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This study explores the effect of various concentrations of Xanthan gum on the rheological behaviour of commercial mayonnaise. The various concentrations of Xanthan gum, ranging from 0.1 to 0.5% based on the weight of the mayonnaise which were mixed in the commercial mayonnaise via a high overhead stirrer at room temperature. The rheological characterizations were carried out on a Brookfield viscometer. Using Mitschka's method, the recorded data was changed into rheological parameters. Three rheological models, namely the Power-law model, Bingham model and Herschel-Bulkley model, used to determine the flow parameters of the samples. All the samples showed shear thinning behaviour at least in the shear rate used in this study. According to the goodness of fit (regression coefficient), the power law model was the best for determining flow parameters. It was observed that the consistency viscosity (K) increases with an increase in Xanthan gum concentration, at least for the concentration ranges used in this research. The higher value of K indicates that the mayonnaise becomes thick with Xanthan gum and will require higher yield stress to start flow. It was interesting to note that at 0.1% Xanthan gum concentration, the power index reached a plateau value of 0.1135. [ABSTRACT FROM AUTHOR]

The rheological behaviour of dilute soil-water mixtures, such as hyperconcentrated mixtures and interstitial fluids in debris flows, can significantly affect the flow dynamics of flow-type landslides. These mixtures often contain clay, silt, and sandy particles. Despite great efforts, the effects of soil type and texture on the rheological behaviour of these mixtures are still not well understood. To tackle this issue, an experimental investigation is carried out using a narrow-gap rotational viscometer to evaluate the interactions from colloidal (clay) and non-colloidal (silt and sand) particles and possibility of flow regime change. The flow curves of dilute mixtures are determined with and without a dispersion agent. A functional curve between spindle speed and Reynolds Number or Froud Number is proposed to distinguish different flow regimes in the narrow-gap rotational viscometer. Results demonstrate the applicability of the Bingham model for describing the bulk rheological behaviour of dilute mixtures. The mixture viscosity governs the contribution of the hydrodynamic effects from all particles, while the yield stress governs the contribution of the colloidal effects from colloidal particles. Results also reveal that for dilute mixtures containing particles up to medium sand size, the main cause of the flow regime change is the flow boundary conditions. [ABSTRACT FROM AUTHOR]

Unreasonable choice of solid content (SC) and cement-to-tailings ratio (c/t), including pipeline networking system, will lead to some pipeline problems, such as blockage, wear, and rupture. Hence, this study deals with the rheology and sedimentation characteristics of fresh CTB slurry. Samples having a SC value of 65, 67 and 69wt.%, as well as a c/t ratio of 1:2, 1:1 and 1:4, were prepared and exposed to their rheological tests. Likewise, the sedimentation properties of CTB slurry was studied by picking polyacrylamide (PAM) as flocculant. Results showed that: (1) CTB's slump reduced with growing SC and c/t values when SC was kept constant. (2) The viscosity and shear stress increased with increasing SC values, signifying a linear link between shear stress and stress rate. (3) There was also an exponential link between sedimentation rate and PAM flocculant content in CTB. When PAM value increased from 75 to 80 g/t, a clear difference was observed in the clarification layer height (CLH). The CLH increments were also 7.5 and 7.14% for a ST of 20 and 30 min, respectively. Finally, this work will greatly contribute to the mining industry in assessing the transport aspect of CTB slurry to underground mined-out stopes. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study to evaluate the effect of local mineral additions (pozzolan, slag and limestone) on the rheological behaviour of based cement binder's pastes. The binary, ternary and quaternary binder pastes were prepared with the partial clinker cement replacement limited up to 20%, according with type CEM II specifications. The cements were characterized by their geometric shapes, the reactivity and the chemical composition. An experimental design plan was used to modelling the rheological behaviour of pastes. The relatives yield stress and plastic viscosity of binder's pastes, with normal consistency, were determined. The results showed that all the tested compositions with additions follow the same rheological behaviour law according to the Bingham model. The binder pastes rheological parameters (yield stress and viscosity) are affected by mineral additions. The highest values of the rheological parameters were measured in binary and ternary cements with limestone and pozzolan. On the other hand, the lower viscosity among the tested pastes was obtained with slag addition. The statistical approach allowed us to obtain a satisfactory modelling of viscosity and yield stress with a coefficient of determination R2 = 0.91 and 0.92, respectively and a satisfactory correlation between the viscosity and the water/binder ratio (W/B) for a normal consistency with a coefficient of determination R2 = 0.91. [ABSTRACT FROM AUTHOR]

Poly-(lactic acid) (PLA) is a biodegradable polymer from renewable resources produced as potential alternative to the synthetic polymers. One of the alternative applications is a preparation of PLA fibres. The PLA fibres prepared by classical spinning technology do not have good mechanical properties, especially elongation at the break. The prepared PLA fibres are very brittle with bad processability. The modification of the PLA fibres with plasticisers and additives/nanoadditives is one of the perspective ways for improvement of processability of the PLA fibres and increasing of multifunctional properties of these fibres. This work focuses on the preparation of fibres from various types of PLA modified with nucleating agent talc. The effect of content of various PLAs and additives on rheological properties of blends was evaluated. The thermal, mechanical and thermo-mechanical properties of prepared fibres from PLAs and modifiers were monitored. [ABSTRACT FROM AUTHOR]

