there has not been a sufficient energy source to replace crude oil has broadly integrated, so there is an urgent need to maximize the extraction of the original oil in-place for every reservoir, and accelerating the development of enhanced oil recovery (EOR technologies. Polymer flooding by hydrophobically associated polyacrylamides (HAPAM is a widely used technique through EOR technology. For successful application of these polymers, one should evaluate rheological and solution properties at simulated reservoir conditions as a function of polymer concentration, salinity, temperature and shear rate. The results showed that these copolymers exhibit favorable salt tolerance, temperature resistance, and recoverable viscosity after shearing, reasonable thickening behavior and improved viscosity enhancement properties due to presence of hydrophobic association in the copolymer main chains. Moreover, its capacity for oil production improvement was evaluated during flooding experiments through one dimensional sandstone model at simulated reservoir conditions.

  17. New Evidences on the Process Sensitivity of Some Renewable Blends Based on Starch considering Their Melt Rheological Properties

    Directory of Open Access Journals (Sweden)

    Doina Dimonie

    2016-01-01

    Full Text Available The degradability and processability of new renewable materials based on starch and PVOH were studied using the melt flow index (MFI method by measuring the melt rheological properties which depend not only on the extrusion conditions and material formulation but also on the macromolecule characteristics which can be modified by chemical degradation. These results were correlated with other material properties like color and cross-linking degree. The obtained results show that flowing in the melted state of the studied materials is accompanied by a second process of chains chemical degradation. It was observed that, at the same level of additivation, under identical extrusion conditions, the melted blends with corn starch as main component are highly mechanically sensitive and degrade mostly by chains scission and those with PVOH as major component are highly temperature sensitive and degrade mainly by cross-linking. The obtained results show also that each PVOH-starch blend requires particular formulation and individual windows of melt processing conditions. These results are a good proof that the MFI method is a good path to study the degradability and moldability of process sensitive polymeric materials like those based on starch and PVOH.

  18. Rheological, baking, and sensory properties of composite bread dough with breadfruit (Artocarpus communis Forst) and wheat flours.

    Science.gov (United States)

    Bakare, Adegoke H; Osundahunsi, Oluwatooyin F; Olusanya, Joseph O

    2016-07-01

    The rheological (Pasting, farinograph, and alveograph) properties of wheat flour (WF) replaced with breadfruit four (05-40%) was analyzed. Baking and sensory qualities of the resulting bread were evaluated. Differences in baking properties of loaves produced under laboratory and industrial conditions were analyzed with t-test, whereas ANOVA was used for other analyses. Peak and final viscosities in the composite blends (CB) ranged from 109.20 to 114.06 RVU and 111.86 to 134.40 RVU, respectively. Dough stability decreased from 9.15 to 0.78 min, whereas farinograph water absorption increased 59.7-65.9%. Alveograph curve configuration ratio increased from 1.27 to 7.39, whereas specific volume (Spv) of the loaves decreased from 2.96 to 1.32 cm(3)/g. The Spv of WF loaves were not significantly different (P > 0.05) from that of the 5% CB, whereas production conditions had no significant effects on absorbed water (t = 0.532, df = 18 P = 0.3005), weight loss during baking (t = 0.865, df = 18, P = 0.199), and Spv (t = 0.828, df = 14.17, P = 0.211). The sensory qualities of the 5% blend were not significantly different from the WF.

  19. Effects of cellulose fiber with different fiber length on rheological properties of wheat dough and quality of baked rolls.

    Science.gov (United States)

    Lauková, Michaela; Kohajdová, Zlatica; Karovičová, Jolana; Kuchtová, Veronika; Minarovičová, Lucia; Tomášiková, Lenka

    2017-09-01

    Powdered cellulose is often used in cereal processing industry. The effects of partial replacement (0.5%, 1%, 2% and 5%) of wheat flour by cellulose fiber with different fiber length (80, 120 and 220 µm) on rheological properties of wheat dough and qualitative parameters of baked rolls were studied. Sensory evaluation of baked products was also performed. Mixing and pasting properties of dough were determined by Mixolab. Generally, cellulose-enriched dough was characterized with higher water absorption, dough stability and parameters C2 and C3. Moreover, it was found that parameters C4 and C5 increased with increasing cellulose fiber length. From the results, it was also concluded that the physical parameters of baked rolls containing cellulose were reduced. It was also observed that the incorporation of cellulose fiber with shorter fiber length concluded in lower rolls volume compared to cellulose fiber with long fiber length. Texture analyses showed that the firmness of rolls containing cellulose at the substitution level 5% was significantly higher than those of the control, whereas the springiness of wheat rolls was not significantly affected. It was also recorded that the firmness and cohesiveness of baked rolls were higher after the addition of cellulose fiber with shorter fiber length. Sensory evaluation indicated that baked rolls with cellulose addition up to 1% were comparable with control rolls. Results also showed that higher levels of cellulose significantly decreased crust, taste, color and porosity of rolls.

  20. A study of influence of material properties on magnetic flux density induced in magneto rheological damper through finite element analysis

    Directory of Open Access Journals (Sweden)

    Gurubasavaraju T. M.

    2018-01-01

    Full Text Available Magnetorheological fluids are smart materials, which are responsive to the external stimulus and changes their rheological properties. The damper performance (damping force is dependent on the magnetic flux density induced at the annular gap. Magnetic flux density developed at fluid flow gap of MR damper due to external applied current is also dependent on materials properties of components of MR damper (such as piston head, outer cylinder and piston rod. The present paper discus about the influence of different materials selected for components of the MR damper on magnetic effect using magnetostatic analysis. Different materials such as magnetic and low carbon steels are considered for piston head of the MR damper and magnetic flux density induced at fluid flow gap (filled with MR fluid is computed for different DC current applied to the electromagnetic coil. Developed magnetic flux is used for calculating the damper force using analytical method for each case. The low carbon steel has higher magnetic permeability hence maximum magnetic flux could pass through the piston head, which leads to higher value of magnetic effect induction at the annular gap. From the analysis results it is observed that the magnetic steel and low carbon steel piston head provided maximum magnetic flux density. Eventually the higher damping force can be observed for same case.

  1. Effect of temperature on the rheological properties with shear stress limit of iron oxide nanoparticle modified bentonite drilling muds

    Directory of Open Access Journals (Sweden)

    Ahmed S. Mohammed

    2017-09-01

    Full Text Available In this study, the effect of temperature on the rheological properties and weight loss of a water based bentonite drilling mud modified with iron oxide nanoparticle (nanoFe2O3 was investigated. The bentonite contents in the drilling muds were varied up to 6% by the weight of water and temperature was varied from 25 °C to 85 °C. The nanoFe2O3 content was varied between 0 and 1% by the weight of the drilling mud to modify the rheological properties of the drilling mud. The nanoFe2O3 and bentonite clay were characterized using the X-ray diffraction analysis (XRD and thermal gravimetric analysis (TGA. In the TGA study, the total weight loss at 800 °C for the bentonite decreased from 13% to 1.16%, a 91% reduction when the bentonite clay was mixed with 1% of nanoFe2O3. The results also showed that 1% of nanoFe2O3 increased the rheological properties of the drilling mud. The nanoFe2O3 modification increased the yield stress (τo and plastic viscosity (PV by 45–200% and 20–105% respectively based on the bentonite content and temperature of the drilling mud. The shear thinning behavior of the bentonite drilling mud with and without nanoFe2O3 has been quantified using the hyperbolic model and compared with three parameters Herschel–Bulkley model. The results showed that the hyperbolic model predicted the shear thinning relationship between the shear stress and shear strain rate of the nanoFe2O3 modified bentonite drilling mud very well. Also the hyperbolic model has a maximum shear stress limit whereas the Herschel–Bulkley model did not have a limit on the maximum shear stress. Based on the hyperbolic model the maximum shear stress for the 2%, 4% and 6% bentonite drilling muds without nanoFe2O3 at room temperature were 25 Pa, 35 Pa and 51 Pa respectively. The maximum shear stress for the 2%, 4% and 6% bentonite drilling muds modified with 1% nanoFe2O3 at 25 °C were 59 Pa, 84 Pa and 140 Pa respectively, hence an increase of 135–175

  2. Surface treatments for improved performance and properties

    International Nuclear Information System (INIS)

    Burke, J.J.; Weiss, V.

    1982-01-01

    This book considers the characteristics, structures, and properties of surfaces. Divides the subject into the physical and chemical characteristics of metallic and nonmetallic surfaces, emerging surface modification techniques, surface structure and mechanical properties, and relationships between properties and processing for nonmetallic materials. Explores various methods of surface modification that can produce improved materials properties. Discusses such wide-ranging topics as the characterization of surfaces, reaction kinetics, the chemistry of gaseous hydrogen embrittlement, the effect of surface modification on corrosion, protection against high-temperature corrosion of surfaces, the effect of high temperatures developed during plating on the microstructure and microhardness of steel, near-surface modifications that will improve the crack-tolerant behavior of high-strength alloys, fretting corrosion and fretting fatigue, surface treatments for enhanced bonding between inorganic surfaces and polymers, and the relationships between surface structure, ceramic processing, and mechanical properties. Recommended for workers and researchers in materials science, surface science, and mechanical engineering. Constitutes the proceedings of the Twenty-sixth Sagamore Army Materials Research Conference (entitled ''Surface Treatments for Improved Performance and Properties'') held in New York in 1979

  3. Effect of the addition of hydrocolloids on the rheological and baking properties of the products with added spelt flour (Triticum spelta L.

