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1
Southwick, J. G., and C. W. Manke. "Molecular Degradation, Injectivity, and Elastic Properties of Polymer Solutions." SPE Reservoir Engineering 3, no. 04 (November 1, 1988): 1193–201. http://dx.doi.org/10.2118/15652-pa.
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2
LINDNER, ANKE, DANIEL BONN, EUGENIA CORVERA POIRÉ, MARTINE BEN AMAR, and JACQUES MEUNIER. "Viscous fingering in non-Newtonian fluids." Journal of Fluid Mechanics 469 (October 15, 2002): 237–56. http://dx.doi.org/10.1017/s0022112002001714.
Повний текст джерелаАнотація:
We study the viscous fingering or Saffman–Taylor instability in two different dilute or semi-dilute polymer solutions. The different solutions exhibit only one non-Newtonian property, in the sense that other non-Newtonian effects can be neglected. The viscosity of solutions of stiff polymers has a strong shear rate dependence. Relative to Newtonian fluids, narrower fingers are found for rigid polymers. For solutions of flexible polymers, elastic effects such as normal stresses are dominant, whereas the shear viscosity is almost constant. Wider fingers are found in this case. We characterize the non-Newtonian flow properties of these polymer solutions completely, allowing for separate and quantitative investigation of the influence of the two most common non-Newtonian properties on the Saffman–Taylor instability. The effects of the non-Newtonian flow properties on the instability can in all cases be understood quantitatively by redefining the control parameter of the instability.
3
Shima, A., T. Tsujino, H. Nanjo, and N. Miura. "Cavitation Damage in Polymer Aqueous Solutions." Journal of Fluids Engineering 107, no. 1 (March 1, 1985): 134–38. http://dx.doi.org/10.1115/1.3242431.
Повний текст джерелаАнотація:
Cavitation damage tests in polymer solutions are made with a vibratory cavitation apparatus. It is possible for this device to suppress the degradation of polymer by ultrasonic cavitation. Polymer solutions used are 100 wppm, 500 wppm, and 1000 wppm solutions of Polyox. The weight loss in 100 wppm Polyox solution is larger than that in water, but in 500 wppm and 1000 wppm Polyox solutions the weight losses after 60 min exposure to cavitation are relatively small. It is indicated that the cavitation damage in polymer solutions is subject to the effective influence of elastic properties of liquids.
4
Zhu, Shijie, Xinsheng Xue, Jian Zhang, Shilun Zhang, and Zhezhi Liu. "Application and Optimization of the Rheological Model for a Hydrophobically Associating Dendrimer Polymer." Polymers 14, no. 9 (April 26, 2022): 1747. http://dx.doi.org/10.3390/polym14091747.
Повний текст джерелаАнотація:
Polymer flooding is one of the most important enhancing oil recovery (EOR) technologies in the world. With the optimization of polymer synthesis, the performance of polymer solutions has been greatly improved, which can adapt to more complex oil and gas reservoirs. However, with the continuous improvement of the properties of polymer solutions, the elastic property of polymer solutions is significantly improved, and the rheological law has also changed. This series of changes affects the application of polymer flooding reservoir numerical simulation technology. Therefore, constructing an accurate description model and precise limitation conditions is particularly important. The rheological curve with a wide shear range (0.1~10,000 s−1) and the viscoelasticity of the two polymers (partially hydrolysed polyacrylamide (HPAM) and dendritic hydrophobic association polymer (DHAP)) were analyzed and tested by a rotating rheometer. The results showed that under the experimental conditions, the rheological curve of both polymers can be described by the Carreau rheological model. Meanwhile, the structural viscosity of the hydrophobically associating polymer solution (DHAP) greatly improved the elasticity of the solution and led to the change of elastic modulus. Considering the influence of elastic characteristics on the rheological curve, the relaxation time spectrum derived from small vibration experimental data was used to limit the characteristic relaxation time, that is, the value range of λ. It was observed that the experimental data were highly matched with the nonlinear regression fitting curve of the Carreau rheological model. Therefore, the relationship between different test parameters should be fully considered while studying the rheological constitutive equation of viscoelastic fluid, so as to optimize and improve the equation of it.
5
Zhu, Shijie, Xinsheng Xue, Jian Zhang, Shilun Zhang, and Zhezhi Liu. "Application and Optimization of the Rheological Model for a Hydrophobically Associating Dendrimer Polymer." Polymers 14, no. 9 (April 26, 2022): 1747. http://dx.doi.org/10.3390/polym14091747.
Повний текст джерелаАнотація:
Polymer flooding is one of the most important enhancing oil recovery (EOR) technologies in the world. With the optimization of polymer synthesis, the performance of polymer solutions has been greatly improved, which can adapt to more complex oil and gas reservoirs. However, with the continuous improvement of the properties of polymer solutions, the elastic property of polymer solutions is significantly improved, and the rheological law has also changed. This series of changes affects the application of polymer flooding reservoir numerical simulation technology. Therefore, constructing an accurate description model and precise limitation conditions is particularly important. The rheological curve with a wide shear range (0.1~10,000 s−1) and the viscoelasticity of the two polymers (partially hydrolysed polyacrylamide (HPAM) and dendritic hydrophobic association polymer (DHAP)) were analyzed and tested by a rotating rheometer. The results showed that under the experimental conditions, the rheological curve of both polymers can be described by the Carreau rheological model. Meanwhile, the structural viscosity of the hydrophobically associating polymer solution (DHAP) greatly improved the elasticity of the solution and led to the change of elastic modulus. Considering the influence of elastic characteristics on the rheological curve, the relaxation time spectrum derived from small vibration experimental data was used to limit the characteristic relaxation time, that is, the value range of λ. It was observed that the experimental data were highly matched with the nonlinear regression fitting curve of the Carreau rheological model. Therefore, the relationship between different test parameters should be fully considered while studying the rheological constitutive equation of viscoelastic fluid, so as to optimize and improve the equation of it.
6
Dealy, John M. "Rheology of Molten Polymers." MRS Bulletin 16, no. 8 (August 1991): 24–26. http://dx.doi.org/10.1557/s0883769400056281.
Повний текст джерелаАнотація:
The term “polymeric liquids” is used to describe both solutions of polymers and molten polymers. All polymeric liquids exhibit non-Newtonian flow behavior, including a shear stress-dependent viscosity and elasticity. However, concentrated solutions and melts of polymers whose molecular weights exceed a certain critical value (the “critical molecular weight for entanglement,” Mc) exhibit quite remarkable deviations from classical fluid behavior, especially marked elasticity. Among the remarkable rheological phenomena exhibited by these materials are elastic recoil and flow-induced an-isotropy. Indeed, in certain situations, such materials can exhibit elastic effects that are almost indistinguishable from those exhibited by cross-linked rubbers. This behavior is important, because most commercial “thermoplastics,” such as polyethylene and polystyrene, have high molecular weights (M > Mc) and are processed in the molten state.A given generic polymer, polyethylene for example, can exhibit a wide range of properties depending on the molecular weight distribution. Another important aspect of molecular structure is branching. For many monomers (the molecular building blocks that make a polymer molecule), two types of polymer structure are possible, linear and branched. For example, ethylene can be polymerized in two ways to form either linear polyethylene or branched polyethylene. Branching enhances the non-Newtonian and elastic aspects of the melt flow behavior. Yet another possible aspect of polymer molecular structure is the presence of a comonomer.
7
Simonov-Emel’yanov, I. D., and A. V. Petrov. "Structure and Visco-Elastic Properties of Polymer Solutions for Electrospinning Fibers." Fibre Chemistry 49, no. 3 (September 2017): 161–66. http://dx.doi.org/10.1007/s10692-017-9863-1.
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8
Gupta, Anupam, and Dario Vincenzi. "Effect of polymer-stress diffusion in the numerical simulation of elastic turbulence." Journal of Fluid Mechanics 870 (May 10, 2019): 405–18. http://dx.doi.org/10.1017/jfm.2019.224.
Повний текст джерелаАнотація:
Elastic turbulence is a chaotic regime that emerges in polymer solutions at low Reynolds numbers. A common way to ensure stability in numerical simulations of polymer solutions is to add artificially large polymer-stress diffusion. In order to assess the accuracy of this approach in the elastic turbulence regime, we compare numerical simulations of the two-dimensional Oldroyd-B and FENE-P models sustained by a cellular force with and without artificial diffusion. We find that artificial diffusion can have a dramatic effect even on the large-scale properties of the flow and we show some of the spurious phenomena that may arise when artificial diffusion is used.
9
Clarke, A., A. M. Howe, J. Mitchell, J. Staniland, and L. A. Hawkes. "How Viscoelastic-Polymer Flooding Enhances Displacement Efficiency." SPE Journal 21, no. 03 (June 15, 2016): 0675–87. http://dx.doi.org/10.2118/174654-pa.