Rheological behaviour of the mushy zone is dependent on the microstructure and related to parameters such as temperature, shear rate and shear strain/time. However, constitutive modelling of the rheological behaviour is difficult due to the diversity of the parameters. This study focuses on the influence of the microstructure and the above parameters on the rheological behaviour of partially solidified A356 alloy and establishing a constitutive model accordingly. During solidification, the evolution of α-Al phase leads to the changes of the apparent viscosity of mushy zone. Steady-state viscosity and peak viscosity measured by rotational rheometry reveal the thixotropy of the mushy zone. The thixotropic strength is found to increase with increasing shear rate and decreasing temperature. The peak viscosity, as well as the steady-state viscosity, is found to obey a power law model and is modelled using the power law model with the coupling of temperature and shear rate. Furthermore, a constitutive model with temperature, shear rate, shear tress and shear strain/time as parameters which describes the rheological behaviour of the mushy zone of partially solidified A356 alloy accurately and completely is established. Comparing with previously reported experimental results, the FEM simulation employing the constitutive model works well in enabling visualization of the viscoelastic filling process of A356 alloy in mushy zone. The constitutive model provides a solution for characterizing the forming behaviour of other mushy zone/semi-solid aluminium alloys with corresponding rheological parameters. Image 1 • Rheological behaviour of partially solidified A356 alloy is studied. • Thixotropic strength increases with increasing shear rate/decreasing temperature. • Peak viscosity, as well as steady-state viscosity, obeys a power law model. • A novel constitutive model of partially solidified A356 alloy is established. • The model provides a solution for characterizing the forming behaviour of alloys. [ABSTRACT FROM AUTHOR]

Highlights • A novel technique to characterize thixotropic behavior of water based MWCNT nanofluids is proposed. • Effect of temperature on viscosity of MWCNT nanofluids has been conducted at three shear rates (5, 50 and 500 s−1). • A new accurate correlation as a function of concentration, temperature and shear rate is proposed. Abstract The rheological properties of water based MWCNT nanofluids are investigated at five different low volume concentrations (0.0047%, 0.0238%, 0.0571%, 0.1428%, 0.2381%) and five low temperatures (275 K, 277 K, 279 K, 281 K, 283 K) by a novel experimental method in the present study. The present methodology combines the 3ITT test and the DSO test. Measurements show that the nanofluids are featured with clear thixotropy and shear thinning behaviors when the concentration is above 0.0571%. It is further shown that the thixotropy becomes less obvious as the concentration lowers implying a stronger Newtonian fluid characteristic. Therefore the concentration of 0.0571% can be regarded as the critical point quantifying the transition from Newtonian to non-Newtonian and this critical concentration is independent of temperature. It is also observed that relative viscosity increases slightly with temperature at medium shear rate. Moreover, temperature sweep measurement suggests that the viscosity decreases with temperature firstly and it increases beyond a critical temperature, which can be curbed by raising the shear rate for solutions with concentration lower than 0.0571%. The dependency of the relative viscosity of the MWCNT nanofluids on shear rate, temperature and concentration is obtained and a new and accurate correlation is developed for engineering application. [ABSTRACT FROM AUTHOR]

In this article, the molecular-weight dependence of the phase structure, rheological behaviour and thermal stability of a main-chain liquid crystalline polyester (PBDPS) with strong π-π interaction was investigated in details by differential scanning calorimetry, polarising optical microscopy, wide-angle X-ray diffraction, dynamic oscillatory rheological measurements and thermogravimetric analysis. While the molecular weight of PBDPS is 5.2k, it shows smectic B and smectic A phases prior to isotropic phase. With increasing molecular weight, smectic B phase of PBDPS gradually disappeared. Moreover, the smecitc B to smectic A (Tlc) and smectic A to isotropic (Ti) phase transition temperatures decreased as increased molecular weight. The rheology results suggested that fluid type of PBDPSs changed from Newtonian fluid to pseudo-plastic fluid as the molecular weight of PBDPS increased. In addition, the zero-shear viscosity (η0) of PBDPS showed a power law relationship () with molecular weight of PBDPS. All the PBDPSs showed good thermal stability with an initial decomposition temperature higher than 360°C. [ABSTRACT FROM AUTHOR]