    Directory of Open Access Journals (Sweden)

    Tatiana Bojňanská

    2016-01-01

    Full Text Available The paper presents the results of the evaluation of the effect of additives on the rheological properties of composite flour made of wheat flour in the amount of 70% and spelt flour at 30%. As additives guar gum (0.5% by weight of flour and xanthan gum (0.16% by weight of flour were used. Properties of produced control dough and doughs with hydrocolloids were evaluated by means of rheological appliances by Farinograph, Extenzograph, Amylograph and Rheofermentometer. Based on the observed results it can be concluded that the addition of xanthan gum has a positive effect on increasing of farinographic water absorption capacity, extension of dough development time and dough stability and generally positively affected farinographic properties. The addition of guar gum has improved especially extensographic properties as extensographic energy and extensographic resistance. Based on amylographic evaluation of control doughs and doughs with additives it can be stated that in the dough with guar gum the amylographic maximum has slightly increased. Hydrocolloid guar gum contributed to an increased retention capacity of dough observed. Based on our measurements we can indicate that addition of guar and xanthan gum contributed to an increased rheological quality of doughs prepared with addition of flour from spelt wheat. With reference to the baking experiment it was found that the use of hydrocolloids has a positive effect on the improvement of the baking properties, in particular larger volume, specific volume, and the volume yield of the dough with the addition of guar and xanthan gum compared to the control. Our results showed that aditives significantly influenced rheological qualities of dough and a baking quality of products. These findings thus allow optimizing the recipe in order to increase the technological quality of leavened bakery products.

  4. Impact of different sequences of mechanical and thermal processing on the rheological properties of Porphyridium cruentum and Chlorella vulgaris as functional food ingredients.

    Science.gov (United States)

    Bernaerts, Tom M M; Panozzo, Agnese; Verhaegen, Katrien A F; Gheysen, Lore; Foubert, Imogen; Moldenaers, Paula; Hendrickx, Marc E; Van Loey, Ann M

    2018-04-10

    Microalgae are a promising and sustainable source for enhancing the nutritional value of food products. Moreover, incorporation of the total biomass might contribute to the structural properties of the enriched food product. Our previous study demonstrated the potential of Porphyridium cruentum and Chlorella vulgaris as multifunctional food ingredients, as they displayed interesting rheological properties after applying a specific combination of mechanical and thermal processing. The aim of the current study was to investigate the impact of a different sequence of high pressure homogenization (HPH) and thermal processing on the thickening and gelling potential of these microalgal biomasses in aqueous suspensions. Thermal processing largely increased the gel strength and viscosity of both microalgae, which was ascribed to larger and stronger aggregates as a result of partial solubilization of polymers, while subsequent HPH generally reduced the rheological properties. Interestingly, large amounts of intact cells were still observed for both microalgae when HPH was performed after a thermal treatment, irrespective of the applied homogenization pressure, implying that cell disruption was hindered by the preceding thermal treatment. Although thermal processing was regarded as the most effective processing technique to obtain increased rheological properties, the combination with a preceding HPH treatment should still be considered when cell disruption is desired, for instance to increase the bioavailability of intracellular components. Finally, biomass of P. cruentum showed the largest potential for use as a structuring agent, as the gel strength and viscosity in thermally treated suspensions of this microalga were about 10 times higher than for C. vulgaris.

  5. Pectin extraction from lemon by-product with acidified date juice: rheological properties and microstructure of pure and mixed pectin gels.

    Science.gov (United States)

    Masmoudi, M; Besbes, S; Ben Thabet, I; Blecker, C; Attia, H

    2010-04-01

    The microstructure and the rheological properties of lemon-pectin mixtures were studied and compared to those of pure lemon (high methoxyl: HM) and date (low methoxyl: LM) pectins. Rheological properties were carried out in the presence of 30%, 45% and 60% sucrose, and increasing calcium concentrations (0-0.1%). The presence of date with lemon pectin led to a gel formation at 45% sucrose and in the presence of calcium, which was not the case for lemon pectin alone under the same conditions. It is suggested that lemon and date pectins interacted, leading to gel formations at different gelling temperatures, which were strongly dependent on degree of methylation. These results were confirmed by scanning electron microscopy, which revealed inhomogeneous gels where dense aggregated network and loose, open network areas were present. Addition of calcium to pectin mixture gels led to stronger and faster gel formation.

  6. From peptides and proteins to micro-structure mechanics and rheological properties of fibril systems

    NARCIS (Netherlands)

    Linden, van der E.

    2012-01-01

    This article provides a summary of an example of how relationships between molecular scale properties and macroscopic properties are formulated, in this case with a focus on fibril microstructures and according system elasticity. Entropy plays a dominant role on all length scales. The elasticity is

  7. Rheology and Confocal Reflectance Microscopy as Probes of Mechanical Properties and Structure during Collagen and Collagen/Hyaluronan Self-Assembly

    Science.gov (United States)

    Yang, Ya-li; Kaufman, Laura J.

    2009-01-01

    In this work, the gelation of three-dimensional collagen and collagen/hyaluronan (HA) composites is studied by time sweep rheology and time lapse confocal reflectance microscopy (CRM). To investigate the complementary nature of these techniques, first collagen gel formation is investigated at concentrations of 0.5, 1.0, and 1.5 mg/mL at 37°C and 32°C. The following parameters are used to describe the self-assembly process in all gels: the crossover time (tc), the slope of the growth phase (kg), and the arrest time (ta). The first two measures are determined by rheology, and the third by CRM. A frequency-independent rheological measure of gelation, tg, is also measured at 37°C. However, this quantity cannot be straightforwardly determined for gels formed at 32°C, indicating that percolation theory does not fully capture the dynamics of collagen network formation. The effects of collagen concentration and gelation temperature on kg, tc, and ta as well as on the mechanical properties and structure of these gels both during gelation and at equilibrium are elucidated. Composite collagen/HA gels are also prepared, and their properties are monitored at equilibrium and during gelation at 37°C and 32°C. We show that addition of HA subtly alters mechanical properties and structure of these systems both during the gelation process and at equilibrium. This occurs in a temperature-dependent manner, with the ratio of HA deposited on collagen fibers versus that distributed homogeneously between fibers increasing with decreasing gelation temperature. In addition to providing information on collagen and collagen/HA structure and mechanical properties during gelation, this work shows new ways in which rheology and microscopy can be used complementarily to reveal details of gelation processes. PMID:19217873

  8. Functional and rheological properties of proteins in frozen turkey breast meat with different ultimate pH.

    Science.gov (United States)

    Chan, J T Y; Omana, D A; Betti, M

    2011-05-01

    Functional and rheological properties of proteins from frozen turkey breast meat with different ultimate pH at 24 h postmortem (pH(24)) have been studied. Sixteen breast fillets from Hybrid Tom turkeys were initially selected based on lightness (L*) values for each color group (pale, normal, and dark), with a total of 48 breast fillets. Further selection of 8 breast samples was made within each class of meat according to the pH(24). The average L* and pH values of the samples were within the following range: pale (L* >52; pH ≤5.7), normal (46 meat, respectively. Ultimate pH did not cause major changes in the emulsifying and foaming properties of the extracted sarcoplasmic and myofibrillar proteins. An SDS-PAGE profile of proteins from low and normal pH meat was similar, which revealed that the extent of protein denaturation was the same. Low pH meat had the lowest water-holding capacity compared with normal and high pH meat as shown by the increase in cooking loss, which can be explained by factors other than protein denaturation. Gel strength analysis and folding test revealed that gel-forming ability was better for high pH meat compared with low and normal pH meat.Dynamic viscoelastic behavior showed that myosin denaturation temperature was independent of pH(24). Normal and high pH meat had similar hardness, springiness, and chewiness values as revealed by texture profile analysis. The results from this study indicate that high pH meat had similar or better functional properties than normal pH meat. Therefore, high pH meat is suitable for further processed products, whereas low pH meat may need additional treatment or ingredient formulations to improve its functionality.

  9. Experimental Study of Rheological Properties and Oil Displacement Efficiency in Oilfields for a Synthetic Hydrophobically Modified Polymer.

    Science.gov (United States)

    Liu, Pengcheng; Mu, Zhenbao; Wang, Chao; Wang, Yanling

    2017-08-18

    In a previous study, we developed a synthetic hydrophobically modified hydroxyethyl cellulose (HEC) using bromododecane (BD), which we denote as BD-HMHEC. In this work, we continually investigate the rheological properties and its oil displacement efficiency in PuTao well area in Daqing oilfields, China. Results show that BD-HMHEC solution has good viscosification, thermal-resistance, salt-tolerance, shear resistance, and acid/alkali resistance. The storage modulus (G') and the loose modulus (G") of the BD-HMHEC solutions increase significantly with increasing BD-HMHEC concentration, and the solution becomes viscoelastic at a sufficiently high BD-HMHEC concentration. The core flooding results showed BD-HMHEC flooding improves oil recovery by 7-14% in comparison with HEC flooding at concentrations of 4,000 mg/L under equivalent conditions. Moreover, BD-HMHEC flooding improves oil recovery by 7-8% after conducting water and hydrolyzed polyacrylamide (HPAM) flooding. The oil displacement mechanism of BD-HMHEC solutions is discussed based on a visual evaluation. The results indicate that BD-HMHEC flooding is a feasible means for improving oil recovery after water/HPAM flooding.

  10. Textural and rheological properties of Pacific whiting surimi as affected by nano-scaled fish bone and heating rates.

    Science.gov (United States)

    Yin, Tao; Park, Jae W

    2015-08-01

    Textural and rheological properties of Pacific whiting (PW) surimi were investigated at various heating rates with the use of nano-scaled fish bone (NFB) and calcium chloride. Addition of NFB and slow heating improved gel strength significantly. Activity of endogenous transglutaminase (ETGase) from PW surimi was markedly induced by both NFB calcium and calcium chloride, showing an optimal temperature at 30°C. Initial storage modulus increased as NFB calcium concentration increased and the same trend was maintained throughout the temperature sweep. Rheograms with temperature sweep at slow heating rate (1°C/min) exhibited two peaks at ∼ 35°C and ∼ 70°C. However, no peak was observed during temperature sweep from 20 to 90°C at fast heating rate (20°C/min). Protein patterns of surimi gels were affected by both heating rate and NFB calcium concentration. Under slow heating, myosin heavy chain intensity decreased with NFB calcium concentration, indicating formation of ε-(γ-glutamyl) lysine cross-links by ETGase and NFB calcium ion. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Isolation and rheological properties of tamarind seed polysaccharide from tamarind kernel powder using protease enzyme and high-intensity ultrasound.

