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    Tytuł:
    Effect of carbomer microgel pH and concentration on the Herschel–Bulkley parameters
    Autorzy:
    Story, Anna
    Story, Grzegorz
    Jaworski, Zdzisław
    Powiązania:
    https://bibliotekanauki.pl/articles/185315.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    microgel
    Carbopol
    Herschel–Bulkley model
    yield stress fluid
    mikrożel
    Model Herschela-Bulkleya
    Opis:
    The article presents an experimental investigation of the rheological properties of carbomer microgels.All of the tested fluids were made up from commercial polyacrylic acid, Carbopol Ultrez 30. Intotal, eighteen microgels were prepared, differing in concentration; 0.2, 0.4 and 0.6 wt%, with sixlevels of neutralisation for pH from 4.0 to 9.0. Based on the experimental flow curves it was foundthat all tested microgels are yield stress shear-thinning fluids. Therefore, the Herschel–Bulkley modelwas used and its rheological parameters were determined. It was found that both the concentrationand the pH value significantly affected the yield stress. As the Carbopol concentration increased,the yield point also increased. With the increasing value of pH, the yield stress first increased untila certain maximum level and then decreased. The maximum values of yield stress were obtained forpH=6to 7, depending on polymer concentration. It was also found that flow curves of the testedmicrogels could be described using one universal master curve, thus they have common rheologicalbehaviour.
    Źródło:
    Chemical and Process Engineering; 2020, 41, 3; 173--182
    0208-6425
    2300-1925
    Pojawia się w:
    Chemical and Process Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental and numerical investigation of axialand tangential forces in a stirred tank with yield-stress fluids
    Autorzy:
    Story, Anna
    Story, Grzegorz
    Jaworski, Zdzisław
    Powiązania:
    https://bibliotekanauki.pl/articles/2086783.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    mixing
    yield-stress fluid
    axial force
    tangential force
    CFD
    mieszanie
    płyn do granicy plastyczności
    siła osiowa
    siła styczna
    Opis:
    Complex rheological properties of yield-stress materials may lead to the generation of an intensive mixing zone near a rotating impeller. From the practical point of view, the zone should cover most of the stirred liquid. According to the literature review, several parameters may affect the size of the mixing zone, in particular forces exerted on the liquid. This paper presents both experimental and numerical investigation of axial and tangential forces generated during mechanical mixing of yield-stress fluids in a stirred tank. The tested fluids were aqueous solutions of Carbopol Ultrez 30 of concentration either 0.2 or 0.6 wt% and pH = 5.0. The study was performed for three types of impeller, pitched blade turbine, Prochem Maxflo T and Rushton turbine, in a broad range of their rotational speed, = 60 − 900 rpm. The axial and tangential forces were calculated from the apparent mass of the stirred tank and torque, respectively. The experimental results were compared with CFD predictions, revealing their good agreement. Analysis of the generated forces showed that they are dependent on the rheological characteristic of liquid and the impeller type. It was also found that although axial force was smaller than tangential force, it significantly increased the resultant force.
    Źródło:
    Chemical and Process Engineering; 2021, 42, 2; 173--190
    0208-6425
    2300-1925
    Pojawia się w:
    Chemical and Process Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experiments and analysis of the limit stresses of a magnetorheological fluid
    Autorzy:
    Horak, Wojciech
    Stępień, Barbara
    Sapiński, Bogdan
    Powiązania:
    https://bibliotekanauki.pl/articles/2204687.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
    Tematy:
    magnetorheological fluid
    yield stress
    flow stress
    dynamic properties
    rheology
    Opis:
    This paper presents the results of a rheological test of a commercial magnetorheological (MR) fluid (MRF-132DG). The research includes the problem of measuring and interpreting limit stresses under conditions close to the magnetic saturation of the fluid. Four different limit stresses were determined, two related to the yield point and two related to the flow point. Methods for determining limit stresses, especially due to excitation conditions, were also analysed. The aim of this study is to determine the effect of selected parameters on the values of limit stresses of the selected MR fluid. An additional objective is to highlight the problems of defining and interpreting individual limit stresses in MR fluids, particularly in the context of selecting the values of these stresses for the purpose of modeling systems with MR fluids.