Abstract Energy efficiency of systems stands out as a critical parameter to achieve sustainability. Heat transfer processes spend an important part of overall energy consumption, so the enhancement of its efficiency is an important research field. Nanofluids have received increasing attention to reach this goal because of its initial conception as thermal-improved working fluids. Nevertheless, the increase in thermal conductivity produced by the dispersion of nanoparticles should not be the only focus. In forced convection processes, viscosity plays an important role in achieving an improvement of the exchange of heat. In addition, the energy consumption needed to pump the new fluid is directly related to its viscosity. In this work, the rheological behaviour of different loaded functionalized graphene nanoplatelet dispersions (nanoparticle mass concentrations, wt%, of 0.25, 0.50, 0.75 and 1.0) in three based fluids (water, propylene glycol:water mixture at 30:70 wt% and propylene glycol:water mixture at 50:50 wt%) has been investigated by using a rotational rheometer. A double cone geometry was employed together with a cover specially appropriated to help thermostatization and avoid evaporation at high temperatures. The viscosity curves in the shear rate range from 10 to 1000 s−1, with 10 points per decade, and in the temperature range from 283.15 to 353.15 K, with 10 K step, were determined for the three base fluids and the twelve different nanofluids. The dynamic viscosities values of the base fluids were compared with those available in the literature, absolute average deviations being lower than the experimental uncertainty. The dynamic viscosities of the nanofluids were obtained for the Newtonian ranges and their dependences with temperature and nanoadditive concentration were analysed, as well as the influence of the base fluid on these trends. Furthermore, the fitting parameters of an equation that models temperature and nanoparticle concentration dependences are provided, which allow to describe viscosity data for each of the three sets of nanofluids with deviations lower than 1.8%. Finally, linear viscoelastic oscillatory experiments were performed for those samples that showed evidences of Non-Newtonian behaviour in the non-linear tests. These oscillatory tests were carried out in the deformation range from 0.1 to 1000% at constant frequency, 1 Hz, and at 283.15 and 293.15 K. Unlike the base fluids and other nanofluids sets, the nanofluids of the analysed propylene glycol:water 50:50 nanofluid set at 283.15 K and 293.15 K present a clear shear thinning (pseudoplastic) non-Newtonian behaviour, the Newtonian plateaus being easily identified as the concentration rises in the lowest deformations range. [ABSTRACT FROM AUTHOR]

Developing an industrial liquid fuel based on charcoal and water was the target of the present work. The relevance of this study is justified by the high energy potential of charcoal, its renewable nature, the easiness of storage and transportation in the liquid form, and by all the associated economic and environmental advantages derived thereof. The ability of a commercially available charcoal to be dispersed in water was evaluated by analysing the rheological behaviour of the resulting charcoal water slurries (ChWS). The charcoal was ground in a conventional ball mill and dispersed in water with the aid of different surfactants. The effects of the most relevant factors influencing the rheological properties of the suspensions were evaluated, including: (i) type of surfactant and its added amount on the fuel viscosity (η) at a given solids fraction; (ii) the charcoal content, which should be as high as possible. The results enabled selecting the most efficient surfactant and its optimal amount required for minimising the fuel viscosity (η) and enhancing the stability of the suspensions. Stable ChWS containing 60 wt.% solids and 1 wt.% surfactant and exhibiting adequate flow properties were successfully obtained. [ABSTRACT FROM AUTHOR]

The low thermal conductivity of the fluids usually used in heat exchange processes (water, oils, glycols…) has proved to be one of the limiting factors in improving their heat transfer performance. These traditional fluids enhance their thermal capabilities by dispersing nano-sized particles with high thermal conductivity, as many researches have revealed in the last decades. Although the thermal conductivity of nanofluids has centred the interest of the heat transfer community, the rheological behaviour of the resulting dispersions is very influential in the heat transfer process, pressure drops and pumping powers. In this work, different samples of functionalized graphene nanoplatelets dispersed into two different binary mixtures of propylene glycol and water at 10:90 wt% and 30:70 wt% have been analysed by using a DHR-2 rotational rheometer equipped with concentric cylinder geometry. Firstly, the flow curves for Krytox GPL102 oil, pure propylene glycol, and the two binary mixtures of propylene glycol and water used as base fluids were experimentally obtained. These values were used to check our experimental procedure finding a good agreement between them and those reported and well known in the literature, with an absolute average deviation of 2.0%. Then, the viscosity-shear rate curves in the temperature range from 278.15 to 323.15 K were obtained for the different graphene nanofluid sets. Furthermore, a new equation was proposed in this work to describe the viscosity dependence on both the temperature and the nanoparticles volume concentration of graphene nanoplatelet nanofluids with an absolute average deviation with respect to our experimental data lower than 2%. Additionally, oscillatory tests of the samples were performed observing pseudoplastic behaviour for the nanofluids at lower angular frequencies. [ABSTRACT FROM AUTHOR]

Barley sorting is an important step for selecting grain of required quality for malting prior to brewing. However, brewing with unmalted barley with added enzymes has been thoroughly proven, raising the question of whether traditional sorting for high quality malting-barley is still necessary. To gain more insight on this, we examine realtime viscosity of sorted-out and unsorted barley during downscaled mashing with added enzymes in comparison with malting quality sorted barley. A rapid visco analyser was used to simulate brewery mashing process at lab scale together with two commercial enzymes (Ondea ® -Pro and Cellic ® -CTec2). During downscaled mashing, viscosity profile of sorted-out barley was markedly different from others, irrespective of enzyme type, whereas a small difference was observed between the sorted and un-sorted barley. Furthermore, whilst sorted-out barley generated lowest sugar-concentration, unsorted and sorted barley resulted in higher sugar-content, regardless of the enzyme used. In terms of filterability, the Ondea ® -Pro treatment resulted in significantly lower-turbidity and smaller particle-size compared to Cellic ® -CTec2; however, this effect was observed in sorted and unsorted barley but not in sorted-out barley. Consequently, we find that unsorted barley demonstrates great potential for brewing with added enzymes and its use may help to improve sustainability of the brewing process. [ABSTRACT FROM AUTHOR]