    Science.gov (United States)

    Poommarinvarakul, Sukhum; Tattiyakul, Jirarat; Muangnapoh, Chirakarn

    2010-06-01

    The effectiveness of using protease and combinations of protease and high-intensity ultrasound for high-purity, high-yield tamarind seed polysaccharide (TSP) production was investigated. Tamarind kernel powder (TKP) suspension was treated with protease alone at 0.16, 0.48, and 0.80 units/mL and with protease-ultrasound combinations over 3 different orders of sequence (before, simultaneous with, and after protease digestion) using combinations of 0.48 units/mL protease and high-intensity ultrasound at 25% and 50% amplitude for 15 and 30 min. The long protease digestion time could produce high-purity isolated TSP, but the polysaccharide yields were lower. The polysaccharide purity and yield were highly improved, even at a shorter protease digestion time, when the protease treatment was combined with high-intensity ultrasound. The increased amplitude level and sonication time decreased the average molecular weight of the polysaccharide. The rheological properties of the TKP and the isolated TSP, from nondestructive oscillatory measurements, demonstrated that the latter present a viscoelastic solution. The decreasing of protein content resulted in better elasticity of the solution. The power law model could be used to fit the down curve between shear rate and shear stress data. The consistency coefficient (K) increased while the flow behavior index decreased with the increased purity of the polysaccharide as a result of increasing increased digestion time, enzyme concentration, sonication power, and sonication time.

  12. Thermophysical and rheological properties of dulce de leche with and without coconut flakes as a function of temperature

    Directory of Open Access Journals (Sweden)

    Vanessa Camarinha Barbosa

    2013-03-01

    Full Text Available Dulce de leche (DL, a dairy dessert highly appreciated in Brazil, is a concentrated product containing about 70% m/m of total solids. Thermophysical and rheological properties of two industrial Brazilian Dulce de leche formulations (classic Dulce de leche and Dulce de leche added with coconut flakes 1.5% m/m were determined at temperatures comprised between 28.4 and 76.4 °C. In general, no significant differences (p < 0.05 were observed in the presence of coconut flakes in the two formulations. Heat capacity varied from 2633.2 to 3101.8 J/kg.°C; thermal conductivity from 0.383 to 0.452 W/m.°C; specific mass from 1350.7 to 1310.7 kg/m³; and, thermal diffusivity from (1.082 × 10-7 to 1.130 × 10-7 m²/s. The Bingham model was used to properly describe the non-Newtonian behavior of both formulations, with yielding stress values varying from 27.3 to 17.6 Pa and plastic viscosity from 19.9 to 5.9 Pa.s.

  13. Synthesis, rheological behavior and swelling properties of copolymer hydrogels based on poly(N-isopropylacrylamide with hydrophilic monomers

    Directory of Open Access Journals (Sweden)

    D. Aliouche

    2013-09-01

    Full Text Available In this study, hydrogels of poly(N-isopropylacrylamide-co-acrylamide and poly(N-isopropylacrylamide-co-acrylic acid having a thermoresponsive character were prepared by aqueous free-radical co-polymerization using the ammonium persulfate/N,N,N',N'-tetramethylethylenediamine (APS/TEMED redox-pair initiator system in the presence of N,N'-methylenebisacrylamide (MBAAm crosslinker. (NIPAAm-co-AAm and (NIPAAm-co-AAc hydrogels with different thermoresponsive properties were obtained by fixing the initial NIPAAm/AAm mole ratio and and (NIPAAm-co-AAc mole ratio to 80/20 and changing the crosslinker concentration. The copolymers were characterized with infrared spectroscopy (IR and differential scanning calorimetry (DSC techniques. The swelling response of the copolymers networks as a function of time, temperature and swelling environment has been observed to be dependent on both structural aspects of the polymers and swelling environment. The swelling has been observed to be decrease with increase in MBAAm in the copolypolymers networks. Rheological behavior was studies in oscillatory module. All copolymers have a viscoelastic behaviour. We note that the elastic modulus G' increases with increasing hydrophilic monomers.DOI: http://dx.doi.org/10.4314/bcse.v27i3.14

  14. Morphology, microstructure and rheological properties of SAN (styrene-acrylonitrile)/EPDM (ethylene-propylene-diene monomer) nanocomposites: Investigating the role of organoclay type and order of mixing

    Energy Technology Data Exchange (ETDEWEB)

    Jeddi, Javad; Yousefzade, Omid [Department of Polymer Engineering and Color Technology, Amirkabir University of Technology, Tehran, 15875-4413 (Iran, Islamic Republic of); Babaei, Amir, E-mail: a.babaei@gu.ac.ir [Polymer Engineering Department, Faculty of Engineering, Golestan University, 4918888369, Gorgan (Iran, Islamic Republic of); Ghanbar, Sadegh; Rostami, Amir [Department of Polymer Engineering and Color Technology, Amirkabir University of Technology, Mahshahr Campus, Mahshahr, 6351716178 (Iran, Islamic Republic of)

    2017-02-01

    The object of this work was to investigate the preferential localization of nanoclay platelets in SAN/EPDM (80/20) blend in terms of thermodynamic and kinetic considerations. In this way, effects of two organoclay types and mixing sequences on the morphology, microstructure and rheological properties of prepared blends were studied. Calculations based on the thermodynamic point of view suggested both nanoclay types should be localized in the SAN phase. The XRD results demonstrated that SAN phase as a matrix played a more significant role in the intercalation/exfoliation of organoclays rather than dispersed EPDM phase. Linear viscoelastic studies showed a high tendency for both of organoclays to be localized in the SAN component as well as better dispersion state of cloisite 30B organoclay. The results of creep and creep-recovery experiments revealed the reversible deformation of nanocomposites decreased with increasing degree of organoclay dispersion. The calculated retardation spectrums indicated the dominant role of filler – filler interaction on the melt viscoelastic response of ternary nanocomposites. In addition, scanning electron microscopy (SEM) was employed to study the correlation between the rheological properties, and microstructure and morphological features of blends. - Highlights: • SAN/EPDM/organoclay nanocomposite was prepared with different mixing sequences. • The location of organoclay in SAN/EPDM blend controlled by thermodynamic parameters. • The dispersed phase size decreased in presence of organoclay. • Correlation between rheological properties and microstructure has been established.

  15. Effects of Lateral Heterogeneity and Power Law Rheology on Glacially Induced Surface Motion and Gravity Rate of Change

    Science.gov (United States)

    Wu, P.; Wang, H.; van der Wal, W.

    2006-12-01

    Modern geodetic measurements from GPS, satellite altimetry, tide-gauges, Satellite Laser Ranging (SLR) and space-borne gravimetry (such as GRACE) have been used to monitor global change. Since these measurements contain contributions from glacial isostatic adjustment (GIA) and other tectonic processes, they must be modeled and removed in order to observe current climate change. In the past, most GIA models assumed that the earth is laterally homogeneous and the rheology is linear. The aim of this paper is to investigate the effects of lateral heterogeneity and Power-Law rheology on GIA induced land uplift rate, horizontal velocities, relative sealevels, J-dot and the secular gravity rate of change in the southern part of Hudson Bay, which is detected by the GRACE mission. Here, GIA is modeled with a spherical, self-gravitating, compressible viscoelastic, laterally heterogeneous earth using the Finite-Element Method. The effect of gravitationally self-consistent sea levels in realistic oceans is also included. Lateral variations in mantle viscosities and lithospheric thickness are inferred from the seismic tomography model S20A using well known scaling relationships. Power-Law rheologies in the whole mantle or in combination with linear rheologies in the upper or lower mantle are also investigated. Both ICE-5G and ICE-4G deglaciation models are used to investigate their effect on the pattern of rebound. Preliminary results show that both lateral heterogeneity and power-law rheology have strong effects on the direction and magnitude of horizontal velocities. The effects of lateral heterogeneity and power-law rheology are also large enough to be detected in land uplift rate, relative sealevels, J-dot and gravity rate of change. Their implication on observing the effects of global warming will also be discussed.

  16. Chickpea (Cicer arietinum steep liquor as a leavening agent: Effect on dough rheology and sensory properties of bread

    Directory of Open Access Journals (Sweden)

    Saad Ahmed M.

    2015-01-01

    Full Text Available Dough fermentation is one of the oldest process in food technologies. It has been recently intensively studied for its impact on the sensory, structural, nutritional and shelf life properties of leavened baked products. The goals of this work were to investigate chickpea steep liquor (CSL as a dough-leavening agent and to study the effect of CSL on the dough rheology and sensory properties of leavened bread. CSL was prepared by submerging chickpea seeds in boiled distilled water (1:2, w/v for 24 h at 37оC, and then obtained liquor was filtered and freeze-dried to obtain CSL. The addition of CSL to wheat flour (WF brought changes in the dough mixing behavior as measured by the farinograph. An increase in the farinograph water absorption of WF dough was observed when 4.5% CSL and 1.5% yeast was added, while arrival time was not affected. Addition of CSL to the dough at a content of 4.5, 9.0 and 13.5 g CSL/300 g WF caused an increase in dough stability. The CSL addition also increased mechanical tolerance index, dough weakening and mixing time. Dough development time for all blends was higher than the control (1.2-1.5 min, while between the CSL samples no significant difference was observed. The loaf weight slightly increased from 146.2 g for control to 152.2 g for CSL fermented bread, whereas the loaf volume and specific volume of CSL-fermented bread were lower than the control. The combination of yeast and CSL increased the acceptability of bread with the increasing level of both leavening agents’. The results show that CSL could be used as an alternative to yeast for syngas fermentation. On the other hand, CLS is rich in nutrients and lower in cost compared to yeast.

