scholarly journals The Rheological Studies on Poly(vinyl) Alcohol-Based Hydrogel Magnetorheological Plastomer

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2332
Author(s):  
Norhiwani Mohd Hapipi ◽  
Saiful Amri Mazlan ◽  
U. Ubaidillah ◽  
Koji Homma ◽  
Siti Aishah Abdul Aziz ◽  
...  
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Crosslinking Agent ◽  
Shear Thickening ◽  
Artificial Muscle ◽  
High Energy ◽  
Poly Vinyl Alcohol ◽  
Biomedical Sensors ◽  
Wide Range ◽  
Soft Actuators

The freezing–thawing method has been commonly used in the preparation of polyvinyl alcohol hydrogel magnetorheological plastomer (PVA HMRP). However, this method is complex and time consuming as it requires high energy consumption and precise temperature control. In this study, PVA HMRP was prepared using a chemically crosslinked method, where borax is used as crosslinking agent capable of changing the rheological properties of the material. Three samples of PVA HMRP with various contents of carbonyl iron particles (CIPs) (50, 60, and 70 wt.%) were used to investigate their rheological properties in both steady shear and dynamic oscillation modes. Results showed the occurrence of shear thickening behaviour at low shear rate (γ > 1 s−1), where the viscosity increased with the increased of shear rate. Moreover, the storage modulus of the samples also increased increasing the oscillation frequency from 0.1 to 100 Hz. Interestingly, the samples with 50, 60 70 wt.% of CIPs produced large relative magnetorheological (MR) effects at 4916%, 6165%, and 10,794%, respectively. Therefore, the inclusion of borax to the PVA HMRP can offer solutions for a wide range of applications, especially in artificial muscle, soft actuators, and biomedical sensors.

Preparation of SiO2/PEG Shear Thickening System by Centrifugal Dispersion

2012 ◽  
Vol 560-561 ◽  
pp. 586-590 ◽  
Author(s):  
Biao Yang ◽  
Sheng Wang ◽  
Guo Zhi Xu ◽  
Fei Xin
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
High Speed ◽  
Rotation Speed ◽  
Loss Modulus ◽  
Shear Thickening ◽  
Angular Frequency ◽  
Revolution Speed ◽  
Centrifugal Dispersion ◽  
The Revolution

The nano-SiO2/polyethylene glycol (PEG) dispersion system was prepared by centrifugal mixing, and its rheological properties were investigated. The results showed the revolution and rotation speed during the centrifugal mixing have a significant effect on the rheological properties of SiO2/PEG system. When the revolution speed of the centrifugal mixer was fixed at a high speed of 1200rpm, the shear thickening effect of SiO2/PEG was gradually increased with the decrease of rotation speed, and the maximum viscosity (η) of 12340 mPa•s appeared at the rotation speed of 200 rpm. At the low revolution speed of 700 rpm, the increase of the rotation speed significantly enhanced the shear thickening effect. When the rotation speed was 700rpm, the maximum viscosity was up to 86130mPa s. In steady state experiments, the systems show a shear-thinning property under low shear rate. When the shear rate exceeded a critical value (γ= 24.92 s-1), the viscosity first increased, and then decreased sharply. In the dynamic experiments, with the increase of angular frequency (ω), the loss modulus (G″) also increased and the systems behaved as a shear-thickening fluid.

scholarly journals Physico-chemical characteristics of gamma irradiation crosslinked poly(vinyl alcohol)/magnetite ferrogel composite

2014 ◽  
Vol 68 (6) ◽  
pp. 743-753 ◽  
Author(s):  
Milena Marinovic-Cincovic ◽  
Aleksandra Radosavljevic ◽  
Jelena Krstic ◽  
Jelena Spasojevic ◽  
Natasa Bibic ◽  
...  
Keyword(s):  
Gamma Irradiation ◽  
Vinyl Alcohol ◽  
Magnetic Particles ◽  
Heating Temperature ◽  
Crosslinking Agent ◽  
Poly Vinyl Alcohol ◽  
Chemical Characteristics ◽  
Physico Chemical ◽  
Soft Actuators ◽  
Pva Hydrogel

Magnetic field sensitive gels, ferrogels are new promising class of hydrogels. The coupling of hydrogels and magnetic particles has potential application in soft actuators such as artificial muscles or for hyperthermia application. Here a composite of magnetite particles (Fe3O4) and poly(vinyl alcohol) (PVA) hydrogel is developed using gamma irradiation as a crosslinking agent. PVA and Fe3O4 were chosen because of their well-established biocompatibility, radiation crosslinking potential (PVA), mild magnetic properties and the Curie point near desired heating temperature range (Fe3O4). Physico-chemical characteristics of these systems show the effect of the presence of particles in the process of radiation-induced crosslinking. Obtained PVA/Fe3O4 ferrogel composite has greater swelling capacity, activation energy of dehydration and dehydration rate compared to PVA hydrogel, crosslinked under the same conditions.