Rheological properties of micellar solutions of a cationic Gemini surfactant, 2-hydroxypropyl-1,3-bis (dodecyldimethylammonium chloride), are studied as a function of aging time and salt addition. The results show that the self-aggregating behaviour in solution changes as a factor of time, probably due to intermolecular hydrogen bonds. The viscosity of the solution undergoes a series of visible changes so that the solution changes from a flow state to highly viscoelastic state, and finally, to a transparent solid, with a corresponding 4–6-fold increase in zero shear state viscosity. Rheology and freeze fracture transmission electron microscopy (FF-TEM) measurements show rod-like micelles at the beginning, which then change to wormlike micelles, and eventually to a quasi-gel-like network. Addition of an inorganic salt (NaCl) induces salting out, while the addition of an organic salt (NaSal) promotes micellar growth. At a fixed NaSal-to-surfactant molar ratio of 3:5, all solutions show Maxwell fluid behaviour and maximum zero-shear-rate viscosity; these trends can be attributed to the formation of a network structure between the cationic ions of the surfactant and Sal–as the surfactant concentration increases. Crystal analysis further confirms the presence of structures linked by intermolecular hydrogen bonds. [ABSTRACT FROM PUBLISHER]

The paper aims to assess the elastic-plastic behaviour of the honed pipes made of steel type E355 subjected to cyclic interior pressure using experimental methods and numerical analysis. In every industry domain, the pipes with thin or thick walls subjected to internal pressure are used. Regardless of the material they are used, the pipes are stressed on axial and circumferential directions, in time. Being subjected to variations of pressure or increasing of pressure over the allowable limit, the pipes can explode causing many damages. The pipes explosion subjected to internal pressure can be predicted knowing the elastic-plastic behavior of the pipe. Starting from theory of stresses in thin and thick pipes, the paper approaches the elastic - viscous and plastic behavior of the steel pipes subjected to periodical internal pressure by experimental. Besides identifying the rheological behavior of thin and thick pipes experimentally tested, the state of stresses and strains were analyzed by numerical method. The behavior of thick wall pipes differs from that of thin-walled pipes, both in terms of rheological and state of stresses and strains. The paper combines experiment and numerical methods for determining the probabilistic burst of the steel pipe. The samples (thin and thick wall pipes) were subjected to 20 loading cycles at 400 bar: the first 10 cycles of loading and unloading were produced for 60 second/cycle and than the other 10 cycles were produced for 120 second/cycle. The exterior diameter of tested pipes was measured both after 30 seconds of loading and after 30 seconds without pressure. These measurements were repeated for each cycle. [ABSTRACT FROM AUTHOR]

O objetivo deste trabalho foi estudar o comportamento reológico dos sucos mistos de manga, goiaba e acerola, adicionados de fitoquímicos, em sete temperaturas (10, 20, 30, 40, 50, 60 e 70 ºC), e o efeito da temperatura na viscosidade aparente. As análises reológicas foram conduzidas em um reômetro de cilindros concêntricos, marca Brookfield, modelo R/S plus SST 2000. Os valores experimentais de tensão de cisalhamento versus taxa de deformação foram ajustados pelos modelos de Ostwald-de-Waele (Lei da Potência), Casson e Herschel-Bulkley. Observou-se que os três modelos apresentaram altos coeficientes de determinação (R² > 0,978), indicando que qualquer um destes pode ser utilizado para descrever o comportamento reológico dos sucos, caracterizados como fluidos não newtonianos com características pseudoplásticas. O efeito da temperatura no comportamento reológico dos sucos foi descrito pela Equação de Arrhenius e foi possível observar um decréscimo no valor da viscosidade aparente com o aumento da temperatura.The aim of this work was to study the rheological behaviour of mixed juices of mango, guava and acerola with added phytochemicals at seven temperatures (10, 20, 30, 40, 50, 60 and 70 ºC), and the effect of temperature on the apparent viscosity. The rheological analyses were carried out using a Brookfield R/S plus SST 2000 rheometer with concentric cylinders. The experimental data for shear stress versus shear rate were fitted to the following models: Ostwald-de-Waele (Power Law), Casson and Herschel-Bulkley. The three models presented high determination coefficient values (R² > 0.978), indicating that any of them could be used to describe the rheological behaviour of the juices. The juices presented non-Newtonian behaviour and pseudoplastic characteristics. The effect of temperature on the rheological behaviour of the juices was described by the Arrhenius equation. The values for apparent viscosity decreased with increase in temperature.