  17. Interdisciplinary study of the Mw8.3 Illapel earthquake (Chile): Rheology and frictional property of the central Chile megathrust

    Science.gov (United States)

    Poli, Piero; Frank, William; Maksymowicz, Andrei; Ruiz, Sergio; Perfettini, Hugo

    2017-04-01

    We present an interdisciplinary study for the magnitude 8.3 Illapel earthquake, which stroke the central Chile in September 2015. Our work includes historical seismicity, geological, geodetic and seismological information, and aim at deriving a quantitative seismotectonic model for the study area. We first analyze the historical seismicity, magnetic data, the bathymetry and geodetic coupling, to recognize creeping areas, located all around the M8.3 asperity. The comparison of the recognized creeping zones with earthquake swarm activity and repeating earthquakes occurring before and after the main shock, suggests that several slow slip episodes took place in the 20 years before the main shock. The same areas are recognized as barrier for the propagation of the Illapel earthquake, and accommodated the large afterslip. By combination of geological and seismological data, we recognize these creeping areas as being fluid saturated fracture zones, thus posing constrains on the rheology of the plate interface. We then perform a detailed study of aftershocks activity, to study the postseismic slip. We first build a high-resolution aftershock catalog, by using template-matching technique. We then make use of the rate and state formalism to fit the spatiotemporal evolution of aftershocks, and thus deriving quantitative information about the frictional properties of the plate interface. This novel approach is validated with GPS data, and reveals strong variation of frictional properties along the plate interface, in agreement with the presence of fluid saturated regions. These regions modulated the stress evolution before and after the main shock, and controlled the dynamic propagation the Illapel earthquake. Our study reveals the importance of interdisciplinary study of subduction zones, in providing detailed information about small-scale coupling, which can offer fundamental insights about the earthquake cycle and hazard.

  18. Rheological properties of poly (vinylpiyrrolidone) as a function of average molecular weight and its applications

    DEFF Research Database (Denmark)

    Marani, Debora; Sudireddy, Bhaskar Reddy; Kiebach, Ragnar

    characterized regarding their viscosimetric properties in ethanol. Average molecular weights (Mw, Mn, and Mz) have been determined by gel permeation chromatography (GPC), and then used in a numerical method to evaluate the viscosity average molecular weight (Mv) via the Mark-Houwink-Sakurada (MHS) equation...

  19. Molecular assembly, interfacial rheology and foaming properties of oligofructose fatty acid esters

    NARCIS (Netherlands)

    Kempen, van S.E.H.J.

    2013-01-01

    Aerated food products consist of air bubbles that are surrounded by a matrix that can be either liquid or solid. Due to the large number of air bubbles that are generally present in aerated products, these systems contain a large interfacial area. Therefore, the properties of the interfaces are

  20. Interfacial rheological properties of adsorbed protein layers and surfactants: a review

    NARCIS (Netherlands)

    Bos, M.A.; Vliet, van T.

    2001-01-01

    Proteins and low molecular weight (LMW) surfactants are widely used for the physical stabilisation of many emulsions and foam based food products. The formation and stabilisation of these emulsions and foams depend strongly on the interfacial properties of the proteins and the LMW surfactants.

  1. Polyesters Based on Linoleic Acid for Biolubricant Basestocks: Low-Temperature, Tribological and Rheological Properties

    Science.gov (United States)

    Abdullah, Bashar Mudhaffar; Zubairi, Saiful Irwan; Huri, Hasniza Zaman; Hairunisa, Nany; Yousif, Emad; Basu, Roma Choudhury

    2016-01-01

    Presently, plant oils which contain high percentage of linoleic acid 1 are perceived to be a viable alternative to mineral oil for biolubricant applications due to their biodegradability and technical properties. In order to get biodegradable lubricant, triester derivatives compounds (1–5) were synthesized and characterized. The processes involved were monoepoxidation of linoleic acid 2, oxirane ring opening 3, esterification 4 and acylation 5. The structures of the products were confirmed by FTIR, 1H and 13C-NMR and LC-MS. The results that showed lowest temperature properties were obtained for triester 5, with a pour point value (PP) of -73°C, highest onset temperature (260°C) and lowest volatility at 0.30%. Viscosity index (VI) increased for the ester’s synthetic compounds (2, 3, 4, 5), while the PP decreased. This behavior is the result of the increase of the chain length of the branching agents. Triester based linoleic acid has improved properties such as low-temperature and tribological properties. These results will make it feasible for plant oil to be used for biolubricants, fuels in chain saws, transmission oil and brake fluid. PMID:27008312

  2. Interfacial rheological properties of adsorbed protein layers and surfactants : a review

    NARCIS (Netherlands)

    Bos, M.A.; Vliet, T. van

    2001-01-01

    Proteins and low molecular weight (LMW) surfactants are widely used for the physical stabilisation of many emulsions and foam based food products. The formation and stabilisation of these emulsions and foams depend strongly on the interfacial properties of the proteins and the LMW surfactants.

  3. Rheological and mechanical properties and interfacial stress development of composite cements modified with thio-urethane oligomers.

    Science.gov (United States)

    Bacchi, Ataís; Pfeifer, Carmem S

    2016-08-01

    Thio-urethane oligomers have been shown to reduce stress and increase toughness in highly filled composite materials. This study evaluated the influence of thio-urethane backbone structure on rheological and mechanical properties of resin cements modified with a fixed concentration of the oligomers. Thio-urethane oligomers (TU) were synthesized by combining thiols - pentaerythritol tetra-3-mercaptopropionate (PETMP) or trimethylol-tris-3-mercaptopropionate (TMP) - with isocyanates - 1,6-hexanediol-diissocyante (HDDI) (aliphatic) or 1,3-bis(1-isocyanato-1-methylethyl)benzene (BDI) (aromatic) or dicyclohexylmethane 4,4'-diisocyanate (HMDI) (cyclic), at 1:2 isocyanate:thiol, leaving pendant thiols. 20wt% TU were added to BisGMA-UDMA-TEGDMA (5:3:2). 60wt% silanated inorganic fillers were added. Near-IR was used to follow methacrylate conversion and rate of polymerization ( [Formula: see text] ). Mechanical properties were evaluated in three-point bending (ISO 4049) for flexural strength/modulus (FS/FM, and toughness), and notched specimens (ASTM Standard E399-90) for fracture toughness (KIC). PS was measured on the Bioman. Viscosity (V) and gel-points (defined as the crossover between storage and loss shear moduli (G'/G″)) were obtained with rheometry. Glass transition temperature (Tg), cross-link density and homogeneity of the network were obtained with dynamic mechanical analysis. Film-thickness was evaluated according to ISO 4049. DC and mechanical properties increased and [Formula: see text] and PS decreased with the addition of TUs. Gelation (G'/G″) was delayed and DC at G'/G″ increased in TU groups. Tg and cross-link density dropped in TU groups, while oligomers let to more homogenous networks. An increase in V was observed, with no effect on film-thickness. Significant reductions in PS were achieved at the same time conversion and mechanical properties increased. The addition of thio-urethane oligomers proved successful in improving several key properties

  4. Rheological Properties, Water-Holding and Oil-Binding Capacities of Particulate β-Glucans Isolated from Spent Brewer’s Yeast by Three Different Procedures

    Directory of Open Access Journals (Sweden)

    Vlatka Petravić-Tominac

    2011-01-01

    Full Text Available Particulate β-glucans were isolated from brewer’s yeast using three different procedures – alkaline (A, alkaline-acidic (AA and alkaline-acidic with mannoprotein removal (AAM and dried using three different methods – air drying (AD, lyophilization (L and spray drying (SD. In this work, the obtained β-glucan preparations were tested for their microstructure, rheological properties, swelling, water-holding and oil-binding capacities. According to their rheological properties, suspensions containing 1 and 2 % (by mass of spray-dried samples belong to the category of dilatant fluids. Among the spray-dried samples, rheological behaviour and water-holding capacity of the preparation AA-SD differed from those obtained by other two procedures (A-SD and AAM-SD. Concerning different drying methods applied, swelling was the lowest in the lyophilized samples and the most pronounced in the air-dried ones. Oil-binding capacity was the highest in the lyophilized preparations and increased proportionally to the number of processing steps applied in the isolation procedure.

  5. Rheological measurements on cement grouts

    International Nuclear Information System (INIS)

    Dalton, M.J.

    1986-06-01

    This report describes the techniques which have been developed at Winfrith for assessing the rheological properties of cement grouts. A discussion of the theory of rheology and its application to cement is given and the methodology for calibrating a special paddle measuring system for a commercial viscometer is described. The use of the system for determining flow curves, equilibrium viscosity, viscosity as a function of shearing time and structure changes is also discussed. (author)

  6. Reaction mechanism and rheological properties of polypropylene irradiated under various atmospheres

    Science.gov (United States)

    Lugão, Ademar B.; Hutzler, Beatriz; Ojeda, Telmo; Tokumoto, Shinichi; Siemens, Richard; Makuuchi, Keizo; Villavicencio, Anna.-Lucia C. H.

    2000-03-01

    It is well-known that the melt-strength properties of a polymer increases with molecular weight and with long chain branching due to the increase in the entanglement level. This study is a contribution for the understanding of the following points: — the role of branching, crosslinking and degradation on melt strength properties; — the mechanism and the kinetics of PP irradiation with time of irradiation and the importance of double bond formation. The results showed that degradation was the major reaction in the initial step of irradiation no matter the atmosphere and or antioxidant. However, double bond formation increased the production of branching and crosslinking reactions. Double bond formation had no effect on the crystallization kinetics, on the other hand, long chain branching had a marked effect on the crystallization temperature.

