Dispersion of Basil seed gum has high viscosity and exhibits shear-thinning behavior. This study aimed to analyze the influence of microwave treatment (MT) at various time intervals (0, 1, 2, and 3 ...min) on the viscosity and rheological behavior of Basil seed gum dispersion (0.5%, w/v). The finding of this study revealed that the apparent viscosity of Basil seed gum dispersion (non-treated dispersion) reduced from 0.330 Pa.s to 0.068 Pa.s as the shear rate (SR) increased from 12.2 s−1 to 171.2 s−1. Additionally, the apparent viscosity of the Basil seed gum dispersion reduced from 0.173 Pa.s to 0.100 Pa.s as the MT time increased from 0 to 3 min (SR = 61 s−1). The rheological properties of gum dispersion were successfully modeled using Power law (PL), Bingham, Herschel–Bulkley (HB), and Casson models, and the PL model was the best one for describing the behavior of Basil seed gum dispersion. The PL model showed an excellent performance with the maximum r-value (mean r-value = 0.942) and the minimum sum of squared error (SSE) values (mean SSE value = 5.265) and root mean square error (RMSE) values (mean RMSE value = 0.624) for all gum dispersion. MT had a considerable effect on the changes in the consistency coefficient (k-value) and flow behavior index (n-value) of Basil seed gum dispersion (p < 0.05). The k-value of Basil seed gum dispersion decreased significantly from 3.149 Pa.sn to 1.153 Pa.sn (p < 0.05) with increasing MT time from 0 to 3 min. The n-value of Basil seed gum dispersion increased significantly from 0.25 to 0.42 (p < 0.05) as the MT time increased. The Bingham plastic viscosity of Basil seed gum dispersion increased significantly from 0.029 Pa.s to 0.039 Pa.s (p < 0.05) while the duration of MT increased. The Casson yield stress of Basil seed gum dispersion notably reduced from 5.010 Pa to 2.165 Pa (p < 0.05) with increasing MT time from 0 to 3 min.
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Three techniques for the analysis of ketchup viscosity (Brookfield, consistometer Bostwick and Ford Cup viscometer) are compared. Fifteen production batches obtained from the Elpidio Aguilar factory, ...Havana, Cuba were sampled. Viscosity was determined in 2kg samples from each batch, using the three methods. Results showed that viscosity measurements using the 2.5rpm Brookfield viscometer at ambient temperature (26-27°C) are more reliable due to its precision and repetitiveness. The good correlation between consistometer and calculated viscosity predicts reliable values of apparent viscosity by Bostwick consistometer. The ketchup presents creep effort and the Herschel-Bulkley model is adequate to describe its flow behavior.
In present work, the abrasive-free jet polishing (AFJP) of bulk single-crystal KDP was first fulfilled, when using a newly-designed low-viscosity microemulsion as the AFJP fluid. The novel AFJP fluid ...shows a typical water-in-oil structure, in which the water cores uniformly distribute in the BmimPF6 IL, with a particle size of about 20-25 nm. What's more, the AFJP fluid is a controllable and selective non-abrasive jet fluid that the shape of the removal function is regular and smooth, presenting a similar Gaussian function, meanwhile, the dispersion coefficient of the removal rate is only 1.9%. Finally, the surface quality of the bulk single-crystal KDP is further improved by AFJP, meanwhile, the subsurface damage is first obviously mitigated.
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The purpose of this paper is to compare the dynamic viscosity and steady viscosity characteristics of high-viscosity modified asphalt binder (HVA) and to analyze the applicability of the Cox–Merz ...rule as well as of the different zero shear viscosity (ZSV) test methods for HVA. To this end, seven kinds of asphalt binders including base asphalt binder, traditional modified asphalt binder with 4.5% styrene-butadiene-styrene (SBS), commercial HVA, and four self-shearing HVAs were prepared. The frequency sweep test and shear rate sweep test were conducted to obtain dynamic viscosity and steady viscosity, and the Cross model, Carreau model, and Carreau–Yasuda model were used to calculate ZSV based on these two types of viscosity. The results show that both the dynamic and steady viscosity tests prove that asphalt binder exhibits shear-thinning and yield stress behavior. Besides, there is a critical shear rate in the shear rate sweep test and the critical shear rate decreases with the increase of modifier content. The empirical Cox–Merz rule has good applicability in the Newtonian plateau region of base asphalt binder, but it is only applicable to a partial shear-thinning range of modified asphalt binder. Noteworthily, it fails when applied to HVA-C. The frequency sweep test is only suitable for determining the ZSV of base asphalt binder but not applicable at all to the modified asphalt binder because there is no Newtonian plateau in the dynamic viscosity, and the fitting results based on model extrapolation have huge errors as well as vary with the number of iterations. However, the shear rate sweep test is suitable for testing ZSV for both base and modified asphalt binders. Furthermore, it should be pointed out that ZSV obtained by model fitting is not a steady viscosity at zero shear rate but a Newtonian viscosity at a low shear rate, so low shear viscosity (LSV) is a more accurate concept.