Nanofluids, dispersions of nanosized solid particles in liquids, have been conceived as thermally-improved heat transfer fluids from their conception. More recently, they have also been considered as alternative working fluids to improve the performance of direct absorption solar thermal collectors, even at low nanoadditive concentrations. Carbon-based nanomaterials have been breaking ground in both applications as nanoadditives during the last decade due to their high thermal conductivities and the huge transformation of optical properties that their addition involves. In any application field, rheological behavior became a central concern because of its implications in the pumping power consumption. In this work, the rheological behavior of four different loaded dispersions (0.25, 0.50, 1.0, and 2.0 wt%) of six carbon-based nanomaterials (carbon black, two different phase content nanodiamonds, two different purity graphite/diamond mixtures, and sulfonic acid-functionalized graphene nanoplatelets) in ethylene glycol:water mixture 50:50 vol% have been analysed. For this purpose, a rotational rheometer with double cone geometry was employed, which included a special cover to avoid mass losses due to evaporation at elevated temperatures. The flow curves of the twenty-four nanofluids and the base fluid were obtained by varying the shear rate between 1 and 1000 s−1 for seven different temperatures in the range from 283.15 to 353.15 K. The shear-thinning behaviors identified, as well as their dependences on carbon-based nanomaterial, concentration, and temperature, were analyzed. In addition, oscillatory tests were performed for samples with the clearest Non-Newtonian response, varying the deformation from 0.1 to 1000% with constant frequency and temperature. The dependence of the behaviors identified on the employed carbon-based nanomaterial was described.

• Effect of Al 2 O 3 -Fe 2 O 3 ratios on the rheological behaviour and dynamic viscosity of hybrid nanofluid are investigated. • Hybrid nanofluid for all compositions of Al 2 O 3 -Fe 2 O 3 indicates a Newtonian fluid characteristic. • Bayesian approach was used to optimize the ANN model. • A great correlation model with values of more than 99.99% The present study is a pure experimental investigation of the viscosity and rheological properties of the Al 2 O 3 -Fe 2 O 3 hybrid nanofluid and the development of a new correlation. The main purpose of the study is to evaluate the effect of the Al 2 O 3 -Fe 2 O 3 mixture ratio on the viscosity property and develop a correlation for the viscosity prediction. The Al 2 O 3 and Fe 2 O 3 were first characterized using XRD diffraction and the FESEM technique. The nanofluid was prepared using a two-step method using base fluid consisting of water and ethylene glycol mixture at 60/40 ratios. Five different Al 2 O 3 -Fe 2 O 3 nanoparticle compositions were investigated experimentally for the viscosity and rheological properties at temperatures between 0 and 100 °C. The experimental data shows that the Al 2 O 3 -Fe 2 O 3 composition of 40/60 resulted in the highest viscosity value at all temperatures investigated, while the 60/40 composition recorded the lowest viscosity value. Besides, the increase in temperature of nanofluid shows a maximum viscosity reduction of 87.2 % as the temperature is increased from 0 to 100 °C. Also, the rheological analysis on a hybrid nanofluid for all compositions of Al 2 O 3 -Fe 2 O 3 indicates a Newtonian fluid characteristic. The experimental research data was utilized to create an artificial neural network (ANN)-based architecture. An autoregressive method called the Bayesian approach was adopted for training hyperparameters. During model training, the autoregressive technique assisted in achieving outstanding correlation values of more than 99.99 % with minimal mean squared errors as low as 0.000036. [ABSTRACT FROM AUTHOR]

The rheological behaviour of egg yolk after different storage periods and temperatures was investigated using rotational viscometer. The eggs were stored for 1, 2, 3, 4 and 8 weeks at constant temperatures: 4 °C, 8 °C, 12 °C and 16 °C. The apparent viscosity was measured as a function of shear rate. For given shearing rate, the viscosity was measured in dependence on shearing time. The decrease of viscosity with storage time is attributed to the balance of different osmotic pressure from yolk and albumen of fresh egg. The yolk (with higher dry matter then albumen) absorbs water from albumen through vitelline membrane. It was found that yolk samples exhibited shear-thinning and thixotropic behaviour. The shear-thinning behaviour was fitted well into simple models. The resting of sample at room temperature caused increase of viscosity. This effect is explained by drying off of testing yolk, the regeneration of yolk structures and changing chemical composition during resting. The time-dependant viscosity decreased rapidly with time and at lower share rates reached an equilibrium stage. The time-dependant viscosity was also found to decrease with storage time. The value of pH was changed (increased) during storing. No clear dependence between pH value and viscosity was confirmed.