  7. Reaction mechanism and rheological properties of polypropylene irradiated under various atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Lugao, A.B. E-mail: ablugao@net.ipen.br; Hutzler, B.; Ojeda, T.; Tokumoto, S.; Siemens, R.; Makuuchi, K.; Villavicencio, A.L.C.H

    2000-03-01

    It is well-known that the melt-strength properties of a polymer increases with molecular weight and with long chain branching due to the increase in the entanglement level. This study is a contribution for the understanding of the following points: -- the role of branching, crosslinking and degradation on melt strength properties; -- the mechanism and the kinetics of PP irradiation with time of irradiation and the importance of double bond formation. The results showed that degradation was the major reaction in the initial step of irradiation no matter the atmosphere and or antioxidant. However, double bond formation increased the production of branching and crosslinking reactions. Double bond formation had no effect on the crystallization kinetics, on the other hand, long chain branching had a marked effect on the crystallization temperature.

  8. Molecular dynamics simulation of the rheological and dynamical properties of a model alkane fluid under confinement

    International Nuclear Information System (INIS)

    Cui, S.T.; Cummings, P.T.; Cochran, H.D.

    1999-01-01

    We study the effect of wall endash fluid interactions on the state conditions and the effective properties of a model dodecane fluid confined between parallel solid walls. A significant increase in the effective density of the confined fluid is observed with increasing strength of the wall endash fluid interaction. The effect of the wall endash fluid interaction on the rotational relaxation and diffusional relaxation of the fluid is seen in the significant slowing down of the relaxation with increasing wall endash fluid interaction strength. The difference between the confined fluid and the three-dimensional bulk fluid is demonstrated by the strong anisotropy of the dynamical properties, the molecular rotation, and self-diffusion. The viscosity of the confined fluid shows a large difference between weak and strong wall endash fluid interactions, and a significant difference from bulk fluid at low shear rate. copyright 1999 American Institute of Physics

  9. Graphene oxide liquid crystals: synthesis, phase transition, rheological property, and applications in optoelectronics and display.

    Science.gov (United States)

    Lin, Feng; Tong, Xin; Wang, Yanan; Bao, Jiming; Wang, Zhiming M

    2015-12-01

    Graphene oxide (GO) liquid crystals (LCs) are macroscopically ordered GO flakes dispersed in water or polar organic solvents. Since the first report in 2011, GO LCs have attracted considerable attention for their basic properties and potential device applications. In this review, we summarize recent developments and present a comprehensive understanding of GO LCs via many aspects ranging from the exfoliation of GO flakes from graphite, to phases and phase transitions under various conditions, the orientational responses of GO under external magnetic and electric fields, and finally Kerr effect and display applications. The emphasis is placed on the unique and basic properties of GO and their ordered assembly. We will also discuss challenges and issues that need to be overcome in order to gain a more fundamental understanding and exploit full device potentials of GO LCs.

  10. Using Greener Gels to Explore Rheology

    Science.gov (United States)

    Garrett, Brendan; Matharu, Avtar S.; Hurst, Glenn A.

    2017-01-01

    A laboratory experiment was developed to investigate the rheological properties of a green calcium-cross-linked alginate gel as an alternative to the traditional borax-cross-linked poly(vinyl alcohol) gel. As borax is suspected of damaging fertility and the unborn child, a safe, green alternative is necessary. The rheological properties of a…

  11. Rheological properties, shape oscillations, and coalescence of liquid drops with surfactants

    Science.gov (United States)

    Apfel, R. E.; Holt, R. G.

    1990-01-01

    A method was developed to deduce dynamic interfacial properties of liquid drops. The method involves measuring the frequency and damping of free quadrupole oscillations of an acoustically levitated drop. Experimental results from pure liquid-liquid systems agree well with theoretical predictions. Additionally, the effects of surfactants is considered. Extension of these results to a proposed microgravity experiment on the drop physics module (DPM) in USML-1 are discussed. Efforts are also underway to model the time history of the thickness of the fluid layer between two pre-coalescence drops, and to measure the film thickness experimentally. Preliminary results will be reported, along with plans for coalescence experiments proposed for USML-1.

  12. How granular vortices can help understanding rheological and mixing properties of dense granular flows

    Directory of Open Access Journals (Sweden)

    Rognon Pierre

    2017-01-01

    Full Text Available Dense granular flows exhibit fascinating kinematic patterns characterised by strong fluctuations in grain velocities. In this paper, we analyse these fluctuations and discuss their possible role on macroscopic properties such as effective viscosity, non-locality and shear-induced diffusion. The analysis is based on 2D experimental granular flows performed with the stadium shear device and DEM simulations. We first show that, when subjected to shear, grains self-organised into clusters rotating like rigid bodies. The average size of these so-called granular vortices is found to increase and diverge for lower inertial numbers, when flows decelerate and stop. We then discuss how such a microstructural entity and its associated internal length scale, possibly much larger than a grain, may be used to explain two important properties of dense granular flows: (i the existence of shear-induced diffusion of grains characterised by a shear-rate independent diffusivity and (ii the development of boundary layers near walls, where the viscosity is seemingly lower than the viscosity far from walls.

  13. Thiolated citrus low-methoxyl pectin: Synthesis, characterization and rheological and oxidation-responsive gelling properties.

    Science.gov (United States)

    Chen, Jinfeng; Ye, Fayin; Zhou, Yun; Zhao, Guohua

    2018-02-01

    In the present study, citrus low-methoxyl pectin was modified by conjugating cysteine via amide bonds, and the resultant polymer (CYS-PEC) was characterized. CYS-PEC conjugates with thiol contents varying from 77.8μmol/g to 296μmol/g were synthesized, and the successful conjugation was evidenced by elemental, and FT-IR analyses. The sulfur in CYS-PEC is predominately in the thiol form, with a minor fraction forming disulfide bonds (∼15%), which occur when thiol/disulfide interchange interrupts the intended thiolation. Both native and modified pectin dispersions exhibited strong pseudoplastic properties, and the frequency sweeps revealed them to be dispersions containing microgel particles. Dynamic viscoelastic analysis was used to determine the oxidation-response gelling capacities of polymer dispersions containing H 2 O 2 , especially those that are highly thiolated and have cross-linked gel properties. For oxidation-induced CYS-PEC gels, their gelation time, hardness, viscosity and elastic moduli and swelling-disintegration ratio are dependent on the thiol group content, H 2 O 2 concentration and polymer concentration. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Effect of Porcine Collagen Peptides on the Rheological and Sensory Properties of Ice Cream

    Science.gov (United States)

    2015-01-01

    The effects of low molecular-weight collagen peptides derived from porcine skin were investigated on the physicochemical and sensorial properties of chocolate ice cream. Collagen peptides less than 1 kDa in weight were obtained by sub-critical water hydrolysis at a temperature of 300℃ and a pressure of 80 bar. Ice cream was then prepared with gelatin powder and porcine skin hydrolysate (PSH) stabilizers mixed at seven different ratios (for a total of 0.5 wt%). There was no significant difference in color between the resulting ice cream mixtures. The increase in apparent viscosity and shear thinning of the ice cream was more moderate with PSH added than with gelatin. Moreover, the samples containing more than 0.2 wt% PSH had enhanced melting resistance, while the mixture with 0.2 wt% PSH had the lowest storage modulus at -20℃ and the second highest loss modulus at 10℃, indicating that this combination of hydrocolloids leads to relatively softer and creamier chocolate ice cream. Among the seven types of ice creams tested, the mixture with 0.2 wt% PSH and 0.3 wt% gelatin had the best physicochemical properties. However, in sensory evaluations, the samples containing PSH had lower chocolate flavor scores and higher off-flavor scores than the sample prepared with just 0.5 wt% gelatin due to the strong off-flavor of PSH. PMID:26761823

  15. Ultrasonication effects on thermal and rheological properties of carbon nanotube suspensions.

    Science.gov (United States)

    Ruan, Binglu; Jacobi, Anthony M

    2012-02-14

    The preparation of nanofluids is very important to their thermophysical properties. Nanofluids with the same nanoparticles and base fluids can behave differently due to different nanofluid preparation methods. The agglomerate sizes in nanofluids can significantly impact the thermal conductivity and viscosity of nanofluids and lead to a different heat transfer performance. Ultrasonication is a common way to break up agglomerates and promote dispersion of nanoparticles into base fluids. However, research reports of sonication effects on nanofluid properties are limited in the open literature. In this work, sonication effects on thermal conductivity and viscosity of carbon nanotubes (0.5 wt%) in an ethylene glycol-based nanofluid are investigated. The corresponding effects on the agglomerate sizes and the carbon nanotube lengths are observed. It is found that with an increased sonication time/energy, the thermal conductivity of the nanofluids increases nonlinearly, with the maximum enhancement of 23% at sonication time of 1,355 min. However, the viscosity of nanofluids increases to the maximum at sonication time of 40 min, then decreases, finally approaching the viscosity of the pure base fluid at a sonication time of 1,355 min. It is also observed that the sonication process not only reduces the agglomerate sizes but also decreases the length of carbon nanotubes. Over the current experimental range, the reduction in agglomerate size is more significant than the reduction of the carbon nanotube length. Hence, the maximum thermal conductivity enhancement and minimum viscosity increase are obtained using a lengthy sonication, which may have implications on application.

  16. Rheological, mechanical and tribological properties of carbon-nanofibre reinforced poly (ether ether ketone composites

    Directory of Open Access Journals (Sweden)

    Volker Altstaedt

    2003-12-01

    Full Text Available Poly(ether ether ketone nanocomposites containing vapour-grown carbon nanofibres (CNF were produced using standard polymer processing techniques. At high shear rates no significant increase in resin viscosity was observed. Nevertheless, the addition of the CNFs results in a higher melt strength at 360°C. Electron microscopy confirmed the homogeneous dispersion and alignment of nanofibres in the polymer matrix. Evaluation of the mechanical composite properties revealed a linear increase in tensile stiffness and strength with nanofibre loading fractions up to 15 wt% whilst matrix ductility was maintained up to 10 wt%. An interpretation of the composite performance by short-fibre theory resulted in rather low intrinsic stiffness properties of the vapour-grown CNF. Differential scanning calorimetry was used to investigate crystallization kinetics and degree of crystallinity. The CNFs were found not to act as nucleating sites. Furthermore, unidirectional sliding tests against two different counterpart materials (100Cr6 martensitic bearing steel, X5CrNi18-10 austenitic stainless steel were performed. The carbon nanofibres were found to reduce the wear rate of PEEK significantly.