A Comparison of Rheological Models and Experimental Data of Metallocene Linear Low Density Polyethylene Solutions as a Function of Temperature and Concentration

2016 ◽  
Vol 12 (3) ◽  
pp. 4322-4339
Author(s):  
Salah Hamza
Keyword(s):  
Experimental Data ◽  
Shear Rate ◽  
Rheological Properties ◽  
Power Law ◽  
Low Density Polyethylene ◽  
Effect Of Temperature ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Shear Rates ◽  
Wide Range

Knowledge of rheological properties of polymer and their variation with temperature and concentration have been globally important for processing and fabrication of polymers in order to make useful products. Basheer et al. [1] investigated, experimentally, the changes in rheological properties of metallocene linear low density polyethylene (mLLDPE) solutions by using a rotational rheometer model AR-G2 with parallel plate geometry. Their work covered the temperature range from  to  and  concentration from  to . In this paper, we reconsider Basheer work to describe the rheological behavior of mLLDPE solutions and its dependence on concentration and temperature.Until now, several models have been built to describe the complex behavior of polymer fluids with varying degrees of success. In this article, Oldroyd 4-constant, Giesekus and Power law models were tested for investigating the viscosity of mLLDPE solution as a function of shear rate. Results showed that Giesekus and power law models provide the best prediction of viscosity for a wide range of shear rates at constant temperature and concentration. Therefore, Giesekus and power law models were suitable for all mLLDPE solutions while Oldroyd 4-constant model doesn't.A new proposed correlation for the viscosity of mLLDPE solutions as a function of shear rate, temperature and concentration has been suggested. The effect of temperature and concentration can be adequately described by an Arrhenius-type and exponential function respectively. The proposed correlation form was found to fit the experimental data adequately.

Rheological Characteristics of Surfactant-Based Fluids: A Comprehensive Study

2018 ◽  
Author(s):  
Ahmed H. Kamel
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Rheological Behavior ◽  
Surfactant Concentration ◽  
Flow Direction ◽  
Shear Thinning ◽  
Molecular Structures ◽  
Wide Range ◽  
Unique Nature ◽  
Viscoelastic Surfactant

Surfactant-based fluids, SB fluids exhibit complex rheological behavior due to substantial structural change caused by the molecules self-assembled colloidal aggregation. Various factors affect their rheological properties. Among these factors, surfactant concentration, shear rate, temperature, and salinity are investigated. One of the most popular surfactants, Aromox® APA-T viscoelastic surfactant (VES) is examined. The study focuses on four different concentrations (1.5%, 2%, 3%, and 4%) over a shear rate ranging from 0.0526 sec−1 to 1944 sec−1 using Bohlin rheometer. For salinity effects, two brine solutions are used; 2 and 4% KCl while for temperature effects, a wide range from ambient temperature of 72°F up to 200°F is covered. The results show that SB fluids exhibit a complex rheological behavior due to its unique nature and the various structures form in the solution. In general, SB fluids at all concentrations exhibit a non-Newtonian pseudo-plastic shear thinning behavior. As the surfactant concentration and/or shear increases, a stronger shear thinning behavior can be seen. Increasing solution salinity promotes formation of rod-like micelles and increases its flexibility. Salinity affects micelles’ growth and their rheological behavior is very sensitive to the nature and structure of the added salt. Different molecular structures are formed; spherical micelles occur first and then increased shear rate and/or salinity promotes the formation of rod-like micelles. Later, rod-like micelles are aligned in the flow direction and form a large super ordered structure of micellar bundles or aggregates called shear induced structure (SIS). Different structures implies different rheological properties. Likewise, rheology improves with increasing temperature up to 100°F. Further increase in temperature reverses the effects and viscosity decreases. However, the effects of temperature and salinity diminish at higher shear rates. Furthermore, a rheology master curve is developed to further understand the rheological behavior of SB fluids and correlate rheological properties to its microscopic structure.