A colloidal mixture of nanometre-sized (<100 nm) metallic and non-metallic particles in conventional fluid is called nanofluid. Nanofluids are considered to be potential heat transfer fluids because of their superior thermal and tribological properties. In recent period, nanofluids have been the focus of attention of the researchers. This paper presents a summary of a number of important research works that have been published on rheological behaviour of nanofluids. This review article not only discusses the influence of particle shape and shear rate range on rheological behaviour of nanofluids but also studies other factors affecting the rheological behaviour. These other factors include nanoparticle type, volumetric concentration in different base fluids, addition of surfactant and externally applied magnetic field. From the literature review, it has been found that particle shape, its concentration, shear rate range, surfactant and magnetic field significantly affect the rheological behaviour of any nanofluid. It has been observed that nanofluids containing spherical nanoparticles are more likely to exhibit Newtonian behaviour and those containing nanotubes show non-Newtonian flow behaviour. Furthermore, nanofluids show Newtonian behaviour at low shear rate values while behave as non-Newtonian fluid at high shear rate values. Authors have also identified the inadequacies in the research works so far which require further investigations. [ABSTRACT FROM AUTHOR]

The effects of blending sewage sludge on the properties of coal–sludge slurry (CSS), such as solid loading, apparent viscosity, rheological behaviour and stability, were systematically investigated. The size and morphology of particles, and grinding efficiency were analyzed. The experimental results showed that adding sewage sludge can improve the grinding efficiency and stability of slurry. CSSs prepared from Yanzhou coal, Jiangxinzhou sewage sludge and Yangzi sewage sludge exhibit pseudo-plastic behaviour with an apparent viscosity decreasing with increasing shear rate. Both CSSs, containing 10 wt% Jiangxinzhou sewage sludge and 15 wt% Yangzi sewage sludge, with about 60 wt% solid loading and 1200 mPa s apparent viscosity, are suitable for theirs handling in preparation, transport, storage, atomization, and combustion processes. [ABSTRACT FROM AUTHOR]

In this paper, there are presented properties of bituminous binder modified with new generation of various n -alkane additives used in Warm Mix Asphalt (WMA) technology. Laboratory tests were focused on properties of neat bitumen blended with 18 different n -alkane additives. Based on conventional in Europe binder tests such as penetration, softening point and Fraass breaking point, consistency at service temperature was analysed. Various modifiers with different melting point temperature used in WMA technology are described together with their influence on the binder dynamic viscosity and on rheological properties such as complex modulus and phase angle. In addition dispersion of n -alkane additives in bitumen was examined based on the UV microscopy and binder morphology. It can be found that based on the comparison of the viscosity curves for neat bitumen and bitumen modified with n -alkane additives, it is possible to make first selection of the optimal additive in aspect of the WMA technology. Based on the viscosity curve analysis, for the WMA technology effective additives should present melting temperature in the range of temperature between 90 °C and 130 °C. At this temperature, n -alkane modified bitumen should be more viscosity susceptible, which mean that viscosity should faster decrease with the temperature change, as compared to the neat bitumen. Based on the rheological and morphological assessment, it can be stated that too high melting point of n -alkane additives generate some problem with additive dissolving and homogeneity of binder and does not compensate beneficial changes in bitumen rheological properties. [ABSTRACT FROM AUTHOR]

Sea cucumber is a traditional health food consumed in East Asia. In this study, fucoidan from sea cucumber Apostichopus japonicus (Aj-FUC) was isolated, and its structure and rheological characteristics were elucidated for the first time. Aj-FUC was a branched polysaccharide mainly composed of a novel repeating unit [α- l -Fuc p 2(OSO 3 − )-1 → 3,(α- l -Fuc p- 1 → 4-α- l -Fuc p -1 →)4-α- l -Fuc p 2(OSO 3 − )-1 → 3-α- l -Fuc p 2(OSO 3 − )], clarified by using a combination of infrared spectroscopy, methylation analysis, enzymatic degradation and nuclear magnetic resonance. In steady shear measurement, Aj-FUC manifested a non-Newtonian shear-thinning behaviour at low shear rate (1–100 S −1 ) while exhibiting a non-Newtonian shear-thickening behaviour at high shear rate (100–1000 S −1 ); salts had limited impact on its flow curve. Comparative study on viscosity and rheological behaviour of Aj-FUC and a linear fucoidan extracted from sea cucumber Acaudina molpadioides suggested that the presence of branch structure might significantly influence the rheological characteristics of fucoidan. [ABSTRACT FROM AUTHOR]

The rheological behaviour of polyamic acid (PAA) solution was studied using N,N-dimethylacetamide (DMAc) as a solvent. The results showed that the PAA/DMAc solution with solid contents of 11-15 wt-% was a shear-thinning fluid. The non-Newtonian behaviour of the solution increased with increasing PAA concentration and decreasing temperature. The complex viscosity (η*) increases upon the concentration of PAA solution. Storage modulus and loss modulus increase with increasing frequency and an obvious plateau modulus appears, exhibiting a typical solid-like behaviour at high frequencies. The PAA solution with higher solid content shows lower tangent loss angle (tan δ), higher storage modulus and loss modulus. Increasing temperature plays an opposite role in increasing polymer concentration on complex viscosity, storage modulus, loss modulus and tan δ. [ABSTRACT FROM AUTHOR]

