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1

Analysis of rheological properties of potato starch pastes as a potential binding liquid in the granulation process

Orczykowska Magdalena

Technologia i Jakość Wyrobów

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2023

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R. 68

38--49

EN

The paper presents an assessment of rheological properties of commercial potato starch pastes as a binding liquid source in the process of granulation of single and multi-component loose materials using by Carreau-Yasuda model Based on the obtained results, it was found that high viscosity values of starch pastes and significant stiffness of their internal structure are not a guarantee of resistance of this structure to external forces, and may also reduce the efficiency of the granulation process itself.

PL

W pracy przedstawiono ocenę właściwości reologicznych kleików komercyjnej skrobi ziemniaczanej, jako źródła stanowiącego ciecz wiążącą w procesie granulacji jedno i wieloskładnikowych materiałów sypkich poprzez zastosowanie modelu Carreau-Yasudy. Na podstawie uzyskanych wyników stwierdzono, że wysokie wartości lepkości kleików skrobiowych i znacząca sztywność ich struktury wewnętrznej nie są gwarancją odporności tej struktury na działanie sił zewnętrznych, mogą ponadto obniżać efektywność samego procesu granulacji.

2

Wyznaczanie właściwości reologicznych polimerowych kompozytów drzewnych o dużej zawartości drewna na podstawie reometrii kapilarnej. Cz. 2, Badania reometryczne

Nastaj Andrzej, Chmielewski Marcin, Buziak Kamila, Wilczyński Krzysztof

Przemysł Chemiczny

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2023

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T. 102, nr 3

295--300

PL

Przedstawiono stan wiedzy i przegląd literatury w zakresie właściwości reologicznych polimerowych kompozytów drzewnych. Poddano dyskusji zagadnienie wyznaczania właściwości reologicznych kompozytów drzewnych na podstawie reometrii kapilarnej. Wskazano na rozległe możliwości reometrii kapilarnej w zakresie wyznaczania nie tylko krzywych płynięcia i krzywych lepkości, ale także badania zjawiska poślizgu, oceny granicy płynięcia, różnic naprężeń normalnych oraz lepkości podłużnej. Poddano dyskusji zagadnienie wpływu poprawek reometrycznych Rabinowitscha, Bagleya i Mooneya na położenie krzywej lepkości względem nieskorygowanej krzywej lepkości.

EN

Rheological studies of polymer-wood composite (WPC) with polypropylene matrix contg. 50 or 70% by mass wood filler were performed. Flow and viscosity curves were detd. at 180, 190 and 200°C, and tests of longitudinal viscosity and yield stress at 190°C were carried out. The tested composites had typical pseudoplastic properties, but yield stress, slip phenomenon and stretching (longitudinal viscosity) were obsd. during the flow. The effect of Rabinowitsch, Bagley and Mooney rheometric corrections on the position of the viscosity curve in relation to the uncorrected viscosity curve was discussed.

3

Skrobia ziemniaczana jako źródło cieczy wiążącej w granulacji materiałów sypkich

Derbiszewski Bogdan, Orczykowska Magdalena

Przemysł Chemiczny

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2023

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T. 102, nr 8

839--841

PL

Przedstawiono ocenę możliwości zastosowania kleików z komercyjnej skrobi ziemniaczanej jako źródła stanowiącego ciecz wiążącą w procesie granulacji jedno- i wieloskładnikowych materiałów sypkich. Oceny tej dokonano poprzez analizę właściwości reologicznych badanych kleików skrobiowych, uwzględniając m.in. stabilność struktury tych kleików oraz ich granicę płynięcia. Na podstawie uzyskanych wyników stwierdzono, że wysokie wartości lepkości kleików skrobiowych i znacząca sztywność ich struktury wewnętrznej nie są gwarancją odporności tej struktury na działanie sił zewnętrznych, mogą ponadto obniżać efektywność samego procesu granulacji.

4

Rozpoznanie możliwości wykorzystania koagulantów w procesach rozdzielania układów dyspersyjnych oraz ich wpływ na właściwości reologiczne

Malcher Tadeusz, Warzecha Piotr

Przemysł Chemiczny

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2023

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T. 102, nr 11

1223--1227

PL

Przedstawiono rozpoznanie możliwości zastosowania koagulantów do separacji układów wielofazowych. Separacja jest procesem stosowanym w różnych obszarach gospodarki, takich jak ochrona środowiska, przemysł metalurgiczny i chemiczny. Przedstawiono badania określające podstawowe właściwości fizykochemiczne zawiesiny ziarnistej oraz koagulantów wpływających na efektywność procesu separacji. Ich celem było uzyskanie szczegółowych informacji na temat wpływu koagulantów na proces przemysłowego rozdzielania zawiesin. Badania dodatkowe pozwoliły sklasyfikować płyny pod względem reologicznym oraz określić ich lepkość.

