Linear Viscoelasticity of Polymers and Polymer Nanocomposites: Molecular-Dynamics Large Amplitude Oscillatory Shear and Probe Rheology Simulations

Davris, T Theodoros; Lyulin, Sergey V.; Baljon, Arlette R. C.; Nazarychev, Victor M.; Volgin, Igor V.; Larin, Sergey V.

doi:10.1007/978-3-319-72706-6_12

Cited by 5 publications

(8 citation statements)

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“…The rheological properties of PI R-BAPB were investigated using cyclic shear deformation of the polymer melt [ 75 ], during which the volume of the R-BAPB sample was kept constant using an isochoric-isothermal ensemble (NVT). The value of shear stress σ xy upon applying shear deformation in the XY direction was calculated as - P xy , where P xy is a non-diagonal component of the pressure tensor.…”

Section: Experimental and Theoretical Methodsmentioning

confidence: 99%

“…The time dependences, which were averaged over 10 oscillation cycles of shear stress, were approximated using the formalism of large-amplitude oscillation shear (LAOS) to calculate the rheological characteristics [ 76 , 77 ].

where

is the amplitude at deformation for the n -th harmonic,

and

are the elasticity and loss moduli, correspondingly,

is the cyclic strain rate, and n is the harmonic number [ 75 ]. The complex viscosity η ∗ value is determined using the following equation:

…”

Section: Experimental and Theoretical Methodsmentioning

confidence: 99%

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Rheological and Mechanical Properties of Thermoplastic Crystallizable Polyimide-Based Nanocomposites Filled with Carbon Nanotubes: Computer Simulations and Experiments

et al. 2022

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Recently, a strong structural ordering of thermoplastic semi-crystalline polyimides near single-walled carbon nanotubes (SWCNTs) was found that can enhance their mechanical properties. In this study, a comparative analysis of the results of microsecond-scale all-atom computer simulations and experimental measurements of thermoplastic semi-crystalline polyimide R-BAPB synthesized on the basis of dianhydride R (1,3-bis-(3′,4-dicarboxyphenoxy) benzene) and diamine BAPB (4,4′-bis-(4″-aminophenoxy) biphenyl) near the SWCNTs on the rheological properties of nanocomposites was performed. We observe the viscosity increase in the SWCNT-filled R-BAPB in the melt state both in computer simulations and experiments. For the first time, it is proven by computer simulation that this viscosity change is related to the structural ordering of the R-BAPB in the vicinity of SWCNT but not to the formation of interchain linkage. Additionally, strong anisotropy of the rheological properties of the R-BAPB near the SWCNT surface was detected due to the polyimide chain orientation. The increase in the viscosity of the polymer in the viscous-flow state and an increase in the values of the mechanical characteristics (Young’s modulus and yield peak) of the SWCNT-R-BAPB nanocomposites in the glassy state are stronger in the directions along the ordering of polymer chains close to the carbon nanofiller surface. Thus, the new experimental data obtained on the R-BAPB-based nanocomposites filled with SWCNT, being extensively compared with simulation results, confirm the idea of the influence of macromolecular ordering near the carbon nanotube on the mechanical characteristics of the composite material.

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Section: Experimental and Theoretical Methodsmentioning

confidence: 99%

where

is the amplitude at deformation for the n -th harmonic,

and

are the elasticity and loss moduli, correspondingly,

is the cyclic strain rate, and n is the harmonic number [ 75 ]. The complex viscosity η ∗ value is determined using the following equation:

…”

Section: Experimental and Theoretical Methodsmentioning

confidence: 99%

Rheological and Mechanical Properties of Thermoplastic Crystallizable Polyimide-Based Nanocomposites Filled with Carbon Nanotubes: Computer Simulations and Experiments

et al. 2022

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Section: Introductionmentioning

confidence: 99%

“…Also, the size of the probe is important, and, in order to extract the correct viscoelastic fingerprint of the medium, it must be larger than the radius of gyration, r g , of the polymeric chain . Interestingly, the use of particles with a size lower than the correlation length might give access to the local properties of the system . Notwithstanding, it should be noted at this respect that the question of the probe size effect in microrheology is still open, but it may be exploited to extract interesting features of complex systems at the local scale.…”

Section: Introductionmentioning

confidence: 99%

“…8 Interestingly, the use of particles with a size lower than the correlation length might give access to the local properties of the system. 9 Notwithstanding, it should be noted at this respect that the question of the probe size effect in microrheology is still open, but it may be exploited to extract interesting features of complex systems at the local scale. Within all the broad literature studies concerning microrheological approaches to study complex systems, we have selected those performed in poly(ethylene oxide) (PEO) aqueous solutions, as they have been used as models for the development of passive microrheological techniques based on diffusing wave spectroscopy (DWS) and dynamic light scattering (DLS).…”

