scholarly journals Carbomer microgels as model yield-stress fluids

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Zdzisław Jaworski ◽  
Tadeusz Spychaj ◽  
Anna Story ◽  
Grzegorz Story
Keyword(s):  
Yield Stress ◽  
Soft Matter ◽  
Flow Characteristics ◽  
Wall Slip ◽  
Future Research ◽  
Cross Linking ◽  
Model Yield ◽  
Liquid Transition ◽  
Microgel Particles ◽  
2D And 3D

Abstract The review presents current research results for Carbopol-based microgels as yield-stress materials, covering three aspects: chemical, physical and rheological. Such a joint three-aspect study has no analog in the literature. The chemical aspects of Carbopol polymers are presented in terms of a cross-linking polymerization of acrylic acid, their molecular structure, microgel formulation, polyacid dissociation and neutralization, osmotic pressure and associated immense microgel swelling. The physical characterization is focused on models of the shear-induced solid-to-liquid transition of microgels, which are formed of mesoscopic particles typical for soft matter materials. Models that describe interparticle effects are presented to explain the energy states of microgel particles at the mesoscale of scrutiny. Typical representatives of the models utilize attributes of jamming dispersions, micromechanical and polyelectrolyte reactions. Selected relationships that result from the models, such as scaling rules and nondimensional flow characteristics are also presented. The rheological part presents the discussion of problems of yield stress in 2D and 3D deformations, appearance and magnitude of the wall slip. The theory and characteristics of Carbopol microgel deformation in rotational rheometers are presented with graphs for the steady-state measurements, stress-controlled oscillation and two types of transient shear deformation. The review is concluded with suggestions for future research.

Yield stress and wall slip of kaolinite networks

2021 ◽  
Vol 33 (5) ◽  
pp. 053105
Author(s):  
Aref Abbasi Moud ◽  
Jade Poisson ◽  
Zachary M. Hudson ◽  
Savvas G. Hatzikiriakos
Keyword(s):  
Yield Stress ◽  
Wall Slip

scholarly journals Homotopy pertubation method analysis to MHD flow of a radiative nanofluid with viscous dissipation and ohmic heating over a stretching porous plate

2018 ◽  
Vol 22 (1 Part B) ◽  
pp. 413-422 ◽  
Author(s):  
Hitesh Kumar
Keyword(s):  
Boundary Layer ◽  
Viscous Dissipation ◽  
Reverse Flow ◽  
Ohmic Heating ◽  
Complete Solution ◽  
Porous Plate ◽  
Flow Characteristics ◽  
Mhd Flow ◽  
Future Research ◽  
Layer Flow

An analytical study is performed to explore the flow and heat transfer characteristics of nanofluid (Al2O3-water and TiO3-water) over a linearly stretching porous sheet in the presence of radiation, ohmic heating, and viscous dissipation. Homotopy perturbed method is used and complete solution is presented, the results for the nanofluids velocity and temperature are obtained. The effects of various thermophysical parameters on the boundary-layer flow characteristics are displayed graphically and discussed quantitatively. The effect of viscous dissipation on the thermal boundary-layer is seen to be reverse after a fixed distance from the wall, which is very strange in nature and is the result of a reverse flow. The finding of this paper is unique and may be useful for future research on nanofluid.

scholarly journals Transformation Between 2D and 3D Covalent Organic Frameworks via Reversible [2+2] Cycloaddition

2020 ◽  
Author(s):  
Thaksen Jadhav ◽  
Yuan Fang ◽  
Cheng-Hao Liu ◽  
Afshin Dadvand ◽  
Ehsan Hamzehpoor ◽  
...  
Keyword(s):  
Band Structure ◽  
Absorption Edge ◽  
Room Temperature ◽  
Three Dimensional ◽  
Cross Linking ◽  
Two Dimensional ◽  
Covalent Organic Frameworks ◽  
Doping Behavior ◽  
2D Polymers ◽  
2D And 3D

We report the first transformation between crystalline vinylene-linked two-dimensional (2D) polymers and crystalline cyclobutane-linked three-dimensional (3D) polymers. Specifically, absorption-edge irradiation of the 2D poly(arylenevinylene) covalent organic frameworks (COFs) results in topological [2+2] cycloaddition cross-linking the π-stacked layers in 3D COFs. The reaction is reversible and heating to 200°C leads to a cycloreversion while retaining the COF crystallinity. The resulting difference in connectivity is manifested in the change of mechanical and electronic properties, including exfoliation, blue-shifted UV-Vis absorption, altered luminescence, modified band structure and different acid-doping behavior. The Li-impregnated 2D and 3D COFs show a significant ion conductivity of 1.8×10<sup>−4</sup> S/cm and 3.5×10<sup>−5</sup> S/cm, respectively. Even higher room temperature proton conductivity of 1.7×10<sup>-2</sup> S/cm and 2.2×10<sup>-3</sup> S/cm was found for H<sub>2</sub>SO<sub>4</sub>-treated 2D and 3D COFs, respectively.