EN

PAX XL 19F or PAX 16 coagulants were added to a model aq. suspension of PVC of a specific particle size and at various solid phase concns., mixed and left for phase separation. The turbidity of the overlying water after the separation process was detd., and the rheological tests of the hydrated solid phase were performed and its viscosity was detd. The suspensions formed with PAX XL 19F showed higher viscosity.

5

Niestabilność reologiczna węglanowych mieszanek powlekających zawierających skrobię modyfikowaną

Stanisławska Anna, Gapiński Artur

Przegląd Papierniczy

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2023

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R. 79, nr 2

102--109

PL

Celem niniejszej pracy było zbadanie wpływu dodatku skrobi modyfiko-wanej na stabilność reologiczną mieszanek powlekających zawierających węglan wapnia. Wyznaczone zostały krzywe lepkości i krzywe płynięcia z uwzględnieniem czynnika czasu zarówno dla mieszanek, jak i roztworu skrobi modyfikowanej oraz dyspersji węglanu wapnia. Zawartość skrobi modyfikowanej w mieszankach powlekających wpływa na właściwości reologiczne tych mieszanek, zwiększając ich lepkość i naprężenie ścinające. Wykazano, że mimo reostabilnego charakteru roztworu skrobi i dyspersji węglanu wapnia przygotowane mieszanki powlekające okazały się być płynami reoniestabilnymi. Ich lepkość i naprężenie ścinające zmniejszały się przy wydłużeniu czasu ścinania, co świadczy o właściwościach tiksotropowych. Im większy był dodatek skrobi, tym większa była rozpiętość ramion pętli histerezy krzywych płynięcia i lepkości. A zatem, reologiczna niestabilność mieszanek powlekających wzrastała z dodatkiem skrobi.

EN

The rheological properties of coating color affect its flow behavior during technological process. If upon constant shearing, fluid properties do not change with time, the fluid exhibits rheological stability (rheo-stability). On the other hand, a fluid is said to exhibit rheological instability (rheo-instability) if shear time (for a given shearing conditions) affects its flow behavior. The objective of the conducted research was to examine the effect of modified starch on rheological instability of the coating colors. For this purpose, viscosity curves and flow curves were determined considering the time factor. Such experiments enabled to determine time-dependent rheology. Rheological tests were carried out for calcium carbonate-based coating colors with different starch content (1 pph, 2 pph, 5 pph and 10 pph) as well as for the raw materials used for their preparation, i.e. 10% solution of modified starch and 60% calcium carbonate dispersion. During the research, the rotary rheometer Brookfield RVDV - III+ with the Rheocalc V2.3 control software was used. The measurement principle is based on the determination of the torque for a given shear rate or rotational speed. The measuring element (e.g. spindle, coaxial cylinders), immersed in the test fluid, is set in rotation. A viscous liquid resists the measuring element by generating a torque which is a function of the apparent viscosity of the liquid. During the tests, both RV spindles and DIN coaxial cylinders were used, with the rotating inner cylinder and the stationary outer one. Programs in the B.E.A.V.I.S (Brookfield Engineering Advanced Viscometer Instruction Set) programming language were developed to control the rheometer and collect measurement results. This enabled the experiments to be performed automatically. In order to examine the influence of shear time on the flow and viscosity curves, measurements were made at time intervals of 10, 30 and 60 seconds (the measurement was carried out after 10, 30 or 60 s from the moment of changing the shear conditions, i.e. shear rate or rotational speed). The effect of time on viscosity for constant shear conditions was also investigated. Measurements were made within 4 minutes, and data were collected every 2 seconds. Time factor studies enabled to research rheo-stability and/or rheo-instability (time-dependent rheology). For all tested properties, at least 7 measurements were carried out, and the coefficients of variation did not exceed 4.75%. The starch solution exhibited rheo-stable shear-thinning behavior, whereas calcium carbonate dispersion was a rheo-stable shear thickening fluid. This means that the rheological properties of these liquids depended on shear field but did not depend on shear time (for a given shearing conditions). The content of modified starch in coating colors affects the rheological properties of these liquids, increasing their viscosity and shear stress. It was found that despite the rheo-stable character of both the starch solution and the calcium carbonate dispersion, the prepared coating colors were rheologically unstable as they exhibited time-dependent flow behavior. The viscosity of the coating colors decreased not only with the increase in rotational speed, but also with the increase in shear time. The decrease in their viscosity and shear stress with increasing shear time proves that the tested coating colors exhibited rheo-unstable thixotropic flow behaviors. Additionally, the higher the addition of starch was, the wider was the span of the hysteresis loop arms for both the flow and viscosity curves. Thus, the rheological instability increased with increasing starch content.