  17. Effect of Porcine Collagen Peptides on the Rheological and Sensory Properties of Ice Cream.

    Science.gov (United States)

    Li, Liying; Kim, Jae-Hyeong; Jo, Yeon-Ji; Min, Sang-Gi; Chun, Ji-Yeon

    2015-01-01

    The effects of low molecular-weight collagen peptides derived from porcine skin were investigated on the physicochemical and sensorial properties of chocolate ice cream. Collagen peptides less than 1 kDa in weight were obtained by sub-critical water hydrolysis at a temperature of 300℃ and a pressure of 80 bar. Ice cream was then prepared with gelatin powder and porcine skin hydrolysate (PSH) stabilizers mixed at seven different ratios (for a total of 0.5 wt%). There was no significant difference in color between the resulting ice cream mixtures. The increase in apparent viscosity and shear thinning of the ice cream was more moderate with PSH added than with gelatin. Moreover, the samples containing more than 0.2 wt% PSH had enhanced melting resistance, while the mixture with 0.2 wt% PSH had the lowest storage modulus at -20℃ and the second highest loss modulus at 10℃, indicating that this combination of hydrocolloids leads to relatively softer and creamier chocolate ice cream. Among the seven types of ice creams tested, the mixture with 0.2 wt% PSH and 0.3 wt% gelatin had the best physicochemical properties. However, in sensory evaluations, the samples containing PSH had lower chocolate flavor scores and higher off-flavor scores than the sample prepared with just 0.5 wt% gelatin due to the strong off-flavor of PSH.

  18. Study of Thermal Properties, Turbidity, Effective Factors on Particle Size and Oscillatory Rheology of Pectin-Caseinate Biopolymer Nanocomplexes

    Directory of Open Access Journals (Sweden)

    Sajedeh Bahrani

    2013-02-01

    Full Text Available The biopolymer-based nanocomplexes are a group of nanocapsules that are used for encapsulation and control delivery of nutraceuticals. They are formed by binding of proteins and polysaccharides. In this study, complex formation between pectin and sodium caseinate was taken place by addition of pectin solutions(0.2, 0.45 and 0.7 % w/v into the caseinate solutions (0.5, 1 and 1.5 % w/v and adjusted their pH below isoelecteric point of sodium caseinate. The effect of various factors such as biopolymer concentration, salt concentration, temperature and time of ultrasound on the properties of pectin-casein nanocomplexes was investigated. Differential scanning calorimetry (DSC and particle size analyzer were used for study of complex formation and particle size determination, respectively. The results of DSC and turbidimetry showed complex formation between the pectin and casein at pH below 5 and the results of particle size showed formation of stable dispersion with a minimum size of 86 nm at pH 4.1, caseinate of 1 % w/v and pectin 0.45 % w/v concentration. The ultrasound for more than 1 min reduced particle size and addition of salt at high and low concentrations had different effects on the stability of the colloidal system. The lowering of temperature from 21 to 4°C resulted in smaller particle size of nanocomplexes. The oscillatory rheological results showed that with increasing pectin concentration, viscoelastic moduli were increased and loss moduli were higher than storage modulus.

  19. Effect of coated and uncoated ground flaxseed addition on rheological, physical and sensory properties of Taftoon bread.

    Science.gov (United States)

    Roozegar, M H; Shahedi, M; Keramet, J; Hamdami, N; Roshanak, S

    2015-08-01

    Flaxseed is used to fortify bread. In order to reduce cyanogenic glycosides compounds of flaxseed, ground flaxseed was incubated at 30 °C and heated in a kitchen microwave oven. The cyanogenic compounds of flaxseed were reduced to 13.4 %. Treated ground flaxseed was coated with Arabic gum solution containing ascorbic acid and hydrogenated fat and was stored at 25 °C for 80 days in order to prevent oxidation of flaxseed oil. Results showed that oxidation in coated samples was lower than that in control samples and that there was a significant difference between them (p < 0.01). Coated and uncoated ground flaxseed was added to wheat flour in 5, 15 and 25 % levels in order to produce fortified Taftoon bread. Rheological, physical and organoleptic tests were carried out in order to evaluate dough and bread properties. Results showed that with increasing coated and uncoated ground flaxseed percentages, a decrease in water absorption and an increase in stability, dough development and relaxation time of dough occurred. The lowest water absorption was observed by adding 25 % coated ground flaxseed with hydrogenated fat. The highest dough development and dough stability time were observed by adding 25 % coated ground flaxseed with Arabic gum. Results indicated that coated and uncoated ground flaxseed has a good effect on decreasing the staling rate compared to the control bread. Results of organoleptic test showed that bread with 5 and 15 % coated and uncoated ground flaxseed had better acceptability.

  20. Surface active monomers synthesis, properties, and application

    CERN Document Server

    Borzenkov, Mykola

    2014-01-01

    This brief includes information on the background?of and development of synthesis of various types of surface active monomers. The authors explain the importance of utilization of surface active monomers for creation of surface active polymers? and the various biomedical applications of such compounds . This brief introduces techniques for the synthesis of novel types of surface active monomers, their colloidal and polymerizable properties and application for needs of medicine and biology.

  1. Influence of Heavy Metal Powders on Rheological Properties of Poly(Lactic Acid)

    Science.gov (United States)

    Lebedev, S. M.; Gefle, O. S.; Amitov, E. T.; Berchuk, D. Yu.; Zhuravlev, D. V.

    2017-08-01

    Main properties of poly(lactic acid) (PLA) and composite materials on its basis filled with tungsten and lead powders are investigated. An anomalous decrease of the viscosity of melts of poly(lactic acid)/tungsten and poly(lactic acid)/lead composites is detected. The methods of differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and IR spectroscopy are used for investigation. It is shown that the temperature at which the composites filled with tungsten and lead begin to melt decreases by more than 8 and 3°C in comparison with neat PLA. Our investigations show impossibility of preparing radiation resistant polymer composites based on PLA filled with tungsten and lead powders.

  2. Effect of addition of bottom ash on the rheological properties of fly ash slurry at varying temperature

    Science.gov (United States)

    Kumar, K.; Kumar, S.; Gupta, M.; Garg, H. C.

    2016-09-01

    Presently, fly ash is transporting through slurry pipeline in the thermal power plant. Aim of the present investigation is to examine the rheological behaviour of finer particle (fly ash) slurry suspension with and without addition of coarser particles (bottom ash). Mixture of fly and bottom ash is taken with proportion of 9:1, 8:2 and 7:3 (by weight). The temperature of slurry suspension is varying from 25 to 40°C at solid concentration 30 % (by weight). Rheological tests are conducted with the variation of shear rate from 100 to 300 sec-1 for all slurry samples. Addition of coarse particles of bottom ash in finer particles of fly ash slurry, leads to improve the rheological characteristics of slurry suspension. The addition of bottom ash can result substantial saving in energy consumption with reduction in relative viscosity.

  3. Thermodynamic and rheological properties of solid-liquid systems in coal processing. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Kabadi, V.N.

    1995-06-30

    The work on this project was initiated on September 1, 1991. The project consisted of two different tasks: (1) Development of a model to compute viscosities of coal derived liquids, and (2) Investigate new models for estimation of thermodynamic properties of solid and liquid compounds of the type that exist in coal, or are encountered during coal processing. As for task 1, a model for viscosity computation of coal model compound liquids and coal derived liquids has been developed. The detailed model is presented in this report. Two papers, the first describing the pure liquid model and the second one discussing the application to coal derived liquids, are expected to be published in Energy & Fuels shortly. Marginal progress is reported on task 2. Literature review for this work included compilation of a number of data sets, critical investigation of data measurement techniques available in the literature, investigation of models for liquid and solid phase thermodynamic computations. During the preliminary stages it was discovered that for development of a liquid or solid state equation of state, accurate predictive models for a number of saturation properties, such as, liquid and solid vapor pressures, saturated liquid and solid volumes, heat capacities of liquids and solids at saturation, etc. Most the remaining time on this task was spent in developing predictive correlations for vapor pressures and saturated liquid volumes of organic liquids in general and coal model liquids in particular. All these developments are discussed in this report. Some recommendations for future direction of research in this area are also listed.

  4. Ultrasonication effects on thermal and rheological properties of carbon nanotube suspensions

    Science.gov (United States)

    2012-01-01

    The preparation of nanofluids is very important to their thermophysical properties. Nanofluids with the same nanoparticles and base fluids can behave differently due to different nanofluid preparation methods. The agglomerate sizes in nanofluids can significantly impact the thermal conductivity and viscosity of nanofluids and lead to a different heat transfer performance. Ultrasonication is a common way to break up agglomerates and promote dispersion of nanoparticles into base fluids. However, research reports of sonication effects on nanofluid properties are limited in the open literature. In this work, sonication effects on thermal conductivity and viscosity of carbon nanotubes (0.5 wt%) in an ethylene glycol-based nanofluid are investigated. The corresponding effects on the agglomerate sizes and the carbon nanotube lengths are observed. It is found that with an increased sonication time/energy, the thermal conductivity of the nanofluids increases nonlinearly, with the maximum enhancement of 23% at sonication time of 1,355 min. However, the viscosity of nanofluids increases to the maximum at sonication time of 40 min, then decreases, finally approaching the viscosity of the pure base fluid at a sonication time of 1,355 min. It is also observed that the sonication process not only reduces the agglomerate sizes but also decreases the length of carbon nanotubes. Over the current experimental range, the reduction in agglomerate size is more significant than the reduction of the carbon nanotube length. Hence, the maximum thermal conductivity enhancement and minimum viscosity increase are obtained using a lengthy sonication, which may have implications on application. PMID:22333487

  5. Surface composition and surface properties of water hyacinth ...

    African Journals Online (AJOL)

    The surface composition and surface properties of water hyacinth (Eichhornia crassipes) root biomass were studied before and after extraction with dilute nitric acid and toluene/ethanol (2/1, v/v) followed by ethanol, using Fourier Transform Infra-red (FT-IR) spectroscopy, thermogravimetric analysis, x-ray diffraction, ...