Повний текст джерелаАнотація:
Summary Increasing flooding-solution viscosity with polymers provides a favorable mobility ratio compared with brine flooding and hence improves volumetric sweep efficiency. Flooding with a polymer solution exhibiting elastic properties has been reported to increase displacement efficiency, resulting in a sustained doubling of the recovery enhancement compared with the use of conventional viscous-polymer flooding (Wang et al. 2011). Flooding with viscoelastic-polymer solutions is claimed also to increase recovery more than expected from changes in capillary number alone (Wang et al. 2010). This increase in displacement efficiency by viscoelastic polymers is reported to occur because of changes in the steady-state-flow profile and enhancements in oil stripping and thread formation. However, within the industry there are doubts that a genuine effect is observed, or that improvements in displacement efficiency occur with field-applicable flow regimes (Vermolen et al. 2014). In this study, we demonstrate that flooding with viscoelastic-polymer solutions can indeed increase recovery more than expected from changes in capillary number. We show a mechanism of fluctuations in flow at low Reynolds number by which viscoelastic-polymer solutions provide improvements in displacement efficiency. The mechanism, known as elastic turbulence, is an effect previously unrecognized in this context. We demonstrate that the effect may be obtained at field-relevant flow rates. Furthermore, this underlying mechanism explains both the enhanced capillary-desaturation curves and the observation of apparent flow thickening (Delshad et al. 2008; Seright et al. 2011) for these viscoelastic solutions in porous media. The work contrasts experiments on flow and recovery by use of viscous and viscoelastic-polymer solutions. The circumstances under which viscoelasticity is beneficial are demonstrated. The findings are applicable to the design of formulations for enhanced oil recovery (EOR) by polymer flooding. A combination of coreflooding, micromodel flow, and rheometric studies is presented. The results include single-phase and multiphase floods in sandstone cores. Polymer solutions are viscoelastic [partially hydrolyzed polyacrylamide (HPAM)] or viscous (xanthan). The effects of molecular weight, flow rate, and concentration of the HPAMs are described. The data lead us to suggest a mechanism that may be used to explain the observations of improved displacement efficiency and why the improvement is not seen for all viscoelastic-polymer floods.
10
De Corato, Marco, and Marino Arroyo. "A theory for the flow of chemically responsive polymer solutions: Equilibrium and shear-induced phase separation." Journal of Rheology 66, no. 5 (September 2022): 813–35. http://dx.doi.org/10.1122/8.0000475.
Повний текст джерелаАнотація:
Chemically responsive polymers are macromolecules that respond to local variations of the chemical composition of the solution by changing their conformation, with notable examples including polyelectrolytes, proteins, and DNA. The polymer conformation changes can occur in response to changes in the pH, the ionic strength, or the concentration of a generic solute that interacts with the polymer. These chemical stimuli can lead to drastic variations of the polymer flexibility and even trigger a transition from a coil to a globule polymer conformation. In many situations, the spatial distribution of the chemical stimuli can be highly inhomogeneous, which can lead to large spatial variations of polymer conformation and of the rheological properties of the mixture. In this paper, we develop a theory for the flow of a mixture of solute and chemically responsive polymers. The approach is valid for generic flows and inhomogeneous distributions of polymers and solutes. To model the polymer conformation changes introduced by the interactions with the solute, we consider the polymers as linear elastic dumbbells whose spring stiffness depends on the solute concentration. We use Onsager’s variational formalism to derive the equations governing the evolution of the variables, which unveils novel couplings between the distribution of dumbbells and that of the solute. Finally, we use a linear stability analysis to show that the governing equations predict an equilibrium phase separation and a distinct shear-induced phase separation whereby a homogeneous distribution of solute and dumbbells spontaneously demix. Similar phase transitions have been observed in previous experiments using stimuli-responsive polymers and may play an important role in living systems.
11
Lu, Fei, Jun Song, Bo Wen Cheng, Hong Jun Zang, and Yi Liang. "Rheological Properties of Concentrated 1-Allyl-3-Methylimidazolium Chloride Cellulose Solutions." Advanced Materials Research 199-200 (February 2011): 3–6. http://dx.doi.org/10.4028/www.scientific.net/amr.199-200.3.
Повний текст джерелаАнотація:
The viscosity behaviors and elastic properties of concentrated cellulose 1-allyl-3-methy -limidazolium Chloride solutions were investigated in the concentration from 10 wt% to 25 wt%. Rheological measurement showed that the solution was pesudoplastic fluid. The non-Newtonian behavior was improved and shear-thinning tendency became more pronounced with increasing polymer concentration. The power law index ranged from 0.19 to 0.30. The effects of cellulose concentration to the storage modulus G′ and the loss modulus G″ were analyzed. First normal stress difference (N1) increased with increasing concentration.
12
Blanco-López, Marcos, Álvaro González-Garcinuño, Antonio Tabernero, and Eva M. Martín del Valle. "Steady and Oscillatory Shear Flow Behavior of Different Polysaccharides with Laponite®." Polymers 13, no. 6 (March 22, 2021): 966. http://dx.doi.org/10.3390/polym13060966.
Повний текст джерелаАнотація:
The rheological behavior, in terms of steady and oscillatory shear flow, of Laponite® with different polysaccharides (alginate, chitosan, xanthan gum and levan) in salt-free solutions was studied. Results showed that a higher polymer concentration increased the zero-rate viscosity and decreased the critical strain rate (Cross model fit) as well as increasing the elastic and viscous moduli. Those properties (zero-rate viscosity and critical strain rate) can be a suitable indicator of the effect of the Laponite® on the shear flow behavior for the different solutions. Specifically, the effect of the Laponite® predominates for solutions with large critical strain rate and low zero-rate viscosity, modifying significantly the previous parameters and even the yield stress (if existing). On the other hand, larger higher polymeric concentration hinders the formation of the platelet structure, and polymer entanglement becomes predominant. Furthermore, the addition of high concentrations of Laponite® increases the elastic nature, but without modifying the typical mechanical spectra for polymeric solutions. Finally, Laponite® was added to (previously crosslinked) gels of alginate and chitosan, obtaining different results depending on the material. These results highlight the possibility of predicting qualitatively the impact of the Laponite® on different polymeric solutions depending on the solutions properties.
13
Ashraf, Muhammad Azeem, Bijan Sobhi-Najafabadi, Özdemir Göl, and D. Sugumar. "Finite Element Analysis of a Polymer- Polymer Sliding Contact for Schallamach Wave and Wear." Key Engineering Materials 348-349 (September 2007): 633–36. http://dx.doi.org/10.4028/www.scientific.net/kem.348-349.633.
Повний текст джерелаАнотація:
Sliding polymer-polymer surface contacts, due to their inherent elastic properties, exhibit detachment waves also termed as Schallamach waves. Such waves effect the initiation and propagation of wear along the sliding contacts. This paper presents quasi steady-state analysis of such a sliding contact using finite element. The contact is modeled and nodal solutions for pressure are obtained for small sliding steps. Analysis of orthogonal pressure components at the contact nodes reveals the formation of Schallamach wave phenomenon. Further, appropriate wear law is used for calculation of wear at nodal level.
14
Chami, Souheyla, Nicolas Joly, Patrizia Bocchetta, Patrick Martin, and Djamel Aliouche. "Polyacrylamide Grafted Xanthan: Microwave-Assisted Synthesis and Rheological Behavior for Polymer Flooding." Polymers 13, no. 9 (May 5, 2021): 1484. http://dx.doi.org/10.3390/polym13091484.
Повний текст джерелаАнотація:
Application of polymer-flooding systems in secondary and tertiary oil recovery represents a real challenge for oil industry. In this work, our main objective is to explore possibilities of making use of xanthan-g-polyacrylamide for polymer flooding in a particular Devonian oilfield of medium salinity. The graft polymer was synthesized by using microwave-assisted graft copolymerization reaction of acrylamide on xanthan. The synthesized copolymer with optimized grafting parameters has been characterized by Infrared Spectroscopy and Thermal Analysis (DSC). Rheological analysis by steady shear and oscillatory flow experiments have been subsequently performed for xanthan and grafted xanthan under reservoir conditions. In steady shear, as expected the grafted polymer solutions flow as shear-thinning materials and apparent viscosity showed good fits with Cross’s model. The viscosity losses due to salinity or temperature are more controlled for the grafted xanthan compared to pristine xanthan. When the grafted polymer concentration is increased to 2000 ppm the losses were halved. In oscillatory shear, the copolymer solutions followed a global behavior of semi-dilute entangled systems; furthermore, all dynamic properties were influenced by the brine salinity. Compared to xanthan, the elastic properties of xanthan-g-polyacrylamide solutions have been significantly improved in saline media and the losses in elasticity of grafted polymer solutions are lower.
15
De Tommasi, D., G. Devillanova, F. Maddalena, G. Napoli, and G. Puglisi. "Elastic multi-blisters induced by geometric constraints." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 477, no. 2245 (January 2021): 20200562. http://dx.doi.org/10.1098/rspa.2020.0562.