6

The effect of hyaluronic acid concentration on the rheological and tribological properties of artificial synovial fluid base solutions

Grykin Monika Izabela, Klekotka Marcin, Dąbrowski Jan Ryszard

Polimery

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2023

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Vol. 68, nr 10

555--562

EN

Synovial joints are a basic part of the human body. Lack of proper lubrication of joints can lead to significant wear of their surfaces. The tribological and rheological properties of artificial synovial fluid solutions based on hyaluronic acid were studied. It was found that the concentration of selected hyaluronic acid solutions significantly affects the investigated parameters. The most promising results were obtained for 8 wt% hyaluronic acid solution, which showed the highest viscosity and wettability, and the lowest wear.

PL

Stawy maziowe stanowią podstawową część organizmu człowieka. Brak odpowiedniego smarowania stawów może prowadzić do znacznego zużycia ich powierzchni. W pracy zbadano właściwości tribologiczne i reologiczne roztworów sztucznej cieczy synowialnej na bazie kwasu hialuronowego. Stwierdzono, że stężenie wybranych roztworów kwasu hialuronowego znacząco wpływa na badane parametry. Najlepsze wyniki uzyskano dla 8% mas. roztworu kwasu hialuronowego, który charakteryzował się największą lepkością, zwilżalnością, a także najmniejszym zużyciem.

7

Flotation separation influenced by the rheological properties of diaspore-pyrite mixed pulp

Zhao Yongqing, Li Xianhai

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 6

art. no. 174305

EN

The effects of pyrite and diaspore with different particle sizes on the rheological properties of pulp with butyl xanthate added as a collector were studied, and the mechanism for rheological pyrite separation from diaspore by flotation was probed. The apparent viscosity of the diaspore pulp with different particle sizes was higher than that of pyrite, especially for -30 μm diaspore. Microfine diaspore was an important component affecting the apparent viscosity and yield stress of the diaspore-pyrite mixed pulp, and the pulp became a non-Newtonian fluid when the mass fraction of fine-grained diaspore in the mixed pulp was high. In this study, sodium hexametaphosphate (SHMP) was used to control the rheology of the mixed pulp and improve the pyrite flotation, and the S (sulfur) recovery rate first increased and then decreased with increasing SHMP concentration. The apparent viscosity of the pulp decreased by 3.01% and the S recovery rate increased by 34.83% when the amount of added SHMP was 0.05 mg/kg. The apparent viscosity with 0.50 mg/kg SHMP was 21.76% lower than that seen with the addition of 0.05 mg/kg SHMP, but the S recovery rate was also reduced by 14.94%. Further research showed that the increased SHMP concentration led to increases in the electronegativities of the particle surface and the repulsive force between particles, which prevented agglomeration of the particles, reduced the apparent viscosity and yield stress of the mixed pulp, promoted collisions between the pyrite particles and the bubbles, and reduced the resistance of the air bubbles to flotation.

8

Influence of the non-equilibrium state of real gases on their properties

Aliyev Vasif I., Aslanov Jamaladdin N., Nabiev Nadir I., Rahimova Mahluqa S.