    Źródło:
    Acta Mechanica et Automatica; 2022, 16, 4; 408--416
    1898-4088
    2300-5319
    Pojawia się w:
    Acta Mechanica et Automatica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Electrorheological fluids containing polyelectrolytes
    Ciecze elektroreologiczne zawierające polielektrolity
    Autorzy:
    Krztoń-Maziopa, A.
    Sukiennik, M.
    Bańkowski, A.
    Płocharski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/256156.pdf
    Data publikacji:
    2008
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Technologii Eksploatacji - Państwowy Instytut Badawczy
    Tematy:
    efekt elektroreologiczny
    granica płynięcia
    ciecz ER
    zawiesina elektroreologiczna
    electrorheological effect
    yield stress
    ER fluid
    electrorheological suspension
    Opis:
    Electrorheological (ER) fluids belong to the broadly studied class of so called "intelligent materials" whose properties are sensitive to external stimuli. The ER fluids increase their viscosity upon application of an electric field. This paper reports the results of electrorheological experiments and describes a synthetic procedure leading to an ER suspension exhibiting predetermined characteristics. The fluid was designed for application in a prototype ER clutch.
    Ciecze elektroreologiczne (ER) należą do intensywnie badanej grupy tak zwanych inteligentnych materiałów, których właściwości można modyfikować za pomocą czynników zewnętrznych. Cechą charakterystyczną cieczy ER jest gwałtowny i odwracalny wzrost lepkości pod wpływem przyłożonego pola elektrycznego. Niniejsza praca zawiera wyniki eksperymentów elektroreologicznych i opis syntezy prowadzącej do otrzymania zawiesiny elektroreologicznej spełniającej określone parametry użytkowe. Ciecz została sporządzona w celu zastosowania w prototypowym sprzęgle elektroreologicznym.
    Źródło:
    Problemy Eksploatacji; 2008, 1; 87-99
    1232-9312
    Pojawia się w:
    Problemy Eksploatacji
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Preparation and characterization of nano magnetic fluid for automotive applications
    Autorzy:
    Thanikachalam, J.
    Nagaraj, P.
    Karthikeyan, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/379453.pdf
    Data publikacji:
    2019
    Wydawca:
    Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
    Tematy:
    nano magnetic fluid
    yield stress
    nickel nanoparticles
    viscosity
    sedimentation
    Rate
    płyn nano magnetyczny
    granica plastyczności
    nanocząstki niklu
    lepkość
    szybkość sedymentacji
    Opis:
    Purpose: of this paper is to prepare a nano magnetic fluids with nano additives to have the combined characteristics of high yield stress and better magnetic properties for smart vehicles. This study focuses on increasing the sedimentation time of the fluid using suitable nano additive nickel along with graphene as fillers. Design/methodology/approach: Magnetic nano sized nickel particle based electromagneto-rheological fluid was prepared and graphene nanoparticle with thickness less than 10nm was introduced as an additive to reduce its sedimentation. This added plate like graphene acts as filler which seals the interfaces of nickel particles and thereby it improves the resistance to sedimentation. Triton X 100 was added as the surfactant for the fluid to reduce the agglomeration of the particles. Findings: Morphology of pure nickel and graphene were examined using scanning electron microscopy (SEM) images. Research limitations/implications: The important limitations is that freely dispersed micron sized iron particles could settle over a period of time, in the form of cakes at the bottommost, and it is tedious to recuperate as dispersed phase. In this investigation, nano sized nickel particles were used as additive to reduce the sedimentation of micron sized iron particles so that, the mixture is homogeneous for extended period of time. In future, addition of different types composite additives in the magnetorheological fluid could be made for the better sedimentation control. Practical implications: The sedimentation problem is one of the major drawback in the smart fluids, which can be eliminated by adding nano particles. For conventional fluid, the complete sedimentation will occur in 2 hours while the improved nano magnetic fluid with additive has good resistance to settle the micron sized iron particle up to 10 hours. Originality/value: To prepare a low cost magnetorheological fluid with nano additives like nickel particles along with fillers as graphene nano particles. With this addition of nickel and inclusion of graphene, the sedimentation problem in magnetorheological fluids is significantly reduced. This magnetorheological fluids can be used in brakes and dampers of automobiles.
    Źródło:
    Archives of Materials Science and Engineering; 2019, 96, 2; 49-55
    1897-2764
    Pojawia się w:
    Archives of Materials Science and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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