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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Statics and Dynamics of Bidisperse Polymer Melts: A Monte Carlo Study of the Bond-Fluctuation Model
TL;DR: In this article, a lattice model containing two types of chains with lengths N1 = 20 − x and N2 = 20 + 4x (0 ≤ x ≤ 10 ) is studied.
Journal ArticleDOI
Segmental and Chain Dynamics of Isotactic Polypropylene Melts
TL;DR: In this paper, the properties of isotactic polypropylene (iPP) melts are investigated via atomistic molecular dynamics simulations in the isothermal−isobaric (NPT) ensemble.
Journal ArticleDOI
Rapid and Quantitative Displacement of Poly(ethylene oxide) from MnPS3 and Other Layered Hosts
TL;DR: The reaction of tetraethylammonium salt with the nanocomposites K0.2(C2H4O)2.3M0.9PS3 (M = Mn, Cd) under ambient conditions results in the rapid and quantitative displacement of the polymer and alkali metal to form the alkylammium intercalate.
Journal ArticleDOI
Dynamics of Bottlebrush Networks
Zhen Cao,William F. M. Daniel,Mohammad Vatankhah-Varnosfaderani,Sergei S. Sheiko,Andrey V. Dobrynin +4 more
TL;DR: In this article, the deformation dynamics of bottlebrush networks in a melt state were studied using a combination of theoretical, computational, and experimental techniques, and three main molecular relaxation processes were identified.
Journal ArticleDOI
Molecular dynamics and interactions of aqueous and dichloromethane solutions of polyvinylpyrrolidone.
TL;DR: The predominant relaxation of the polymer is assigned to reorientations of the pyrrolidone side group or torsional motions of the constitutional repeat unit, with additional relaxation pathways including hydrogen bond reorganization in aqueous solution and segmental motion of multiple repeat units.
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.