Nafta-Gaz

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2023

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R. 79, nr 2

84--95

EN

This scientific work presents a study of areas of application and improvement for the Clapeyron–Mendeleev equation to determine the technological parameters of natural and associated petroleum gas under field conditions. As a result of scientific and practical research and laboratory work, the authors, based on the molecular kinetic theory of gases, developed and improved the Clapeyron– Mendeleev equations of state of real gases by adding some genuine parameters for natural and associated petroleum gases produced from oil and gas condensate fields. In this regard, two additional parameters are introduced in the Clapeyron–Mendeleev equation-relative density and relative velocity of gas: and this, as a new scientific result, helps determine any parameter from the seven included in the equation of state of natural and associated petroleum gases developed by the authors. Continuous technological process according to the system of “production, collection, preparation and transportation of products (oil + gas)”, including, separately in non-equilibrium conditions of “collection, preparation and transportation of gas” due to internal energy, causes a natural change in a wide range of basic technological parameters that contribute to frequent changes in the physical and chemical state of the gas. Therefore, this work establishes that one of the main tasks is to show the composition of natural and associated petroleum gas as a result of irreversible transformations of hydrocarbon and acidic components of its internal energy, as a result of which the gas is characterised by a number of patterns in the composition and distribution of components of various hydrocarbon and heterogeneous compositions (i.e., physically and chemically heterogeneous). In these conditions, a practical calculation of gas facilities (gas treatment point, selection of gas separators, field gas pipelines, compressor stations) is carried out to determine process parameters using the Clapeyron–Mendeleev equation of state for real gases, and the results show large errors. This proves once again that many authors have developed equations of state for real gases based on the results of laboratory studies with single-atomic and laboratory gases (hydrogen, nitrogen, oxygen, carbon dioxide, etc.). However, the authors here carried out laboratory studies with products and associated petroleum gas. According to the results of laboratory studies, the authors recommend an improvement of the equation of state of natural and associated petroleum gases.

PL

W pracy przedstawiono studium obszarów zastosowania i doskonalenia równania Clapeyrona–Mendelejewa do wyznaczania parametrów technologicznych gazu ziemnego i towarzyszącego gazu ropopochodnego w warunkach złożowych. W wyniku badań naukowych i praktycznych oraz prac laboratoryjnych autorzy, w oparciu o molekularną teorię kinetyczną gazów, opracowali i udoskonalili równania stanu gazów rzeczywistych Clapeyrona–Mendeleeva poprzez dodanie niektórych parametrów rzeczywistych dla gazu ziemnego i towarzyszących gazów ropopochodnych wydobywanych ze złóż ropnych i kondensatowych. W związku z tym do równania Clapeyrona– Mendeleeva wprowadzono dwa dodatkowe parametry – gęstość względną i prędkość względną gazu, co, jako nowy wynik naukowy, pozwala na wyznaczenie dowolnego parametru z siedmiu parametrów zawartych w opracowanym przez autorów równaniu stanu gazu ziemnego i towarzyszącego gazu ropopochodnego. Ciągły proces technologiczny zgodnie z systemem „produkcji, odbioru, przygotowania i transportu produktów (ropa + gaz)”, w tym osobno w warunkach nierównowagi „odbioru, przygotowania i transportu gazu”, ze względu na energię wewnętrzną powoduje naturalną zmianę w szerokim zakresie podstawowych parametrów technologicznych, które przyczyniają się do częstych zmian stanu fizykochemicznego gazu. Dlatego też przedmiotowa praca jako jedno z głównych zadań stawia przedstawienie składu gazu ziemnego i towarzyszącego mu gazu ropopochodnego powstałego w wyniku nieodwracalnych przemian węglowodorowych i kwasowych składników jego energii wewnętrznej, w wyniku czego gaz ten charakteryzuje się szeregiem prawidłowości pod względem składu i rozprzestrzenienia poszczególnych składników węglowodorowych (o niejednorodnym składzie pod względem fizycznym i chemicznym). W tych warunkach przeprowadzono praktyczne obliczenia dla instalacji gazowych (punkt uzdatniania gazu, dobór separatorów gazu, gazociągi terenowe, tłocznie) w celu określenia parametrów technologicznych z wykorzystaniem równania stanu Clapeyrona–Mendelejewa dla gazów rzeczywistych. Wyniki wykazują duże błędy. Dowodzi to po raz kolejny, że wielu autorów opracowało równania stanu dla gazów rzeczywistych na podstawie wyników badań laboratoryjnych z gazami jednoatomowymi i laboratoryjnymi (wodór, azot, tlen, dwutlenek węgla itp.). Natomiast obecnie autorzy przeprowadzili badania laboratoryjne z udziałem eksploatowanych węglowodorów i towarzyszącego im gazu ropopochodnego. Na podstawie wyników badań laboratoryjnych autorzy zalecili korektę równania stanu dla gazu ziemnego i towarzyszących mu gazów ropopochodnych.