Повний текст джерелаАнотація:
We study a prototypical system describing instability effects due to geometric constraints in the framework of nonlinear elasticity. By considering the equilibrium configurations of an elastic ring constrained inside a rigid circle with smaller radius, we analytically determine different possible shapes, reproducing well-known physical phenomena. As we show, both single- (with different complexity) and multi-blister configurations can be observed, but the lowest energy always corresponds to single-blister solutions. Important physical insight is attained through an analogy between the elastica and the dynamics of a nonlinear pendulum. A complete geometric characterization is attained, proving symmetry and other relevant properties. The effectiveness of the model is tested against a simple experiment by considering a thin polymer strip constrained in a rigid cylinder.
16
Gegel, Natalia O., Anna B. Shipovskaya, Luba S. Vdovykh, and Tatiana S. Babicheva. "Preparation and Properties of 3D Chitosan Microtubes." Journal of Soft Matter 2014 (August 12, 2014): 1–9. http://dx.doi.org/10.1155/2014/863096.
Повний текст джерелаАнотація:
The preparation of 3D chitosan microtubes from polymer solutions in citric and lactic acids by the wet and dry molding methods is described. The mechanism of formation of the insoluble polymeric layer constructing the walls of these microtubes is characterized. The microtubes obtained from chitosan solutions in citric acid are found to have a fragile porous inner layer. For those obtained from chitosan solutions in lactic acid the morphology, elastic-deformation properties, physicomechanical properties, and biocompatibility were assessed. These samples have smooth outer and inner surfaces with no visible defects and high values of elongation at break. The strength of the microtubes obtained by the dry method is much higher than in the case of the wet one. A high adhesion and high proliferative activity of the epithelial-like MA-104 cellular culture on the surface of our microtubular substrates in model in vitro experiments were revealed. Prospects of using chitosan microtubes as vascular prostheses are suggested.
17
Snoeijer, J. H., A. Pandey, M. A. Herrada, and J. Eggers. "The relationship between viscoelasticity and elasticity." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 476, no. 2243 (November 2020): 20200419. http://dx.doi.org/10.1098/rspa.2020.0419.
Повний текст джерелаАнотація:
Soft materials that are subjected to large deformations exhibit an extremely rich phenomenology, with properties lying in between those of simple fluids and those of elastic solids. In the continuum description of these systems, one typically follows either the route of solid mechanics (Lagrangian description) or the route of fluid mechanics (Eulerian description). The purpose of this review is to highlight the relationship between the theories of viscoelasticity and of elasticity, and to leverage this connection in contemporary soft matter problems. We review the principles governing models for viscoelastic liquids, for example solutions of flexible polymers. Such materials are characterized by a relaxation time λ , over which stresses relax. We recall the kinematics and elastic response of large deformations, and show which polymer models do (and which do not) correspond to a nonlinear elastic solid in the limit λ → ∞. With this insight, we split the work done by elastic stresses into reversible and dissipative parts, and establish the general form of the conservation law for the total energy. The elastic correspondence can offer an insightful tool for a broad class of problems; as an illustration, we show how the presence or absence of an elastic limit determines the fate of an elastic thread during capillary instability.
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Ponomarev, Igor I., Ivan Y. Skvortsov, Yulia A. Volkova, Ivan I. Ponomarev, Lydia A. Varfolomeeva, Dmitry Y. Razorenov, Kirill M. Skupov, Mikhail S. Kuzin, and Olga A. Serenko. "New Approach to Preparation of Heat-Resistant “Lola-M” Fiber." Materials 12, no. 21 (October 25, 2019): 3490. http://dx.doi.org/10.3390/ma12213490.
Повний текст джерелаАнотація:
A new approach to the synthesis of polynaphthoylenebenzimidazoles and heat resistant fiber spinning has been developed using an environmentally friendly and energy efficient method, which operates with solutions of pre-polymers based on 3,3’,4,4’-tetraaminodiphenyl ether and 1,4,5,8-naphthalenetetracarboxylic acid dianhydride in N-methylpyrrolidone. Rheological properties of polymer reaction solutions and appropriate coagulant mixtures were investigated for further wet spinning process. The coagulation process was investigated through microscopic observation of solution droplets which imitate jet/fiber cross section surrounded with coagulants of different composition. For the case of the most optimal viscoelastic properties of dopes the best coagulant was found to be a ternary mixture ethanol/water/NMP (20/10/70). Fibers were prepared through the wet spinning from pre-polymers of various molecular weight characterized by intrinsic viscosity. As a result, complex yarns were spun, and their morphology was characterized and mechanical properties were measured. The strength of ~300 MPa and elastic modulus of ~2 GPa and elongation at break of ~20% were reached for the best fibers at average diameter of ~20 µm. After heat treatment “Lola-M” fibers do not burn and do not support combustion in open flame.
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USHIDA, Akiomi, Takatsune NARUMI, Taisuke SATO, and Tomiichi HASEGAWA. "Measurement of flow properties and mean elastic stresses of dilute polymer solutions passing through small slits." Proceedings of the Fluids engineering conference 2019 (2019): OS7–08. http://dx.doi.org/10.1299/jsmefed.2019.os7-08.
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20
Caro-Briones, Rubén, Blanca Estela García-Pérez, Eduardo San Martín-Martínez, Héctor Báez-Medina, Irlanda Grisel Cruz-Reyes, José Manuel del Río, Hugo Martínez-Gutiérrez, and Mónica Corea. "Influence of Carbon Nanotubes Concentration on Mechanical and Electrical Properties of Poly(styrene-co-acrylonitrile) Composite Yarns Electrospun." Polymers 13, no. 21 (October 23, 2021): 3655. http://dx.doi.org/10.3390/polym13213655.
Повний текст джерелаАнотація:
In this work, the influence of carbon nanotubes (CNTs) content on the mechanical and electrical properties of four series of polymeric matrix were made and their cytotoxicity on cells was evaluated to consider their use as a possible artificial muscle. For that, polymer composite yarns were electrospun using polymeric solutions at 10 wt.%. of poly(styrene-co-acrylonitrile) P(S:AN) and P(S:AN-acrylic acid) P(S:AN-AA) at several monomeric concentrations, namely 0:100, 20:80, 40:60, 50:50 (wt.%:wt.%), and 1 wt.% of AA. Carbon nanotubes (CNTs) were added to the polymeric solutions at two concentrations, 0.5 and 1.0 wt.%. PMCs yarns were collected using a blade collector. Mechanical and electrical properties of polymeric yarns indicated a dependence of CNTs content into yarns. Three areas could be found in fibers: CNTs bundles zones, distributed and aligned CNTs zones, and polymer-only zones. PMCs yarns with 0.5 wt.% CNTs concentration were found with a homogenous nanotube dispersion and axial alignment in polymeric yarn, ensuring load transfer on the polymeric matrix to CNTs, increasing the elastic modulus up to 27 MPa, and a maximum electrical current of 1.8 mA due to a good polymer–nanotube interaction.
21
Jouenne, Stephane, and Guillaume Heurteux. "Correlation of Mobility Reduction of HPAM Solutions at High Velocity in Porous Medium with Ex-Situ Measurements of Elasticity." SPE Journal 25, no. 01 (December 16, 2019): 465–80. http://dx.doi.org/10.2118/198899-pa.
Повний текст джерелаАнотація:
Summary When injected at high flow rates in a porous medium, polymer solutions exhibit a resistance to flow that is a signature of chain conformation and size. For biopolymers, which exist in solution as semirigid rods, mobility reduction follows the shear-thinning behavior measured in shear flow on a rheometer. For flexible coils, such as hydrolyzed polyacrylamide (HPAM), flow thickening is observed in a porous medium, whereas bulk viscosity presents a shear-thinning behavior. This difference is the result of the complex flow experienced in the porous medium, combined with the viscoelastic properties at large strains of the solutions. In this study, we investigate the effect of physicochemical parameters such as salinity, polymer concentration, molecular weight, and degradation state on the mobility reduction in a porous medium at high flow rates. All the experiments are performed on a short-length, 4-darcy sintered ceramic core. The bell shape of the mobility-reduction curves (mobility reduction vs. flow rate) is characterized by three parameters: the onset rate of flow thickening (QC), the maximum of mobility reduction (Rmmax), and the flow rate at which this maximum occurs (Qmax). Curves are rescaled by use of the two groups, Rm/Rmmax and β×Q, where β accounts for the shift in Qmax when physicochemical conditions are varied. After rescaling, all the normalized mobility-reduction curves are superposed. We show that the two parameters Rmmax and β are not correlated with the bulk viscosity of the solutions but rather with their elasticity evaluated through screen-factor measurement. This old and rough measurement, widely used in the enhanced-oil-recovery (EOR) community to evaluate “solution elasticity,” is an indirect measurement of the extensional viscosity of polymer solutions. The pertinence and the physical meaning of this rough measurement are assessed through comparison with measurements performed on a newly developed extensional viscometer [EVROC™ (Extensional Viscometer/Rheometer On a Chip), RheoSense, Inc., San Ramon, California, USA], which consists of measuring the pressure drop when the fluid is injected through a hyperbolic contraction (in which the strain rate is constant at the centerline). A correlation of “screen factor” vs. “extensional viscosity” is obtained. These results give some insight on the behavior of polymer solutions in injectivity conditions along with a method to characterize their elastic properties from bulk measurements. Finally, the inadequacy of traditional small-strain viscoelastic measurements to characterize the elastic behavior of polymer solutions at large strain is discussed.