scholarly journals 2D and 3D Bulk Materials for Environmental Remediation: Air Filtration and Oil/Water Separation

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5714
Author(s):  
Ha-Jin Lee ◽  
Won San Choi
Keyword(s):  
Future Research ◽  
Oily Wastewater ◽  
Air Filtration ◽  
Bulk Materials ◽  
Water Separation ◽  
Air Filters ◽  
Technical Problems ◽  
Oil Water Separation ◽  
Oil Water ◽  
2D And 3D

Air and water pollution pose an enormous threat to human health and ecosystems. In particular, particulate matter (PM) and oily wastewater can cause serious environmental and health concerns. Thus, controlling PM and oily wastewater has been a great challenge. Various techniques have been reported to effectively remove PM particles and purify oily wastewater. In this article, we provide a review of the recent advancements in air filtration and oil/water separation using two- and three-dimensional (2D and 3D) bulk materials. Our review covers the advantages, characteristics, limitations, and challenges of air filters and oil/water separators using 2D and 3D bulk materials. In each section, we present representative works in detail and describe the concepts, backgrounds, employed materials, fabrication methods, and characteristics of 2D and 3D bulk material-based air filters and oil/water separators. Finally, the challenges, technical problems, and future research directions are briefly discussed for each section.

The influence of wall slip on yield stress and viscoelastic measurements of cement paste

2001 ◽  
Vol 31 (2) ◽  
pp. 205-212 ◽  
Author(s):  
Aaron W. Saak ◽  
Hamlin M. Jennings ◽  
Surendra P. Shah
Keyword(s):  
Yield Stress ◽  
Cement Paste ◽  
Wall Slip

scholarly journals A multi-component lattice Boltzmann approach to study the causality of plastic events

2020 ◽  
Vol 378 (2175) ◽  
pp. 20190403
Author(s):  
Pinaki Kumar ◽  
Roberto Benzi ◽  
Jeannot Trampert ◽  
Federico Toschi
Keyword(s):  
Yield Stress ◽  
Lattice Boltzmann ◽  
Soft Matter ◽  
Scaling Laws ◽  
System A ◽  
Plastic Event ◽  
Glassy Materials ◽  
Couette Cell ◽  
Soft Glassy Materials ◽  
Concentrated Emulsions

Using a multi-component lattice Boltzmann (LB) model, we perform fluid kinetic simulations of confined and concentrated emulsions. The system presents the phenomenology of soft-glassy materials, including a Herschel–Bulkley rheology, yield stress, ageing and long relaxation time scales. Shearing the emulsion in a Couette cell below the yield stress results in plastic topological re-arrangement events which follow established empirical seismic statistical scaling laws, making this system a good candidate to study the physics of earthquakes. One characteristic of this model is the tendency for events to occur in avalanche clusters, with larger events, triggering subsequent re-arrangements. While seismologists have developed statistical tools to study correlations between events, a process to confirm causality remains elusive. We present here, a modification to our LB model, involving small, fast vibrations applied to individual droplets, effectively a macroscopic forcing, which results in the arrest of the topological plastic re-arrangements. This technique provides an excellent tool for identifying causality in plastic event clusters by examining the evolution of the dynamics after ‘stopping’ an event, and then checking which subsequent events disappear. This article is part of the theme issue ‘Fluid dynamics, soft matter and complex systems: recent results and new methods’.

scholarly journals Hydrogels as dynamic memory with forgetting ability

2020 ◽  
Vol 117 (32) ◽  
pp. 18962-18968 ◽  
Author(s):  
Chengtao Yu ◽  
Honglei Guo ◽  
Kunpeng Cui ◽  
Xueyu Li ◽  
Ya Nan Ye ◽  
...  
Keyword(s):  
Thermal History ◽  
Soft Matter ◽  
Future Research ◽  
Temperature Sensitive ◽  
Thermal Stimulus ◽  
Water Release ◽  
Dynamic Memory ◽  
Learning Time ◽  
Hard Materials ◽  
External Stimuli

The memory of our brain, stored in soft matter, is dynamic, and it forgets spontaneously to filter unimportant information. By contrast, the existing manmade memory, made from hard materials, is static, and it does not forget without external stimuli. Here we propose a principle for developing dynamic memory from soft hydrogels with temperature-sensitive dynamic bonds. The memorizing–forgetting behavior is achieved based on fast water uptake and slow water release upon thermal stimulus, as well as thermal-history-dependent transparency change of these gels. The forgetting time is proportional to the thermal learning time, in analogy to the behavior of brain. The memory is stable against temperature fluctuation and large stretching; moreover, the forgetting process is programmable. This principle may inspire future research on dynamic memory based on the nonequilibrium process of soft matter.

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