9

Rheological behavior of polymer-based drilling fluids: experimental study of temperature effects

Safi Brahim, Aboutaleb Djamila, Haider Soumya

International Journal of Applied Mechanics and Engineering

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2023

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Vol. 28, no. 1

95--104

EN

Drilling fluids most commonly used are generally based on polymers. Polymers such as methylcellulose carboxylate (CMC), polyanionic cellulose (PAC) and xanthan (Xn) have a very important role in the success of drilling operations. Indeed, they are also used to improve certain properties, in particular rheological. However, these polymers can lose their characteristics under the influence of increasing temperature at the bottom of oil wells, thus affecting the ability of the mud to perform its useful role in the drilling operation, namely to raise the cuttings from the bottom of the well to the surface. The present work aims to study the effect of temperature on the main rheological properties (shear stress and plastic viscosity) as well as on the rheological behavior of water-based drilling muds (WBM). WBM_CMC and WBM_PAC (at Xn content fixed) were selected to evaluate the temperature effect (20°C; 40°C; 60°C and 80°C) on the rheological parameters and the rheological behavior. The results revealed that the shear stress and the plastic viscosity of the studied muds were considerably affected by an increase in temperature. A significant decrease in these drilling mud parameters as a function of temperature up to 80°C. A reduction of 58.8% in shear stress and 78.5% in plastic viscosity was observed. The results show that regardless of the test temperature, the shear thinning behavior of the WBM_CMC and WBM_PAC drilling muds is the same as the Herschel-Bulkley model.

10

Lubrication of asymmetric rollers considering viscosity as function of mean temperature

Lanka Swetha, Sajja Venkata Subrahmanyam, Prasad Dhaneshwar

International Journal of Applied Mechanics and Engineering

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2023

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Vol. 28, no. 2

49--63

EN

A theoretical analysis of an asymmetric roller bearing system with cavitation that is hydro-dynamically lightly loaded and lubricated by a thin, incompressible fluid is presented. The lubricant adheres to the non-Newtonian Bingham plastic fluid concept, in which the viscosity of the fluid should change depending on the mean film temperature. The continuity and momentum equations, which regulate fluid flow, are first solved analytically and then numerically using MATLAB. Through graphs and tables, some key bearing features are addressed and further explained. This leads to the conclusion that there is a discernible difference between Newtonian and non-Newtonian fluids in terms of pressure, temperature, load, and traction. The findings are good in line with the body of literature.

11

Evaluation of the antiwear properties of timely changed engine oils

Skonieczna Daria, Vrublevskyi Oleksandr, Szczyglak Piotr

Combustion Engines

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2023

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R. 62, nr 4

116--122

EN

The article presents the results of tests, replaced according to the vehicle manufacturer's recommendations, of engine oils. The sample of engine oils in service came from spark-ignition and compression-ignition vehicles used in urban or mixed mode. During their collection, the type of drive unit, the mileage of the car and the number of kilometers the oil was used for were recorded for each sample (this was the main criterion for differentiating samples). In addition, a control group of samples consisting of fresh oils of the same viscosity grade and distributed by the same producer was set up to observe changes in the parameters of individual lubricants after the operating period. The first part of the empirical study consisted of determining the physico-chemical properties of the lubricants, i.e.: kinematic viscosity, density and water content. The second part involved anti-wear tests using a T-02U tribometer. The use of the tribometer made it possible to record the anti-wear parameter, i.e. moment of friction, and also the load imposed on the friction node, as a result of which it was possible to calculate the friction force and friction coefficient. The research was complemented by an analysis of worn surfaces of the friction node on a microscope. The tests carried out can be used for predictive purposes, in terms of assessing the condition of a lubricant subjected to an operating process in an internal combustion engine.

12

A Mean-Line Flow Model of Viscous Liquids in a Vortex Pump

Li Wenguang

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2022

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Vol. 26, No 2

1--18

EN

The axial, radial and tangential velocity profiles of six fluids were extracted from computational fluid dynamics simulation results at points in a pump chamber 1 mm distant from the blades in a vortex pump at the specific speed of 76. The critical radius was specified in the axial velocity radial profiles to determine the impeller inlet and outlet at six viscosities and part-load, design, and over-load points. A mean-line flow model and hydraulic loss model were built from the profiles. The incidence, incidence loss in the inlet, deviation angle, and slip factor in the outlet were calculated. The impeller theoretical head, pump hydraulic efficiency and volumetric efficiency were analyzed. It was shown that the axial, radial and tangential velocity profiles relate closely to the flow rate as usual, but also the viscosity, especially at low flow rates and in the inlet. The low flow rate and viscosity lead to near zero axial and radial velocities, a faster tangential velocity than the blade speed, negative incidence, and a small incidence loss coefficient in the inlet. The dimensionless critical radius ranged within 0.77–0.89 and reduces with the increasing flow rate and viscosity. The mean slip factor is between 0.11 and 0.20 and rises with the increasing flow rate and viscosity. The mean incidence loss coefficient is within 0.0020–0.15 and augments with the increasing flow rate but increases with the decreasing viscosity under part-load conditions. The theoretical head estimated by using the fluid tangential velocity between the outlet of the impeller and the inlet of the chamber is more reasonable.