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Soradech, Sitthiphong, Pattarawadee Kengkwasingh, Adrian C. Williams, and Vitaliy V. Khutoryanskiy. "Synthesis and Evaluation of Poly(3-hydroxypropyl Ethylene-imine) and Its Blends with Chitosan Forming Novel Elastic Films for Delivery of Haloperidol." Pharmaceutics 14, no. 12 (November 30, 2022): 2671. http://dx.doi.org/10.3390/pharmaceutics14122671.
Повний текст джерелаАнотація:
This study aimed to develop novel elastic films based on chitosan and poly(3-hydroxypropyl ethyleneimine) or P3HPEI for the rapid delivery of haloperidol. P3HPEI was synthesized using a nucleophilic substitution reaction of linear polyethyleneimine (L-PEI) with 3-bromo-1-propanol. 1H-NMR and FTIR spectroscopies confirmed the successful conversion of L-PEI to P3HPEI, and the physicochemical properties and cytotoxicity of P3HPEI were investigated. P3HPEI had good solubility in water and was significantly less toxic than the parent L-PEI. It had a low glass transition temperature (Tg = −38.6 °C). Consequently, this new polymer was blended with chitosan to improve mechanical properties, and these materials were used for the rapid delivery of haloperidol. Films were prepared by casting from aqueous solutions and then evaporating the solvent. The miscibility of polymers, mechanical properties of blend films, and drug release profiles from these formulations were investigated. The blends of chitosan and P3HPEI were miscible in the solid state and the inclusion of P3HPEI improved the mechanical properties of the films, producing more elastic materials. A 35:65 (%w/w) blend of chitosan–P3HPEI provided the optimum glass transition temperature for transmucosal drug delivery and so was selected for further investigation with haloperidol, which was chosen as a model hydrophobic drug. Microscopic and X-ray diffractogram (XRD) data indicated that the solubility of the drug in the films was ~1.5%. The inclusion of the hydrophilic polymer P3HPEI allowed rapid drug release within ~30 min, after which films disintegrated, demonstrating that the formulations are suitable for application to mucosal surfaces, such as in buccal drug delivery. Higher release with increasing drug loading allows flexible dosing. Blending P3HPEI with chitosan thus allows the selection of desirable physicochemical and mechanical properties of the films for delivery of haloperidol as a poorly water-soluble drug.
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Patel, Asha, Rahul Das, and Shishir Kumar Sahu. "Experimental and Numerical Study on Free Vibration of Multiwall Carbon Nanotube Reinforced Composite Plates." International Journal of Structural Stability and Dynamics 20, no. 12 (October 26, 2020): 2050129. http://dx.doi.org/10.1142/s0219455420501291.
Повний текст джерелаАнотація:
The effects of different percentages of multiwall carbon nanotube (MWCNT) on natural frequencies of polymer composite plates of varying edge-to-thickness ratio, aspect ratio and boundary conditions at ambient temperature are investigated experimentally and numerically. Conventional hand lay-up technique is used to prepare the MWCNT polymer composite plates with different percentages of carbon nanotubes (CNTs) mixed to the polymer. The elastic properties are determined experimentally by conducting uniaxial tensile test in the universal testing machine INSTRON 8862 as per ASTM D-3039. A set of experiments were conducted for the natural frequencies of vibration of MWCNT composite plates using the Bruel and Kjaer Fast Fourier Transform (FFT) analyzer with pulse platform. Detailed parametric studies are carried out to determine the effect of weight fraction of CNTs, aspect ratios, edge-to-thickness ratios and boundary conditions on the natural frequency of composite plates. Numerical solutions were obtained by the commercial finite element method (FEM) package ABAQUS. A simulation model is developed using the same geometrical and material properties determined experimentally from which the frequency responses are obtained. The simulation results are found to be consistent with the experimental ones. The results obtained showed an increase in elastic properties and natural frequencies up to 0.3 wt.% of MWCNT and decrease thereafter for all cases due to agglomeration of CNT in the polymer matrix. The morphology and dispersion of the CNTs in composites at micro level are investigated by using scanning electron microscopy (SEM) to further corroborate the behavior of specimens.
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Zhang, C. Y., Y. W. Zhang, K. Y. Zeng, and L. Shen. "Nanoindentation of Polymers with a Sharp Indenter." Journal of Materials Research 20, no. 6 (June 1, 2005): 1597–605. http://dx.doi.org/10.1557/jmr.2005.0200.
Повний текст джерелаАнотація:
A five-step indentation scheme is proposed to extract the elastic and viscoelastic properties of polymeric materials using a sharp indenter. In the formulation, analytical solutions to the elastic-viscoelastic deformation based on the concept of “effective indenters” proposed by both Pharr and Bolshakov [Understanding nanoindentation unloading curves. J. Mater. Res.17, 2660 (2002)] and Sakai [Elastic recovery in the unloading process of pyramidal microindentation. J. Mater. Res.18, 1631 (2003)] were derived. Indentation experiments on polymethylmethacrylate following the five-step scheme were performed. The elastic-viscoelastic parameters were extracted by fitting the solution based on Sakai’s effective indenter to the experimental results using a genetic algorithm. It was found that the solution based on Sakai's effective indenter was able to correctly extract the elastic properties. Based on this prediction and the experimental results, Pharr and Bolshakov's effective indenter profile could be determined. The extracted elastic-viscoelastic parameters using the solution based on Pharr and Bolshakov's effective indenter were independent of the reloading levels.
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Van Tung, Hoang, and Le Thi Nhu Trang. "Thermal postbuckling of shear deformable CNT-reinforced composite plates with tangentially restrained edges and temperature-dependent properties." Journal of Thermoplastic Composite Materials 33, no. 1 (November 5, 2018): 97–124. http://dx.doi.org/10.1177/0892705718804588.
Повний текст джерелаАнотація:
Buckling and postbuckling behaviors of moderately thick composite plates reinforced by single-walled carbon nanotubes (SWCNTs), rested on elastic foundations and subjected to two types of thermal loading are investigated in this article. Carbon nanotubes (CNTs) are reinforced into isotropic polymer matrix according to functional rules in which volume fractions of constituents are graded in the thickness direction. Material properties of constituents are assumed to be temperature-dependent and effective properties of nanocomposite are estimated by extended rule of mixture. Formulations are based on first-order shear deformation theory taking von Karman nonlinearity, initial geometrical imperfection, tangential constraints of edges, and two-parameter elastic foundation into consideration. Approximate solutions are assumed to satisfy simply supported boundary conditions and Galerkin method is applied to derive nonlinear temperature–deflection relations from which buckling temperatures and postbuckling equilibrium paths are determined by an iteration algorithm. Novel findings of the present study are that deteriorative influences of temperature-dependent properties on the postbuckling behavior become more serious as plate edges are partially movable, CNT volume fraction is higher, elastic foundations are stiffer, plates are thicker, and/or temperature linearly changed across the thickness.
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Li, Mengting, Jun Wang, Weiqing Liu, Ruifeng Liang, Hota GangaRao, and Yang Li. "Combined Effects of Sustained Loads and Wet-Dry Cycles on Durability of Glass Fiber Reinforced Polymer Composites." Advances in Materials Science and Engineering 2017 (2017): 1–14. http://dx.doi.org/10.1155/2017/1532360.
Повний текст джерелаАнотація:
This paper deals with durability of glass fiber reinforced polymer (GFRP) composites under the combined effects of sustained tensile loads and wet-dry (WD) cycles. Two different solutions (distilled water and saltwater) were used to imitate the freshwater and marine environments, respectively. Tensile properties of the unconditioned and conditioned specimens were measured to study the durability of GFRP composites under these 2 effects. The response indicated that both tensile strength and elastic modulus increased initially upon WD cycles, which was attributed to both the postcuring of resin and the sustained tensile stress allowing for fastec cure. Further exposure to WD cycles in distilled water or saltwater led to a steady decrease in tensile strength and modulus. WD cycles of saltwater and distilled water have similar effects on the degradation of the tensile properties for unstressed specimens. However, the elastic modulus and elongation at rupture of stressed specimens under WD cycles of saltwater decreased more than those specimens under WD cycles of distilled water. Moreover, increase of sustained loads led to a decrease in tensile strength. Based on Arrhenius method, a prediction model which accounted for the effects of postcure processes was developed. The predicted results of tensile strength and elastic modulus agree well with those obtained from the experiments.
