Journal ArticleDOI
A Theory of the Linear Viscoelastic Properties of Dilute Solutions of Coiling Polymers
TLDR
In this paper, the necessary coordination of the motions of different parts of a polymer molecule is made the basis of a theory of the linear viscoelastic properties of dilute solutions of coiling polymers.Abstract:
The necessary coordination of the motions of different parts of a polymer molecule is made the basis of a theory of the linear viscoelastic properties of dilute solutions of coiling polymers. This is accomplished by use of the concept of the submolecule, a portion of polymer chain long enough for the separation of its ends to approximate a Gaussian probability distribution. The configuration of a submolecule is specified in terms of the vector which corresponds to its end‐to‐end separation. The configuration of a molecule which contains N submolecules is described by the corresponding set of N vectors. The action of a velocity gradient disturbs the distribution of configurations of the polymer molecules away from its equilibrium form, storing free energy in the system. The coordinated thermal motions of the segments cause the configurations to drift toward their equilibrium distribution. The coordination is taken into account by the mathematical requirement that motions of the atom which joins two submolecules change the configurations of both submolecules. By means of an orthogonal transformation of coordinates, the coordination of all the motions of the parts of a molecule is resolved into a series of modes. Each mode has a characteristic relaxation time. The theory produces equations by means of which the relaxation times, the components of the complex viscosity, and the components of the complex rigidity can be calculated from the steady flowviscosities of the solution and the solvent, the molecular weight and concentration of the polymer, and the absolute temperature. Limitations of the theory may arise from the exclusion from consideration of (1) very rapid relaxation processes involving segments shorter than the submolecule and (2) the obstruction of the motion of a segment by other segments with which it happens to be in contact. Another possible cause of disagreement between the theory and experimental data is the polydispersity of any actual polymer; this factor is important because the calculated relaxation times increase rapidly with increasing molecular weight.read more
Citations
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NMR Provides Unique Insight into the Functional Dynamics and Interactions of Intrinsically Disordered Proteins
Aldo R. Camacho-Zarco,Vincent Schnapka,S.Yu. Guseva,Anton Abyzov,Wiktor Adamski,Sigrid Milles,Malene Ringkjøbing Jensen,Lukáš Žídek,Nicola Salvi,Martin Blackledge +9 more
TL;DR: Recent applications of NMR-based approaches to understanding the conformational energy landscape, the nature and time scales of local and long-range dynamics and how they depend on the environment, even in the cell are described.
Journal ArticleDOI
Effects of solvent quality on the dynamics of polymer solutions simulated by dissipative particle dynamics
Guoai Pan,Charles W. Manke +1 more
TL;DR: In this paper, the authors used dissipative particle dynamics (DPD) to model the properties of dilute polymer solutions in steady shear flow. But their simulations were based on a 10-bead chain of FENE connector springs and the solvent as a sea of free DPD particles.
Journal ArticleDOI
Computer simulation of non-Newtonian fluid rheology
TL;DR: Dissipative Particle Dynamics (DPD) is a new simulation technique that focuses on intermediate time and length scales as discussed by the authors, and it is possible to simulate the essential aspects of the rheological behavior of polymeric liquids quite efficiently.
Journal ArticleDOI
Investigations into crazing in glassy amorphous polymers through molecular dynamics simulations
Sudarkodi Venkatesan,Sumit Basu +1 more
TL;DR: In this paper, the authors focus on intrinsic crazes that form spontaneously in the volume of the material and identify and enumerate clusters of entanglement points with high functionality as effective topological constraints on macromolecular chains.
Journal ArticleDOI
Nanoindentation creep and stress relaxation tests of polycarbonate: Analysis of viscoelastic properties by different rheological models
TL;DR: In this article, the authors used feedback-controlled nanoindentation with a Berkovich diamond tip to perform creep and stress relaxation tests on polycarbonate at room temperature for a wide range of loads (10-30000μN) and indentation depths (30-3000nm).
References
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Journal ArticleDOI
Piezoelectric Crystals and Their Applications to Ultrasonics
Warren P. Mason,Hans Baerwald +1 more
TL;DR: Piezoelectric crystals and their application to ultrasonics were discussed in this paper, where the authors proposed a method for the extraction of the ultrasonic properties of these crystals.