13

Heterogeneous polymers degradation – microplastic

Mucha Maria, Mucha Jarosław

Polimery

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2022

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Vol. 67, nr 7-8

293--297

EN

The process of semicrystalline polymers thermo-oxidative degradation was analyzed on the example of isotactic polypropylene (iPP). Oxygen degradation takes place mainly in the amorphous phase into which oxygen diffuses. This leads to oxidation (formation of hydroperoxides) and next the chains scission. The polymer becomes brittle and breaks down into small pieces (e.g. microplastics). The crystalline phase is more difficult to access for oxygen that initiates the thermo-oxidation process. An increase in the crystallinity degree and a decrease in the viscosity of the solutions diluted in p-xylene as a function of the degradation time were observed. The number of iPP chain scission (change in molecular weight) as a function of degradation time was also calculated. These values depend on the polymer initial crystallinity degree and its supermolecular structure.

PL

Na przykładzie izotaktycznego polipropylenu (iPP) przeprowadzono analizę procesu termooksydacyjnej degradacji polimerów semikrystalicznych. Degradacja z udziałem tlenu obydwa się przede wszystkim w fazie amorficznej, do której dyfunduje tlen. Prowadzi to do utleniania (powstawania wodoronadtlenków), a następnie pękania łańcucha polimerowego. Polimer staje się kruchy i rozpada na małe fragmenty (m.in. mikroplastik). Faza krystaliczna jest trudniej dostępna dla tlenu inicjującego proces termoutleniania. Stwierdzono wzrost stopnia krystaliczności i zmniejszenie lepkości roztworów rozcieńczonych w p-ksylenie w funkcji czasu degradacji. Obliczono również liczbę pęknięć łańcucha iPP (zmianę masy cząsteczkowej) w funkcji czasu degradacji. Wielkości te zależą od początkowego stopnia krystaliczności polimeru i jego struktury nadcząsteczkowej.

14

Experimental study on the effect of ions on the surface hydration characteristics of fine quartz

Liu Chunfu, Min Fanfei, Liu Lingyun, Chen Jun, Ren Bao, Lv Kai, Tan Yujiao

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 4

art. no. 150280

EN

The fine quartz particle hydration and effects of metal ions on the hydration characteristics of fine quartz surface are investigated using the rheological experiment. Several important factors affecting hydration factors, such as particle sphericity, solution pH, ion species, ion concentration were investigated. The results show that viscosity and hydration factor of fine quartz suspension increase with the increase of solution pH. wherein quartz particles have more negative charges on the surface in alkaline environment and strong hydration repulsion; The introduction of metal ions enhances the hydration strength of fine quartz surface to a certain extent. In contrast, high valence and high concentration will increase the viscosity of fine quartz suspension, and the hydration factors of particle surface also increase. At the same ion concentration, the order of influence on the hydration factors of fine quartz particles is Mg2+ > Ca2+ > Na+ > K+. This finding has been attributed to the combination of metal ion hydration and its adsorption on the mineral surface. This study will provide the theoretical guiding significance for the refractory coal slime water and other mineral processing wastewater containing quartz particles.

15

Influence of pressure changes on the viscosity of lubricating oil in CFD simulations of conical bearing hydrodynamic lubrication

Czaban Adam, Miszczak Andrzej

Journal of KONBiN

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2022

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Vol. 52, iss. 3

259--277

EN

The aim of this study is to consider the effect of pressure on the viscosity of lubricating oil in the adopted model of hydrodynamic lubrication and on the calculated flow parameters and operating parameters of a conical slide bearing. The numerical analysis consisted in solving the Reynolds type equation for the process of stationary hydrodynamic lubrication.

PL

Celem niniejszej pracy jest zbadanie, w jakim stopniu uwzględnienie wpływu ciśnienia na lepkość oleju smarnego, w przyjętym modelu hydrodynamicznego smarowania, oddziałuje na obliczane parametry przepływowe i eksploatacyjne analizowanego stożkowego łożyska ślizgowego. W badaniach wykorzystano znane z literatury równanie typu Reynoldsa, określające proces stacjonarnego hydrodynamicznego smarowania.