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Ershov, S. V., V. B. Kuznetsov, E. N. Nikiforova, I. A. Suvorov, N. B. Kozlova, and E. N. Kalinin. "Multifunctional analysis of the parameters of a woven reinforcing structure based on the functional properties of a periodic unit cell of a composite material." Plasticheskie massy, no. 9-10 (November 30, 2022): 31–34. http://dx.doi.org/10.35164/0554-2901-2022-9-10-31-34.
Повний текст джерелаАнотація:
Investigations of the parameters of the reinforcing structure in the form of a woven fabric of a polymer composite material were carried out by numerical technologies in order to determine the geometric and elastic-viscous parameters of the elementary periodic cell of the filler, which is regularly repeated in its architecture. The results obtained were used in the development of a computer system for designing and calculating the functional parameters of the unit cell of a reinforcing woven structure of a polymer composite. The created numerical images of the surface of the textile reinforcing structure made it possible to make adjustments to the results of model solutions that increase the accuracy of the software solution of the problem of multifunctional study of the filler parameters in order to highlight the functional properties of the unit periodic cell of the woven structure of the polymer composite.
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Ushida, Akiomi, Taisuke Sato, Takatsune Narumi, and Tomiichi Hasegawa. "Relationship between Flow Properties and Elastic Stresses of Dilute and Ultra-Dilute Polymer Solutions Passing through Small Apertures." Nihon Reoroji Gakkaishi 49, no. 1 (February 15, 2021): 29–39. http://dx.doi.org/10.1678/rheology.49.29.
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Steinberg, Victor. "New direction and perspectives in elastic instability and turbulence in various viscoelastic flow geometries without inertia." Low Temperature Physics 48, no. 6 (June 2022): 492–507. http://dx.doi.org/10.1063/10.0010445.
Повний текст джерелаАнотація:
We shortly describe the main results on elastically driven instabilities and elastic turbulence in viscoelastic inertialess flows with curved streamlines. Then we describe a theory of elastic turbulence and prediction of elastic waves Re ≪ 1 and Wi ≫ 1, which speed depends on the elastic stress similar to the Alfvén waves in magneto-hydrodynamics and in a contrast to all other, which speed depends on medium elasticity. Since the established and testified mechanism of elastic instability of viscoelastic flows with curvilinear streamlines becomes ineffective at zero curvature, so parallel shear flows are proved linearly stable, similar to Newtonian parallel shear flows. However, the linear stability of parallel shear flows does not imply their global stability. Here we switch to the main subject, namely a recent development in inertialess parallel shear channel flow of polymer solutions. In such flow, we discover an elastically driven instability, elastic turbulence, elastic waves, and drag reduction down to relaminarization that contradict the linear stability prediction. In this regard, we discuss briefly normal versus non-normal bifurcations in such flows, flow resistance, velocity and pressure fluctuations, and coherent structures and spectral properties of a velocity field as a function of Wi at high elasticity number.
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Gao, Tong, Howard H. Hu, and Pedro Ponte Castañeda. "Dynamics and rheology of elastic particles in an extensional flow." Journal of Fluid Mechanics 715 (January 9, 2013): 573–96. http://dx.doi.org/10.1017/jfm.2012.536.
Повний текст джерелаАнотація:
AbstractWe investigate the dynamics and rheology of elastic particles in a viscous extensional flow under Stokes flow conditions by means of the large deformation method developed by Gao, Hu & Ponte Castañeda (J. Fluid Mech., vol. 687, 2011, pp. 209–237). The particles are assumed to be homogeneous, incompressible and neo-Hookean solids. When subjected to extensional flow, an initially ellipsoidal (elliptical) elastic particle stretches and rotates simultaneously, tending to deform into a stable ellipsoidal shape with the initial major axis aligned with the extension direction. However, the steady-state solutions may not exist when the particle stiffness is lower than a certain critical value. By using the solution of a single particle, the macroscopic rheological properties are evaluated for a dilute suspension of elastic particles under extension. Similar to some polymer blends, softer particles lead to a larger extensional viscosity for the suspension.
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Stamate, Monica Iliuta, Lacramioara Ochiuz, Daniel Timofte, Bogdan Ciuntu, Cristina Ghiciuc, Simona Gherman, Alina Stefanache, and Ciprian Stamate. "Preparation and Pharmaco-Mechanical Characterization of Ketoprofen- Polyvinyl Alcohol Cryogel for Medical Applications." Revista de Chimie 70, no. 3 (April 15, 2019): 848–52. http://dx.doi.org/10.37358/rc.19.3.7018.
Повний текст джерелаАнотація:
Polyvinyl alcohol is a biocompatible polymer used very commonly both in pharmaceutical and medical fields. Being a water-soluble polymer, it is suitable for the manufacture of hydrogels as well as cryogels used for various medical applications. The present work describes the preparation, structural and physico-mechanical characterization of polyvinyl alcohol cryogels loaded with ketoprofen. By cryogenic technique the polymeric solutions are transformed under certain conditions into porous, elastic and very compressible structures. They are able to absorb a large amount of liquids that they give off by gentle compression. The prepared cryogels were evaluated for different physical, chemical and structural properties, as following: internal morphology, equilibrium swelling ratio and mechanical testing. The cryogel structures show good elasticity and optimal swelling at different temperatures. Due to these properties the studied cryogels are suitable for use in various medical applications involving liquid absorption, mechanical resistance and anti-inflammatory effect.
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Oyen, Michelle L., and Robert F. Cook. "Load–displacement behavior during sharp indentation of viscous–elastic–plastic materials." Journal of Materials Research 18, no. 1 (January 2003): 139–50. http://dx.doi.org/10.1557/jmr.2003.0020.
Повний текст джерелаАнотація:
A model is developed that describes the sharp indentation behavior of time-dependent materials. The model constitutive equation is constructed from a series of quadratic mechanical elements, with independent viscous (dashpot), elastic (spring), and plastic (slider) responses. Solutions to this equation describe features observed under load-controlled indentation of polymers, including creep, negative unloading tangents, and loading-rate dependence. The model describes a full range of viscous–elastic–plastic responses and includes as bounding behaviors time-independent elastic–plastic indentation (appropriate to metals and ceramics) and time-dependent viscous–elastic indentation (appropriate to elastomers). Experimental indentation traces for a range of olymers with different material properties (elastic modulus, hardness, viscosity) are econvoluted and ranked by calculated time constant. Material properties for these polymers, deconvoluted from single load–unload cycles, are used to predict the indentation load–displacement behavior at loading rates three times slower and faster, as well as the steady-state creep rate under fixed load.
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Koumoulos, Elias P., Panagiotis Kainourios, and Costas A. Charitidis. "Assessing the integrity of CFRPs through nanomechanical mapping: the effect of CF surface modification." MATEC Web of Conferences 188 (2018): 01006. http://dx.doi.org/10.1051/matecconf/201818801006.
Повний текст джерелаАнотація:
The purpose of this study is to assess the effect of CF surface modification in enhancement of the wetting properties of carbon fibers in order to improve the adhesion force between the fiber and the polymer matrix; for this, the integrity of CFRPs through nanomechanical mapping was evaluated. The surface of commercial carbon fibers was functionalized through cyclic voltammetry in aqueous electrolyte solutions of H2SO4, in the presence of acrylic acid, methacrylic acid, acrylonitrile and N-vinylpyrrolidone monomers. The produced surface modified carbon fibers were embedded in epoxy resin. Elastic modulus nanoindentation mapping was performed in order for elastic modulus to be calculated, as a qualitative assessment of fibre – matrix interaction. For this, a grid protocol was set up for the integrity assessment of CFRPs through nanomechanical mapping.
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IVANENKO, K. O., та A. M. FAINLEIB. "МАХ PHASE (MXENE) IN POLYMER MATERIALS". Polymer journal 44, № 3 (16 вересня 2022): 165–81. http://dx.doi.org/10.15407/polymerj.44.03.165.
Повний текст джерелаАнотація:
This article is a review of the Mn+1AXn phases (“MAX phases”, where n = 1, 2 or 3), their MXene derivatives and the reinforcement of polymers with these materials. The MAX phases are a class of hexagonal-structure ternary carbides and nitrides ("X") of the transition metal ("M") and the A-group element. The unique combination of chemical, physical, electrical and mechanical properties that combine the characteristics of metals and ceramics is of interest to researchers in the MAX phases. For example, MAX phases are typically resistant to oxidation and corrosion, elastic, but at the same time, they have high thermal and electrical conductivity and are machinable. These properties stem from an inherently nanolaminated crystal structure, with Mn+1Xn slabs intercalated with pure A-element layers. To date, more than 150 MAX phases have been synthesized. In 2011, a new family of 2D materials, called MXene, was synthesized, emphasizing the connection with the MAX phases and their dimension. Several approaches to the synthesis of MXene have been developed, including selective etching in a mixture of fluoride salts and various acids, non-aqueous etching solutions, halogens and molten salts, which allows the synthesis of new materials with better control over the chemical composition of their surface. The use of MAX phases and MXene for polymer reinforcement increases their thermal, electrical and mechanical properties. Thus, the addition of fillers increases the glass transition temperature by an average of 10%, bending strength by 30%, compressive strength by 70%, tensile strength up to 200%, microhardness by 40%, reduces friction coefficient and makes the composite material self-lubricating, and 1 % wt. MAX phases increases thermal conductivity by 23%, Young’s modulus increases. The use of composites as components of sensors, electromagnetic protection, wearable technologies, in current sources, in aerospace and military applications, etc. are proposed.