scholarly journals Rheological properties of traditional balsamic vinegar: New insights and markers for objective and perceived quality

2017 ◽  
Vol 6 (1) ◽  
Author(s):  
Pasquale M. Falcone ◽  
Elisa Sabatinelli ◽  
Federico Lemmetti ◽  
Paolo Giudici
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Dynamic Viscosity ◽  
Flow Instability ◽  
Relaxation Times ◽  
Sensory Properties ◽  
Flow Behaviour ◽  
Shear Rates ◽  
Wide Range ◽  
Balsamic Vinegar

The molecular structure of Traditional Balsamic Vinegar (TBV) undergoes shear-induced and time-dependent jamming transitions due to the high solute concentration and self-assembling phenomena of high molecular size melanoidins with very-long relaxation times (12 years at least or more than 25). The purpose of this work was to perform a descriptive and quantitativeevaluation of relationships between rheological properties, vinegar composition, and perceptual assessment of sensory properties according to the official sensory procedure. With this aim, vinegars having quality traits matching legal requirements for the PDO designation were analyzed for their reducing sugars (glucose and fructose), volatile acidity, fixed acidity, pH, Brix degree, and density as well as for their flow behaviour and dynamic viscosity over a wide range of shear rates. Results showed that flow behaviour of TBV was affected by jamming properties over wide-scale ranges of shear rate producing flow instability below a shear rate of 60s-1. Homogeneous, continuous flow was found at medium-high shear rates with thickening and/or thinning traits. A common onset for the structure scaling was mathematically estimated to occur close to when the density was 1.32 gmL-1. Comparative analysis of rheological, compositional and sensory properties suggested that the colloidal jamming of the vinegar melanoidins dominated the total olfactive and gustative stimuli, and determined the classification of the vinegars that had a higher dynamic viscosity but more homogeneous flow as being of the highest commercial quality category. A robust statistical model was proposed encoding for the top-down decision-making process for quality assignment according to the official sensory procedure, using composition and flow properties as predictor variables. 

NUTRITION VALUE AND RHEOLOGICAL PROPERTIES OF BEAN PUREE

2021 ◽  
Author(s):  
Н.Т. ШАМКОВА ◽  
А.М. АБДУЛХАМИД ◽  
А.В. ЗАБОЛОТНИЙ
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Mechanical Parameters ◽  
Biological Value ◽  
Wide Range ◽  
Nutrition Value

Разработана технология полуфабриката из зерновой фасоли в виде пюреобразной массы. Установлено, что с увеличением скорости сдвига вязкость фасолевого пюре уменьшается, при этом увеличение его влажности приводит к изменению структурно-механических показателей в соответствии с известными данными об ослаблении структурных связей в коагуляционных и коагуляционно-конденсационных системах. Характер течения полуфабриката из зерновой фасоли, высокая пищевая и биологическая ценность доказывают целесообразность его использования в производстве широкого ассортимента кулинарной продукции. The technology of a semi-finished product from a grain bean in the form of a puree-like mass is developed. It has been established that the viscosity of bean pulp decreases with increasing shear rate, while increasing its moisture leads to a change in structural and mechanical parameters in accordance with known data on the weakening of structural bonds in coagulation and coagulation-condensation systems. The nature of the flow of semi-finished products from grain beans, high nutritional and biological value prove the possibility of its use in the production of a wide range of culinary products.

scholarly journals Soft, tough, and fast polyacrylate dielectric elastomer for non-magnetic motor

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Li-Juan Yin ◽  
Yu Zhao ◽  
Jing Zhu ◽  
Minhao Yang ◽  
Huichan Zhao ◽  
...  
Keyword(s):  
High Performance ◽  
Crosslinking Agent ◽  
High Energy ◽  
Dielectric Elastomer ◽  
High Energy Density ◽  
Dielectric Elastomers ◽  
Dielectric Elastomer Actuators ◽  
Response Bandwidth ◽  
Electrically Actuated ◽  
Soft Actuators