In the present study, powder injection moulding (PIM) was used to fabricate ultrafine 98W-1Ni-1Fe preform. The influence of various ball milling times (3, 5 and 10 h) on the characteristics of the ultrafine powder and the rheological behaviour of the injection moulded feedstocks has been investigated over the 105-145°C temperature range and the 1·79-596·1 s-1 shear range. The results show that all the feedstocks exhibit pseudoplastic flow behaviour. The increase in ball milling time could reduce the viscosity of the feedstock and enhance the shear stability by greatly diminishing the agglomeration of ultrafine particles. However, the powder ball milled for 5 h can produce a feedstock with better thermostability and comprehensive rheology. Therefore, compared with the powder ball milled for 3 and 10 h, the powder milled for 5 h is more suitable for ultrafine 98W-1Ni-1Fe PIM. [ABSTRACT FROM AUTHOR]

Abstract: An aluminous cement (Secar 71 from Lafarge) has been used for preparing millimetre thick films by tape casting. Slurry preparation is described. The effect of several dispersants has been studied. The optimum dispersion, associated with the minimum viscosity, is obtained with minimal amounts of dispersant in the case of acetic and propionic acids. Indeed, the corresponding quantities of dispersant are less than 0.5% by weight relative to cement. In addition to its dispersive role, acetic acid plays a role in the setting. It has a retarding effect below 1% by weight relative to the mass of cement and from this amount, it plays an accelerating role on setting. Tapes prepared with cement, water, acetic acid, PEG 300 have been left to set in different environments at 20°C (50% or 95% relative humidity, water). The formation of aluminous calcium hydrates is most important when setting is done in water. Lastly, the advantage of setting in water is also discussed with respect to the elimination of the different organic products that have been used for tape casting. [Copyright &y& Elsevier]

Compression and stirring tests were performed to investigate the rheological behaviour of wrought aluminium alloys with varying processing parameters, such as liquid fraction, strain rate, shear rate and materials. The present paper shows the results of an experimental investigation using Al2024, Al6061 and AI7075. Specimens of each aluminium alloy were characterised by their rheological behaviour during partial melting and holding in the semisolid state. The compression and stirring tests allow the apparent viscosity of the alloys to be determined as a function of the liquid fraction and shear rate. Moreover, the change of grain size and shape was examined by considering shear rate, stirring time and liquid fraction during stirring. These experimental results could be used in flow and solidification analyses and could be useful for manufacturing good rheological products by observing the microstructures according to changes in solid fraction and compression rates. [ABSTRACT FROM AUTHOR]

Abstract: Experiments are carried out on the rheological behaviour of ethylene glycol (EG) based titanate nanotubes (TNT) nanofluids containing 0.5, 1.0, 2.0, 4.0 and 8.0 wt.% TNT at 20–60 °C. The results show a very strong shear thinning behaviour of the TNT nanofluids and big influences of particle concentration and temperature on the zero shear viscosity (ZSV) and high shear viscosity (HSV), for which the conventional form of Brenner & Condiff Equation fails to predict. Theoretical analyses show that these experimentally observed phenomena can be well interpreted by the conventional colloid theory if particle shape and aggregation effects are taken into account and different relative importance of the Brownian diffusion and convection at different shear rates. It is suggested that nanofluids containing tube / rod-like nanoparticles with effective aspect ratio (r a) and effective volume fraction (φ a) can be classified into dilute nanofluids with 0 < φ a <1/r a 2, semi-dilute nanofluids with 1/r a 2 < φ a <1/r a, semi-concentrated and concentrated nanofluids with 1/ra < φ a. [Copyright &y& Elsevier]

Abstract: Systematic experiments have been carried out on the thermal and rheological behaviour of the ionic liquid, 1-butyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}imide, [C4mim][NTf2], and, for the first time, on the forced convective heat transfer of an ionic liquid under the laminar flow conditions. The results show that the thermal conductivity of the ionic liquid is ∼0.13Wm−1 K−1, which is almost independent of temperature between 25 and 40°C. Rheological measurements show that the [C4mim][NTf2] liquid is a Newtonian fluid with its shear viscosity decreasing with increasing temperature according to the exponential law over a temperature range of 20–90°C. The convective heat transfer experiments demonstrate that the thermal entrance length of the ionic liquid is very large due to its high viscosity and low thermal conductivity. The convective heat transfer coefficient is observed to be much lower than that of distilled water under the same conditions. The convective heat transfer data are also found to fit well to the convectional Shah’s equation under the conditions of this work. [Copyright &y& Elsevier]

Abstract: The structural analysis and rheological behaviour of unheated Nahar seed oil and oil heated at two different temperatures viz. (250±5)°C and (315±5)°C for a specified time, and the coating performance of the films of the same have been studied. The various physical properties of the unheated and heated oil were studied by determining acid value, iodine value, saponification value and specific gravity. The structural variation during heat treatment at different temperatures was analysed by FT-IR, 1H NMR spectroscopies and GPC analysis. The rheological behaviour i.e. variation of viscosity with time of the heated oil has been studied by Brookfield viscometer. Also an attempt has been made to establish the co-relationships between variation of viscosity and time of heating of the heated oil. The coating performance of the films prepared from unheated and heated Nahar oil has been investigated by measuring pencil hardness, gloss, flexibility, pressure test and chemical resistance. The films from heated oil showed better drying time over the film from unheated oil. [Copyright &y& Elsevier]