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Yartsev, B., V. Ryabov, and L. Parshina. "Dissipative properties of three-layered composite structures. 2. Solution method." Transactions of the Krylov State Research Centre 1, no. 399 (March 15, 2022): 55–64. http://dx.doi.org/10.24937/2542-2324-2022-1-399-55-64.
Повний текст джерелаАнотація:
Object and purpose of research. This paper discusses a three-layered plate made up by two rigid anisotropic layers and soft isotropic medium layer of viscoelastic polymer. Each of the two rigid layers is an anisotropic structure formed by a finite number of arbitrarily oriented orthotropic viscoelastic composite layers. The purpose of this work is to develop a numerical solution method for decaying vibration equations of three-layered unsupported rectangular plates. Materials and methods. The system of algebraic equations is constructed as per Ritz method using Legendre polyno-mials as coordinate functions. The first step is to find real solutions. To find complex natural frequencies of the system, their initial values are taken as real natural frequencies thus found, with subsequent calculation of complex frequencies as per the method of third-order iterations. Main results. This paper discusses the results of convergence analysis for a numerical solution of differential motion equations with respect to an unsupported rectangular three-layered plate with transversally isotropic rigid layers. The material for these rigid lay-ers is unidirectional carbon-reinforced plastic (CRP) with elastic dissipation properties, within the investigated range of frequencies and temperatures, independent on its vibration frequency. For the soft isotropic medium layer of viscoelastic polymer, temperature-frequency curve governing the real part of complex elasticity modulus and mechanical loss coefficient is taken into account. Validation of the mathematical model and the numerical solution method, the comparison of calculated and experimental natural frequencies and mechanical loss coefficients for the two variants of three-layered unsupported plate has demonstrated their good correlation. Conclusion. This paper suggests and validates the numerical solution method for decaying vibration equations of three-layered unsupported rectangular plate made up by two rigid monoclinic layers and soft isotropic medium layer of viscoelastic polymer.
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Bai, Er-Lei, Gao-Jie Liu, Jin-Yu Xu, and Bing-Lin Leng. "Tensile and Fixed Elongation Properties of Polymer-Based Cement Flexible Composite under Water/Corrosive Solution Environment." Materials 13, no. 9 (May 7, 2020): 2155. http://dx.doi.org/10.3390/ma13092155.
Повний текст джерелаАнотація:
This study examined the tensile and fixed elongation properties of flexible composite made of styrene–acrylic, vinyl acetate-ethylene copolymer emulsion (VAE emulsion), and cement as cementitious material for airport pavement joint sealant. Quantitative analysis of the elastic recovery ratio and a series of specimen tensile indicators after water immersion, drying–wetting cycles, and corrosive solution (H2SO4, NaOH, and jet fuel) immersion were performed. Results showed excellent polymer-based cement flexible composite (PCFC) resistance against water and corrosive solution erosion, such as failure mode, elastic recovery, tensile strength, and energy absorption. When the level of water/corrosive solution erosion (immersion time, cycles) were increased, the tensile and fixed elongation properties progressively decreased. Specimens retained more than 60% elastic recovery ratio after water/corrosive solution erosion immersion for 30 days. According to erosion testing as per immersion time in corrosive solution, jet fuel had the maximum effect, NaOH solution had the least effect, and H2SO4 solution had an intermediary effect. At immersion time in the range of 1–30 days, the tensile strength does not change by more than 0.07 MPa. Within the limits of the fixed elongation tests, cohesive failure occurred after jet fuel immersion for 30 days, adhesive failure occurred after H2SO4 solution immersion for 30 days but was normal in other cases.
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Selvamani, Rajendran, M. Mahaveer Sree Jayan, and Farzad Ebrahimi. "Nonlinear ultrasonic waves in a magneto-flexo-thermally actuated single walled armchair carbon nanotube embedded on polymer matrix." World Journal of Engineering 18, no. 1 (November 23, 2020): 1–13. http://dx.doi.org/10.1108/wje-02-2020-0066.
Повний текст джерелаАнотація:
Purpose The purpose of this paper is concerned with the study of nonlinear ultrasonic waves in a magneto-flexo-thermo (MFT) elastic armchair single-walled carbon nanotube (ASWCNT) resting on polymer matrix. Design/methodology/approach A mathematical model is developed for the analytical study of nonlinear ultrasonic waves in a MFT elastic armchair single walled carbon nanotube rested on polymer matrix using Euler beam theory. The analytical formulation is developed based on Eringen’s nonlocal elasticity theory to account small scale effect. After developing the formal solution of the mathematical model consisting of partial differential equations, the frequency equations have been analysed numerically by using the nonlinear foundations supported by Winkler-Pasternak model. The solution is obtained by ultrasonic wave dispersion relations. Findings From the literature survey, it is evident that the analytical formulation of nonlinear ultrasonic waves in an MFT elastic ASWCNT embedded on polymer matrix is not discussed by any researchers. So, in this paper the analytical solutions of nonlinear ultrasonic waves in an MFT elastic ASWCNT embedded on polymer matrix are studied. Parametric studies is carried out to scrutinize the influence of the nonlocal scaling, magneto-electro-mechanical loadings, foundation parameters, various boundary condition and length on the dimensionless frequency of nanotube. It is noticed that the boundary conditions, nonlocal parameter and tube geometrical parameters have significant effects on dimensionless frequency of nanotubes. Originality/value This paper contributes the analytical model to find the solution of nonlinear ultrasonic waves in an MFT elastic ASWCNT embedded on polymer matrix. It is observed that the increase in the foundation constants raises the stiffness of the medium and the structure is able to attain higher frequency once the edge condition is C-C followed by S-S. Further, it is noticed that the natural frequency is arrived below 1% in both local and nonlocal boundary conditions in the presence of temperature coefficients. Also, it is found that the density and Poisson ratio variation affects the natural frequency with below 2%. The results presented in this study can provide mechanism for the study and design of the nano devices such as component of nano oscillators, micro wave absorbing, nano-electron technology and nano-electro--magneto-mechanical systems that make use of the wave propagation properties of ASWCNTs embedded on polymer matrix.
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Jagdale, Purva P., Di Li, Xingchen Shao, Joshua B. Bostwick, and Xiangchun Xuan. "Fluid Rheological Effects on the Flow of Polymer Solutions in a Contraction–Expansion Microchannel." Micromachines 11, no. 3 (March 8, 2020): 278. http://dx.doi.org/10.3390/mi11030278.
Повний текст джерелаАнотація:
A fundamental understanding of the flow of polymer solutions through the pore spaces of porous media is relevant and significant to enhanced oil recovery and groundwater remediation. We present in this work an experimental study of the fluid rheological effects on non-Newtonian flows in a simple laboratory model of the real-world pores—a rectangular sudden contraction–expansion microchannel. We test four different polymer solutions with varying rheological properties, including xanthan gum (XG), polyvinylpyrrolidone (PVP), polyethylene oxide (PEO), and polyacrylamide (PAA). We compare their flows against that of pure water at the Reynolds ( R e ) and Weissenburg ( W i ) numbers that each span several orders of magnitude. We use particle streakline imaging to visualize the flow at the contraction–expansion region for a comprehensive investigation of both the sole and the combined effects of fluid shear thinning, elasticity and inertia. The observed flow regimes and vortex development in each of the tested fluids are summarized in the dimensionless W i − R e and χ L − R e parameter spaces, respectively, where χ L is the normalized vortex length. We find that fluid inertia draws symmetric vortices downstream at the expansion part of the microchannel. Fluid shear thinning causes symmetric vortices upstream at the contraction part. The effect of fluid elasticity is, however, complicated to analyze because of perhaps the strong impact of polymer chemistry such as rigidity and length. Interestingly, we find that the downstream vortices in the flow of Newtonian water, shear-thinning XG and elastic PVP solutions collapse into one curve in the χ L − R e space.
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Grün, G., and S. Metzger. "On micro–macro-models for two-phase flow with dilute polymeric solutions — modeling and analysis." Mathematical Models and Methods in Applied Sciences 26, no. 05 (February 25, 2016): 823–66. http://dx.doi.org/10.1142/s0218202516500196.
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By methods from nonequilibrium thermodynamics, we derive a diffuse-interface model for two-phase flow of incompressible fluids with dissolved noninteracting polymers. The polymers are modeled by dumbbells subjected to general elastic spring-force potentials including in particular Hookean and finitely extensible, nonlinear elastic (FENE) potentials. Their density and orientation are described by a Fokker–Planck-type equation which is coupled to a Cahn–Hilliard and a momentum equation for phase-field and gross velocity/pressure. Henry-type energy functionals are used to describe different solubility properties of the polymers in the different phases or at the liquid–liquid interface. Taking advantage of the underlying energetic/entropic structure of the system, we prove existence of a weak solution globally in time for the case of FENE-potentials. As a by-product in the case of Hookean spring potentials, we derive a macroscopic diffuse-interface model for two-phase flow of Oldroyd-B-type liquids.