16

Convective Heat Transfer in Heat Exchangers Using Nanofluids: A Review

Reddy Goda Sreenivasulu, Kalaivanan Ramasamy, Kumar Rampelli Uday, Krishna Varma K. P. V.

Ecological Engineering & Environmental Technology

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2022

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Vol. 23, iss. 3

193--201

EN

Enhancing the Convective heat transfer in the carrier fluids, by augmenting the thermal conductivity in fluids, with nano particles is one of the passive techniques. Enhancement in the thermal conductivity in the carrier fluids can be achieved by suspending particles of nano-size into the base fluids, such colloidal suspensions are called as nanofluids. Nanofluids are proven fluids which improve the convective transfer of heat in the base fluids in the heat exchangers. But still, there are lot of challenges that are existing in understanding the mechanisms of enhancement of convective heat transfer for large scale applications. In this work, an attempt is made to summarize recent advancements on augmentation of convective heat transfer in heat exchangers in turbulent flows using various nanofluids and present various setbacks for the development of nanofluids for critical applications.

17

Artificial Neural Network Technique for Estimating the Thermo-Physical Properties of Water-Alumina Nanofluid

Ravi Babu Sajja, Krishna Varma K. P. V., Mohan Kunapuli Siva Satya

Ecological Engineering & Environmental Technology

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2022

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Vol. 23, iss. 2

97--106

EN

With its superior thermo-physical characteristics to the carrier fluid, nanofluid is the most impactful heat transfer fluid. Thermal conductivity, density, viscosity, specific heat, coefficient of volumetric expansion, and other thermo-physical parameters play an important part in the thermal management of any heat transfer application. This thermal management governs the service life of an equipment or apparatus, which dissipates heat during its operation. If the equipment is well-managed thermally, then its service life will be extended. Otherwise the equipment stops functioning due to excess heat. Thermo-physical properties of nanofluid vary with the change in the concentration of nanoparticles. Estimation of the properties with the varying concentrations of the nanoparticles is time consuming and is economically not viable. There were many empirical models available in the literature for determining the thermo-physical properties of nanofluids. However, each model provides different values of thermo-physical properties and choosing the best model among the models available is a complex task. In this regard, to avoid the complication in choosing the best model, and in order to envisage the thermo-physical properties of the nanofluid, the Artificial Neural Network (ANN) technique was used. This technique is widely used among the researchers for various applications. The ANN approach was utilized in this work to estimate viscosity and thermal conductivity of water-based Al2O3 nanofluid for volume fractions between 0.01% and 0.1%. For thermal conductivity, mean square error (MSE) was observed as 4.504e-09 and for viscosity, it was observed as 6.4742e-09. Training times were 5 seconds and 4 seconds for thermal conductivity and viscosity datasets, respectively.

18

Diffusive solute transport in hollow fiber dialyzers is not affected by variable feed viscosity

Schneditz Daniel, Sauseng Notburga

Biocybernetics and Biomedical Engineering

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2022

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Vol. 42, no. 4

1112--1122

EN

Dialyzer clearance (K) for hemodialysis is usually predicted from the mass transfer area product (K0A) provided in manufacturer data sheets without accounting for elevated feed-viscosity when treating blood. The boundary layer model for mass transport across hollow fiber membranes, however, predicts an increase in mass transfer resistance (1/K0) and a decrease in K with increasing feed-viscosity. The effect of increased feed-side viscosity relative to baseline crystalloid viscosity on small solute K and 1/K0 was therefore examined in commercial high- (HF) and low-flux (LF) dialyzers in lab-bench studies using standard dialysis equipment in the normal operating range. Homogeneous colloid solutions and bovine plasma were used to simulate the range of relative viscosities (ηrel) and oncotic pressures expected under in-vivo conditions. Internal filtration (IF) was quantified by a mathematical model to obtain diffusive transport characteristics (K’, 1/K'0). An up to 5-fold increase in ηrel caused a small increase in K and a small decrease in 1/K0 in HF, but not in LF dialyzers. After correction for a small convective contribution by IF, K’ and 1/K'0 remained constant in both LF and HF dialyzers. Diffusive transport characteristics of commercial HF and LF dialyzers are independent of variable feed-side viscosity. This suggests an insignificant contribution of the feed-side boundary layer resistance in dialyzers optimized for operation in hemodialysis. Increasing the feed-side viscosity, however, increases the convective component of dialyzer solute transport because of IF. Diffusive dialyzer clearance predicted from the dialyzer K0A is independent of elevated feed-viscosity.