AbstractDielectric elastomer actuators (DEAs) with large electrically-actuated strain can build light-weight and flexible non-magnetic motors. However, dielectric elastomers commonly used in the field of soft actuation suffer from high stiffness, low strength, and high driving field, severely limiting the DEA’s actuating performance. Here we design a new polyacrylate dielectric elastomer with optimized crosslinking network by rationally employing the difunctional macromolecular crosslinking agent. The proposed elastomer simultaneously possesses desirable modulus (~0.073 MPa), high toughness (elongation ~2400%), low mechanical loss (tan δm = 0.21@1 Hz, 20 °C), and satisfactory dielectric properties ($${\varepsilon }_{{{{{{\rm{r}}}}}}}$$ ε r  = 5.75, tan δe = 0.0019 @1 kHz), and accordingly, large actuation strain (118% @ 70 MV m−1), high energy density (0.24 MJ m−3 @ 70 MV m−1), and rapid response (bandwidth above 100 Hz). Compared with VHBTM 4910, the non-magnetic motor made of our elastomer presents 15 times higher rotation speed. These findings offer a strategy to fabricate high-performance dielectric elastomers for soft actuators.

scholarly journals PENGARUH DIOCTYL ADIPATE TERHADAP SIFAT RHEOLOGIKAL HTPB TERPLASTISISASI (EFFECT OF DIOCTYL ADIPATE ON THE RHEOLOGICAL PROPERTIES OF PLASTICIZED HTPB)

2019 ◽  
Vol 16 (2) ◽  
pp. 139
Author(s):  
Afni Restasari ◽  
Luthfia Hajar Abdillah ◽  
Rika Suwana Budi ◽  
Kendra Hartaya
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Rheological Properties ◽  
Shear Thickening ◽  
Dioctyl Adipate

Pengembangan pengetahuan terhadap sifat rheologikal isian cair dari propelan berguna untuk mendapatkan sifat slurry yang optimum. Pengembangan ini dapat dimulai dari campuran HTPB-DOA sehingga penelitian ini bertujuan untuk mengetahui pengaruh DOA terhadap sifat rheologikal HTPB-DOA yang meliputi sifat alir terhadap shear rate, viskositas dan viskositas saat zero shear rate. Dalam metodenya, DOA divariasi 0, 5, 10, 15 dan 20% dan dicampur dengan HTPB. Sifat rheologikal dipahami dengan mengukur viskositasnya pada kecepatan putar 0,5; 1; 1,5; 2; 2,5; 3; 4 dengan spindel tipe 2 dari viskometer Brookfield dan menganalisa grafik shear stress vs shear rate serta viskositas vs shear rate. Berdasarkan analisa tersebut, diketahui bahwa campuran HTPB-DOA bersifat shear thickening. Semakin banyak DOA yang ditambahkan, semakin rendah viskositas campuran, semakin rendah nilai viskositas pada zero shear rate dan semakin kuat sifat shear thickening dari campuran.

Influence of Temperature and Shear Rate on Rheological Properties of CTAC/NaSal Aqueous Solution

2019 ◽  
Vol 12 (4) ◽  
pp. 296-311
Author(s):  
Mingjun Pang ◽  
Chengcheng Xie
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Shear Viscosity ◽  
Chemical Engineering ◽  
Sodium Salicylate ◽  
Shear Thickening ◽  
Shear Thinning ◽  
Power Law Function ◽  
Cetyltrimethyl Ammonium ◽  
Increasing Temperature

Background: It is very important for understanding the turbulence drag-reducing mechanism and for improving product quality in the fields of pharmaceutical and chemical engineering to deeply investigate the rheological properties of surfactants solutions. Methods: The rheological properties of Cationic surfactant (Cetyltrimethyl Ammonium Chloride)/Sodium salicylate were measured and analyzed with the MCR302 rheometer. Results: The present results show that the shear viscosity of CTAC/NaSal solution with the exception of 0.9375mmol·L-1 can show the Newtonian characteristic, the shear-thickening, the shear-thinning and the stable shear properties with changing shear time. The induction time increases with a shear rate as a power law function relation tind=aγb. Conclusion: The shear viscosity of the CTAC/NaSal solution can be divided into three regions with shear rate, and its flow curve conforms to a linear function in the logarithmic coordinate. When the concentration and the shear rate are relatively high, the viscosity curve of the CTAC/NaSal solution appears "platform" at the high temperature. When the shear rate is greater than 90s-1, the shear viscosity only appears shear thinning with increasing temperature.

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