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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Journal ArticleDOI
Aging Wiener-Khinchin Theorem.
N. Leibovich,Eli Barkai +1 more
TL;DR: Two aging Wiener-Khinchin theorems relating the power spectrum to the time- and ensemble-averaged correlation functions are formulated, and when the scaling function ϕ(EA)(x) exhibits a nonanalytical behavior in the vicinity of its small argument the authors obtain the aging 1/f-type of spectrum.
Journal ArticleDOI
Understanding and control of interactions between carbon nanotubes and polymers for manufacturing of high-performance composite materials
Cécile A. C. Chazot,A. John Hart +1 more
TL;DR: In this paper, a review summarizes the fundamental principles that govern CNT-polymer interaction and how polymer characteristics coupled with CNT network properties influence polymer wetting and infiltration, governing the final composite morphology.
Journal ArticleDOI
Reversibly Switchable Polymer Brushes with Hydrophobic/Hydrophilic Behavior: A Langevin Dynamics Study
TL;DR: In this paper, the authors analyzed the process of switching upon sudden change of the solvent quality for various solvent selectivities, chain lengths, and grafting densities of a two-layer system with collapsed hydrophobic and swollen hydrophilic phase.
Book ChapterDOI
Rheological methods in the characterisation of food biopolymers
TL;DR: The rheological techniques used in food biopolymer research for the investigation of dilute and concentrated solutions, aqueous gels and high-solids systems, biphasic systems, and to indicate the principles on which they are based are described.
Journal ArticleDOI
Multiscale molecular modeling of SWCNTs/epoxy resin composites mechanical behaviour
TL;DR: In this paper, the effect of the diameter and weight fraction of single walled carbon nanotubes (SWCNTs) on mechanical behaviour and glass transition temperature (Tg) of reinforced epoxy resin composites was investigated.
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.