In the present work, we demonstrate that zero‐shear viscosity is a sensitive rheological function to detect phase inversion in immiscible binary polymer blends characterized by a viscosity ratio ...larger than one. The phase inversion of poly(propylene) (PP)/low‐density poly(ethylene) (LDPE) and poly(styrene) (PS)/LDPE, at various compositions, was assessed via our novel approach. For both blends, three distinctive regions could be determined through zero‐shear viscosity measurements; the LDPE matrix, the co‐continuous phase, and the PS or PP matrix. For PP/LDPE blends, the co‐continuous structure was between 50 and 75 wt.% PP, and for PS/LDPE blends the co‐continuous structure was between 45 and 75 wt.% PS, in agreement with scanning electron microscopy analysis, empirical model predictions, and literature data.
Highlights
Phase inversion revealed via viscosity measurements.
Limitations of linear viscoelastic models for immiscible blends assessed.
Phase inversion via zero‐shear viscosity measurements.
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Cilia/flagella are whip-like, cellular appendages, widely conserved across the eukaryotes, that move a single cell through fluid, or move fluid across epithelial tissue. The flagella in the ...biflagellate alga Chlamydomonas reinhardtii are homologous to those found in humans, for example in sperm cells, and therefore, studying flagella in the algae can shed light on human disease. In this thesis, I develop a new quantitative framework for characterising flagellar activity, beginning by tracking the waveforms of C. reinhardtii flagella, and using the tracked waveforms to estimate various parameters that are relevant to flagellar beating, including frequency, amplitude, synchrony, hydrodynamic and elastic moments, curvature propagation and beat variability. These parameters have been estimated for wild-type and outer-dynein mutant flagella, as well as those immersed in a higher-viscosity medium, and for actively regrowing flagella. The results show that flagella of the mutant strain propagate weaker beats than in the wild type, while those in a raised viscosity are weaker still. For example, in a novel measure of the strength of curvature propagation, the mutant is 38% weaker, and the high-viscosity flagella 80% weaker, than the wild type. Additionally, the dynein mutant shows increased variability of the centre of force, but not the beat frequency. These results could aid with diagnosis of diseases caused by defective cilia, such as primary ciliary dyskinesia, as well as gaining further insight into the mechanisms of diseases caused by excessively viscous mucus, such as cystic fibrosis. Regrowing flagella were found to gradually recover their full-length parameters, but this increase in length was accompanied by an increase in the noise with which they beat, and a temporary aberration in the other flagellum.
Comb and bottlebrush polymers present a wide range of rheological and mechanical properties that can be controlled through their molecular characteristics, such as the backbone and side chain lengths ...as well as the number of branches per molecule or the grafting density. This review investigates the impact of these characteristics specifically on the zero shear viscosity, strain hardening behavior, and plateau shear modulus. It is shown that for a comb polymer with an entangled backbone and entangled side chains, a maximum in the strain hardening factor and minimum in the zero shear viscosity η0 can be achieved through selection of an optimum number of branches q. Bottlebrush polymers with flexible filaments and extremely low plateau shear moduli relative to linear polymers open the door for a new class of solvent‐free supersoft elastomers, where their network modulus can be controlled through both the degree of polymerization between crosslinks, nx, and the length of the side chains, nsc, with GBB0≈ρkTnx−1(nsc+1)−1.
Comb and bottlebrush polymers exhibit unusual rheological properties compared to their linear analogs due to side‐chain crowding. Investigation of the melt rheology of model branched polymers with controlled grafting density, side chain, and backbone lengths allows correlation of macroscopic flow properties such as zero shear viscosity, plateau modulus, and strain‐hardening behavior to conformational regimes by means of scaling analysis and tube theory.
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Temperature‐dependent viscosity is critical to decipher two profound questions in condensed matter physics, namely the glass transition and the relaxation of amorphous solids. However, direct ...measurement of viscosity over a large temperature range is extremely difficult. Here, using classical molecular dynamics (MD) simulations, we report a novel method to calculate the equilibrium viscosity of supercooled liquid both above and below the glass transition temperature (Tg) and to estimate the nonequilibrium viscosity of glass down to room temperature. Based on the shoving model, we derived an analytical formula showing that the shear viscosity in logarithmic scale changes linearly with the shear‐induced variation in shear modulus or potential energy of the glass‐forming system. The shear viscosity as a function of steady‐state potential energy of liquid under different shear strain rates can be directly calculated in MD simulations; together with its equilibrium potential energy, one can extrapolate the zero‐strain‐rate equilibrium viscosity. We verified the proposed model by reliably calculating equilibrium viscosity near Tg of four glass‐forming systems (Kob–Andersen system, silica, Cu45.5Zr45.5Al9, and silicon) with different fragilities. Furthermore, our model can estimate the nonequilibrium viscosity of glass below Tg; the upper‐bound nonequilibrium viscosity of amorphous silica and silicon at room temperature are calculated to be ~1032 and 1025 Pa·s, respectively.
Equilibrium viscosity calculated in this work for silica and Cu45.5Zr45.5Al9 in comparison with experiments in the Angell's plot.
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