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Chatbi, Mohammed, Zouaoui Rabie Harrat, Tahir Ghazoul, and Mohamed Bachir Bouiadjra. "Free vibrational analysis of composite beams reinforced with randomly aligned and oriented carbon nanotubes, resting on an elastic foundation." Journal of Building Materials and Structures 9, no. 1 (February 21, 2022): 22–32. http://dx.doi.org/10.34118/jbms.v9i1.1895.
Повний текст джерелаАнотація:
The main interest of this paperwork is to examinate the dynamic behavior (free vibrational response) of carbon nanotubes (CNT) composite beams standing on an elastic foundation of Winkler-Pasternak’s. The affected beam consists of a polymer matrix reinforced with single-wall carbon nanotubes (SWCNT’s), in which, a large number of CNT’s reinforcement of infinite length are distributed in a linear elastic polymer matrix. In this study the CNT’s are considered either aligned or randomly oriented on the matrix.
A refined high-order beam theory (RBT) is adopted in the present analysis using a new shape function. The refined beam theory which is summarized by differentiating the displacement along the beam transverse section into shear and bending components, initially the material properties of the composite beam (CNTRC) are estimated using the Mori-Tanaka’s method. The beam is considered simply supported on the edge-lines. NAVIER’s solutions are proposed to solve the boundary conditions problems. Since there are no results to compare with in the literature; the results in this study are compared with a free vibrational analysis of an isotropic beam. Several aspects such as the length/thickness ratio, volume fraction of nanotubes, and vibrational modes are carried out in the parametric study.
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Serio, Francesca, Marta Miola, Enrica Vernè, Dario Pisignano, Aldo Boccaccini, and Liliana Liverani. "Electrospun Filaments Embedding Bioactive Glass Particles with Ion Release and Enhanced Mineralization." Nanomaterials 9, no. 2 (February 1, 2019): 182. http://dx.doi.org/10.3390/nano9020182.
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Efforts in tissue engineering aim at creating scaffolds that mimic the physiological environment with its structural, topographical and mechanical properties for restoring the function of damaged tissue. In this study we introduce composite fibres made by a biodegradable poly(lactic acid) (PLLA) matrix embedding bioactive silica-based glass particles (SBA2). Electrospinning is performed to achieve porous PLLA filaments with uniform dispersion of bioactive glass powder. The obtained composite fibres show in aligned arrays significantly increased elastic modulus compared with that of neat polymer fibres during uniaxial tensile stress. Additionally, the SBA2 bioactivity is preserved upon encapsulation as highlighted by the promoted deposition of hydroxycarbonate apatite (HCA) upon immersion in simulated body fluid solutions. HCA formation is sequential to earlier processes of polymer erosion and ion release leading to acidification of the surrounding solution environment. These findings suggest PLLA-SBA2 fibres as a composite, multifunctional system which might be appealing for both bone and soft tissue engineering applications.
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Kondratov, Alexander, Valery Konyukhov, Stanislav Yamilinets, Ekaterina Marchenko, and Gulsharat Baigonakova. "Compression Relaxation of Multi-Structure Polymer Composites in Penetrating Liquid Medium." Polymers 14, no. 23 (November 28, 2022): 5177. http://dx.doi.org/10.3390/polym14235177.
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Multi-structural polymer composites are widely used in the mechanical engineering, automotive, aviation and oil refining industries, as well as in the printing industry as a shock-absorbing deckle on the offset cylinders of printing machines. During offset printing, composites come into contact with inks and washing solutions, the components of which penetrate the material and cause the polymers to swell. This process degrades the print quality, and for this reason the study of its features is relevant. The prerequisites for this work are the study of the fundamental laws of diffusion and sorption of liquids by polymers with different micro- and macro-structures in different physical states and in different forms (e.g., films, sheets, fibers and fabrics). The combination of polymer materials in the composition of multi-structural fabric blankets makes it possible to obtain materials with unique mechanical properties and high resistance to liquid penetrating media and to use them in high-tech processes of multi-color printing with high resolution and color rendering. This article reports for the first time the kinetics and thermodynamics results obtained from the swelling of multi-structural polymeric blankets in solvents used in printing, and the effect of sorption of different polar liquids on the viscoelastic strain under compression during the operation of the damping systems of printing machines. Using mathematical models of activated liquid diffusion in polymers and deformation of a viscoelastic body, the swelling rate constants, solvent diffusion coefficients (the kinetic characteristics of the swelling process) and Flory–Huggins parameters (the thermodynamic characteristics of the interaction of the solvent with the composite) for composite–solvent systems with several chemical composition variants were determined. The elastic modulus and the viscosity coefficient of the composite under liquid saturation were calculated based on the experimental cyclic compression data. The range of change in the compression and restoration times of the polymeric blankets (0.09 s ÷ 0.78 s) was determined. It was shown that the composite swelled to a limited extent in all the studied liquids. All solvents used were thermodynamically poor (χ > 0.5). It has been established that rubber–fabric blankets coated with nitrile rubber are the least resistant to the action of dichloroethane, and that blankets with layers of polyolefins are not resistant to ethyl acetate. Water significantly affects the physicochemical properties of rubber–fabric blankets with a large proportion of cotton fabric layers. The data obtained can serve as a basis for optimizing the compositions of inks and cleaning solutions, as well as a theoretical basis for the thermodynamics of composite–solvent systems.
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Nečasová, Barbora, Pavel Liška, Jakub Kelar, and Jiří Šlanhof. "Comparison of Adhesive Properties of Polyurethane Adhesive System and Wood-plastic Composites with Different Polymers after Mechanical, Chemical and Physical Surface Treatment." Polymers 11, no. 3 (March 1, 2019): 397. http://dx.doi.org/10.3390/polym11030397.
Повний текст джерелаАнотація:
The cost of most primary materials is increasing, therefore, finding innovative solutions for the re-use of residual waste has become a topic discussed more intensely in recent years. WPCs certainly meet some of these demands. The presented study is focused on an experimental analysis of the effect of surface treatment on the adhesive properties of selected WPCs. Bonding of polymer-based materials is a rather complicated phenomenon and modification of the bonded area in order to improve the adhesive properties is required. Two traditional types of surface treatments and one entirely new approach have been used: mechanical with sandpaper, chemical with 10 wt % NaOH solution and physical modification of the surface by means of a MHSDBD plasma source. For comparison purposes, two high-density polyethylene based products and one polyvinyl-chloride based product with different component ratios were tested. A bonded joint was made using a moisture-curing permanently elastic one-component polyurethane pre-polymer adhesive. Standardized tensile and shear test methods were performed after surface treatment. All tested surface treatments resulted in an improvement of adhesive properties and an increase in bond strength, however, the MHSDBD plasma treatment was proven to be a more suitable surface modification for all selected WPCs.
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Goncharova, P. S., G. V. Korobejnikov, E. V. Pavlenko, S. V. Borisov, M. A. Vaniev, A. B. Kochnov, and I. A. Novakov. "EFFECT OF THE MOLECULAR MASS OF POLYVINYLBUTIRAL ON THE PROPERTIES OF POLYMERS BASED ON PHOSPHORUS-CONTAINING DIMETHACRYLATE." IZVESTIA VOLGOGRAD STATE TECHNICAL UNIVERSITY, no. 12(247) (December 24, 2020): 60–65. http://dx.doi.org/10.35211/1990-5297-2020-12-247-60-65.
Повний текст джерелаАнотація:
The effect of the molecular weight of polyvinylbutyral dissolved in phosphorus-containing dimethacrylate on the rheological characteristics of solutions and the properties of polymers based on them has been studied. It was found that the dynamic viscosity of solutions containing 3% PVB with a molecular weight of 43,000, 57,000, and 95,000 g/mol compared with the viscosity of the phosphorus-containing dimethacrylate itself significantly increases. Depending on the molecular mass of polyvinylbutyral, materials obtained under the conditions of photochemically initiated polymerization are characterized by an increase of the elastic modulus during static bending up to 53% at a constant level of oxygen index values.
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Winnik, Françoise M., Alexander Adronov, and Hiromi Kitano. "Pyrene-labeled amphiphilic poly-(N-isopropylacrylamides) prepared by using a lipophilic radical initiator: synthesis, solution properties in water, and interactions with liposomes." Canadian Journal of Chemistry 73, no. 11 (November 1, 1995): 2030–40. http://dx.doi.org/10.1139/v95-251.