19

Air permeability and sorptivity of concrete modified with viscosity modifying agents

Kubissa Wojciech, Prałat Karol, Kania Szymon

Archives of Civil Engineering

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2022

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Vol. 68, nr 1

223--240

EN

The paper presents the effect of a viscosity modifying admixture (VMA) on the air permeability, sorptivity and strength parameters (compressive and tensile strength) of concrete. The Atlas VM-500 admixture used in the research is a well-known additive that is commonly applied in concrete technology. Air permeability tests were carried out using the Torrent method. It was found that viscosity modifying admixtures (VMAs) have a significant impact on the permeability of concrete. The lowest values of the kT coefficient were obtained for specimens that matured in a water environment, and which contained 0.5% of VMA. This amount of additive reduced permeability by 34% when compared to the reference series of concrete. For air-conditioned specimens with 1.2% of VMA, the maximum decrease was 28% when compared to the reference samples. In the case of samples conditioned in an environment with an increased humidity, the maximum decrease occurred with a lower VMA content of 0.5% and amounted to 27% when compared to the reference samples. In addition, it was shown that the addition of 1.2% of VMA improved the compressive strength of concrete by 2.3% during its curing in water. In turn, this amount of VMA deteriorated its strength by 10.4% when the specimens were conditioned in air, and by 8.1% when they were conditioned in high humidity.

PL

Mineralne materiały budowlane, w tym także betony cementowe posiadają porowatą strukturę, które bardzo łatwo mogą penetrować ciecze i gazy znajdujące się w środowisku naturalnym. Dlatego też wprowadza się miarę, powiazaną z trwałością betonu tzw. przepuszczalność, którą określić można na drodze pomiaru wielkości charakteryzujących przepływ cieczy lub gazów. Bardzo często na potrzeby oceny potencjalnej trwałości betonu prowadzony jest pomiar nasiąkliwości lub sorpcyjności [6-8, 33]. W celu oceny przepuszczalności coraz częściej uznanie znajduje metoda Torrenta [19-21]. Pomiar ten ogranicza się do przepływu powietrza w kilkucentymetrowej, powierzchniowej warstwie betonu. Na przepuszczalność betonu mierzoną różnymi metodami, bardzo istotny wpływ ma jego stan wilgotnosciowy [29-32]. W przypadku metody Torrenta problem ten został przez jej twórców rozwiązany na drodze doświadczalnego ustalenia tego wpływu i wyposażeniu aparatu w sondę do pośredniego pomiaru wilgotności betonu, której zastępczą miarą jest jego oporność właściwa. Celem niniejszej pracy było określenie wpływu zastosowanych w betonach dodatków VMA na przepuszczalność powietrza oraz sorpcyjność, jak i parametry wytrzymałościowe (ściskanie i rozłupywanie) otrzymanych kompozytów, pielegnowanych przez 28 dni w zróżnicowany sposób.

20

Influence of Adhesive Compound Viscosity on the Strength Properties of 1.0503 Steel Sheets Adhesive Joints

Miturska-Barańska Izabela, Rudawska Anna

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 2

196-205

EN

The presented study concerned the comparison of the adhesive joints strengths of 1.0503 carbon steel sheets of higher quality, which were made using adhesive compounds characterized by different viscosity index of the components. Three types of commercial epoxy resins were used: Epidian 5, Epidian 53 and Epidian 57, as well as two types of curing agents: polyamide (PAC) and amine (Z-1). The surfaces of the test specimens were subjected to a pre-treatment operation in the process of a mechanical machining with an abrasive coated tool of P320 gradation. The surface roughness measurements were carried out as a control. The single-lap adhesive joints were the subject of the strength testing. The strength tests carried out on a Zwick/Roell Z150 testing machine concerned the comparison of the strength of the adhesive joints loaded in shear. Statistical analysis was performed on the results obtained. It was observed, among others, that the adhesive joints prepared with the epoxy adhesive compounds containing the polyamide curing agent showed much higher the shear strength than the adhesive joints made with the epoxy adhesive compounds containing the amine curing agent. Moreover, the use of the polyamide curing agent in the adhesive compounds with the epoxy resins resulted in formation of a more elastic adhesive layer, for which higher elongation was observed than in the case of the epoxy compound with the amine curing agent.