  6. The unusual properties of beryllium surfaces

    International Nuclear Information System (INIS)

    Stumpf, R.; Hannon, J.B.

    1994-01-01

    Be is a ''marginal metal.'' The stable phase, hcp-Be, has a low Fermi-level density of states and very anisotropic structural and elastic properties, similar to a semiconductor's. At the Be(0001) surface, surface states drastically increase the Fermi-level density of states. The different nature of bonding in bulk-Be and at the Be(0001) surface explains the large outward relaxation. The presence of surface states causes large surface core-level shifts by inducing a higher electrostatic potential in the surface layers and by improving the screening at the surface. The authors experimental and theoretical investigations of atomic vibrations at the Be(0001) surface demonstrate clearly that Be screening of atomic motion by the surface states makes the surface phonon dispersion fundamentally different from that of the bulk. Properties of Be(0001) are so different from those of the bulk that the surface can be considered a new ''phase'' of beryllium with unique electronic and structural characteristics. For comparison they also study Be(11 bar 20), a very open surface without important surface states. Be(11 bar 20) is the only clean s-p metal surface known to reconstruct (1 x 3 missing row reconstruction)

  7. Competitive adsorption from mixed hen egg-white lysozyme/surfactant solutions at the air-water interface studied by tensiometry, ellipsometry, and surface dilational rheology.

    Science.gov (United States)

    Alahverdjieva, V S; Grigoriev, D O; Fainerman, V B; Aksenenko, E V; Miller, R; Möhwald, H

    2008-02-21

    The competitive adsorption at the air-water interface from mixed adsorption layers of hen egg-white lysozyme with a non-ionic surfactant (C10DMPO) was studied and compared to the mixture with an ionic surfactant (SDS) using bubble and drop shape analysis tensiometry, ellipsometry, and surface dilational rheology. The set of equilibrium and kinetic data of the mixed solutions is described by a thermodynamic model developed recently. The theoretical description of the mixed system is based on the model parameters for the individual components.

  8. The influence of Glu-1 and Glu-3 loci on dough rheology and bread-making properties in wheat (Triticum aestivum L.) doubled haploid lines.

    Science.gov (United States)

    Langner, Monika; Krystkowiak, Karolina; Salmanowicz, Bolesław P; Adamski, Tadeusz; Krajewski, Paweł; Kaczmarek, Zygmunt; Surma, Maria

    2017-12-01

    The major determinants of wheat quality are Glu-1 and Glu-3 glutenin loci and environmental factors. Additive effects of alleles at the Glu-1 and Glu-3 loci, as well as their interactions, were evaluated for dough rheology and baking properties in four groups of wheat doubled haploid lines differing in high- and low-molecular-weight glutenin composition. Flour quality, Reomixer (Reologica Instruments, Lund, Sweden), dough extension, Farinograph (Brabender GmbH, Duisburg, Germany) and baking parameters were determined. Groups of lines with the alleles Glu-A3b and Glu-B3d were characterized by higher values of dough and baking parameters compared to those with the Glu-A3e and Glu-B3a alleles. Effects of interactions between allelic variants at the Glu-1 and Glu-3 loci on Reomixer parameters, dough extension tests and baking parameters were significant, although additive effects of individual alleles were not always significant. The allelic variants at Glu-B3 had a much greater effect on dough rheological parameters than the variants at Glu-A3 or Glu-D3 loci. The effect of allelic variations at the Glu-D3 loci on rheological parameters and bread-making quality was non-significant, whereas their interactions with a majority of alleles at the other Glu-1 × Glu-3 loci were significant. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  9. Long-term rheological and transport properties of dry and wet salt rocks

    International Nuclear Information System (INIS)

    Spiers, C.J.; Peach, C.J.; Brzesowsky, R.H.; Schutjens, P.M.T.M.; Liezenberg, J.L.; Zwart, H.J.

    1988-01-01

    This report forms a final report on Aims 1 to 3 of Contract No FI1W-0051-NL. It is opened in Section 2 with a consideration of the theoretical background necessary for a state-of-the-art treatment of compaction creep in granular salt and backfill materials (Aim 3). Fundamental experimental work on compaction creep in wet and dry salt aggregates is presented in Sections 3 and 4 respectively. In Section 5 this is extended to investigate the influence of backfill variables (such as brine content, grain-size distribution, and additives content) on the compaction creep behaviour of granular salt, and to develop a generally applicable constitutive law for salt backfill and cement materials. In Section 6 an optimal (i.e. fast-compaction/retention-efficient) backfill recipe is proposed. Experiments designed to test/verify the applicability of our general constitutive law to this recipe, to determine its permeability versus porosity characteristics, and to clarify the very long term properties and microstructure of both backfill and cement, are also reported. The conclusions drawn complete our work on backfill. Section 7 deals with work done on the long-term constitutive behaviour of salt rock (Aim 1) and on creep-induced dilatancy (Aim 2). Investigations into the permeability characteristics of dilated salt and (fractured) anhydrite rock are reported in Section 8. The report is terminated in Section 9 with an overall summary of results and conclusions

  10. Thermoplastic starch composites with TiO2 particles: Preparation, morphology, rheology and mechanical properties.

    Science.gov (United States)

    Ostafińska, A; Mikešová, J; Krejčíková, S; Nevoralová, M; Šturcová, A; Zhigunov, A; Michálková, D; Šlouf, M

    2017-08-01

    Composites of thermoplastic starch (TPS) with titanium dioxide particles (mTiO 2 ; average size 0.1μm) with very homogeneous matrix and well-dispersed filler were prepared by a two-step method, including solution casting (SC) followed by melt mixing (MM). Light and scanning electron microscopy confirmed that only the two-step procedure (SC+MM) resulted in ideally homogeneous TPS/mTiO 2 systems. The composites prepared by single-step MM contained non-plasticized starch granules and the composites prepared by single-step SC suffered from mTiO 2 agglomeration. Dynamic mechanical measurements showed an increase modulus with increasing filler concentration. In TPS containing 3wt.% of mTiO 2 the stiffness was enhanced by >40%. Further experiments revealed that the recommended addition of chitosan or the exchange of mTiO 2 for anisometric titanate nanotubes with high aspect ratio did not improve the properties of the composites. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Defined wetting properties of optical surfaces

    Science.gov (United States)

    Felde, Nadja; Coriand, Luisa; Schröder, Sven; Duparré, Angela; Tünnermann, Andreas

    2017-10-01

    Optical surfaces equipped with specific functional properties have attracted increasing importance over the last decades. In the light of cost reduction, hydrophobic self-cleaning behavior is aspired. On the other side, hydrophilic properties are interesting due to their anti-fog effect. It has become well known that such wetting states are significantly affected by the surface morphology. For optical surfaces, however, this fact poses a problem, as surface roughness can induce light scattering. The generation of optical surfaces with specific wetting properties, hence, requires a profound understanding of the relation between the wetting and the structural surface properties. Thus, our work concentrates on a reliable acquisition of roughness data over a wide spatial frequency range as well as on the comprehensive description of the wetting states, which is needed for the establishment of such correlations. We will present our advanced wetting analysis for nanorough optical surfaces, extended by a vibration-based procedure, which is mainly for understanding and tailoring the wetting behavior of various solid-liquid systems in research and industry. Utilizing the relationships between surface roughness and wetting, it will be demonstrated how different wetting states for hydrophobicity and hydrophilicity can be realized on optical surfaces with minimized scatter losses.

  12. Metrology and properties of engineering surfaces

    CERN Document Server

    Greenwood, J; Chetwynd, D

    2001-01-01

    Metrology and Properties of Engineering Surfaces provides in a single volume a comprehensive and authoritative treatment of the crucial topics involved in the metrology and properties of engineering surfaces. The subject matter is a central issue in manufacturing technology, since the quality and reliability of manufactured components depend greatly upon the selection and qualities of the appropriate materials as ascertained through measurement. The book can in broad terms be split into two parts; the first deals with the metrology of engineering surfaces and covers the important issues relating to the measurement and characterization of surfaces in both two and three dimensions. This covers topics such as filtering, power spectral densities, autocorrelation functions and the use of Fractals in topography. A significant proportion is dedicated to the calibration of scanning probe microscopes using the latest techniques. The remainder of the book deals with the properties of engineering surfaces and covers a w...

  13. A dynamic rheological model for thin-film lubrication

    International Nuclear Information System (INIS)

    Zhang Xiang-Jun; Huang Ying; Guo Yan-Bao; Tian Yu; Meng Yong-Gang

    2013-01-01

    In this study, the effects of the non-Newtonian rheological properties of the lubricant in a thin-film lubrication regime between smooth surfaces were investigated. The thin-film lubrication regime typically appears in Stribeck curves with a clearly observable minimum coefficient of friction (COF) and a low-COF region, which is desired for its lower energy dissipation. A dynamic rheology of the lubricant from the hydrodynamic lubrication regime to the thin-film lubrication regime was proposed based on the convected Maxwell constitutive equation. This rheology model includes the increased relaxation time and the yield stress of the confined lubricant thin film, as well as their dependences on the lubricant film thickness. The Deborah number (De number) was adopted to describe the liquid-solid transition of the confined lubricant thin film under shearing. Then a series of Stribeck curves were calculated based on Tichy's extended lubrication equations with a perturbation of the De number. The results show that the minimum COF points in the Stribeck curve correspond to a critical De number of 1.0, indicating a liquid-to-solid transition of the confined lubricant film. Furthermore, the two proposed parameters in the dynamic rheological model, namely negative slipping length b (indicating the lubricant interfacial effect) and the characteristic relaxation time λ 0 , were found to determine the minimum COF and the width of the low-COF region, both of which were required to optimize the shape of the Stribeck curve. The developed dynamic rheological model interprets the correlation between the rheological and interfacial properties of lubricant and its lubrication behavior in the thin-film regime. (condensed matter: structural, mechanical, and thermal properties)

  14. Effect of enzymatic treatments on the rheological and oil-resisting properties of wheat flour-based frying batters

    Science.gov (United States)

    A new enzymatic approach was introduced to reduce the oil uptake of batter-coated fried foods. Cross-linking (transglutaminase) and cell wall-degrading (viscozyme) enzymes were incorporated into the formulation of wheat flour-based frying batters and their rheological/oil-resisting effects were eva...