Section: ■ Introductionmentioning

confidence: 99%

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Revisiting Polymer–Particle Interaction in PEO Solutions

et al. 2021

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We have measured the electrophoretic mobility and diffusion coefficient of carboxylate-modified and sulfate-modified polystyrene latex particles in poly(ethylene oxide) aqueous solutions. Carboxylate -modified polystyrene particles have shown a bound polymeric layer as the surface net charge vanishes even at very low poly(ethylene oxide) concentration. The polymeric layer causes a lower electrophoretic mobility and slower Brownian diffusion than that corresponding to the bare particles. We show that the diffusion is the result of a significantly increased effective particle size 2 r h eff = 30 nm. This bound layer is not present in sulfate-modified polystyrene latex particles. The interaction between the carboxylate-modified particle surface and the macromolecules has been confirmed by means of atomistic computer simulations. The grafted acrylate copolymers, which come from the preparation procedure of the latex particles, confer more hydrophobic surface ready to interact with the polymer. The simulations suggest that the interaction is modulated not only by the nature of the acrylic acid monomer but also by the length of the grafted copolymer. Our results have important implications for particle selection in microrheology experiments.

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Selection of structural elements of cross-linked polymers used in construction

Аскадский

Matseevich

2021

Vestnik MGSU

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Introduction. For the first time, a model and a principle for constructing an appropriate computer program for the selection of polymer networks with a given interval of a number of physical characteristics are proposed. These characteristics include density, the temperature of the onset of intense thermal degradation, thermal conductivity, water permeability, and the stress-optical coefficient. As an example, 16 smallest base fragments are given, which, when attached to each other, allow the selection of structural fragments of repeating fragments of polymers of the following classes: polyolefins, vinyl polymers, polystyrene, polyamides, polyethers and polyesters, polycarbonates, polyetherketones, polyimides, polysulfides, polysulfones, silicone polymers, polyurethanes, cellulose derivatives, methacrylic polymers, etc. The purpose of the study is to develop a model for writing a computer program that allows the selection of structural fragments of network polymers possessing specified intervals of physical characteristics. For polymers used in the construction industry, the most important are the glass transition temperature, the stress-optical coefficient, density, water permeability, and thermal conductivity. Materials and methods. A repeating fragment of the network is selected from the smallest basic fragments, which are connected to each other using a control matrix of interactions. The matrix contains labels that allow you to control the interaction of carbon with three carbon atoms, with a carbon atom and two nitrogen atoms, with two carbon atoms and one oxygen atom, with two carbon atoms and one nitrogen atom, with four carbon atoms. There are also labels that control the interaction of carbon atoms included in the aromatic cycles with two carbon atoms and one oxygen atom, with four carbon atoms, with four nitrogen atoms, with two carbon atoms and one sulfur atom, and three oxygen atoms. This makes it possible to select a huge amount of cross-linked polymer. Results. As an example, the possible chemical structure of 14 cross-linked nodes of the polymer network is presented and the corresponding calculations are carried out, showing the adequacy of the model and the principle of constructing a computer program. The structures of the five cross-linked nodes of polymer network were used and the following physical characteristics of the resulting networks were calculated: density, the temperature of the onset of intense thermal degradation, water permeability, thermal conductivity, and the stress-optical coefficient. All these characteristics are important for the manufacture of building materials. Conclusions. The results of the work allow us to write a real computer program for the selection of repeating fragments of polymer networks that have a given interval of a number of important physical characteristics of network polymers. Among these characteristics are not only those listed above, but also other characteristics, such as glass transition temperature, Hildebrand solubility parameter, surface energy, heat capacity, intermolecular interaction energy, permittivity, etc.

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Linear Viscoelasticity of Polymers and Polymer Nanocomposites: Molecular-Dynamics Large Amplitude Oscillatory Shear and Probe Rheology Simulations

Cited by 5 publications

References 78 publications

Rheological and Mechanical Properties of Thermoplastic Crystallizable Polyimide-Based Nanocomposites Filled with Carbon Nanotubes: Computer Simulations and Experiments

Rheological and Mechanical Properties of Thermoplastic Crystallizable Polyimide-Based Nanocomposites Filled with Carbon Nanotubes: Computer Simulations and Experiments

Revisiting Polymer–Particle Interaction in PEO Solutions

Selection of structural elements of cross-linked polymers used in construction

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