In this work, cordierite-based glass ceramic tapes were prepared by tape casting from suspensions containing different solids loading and different average particle sizes (PS). Three different empirical models were used to fit the experimental data from relative viscosity measured at a fixed shear rate (500 s−1) versus solids loading. The green tapes were characterised by using scanning electron microscopy (SEM) and Hg porosimetry. The results showed that high values of solids volume fraction and PS ratio between glass and cordierite powders favour homogeneous and dense substrates. The dielectric properties of the sintered tapes were also measured, which met the requirements for the substrates in microelectronic and packaging industries. [Copyright &y& Elsevier]

The rheology of epoxy resin-polysulfone blends and wetting at the blend/glass fibre interface have been studied. Measurements were made in a rotary viscometer and in a modified Wilhelmy apparatus. It was shown that none of the blends investigated revealed non-Newtonian behaviour in the range of shear rates used. The viscosity of the blends increased as polysulfone content increased. Introduction of hardener resulted in a significant increase of the blends viscosity up to 2-3 orders of magnitude. Rheological tests suggested that 15 wt% polysulfone was the highest concentration useful for obtaining composites by solvent-free impregnation technique. These tests suggested that the structure of the cured epoxy-polysulfone blends depended on the modifier concentration. The structures of the blends differed for the blends containing 5 wt% polysulfone and 10-15 wt% polysulfone. All the blends (with the hardener) required at least 30 min at 180°C to achieve final values of the mechanical properties such as storage and loss moduli, loss tangent and complex viscosity. For all epoxy resin-polysulfone/glass fibre systems a complete wetting of the fibres was observed. Surface tension vs. polysulfone content dependency was found to be nonadditive. Surface tension measured was minimal for epoxy resin-5% polysulfone blend, while for other systems the values were close to that of epoxy resin. Modification of epoxy resin by polysulfone did not change the kinetics of the fibres wetting by the blends. [ABSTRACT FROM AUTHOR]

Nanofluids, dispersions of nanosized solid particles in liquids, have been conceived as thermally-improved heat transfer fluids from their conception. More recently, they have also been considered as alternative working fluids to improve the performance of direct absorption solar thermal collectors, even at low nanoadditive concentrations. Carbon-based nanomaterials have been breaking ground in both applications as nanoadditives during the last decade due to their high thermal conductivities and the huge transformation of optical properties that their addition involves. In any application field, rheological behavior became a central concern because of its implications in the pumping power consumption. In this work, the rheological behavior of four different loaded dispersions (0.25, 0.50, 1.0, and 2.0 wt%) of six carbon-based nanomaterials (carbon black, two different phase content nanodiamonds, two different purity graphite/diamond mixtures, and sulfonic acid-functionalized graphene nanoplatelets) in ethylene glycol:water mixture 50:50 vol% have been analysed. For this purpose, a rotational rheometer with double cone geometry was employed, which included a special cover to avoid mass losses due to evaporation at elevated temperatures. The flow curves of the twenty-four nanofluids and the base fluid were obtained by varying the shear rate between 1 and 1000 s−1 for seven different temperatures in the range from 283.15 to 353.15 K. The shear-thinning behaviors identified, as well as their dependences on carbon-based nanomaterial, concentration, and temperature, were analyzed. In addition, oscillatory tests were performed for samples with the clearest Non-Newtonian response, varying the deformation from 0.1 to 1000% with constant frequency and temperature. The dependence of the behaviors identified on the employed carbon-based nanomaterial was described. [ABSTRACT FROM AUTHOR]

HITEC salt (NaNO2-NaO3-KNO3) and solar salt (NaO3-KNO3) are typical molten salts used in concentrated solar power. Adding nanoparticles is an effective method to improve the thermo-physical properties of pure salt. It is indispensable to experimentally study the rheological behaviours of salt seeded with nanoparticles, which can increase the specific heat capacity of pure salt. In this work, the viscosities of HITEC salt were measured with different shear rates in the temperature range of 200 °C to 450 °C firstly, while those of solar salt were measured in the temperature range of 250 °C to 500 °C. The experimental data showed reasonable agreement with the literature correlations, which verify the Newtonian behaviours of pure salts. The evolutions of the viscosities of nanocomposites in the same temperature range were measured and analysed, where the nanocomposites were synthesized with 1 wt.% or 2 wt.% Al2O3 nanopowder and graphene, respectively. Results showed that the addition of Al2O3 nanopowder had relatively little effect on viscosity, and the variations were about −35.4%~8.1% for the HITEC salt nanocomposites and −9.2%~68.1% for the solar salt nanocomposites. While graphene would apparently increase the viscosities of HITEC salt and solar salt, HITEC salt with the addition of graphene showed slight non-Newtonian fluid behaviour. [ABSTRACT FROM AUTHOR]