  15. Influence of pH and temperature on the rheological properties of aqueous dispersions of starch-sodium palmitate complexes

    Science.gov (United States)

    Aqueous dispersions of high-amylose corn starch were steam jet cooked and blended with aqueous solutions of sodium palmitate to form amylose inclusion complexes. The rheology of dispersions of these complexes was examined. Acetic acid was added to reduce the pH, converting complexed sodium palmita...

  16. To Evaluate the Effect of Solvents and Different Relative Humidity Conditions on Thermal and Rheological Properties of Microcrystalline Cellulose 101 Using METHOCEL™ E15LV as a Binder.

    Science.gov (United States)

    Jagia, Moksh; Trivedi, Maitri; Dave, Rutesh H

    2016-08-01

    The solvent used for preparing the binder solution in wet granulation can affect the granulation end point and also impact the thermal, rheological, and flow properties of the granules. The present study investigates the effect of solvents and percentage relative humidity (RH) on the granules of microcrystalline cellulose (MCC) with hydroxypropyl methyl cellulose (HPMC) as the binder. MCC was granulated using 2.5% w/w binder solution in water and ethanol/water mixture (80:20 v/v). Prepared granules were dried until constant percentage loss on drying, sieved, and further analyzed. Dried granules were exposed to different percentage RH for 48 h at room temperature. Powder rheometer was used for the rheological and flow characterization, while thermal effusivity and differential scanning calorimeter were used for thermal analysis. The thermal effusivity values for the wet granules showed a sharp increase beginning 50% w/w binder solution in both cases, which reflected the over-wetting of granules. Ethanol/water solvent batches showed greater resistance to flow as compared to the water solvent batches in the wet granule stage, while the reverse was true for the dried granule stage, as evident from the basic flowability energy values. Although the solvents used affected the equilibration kinetics of moisture content, the RH-exposed granules remained unaffected in their flow properties in both cases. This study indicates that the solvents play a vital role on the rheology and flow properties of MCC granules, while the different RH conditions have little or no effect on them for the above combination of solvent and binder.

  17. Morphology and Structural Properties of Novel Short Linear Glucan/Protein Hybrid Nanoparticles and Their Influence on the Rheological Properties of Starch Gel.

    Science.gov (United States)

    Li, Xiaojing; Ji, Na; Li, Man; Zhang, Shuangling; Xiong, Liu; Sun, Qingjie

    2017-09-13

    Starch nanoparticles were potential texture modifiers. However, they have strong tendency to aggregate and poor water dispersibility, which limited their application. The interaction between glucan (prepared from starch by enzymatic modification) and protein could significantly improve the dispersity of starch nanoparticles and, thus, enhance the rheological properties of food gels. In this work, glucan/protein hybrid nanoparticles were successfully developed for the first time using short linear glucan (SLG) and edible proteins [soy protein isolate (SPI), rice protein (RP), and whey protein isolate (WPI)]. The results showed that the SLG/SPI hybrid nanoparticles exhibited hollow structures, of which the smallest size was approximately 10-20 nm when the SLG/SPI ratio was 10:5. In contrast, SLG/RP nanoparticles displayed flower-like superstructures, and SLG/WPI nanoparticles presented stacked lamellar nanostructures with a width of 5-10 nm and a length of 50-70 nm. In comparison to bare SLG nanoparticles, SLG/SPI and SLG/WPI hybrid nanoparticles had higher melting temperatures. The addition of all nanoparticles greatly increased the storage modulus of corn starch gels and decreased loss tangent values. Importantly, the G' value of starch gels increased by 567% with the addition of flower-like SLG/RP superstructures.

  18. A comparative study of the effects of cone-plate and parallel-plate geometries on rheological properties under oscillatory shear flow

    Science.gov (United States)

    Song, Hyeong Yong; Salehiyan, Reza; Li, Xiaolei; Lee, Seung Hak; Hyun, Kyu

    2017-11-01

    In this study, the effects of cone-plate (C/P) and parallel-plate (P/P) geometries were investigated on the rheological properties of various complex fluids, e.g. single-phase (polymer melts and solutions) and multiphase systems (polymer blend and nanocomposite, and suspension). Small amplitude oscillatory shear (SAOS) tests were carried out to compare linear rheological responses while nonlinear responses were compared using large amplitude oscillatory shear (LAOS) tests at different frequencies. Moreover, Fourier-transform (FT)-rheology method was used to analyze the nonlinear responses under LAOS flow. Experimental results were compared with predictions obtained by single-point correction and shear rate correction. For all systems, SAOS data measured by C/P and P/P coincide with each other, but results showed discordance between C/P and P/P measurements in the nonlinear regime. For all systems except xanthan gum solutions, first-harmonic moduli were corrected using a single horizontal shift factor, whereas FT rheology-based nonlinear parameters ( I 3/1, I 5/1, Q 3, and Q 5) were corrected using vertical shift factors that are well predicted by single-point correction. Xanthan gum solutions exhibited anomalous corrections. Their first-harmonic Fourier moduli were superposed using a horizontal shift factor predicted by shear rate correction applicable to highly shear thinning fluids. The distinguished corrections were observed for FT rheology-based nonlinear parameters. I 3/1 and I 5/1 were superposed by horizontal shifts, while the other systems displayed vertical shifts of I 3/1 and I 5/1. Q 3 and Q 5 of xanthan gum solutions were corrected using both horizontal and vertical shift factors. In particular, the obtained vertical shift factors for Q 3 and Q 5 were twice as large as predictions made by single-point correction. Such larger values are rationalized by the definitions of Q 3 and Q 5. These results highlight the significance of horizontal shift

  19. Rheological properties and physical stability of ecological emulsions stabilized by a surfactant derived from cocoa oil and high pressure homogenization

    Directory of Open Access Journals (Sweden)

    Trujillo-Cayado, L. A.

    2015-09-01

    Full Text Available The goal of this work was to investigate the influence of the emulsification method on the rheological properties, droplet size distribution and physical stability of O/W green emulsions formulated with an eco-friendly surfactant derived from cocoa oil. The methodology used can be applied to other emulsions. Polyoxyethylene glycerol esters are non-ionic surfactants obtained from a renewable source which fulfill the environmental and toxicological requirements to be used as eco-friendly emulsifying agents. In the same way, N,NDimethyloctanamide and α-Pinene (solvents used as oil phase could be considered green solvents. Emulsions with submicron mean diameters and slight shear thinning behavior were obtained regardless of the homogenizer, pressure or number of passes used. All emulsions exhibited destabilization by creaming and a further coalescence process which was applied to the coarse emulsion prepared with a rotor-stator homogenizer. The emulsion obtained with high pressure at 15000 psi and 1-pass was the most stable.El objetivo de este trabajo fue estudiar la influencia del método de emulsificación sobre las propiedades reológicas, la distribución de tamaños de gota y la estabilidad física de emulsiones verdes O/W formuladas con un tensioactivo derivado del aceite de coco respetuoso con el medioambiente. La metodología empleada puede ser aplicada a cualquier otro tipo de emulsiones. Los ésteres polietoxilados de glicerina son tensioactivos no iónicos obtenidos de fuentes renovables que cumplen requisitos medioambientales y toxicológicos para ser usados como agentes emulsionantes ecológicos. Del mismo modo, la N,N-dimetil octanamida y el α-Pineno (disolventes usados como fase oleosa pueden ser considerados como disolventes verdes. Se han obtenido emulsiones con diámetros medio submicrónicos y comportamiento ligeramente pseudoplástico independientemente del equipo, la presión o el número de pasadas empleados. Todas las

  20. Grain quality characteristics and dough rheological properties in Langdon durum-wild emmer wheat chromosome substitution lines under nitrogen and water deficits.

    Science.gov (United States)

    Salmanowicz, Bolesław P; Langner, Monika; Mrugalska, Beata; Ratajczak, Dominika; Górny, Andrzej G

    2017-05-01

    Wild emmer wheat could serve as a source of novel variation in grain quality and stress resistance for wheat breeding. A set of Triticum durum-T. dicoccoides chromosome substitution lines [LDN(DIC)] and the parental recipient cv. Langdon grown under contrasting water and nitrogen availability in the soil was examined in this study to identify differences in grain quality traits and dough rheological properties. Significant genotypic variation was found among the materials for studied traits. This variation was also considerably affected by soil treatments and G × E interactions. The substitutions LDN(DIC-1A) and LDN(DIC-1B) showed separate differentiation in the composition of glutenin sub-units. The results indicated that primarily chromosome DIC-6B is stable source of an enhanced grain protein content and advantageous dough rheological properties. Similar features seem to be shown by the substitutions with the DIC-1A, DIC-2A and DIC-6A, but not under nitrogen shortage, when generally a considerable decrease was noticed in the range of genotypic variation in grain quality. The substitution lines, particularly those with DIC-6B and DIC-6A and to a lesser extent DIC-1A and DIC-2A, were distinguished by advantageous grain quality traits, mixing properties and dough functionality and appear to be the most promising sources of innovative genes for wheat breeding. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.