Повний текст джерелаАнотація:
Fluorescently labeled amphiphilic poly-(N-isopropylacrylamides) (PNIPAM) substituted with a N-[4-(1-pyrenyl)butyl]-N-n-octadecyl group at the chain end were prepared by free-radical polymerization in dioxane of N-isopropylacrylamide (NIPAM) using 4,4′-azobis{4-cyano-N,N-[4-(1-pyrenyl)butyl]-n-octadecyl}pentanamide as the initiator. The solution properties of the polymers in water were studied as a function of polymer concentration and temperature. Quasi-elastic light-scattering measurements and fluorescence experiments monitoring the pyrene excimer and pyrene monomer emissions revealed the presence of multimolecular polymeric micelles below the lower critical solution temperature (LCST) of PNIPAM. These underwent partial, reversible reorganization as they were heated above the LCST. The interactions of the pyrene-labeled amphiphilic PNIPAM with dimyristoylphosphatidylcholine (DMPC) liposomes have been examined in water at 25 °C. From fluorescence experiments it was established that the polymeric micelles are disrupted irreversibly upon contact with the liposomes. The anchoring of the polymer chains occurs by insertion of their hydrophobic tail within the phospholipidic bilayer, as evidenced from a large decrease of the pyrene excimer emission relative to pyrene monomer emission. The copolymers remained anchored within the bilayer as the temperature of the copolymer–liposome suspension was raised above the LCST of PNIPAM. Keywords: liposome, poly-(N-isopropylacrylamide), fluorescence, micelles.
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Lysenkov, E. A., and O. V. Stryutsky. "The effect of silver nanoparticles on the structure and functional properties of antimicrobial polymer nanocomposites based on polyethylene oxide." Physics of Aerodisperse Systems, no. 60 (December 15, 2022): 8–16. http://dx.doi.org/10.18524/0367-1631.2022.60.265598.
Повний текст джерелаАнотація:
The presence of antibacterial materials in biomedicine and related fields of science and technology has become essential. Excellent antibacterial activity and low cytotoxic potential of silver nanoparticles generally depend not only on their size, but also on the distribution in matrix media. The development of stabilized polymer-silver nanocomposites containing nanoparticles is considered to be one of the most promising solutions. We developed a new approach to the synthesis of silver nanoparticles. The structure and properties of antimicrobial nanocomposite materials based on polyethylene oxide and synthesized silver particles were studied using the methods of electron microscopy, differential scanning calorimetry, impedance spectroscopy and disk-diffusion microbiological method. As a result, silver nanoparticles with an average size of about 8-10 nm were obtained. It was established that stabilized silver nanoparticles significantly affect the thermophysical and electrical properties of the polymer matrix at relatively low concentrations of the nanofiller (1-2%). The total electrical conductivity of the systems increases by two orders of magnitude when 2% filler is added. Nanocomposite material containing 2% of silver nanoparticles shows significant activity against Staphylococcus aureus (inhibition zone 22 mm). The novel aproach for synthesis of stabilized silver nanoparticles open a new window of possibilities in the development of new antimicrobial materials, based on various polymer matrix: from thermoplastic to elastic. The developed materials with improved functional characteristics in the future can be used as antimicrobial coatings, antimicrobial films and creams, as well as construction products with the necessary functional characteristics and antimicrobial function.
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Göransson, Peter. "Acoustic and vibrational damping in porous solids." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 364, no. 1838 (December 2, 2005): 89–108. http://dx.doi.org/10.1098/rsta.2005.1688.
Повний текст джерелаАнотація:
A porous solid may be characterized as an elastic–viscoelastic and acoustic–viscoacoustic medium. For a flexible, open cell porous foam, the transport of energy is carried both through the sound pressure waves propagating through the fluid in the pores, and through the elastic stress waves carried through the solid frame of the material. For a given situation, the balance between energy dissipated through vibration of the solid frame, changes in the acoustic pressure and the coupling between the waves varies with the topological arrangement, choice of material properties, interfacial conditions, etc. Engineering of foams, i.e. designs built on systematic and continuous relationships between polymer chemistry, processing, micro-structure, is still a vision for the future. However, using state-of-the-art simulation techniques, multiple layer arrangements of foams may be tuned to provide acoustic and vibrational damping at a low-weight penalty. In this paper, Biot's modelling of porous foams is briefly reviewed from an acoustics and vibrations perspective with a focus on the energy dissipation mechanisms. Engineered foams will be discussed in terms of results from simulations performed using finite element solutions. A layered vehicle-type structure is used as an example.
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CHEN, M. J., L. S. KIMPTON, J. P. WHITELEY, M. CASTILHO, J. MALDA, C. P. PLEASE, S. L. WATERS, and H. M. BYRNE. "Multiscale modelling and homogenisation of fibre-reinforced hydrogels for tissue engineering." European Journal of Applied Mathematics 31, no. 1 (November 22, 2018): 143–71. http://dx.doi.org/10.1017/s0956792518000657.
Повний текст джерелаАнотація:
Tissue engineering aims to grow artificial tissues in vitro to replace those in the body that have been damaged through age, trauma or disease. A recent approach to engineer artificial cartilage involves seeding cells within a scaffold consisting of an interconnected 3D-printed lattice of polymer fibres combined with a cast or printed hydrogel, and subjecting the construct (cell-seeded scaffold) to an applied load in a bioreactor. A key question is to understand how the applied load is distributed throughout the construct. To address this, we employ homogenisation theory to derive equations governing the effective macroscale material properties of a periodic, elastic–poroelastic composite. We treat the fibres as a linear elastic material and the hydrogel as a poroelastic material, and exploit the disparate length scales (small inter-fibre spacing compared with construct dimensions) to derive macroscale equations governing the response of the composite to an applied load. This homogenised description reflects the orthotropic nature of the composite. To validate the model, solutions from finite element simulations of the macroscale, homogenised equations are compared to experimental data describing the unconfined compression of the fibre-reinforced hydrogels. The model is used to derive the bulk mechanical properties of a cylindrical construct of the composite material for a range of fibre spacings and to determine the local mechanical environment experienced by cells embedded within the construct.
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Romanelli Vicente Bertolo, Mirella, Rafael Leme, Virginia da Conceição Amaro Martins, Ana Maria de Guzzi Plepis, and Stanislau Bogusz Junior. "Rheological Characterization of the Influence of Pomegranate Peel Extract Addition and Concentration in Chitosan and Gelatin Coatings." Polysaccharides 2, no. 3 (August 7, 2021): 648–60. http://dx.doi.org/10.3390/polysaccharides2030039.
Повний текст джерелаАнотація:
In this study, the effects of an agro-industrial residue with active properties, pomegranate peel extract (PPE), were evaluated on the rheological properties of potential coatings based on chitosan (C) and gelatin (G). For this, rheological properties of the polymeric solutions were investigated in relation to PPE concentration (2 or 4 mg PPE g−1 solution), and to its incorporation order into the system (in C or in CG mixture). All solutions were more viscous than elastic (G″ > G′), and the change in PPE concentration had a greater influence accentuating the viscous character of the samples in which PPE was added to the CG mixture (CGPPE2 and CGPPE4). PPE addition to the CG mixture increased the angular frequency at the moduli crossover, indicating the formation of a more resistant polymeric network. This tendency was also observed in flow results, in which PPE addition decreased the pseudoplastic behavior of the solutions, due to a greater cross-linking between the polymers and the phenolic compounds. In general, all the studied solutions showed viscosities suitable for the proposed application, and it was possible to state the importance of standardizing the addition order of the components during the preparation of a coating.
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Astakhov, Mikhail V., and Ekaterina V. Slavkina. "Improving the Shock Resistance of Agricultural Composite Units Using Visco-Elastic Fluids." Engineering Technologies and Systems 30, no. 2 (June 30, 2020): 268–86. http://dx.doi.org/10.15507/2658-4123.030.202002.268-286.
Повний текст джерелаАнотація:
Introduction. The use of composite materials in agricultural engineering is known as one of the recommended ways to reduce the weight of the structure and protect against corrosion. The main disadvantages of such products are their low resistance to shock loads that occur during operation. The aim of this study is to develop a glass composite multi-layer structure of the trailer side, capable of withstanding shock loads along with statically applied forces, without including additional reinforcing metal elements in the zones of the possible impacts. Materials and Methods. To increase the impact resistance of the product (after an analysis of modern design solutions) the use of visco-elastic non-Newtonian fluids based on polysilicon by introducing an additional layer into the power element to compensate for impact effects is proposed. Results. On the basis of laboratory testing using statistical processing of the obtained data, the basic mechanical characteristics of non-Newtonian fluid (polysilicon) during impact tests (density, Poisson’s ratio, Young’s modulus, shear modulus) are determined, and graphs of the obtained dependencies are constructed. The temperature of the tested polysilicon samples did not significantly affect their mechanical properties. It is established that starting from the value of relative deformation 0.042, during the impact polysilicon shows linearly elastic properties. Discussion and Conclusion. Based on the received mechanical characteristics, the conclusions about resistance to shock loads of polysilicon as a component of a trailer board element are made. The variant of arrangement of the trailer board structural solution as a multilayer sandwich element with external parts made of polymer composite material with internal filling with fiberglass cells and polysilicon placed in large cells is offered.