scholarly journals Effect of Chitin Whiskers on the Molecular Dynamics of Carrageenan-Based Nanocomposites

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1083 ◽  
Author(s):  
Marta Carsi ◽  
Maria J. Sanchis ◽  
Clara M. Gómez ◽  
Sol Rodriguez ◽  
Fernando G. Torres
Keyword(s):  
Molecular Dynamics ◽  
Casting Process ◽  
Polymer Chains ◽  
Dielectric Relaxation Spectroscopy ◽  
Solution Casting ◽  
Fragility Index ◽  
Relaxation Dynamics ◽  
Dynamic Mobility ◽  
Chitin Nanowhiskers ◽  
Chitin Whiskers

Films of carrageenan (KC) and glycerol (g) with different contents of chitin nanowhiskers (CHW) were prepared by a solution casting process. The molecular dynamics of pure carrageenan (KC), carrageenan/glycerol (KCg) and KCg with different quantities of CHWs as a filler was studied using dielectric relaxation spectroscopy. The analysis of the CHW effect on the molecular mobility at the glass transition, Tg, indicates that non-attractive intermolecular interactions between KCg and CHW occur. The fragility index increased upon CHW incorporation, due to a reduction in the polymer chains mobility produced by the CHW confinement of the KCg network. The apparent activation energy associated with the relaxation dynamics of the chains at Tg slightly increased with the CHW content. The filler nature effect, CHW or montmorillonite (MMT), on the dynamic mobility of the composites was analyzed by comparing the dynamic behavior of both carrageenan-based composites (KCg/xCHW, KCg/xMMT).

scholarly journals Ab initio molecular dynamics study of AlCl4− adsorption on PEDOT conducting polymer chains

2021 ◽  
Vol 7 ◽  
pp. 111-119
Author(s):  
Ben Craig ◽  
Chris-Kriton Skylaris ◽  
Carlos Ponce de Leon ◽  
Denis Kramer
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Conducting Polymer ◽  
Polymer Chains ◽  
Ab Initio Molecular Dynamics

SELF-ASSEMBLED CORE-SHELL POLYMER DIELECTRIC PREPARED BY SOLUTION CASTING PROCESS

2010 ◽  
Vol 113 (1) ◽  
pp. 1-8
Author(s):  
KAI CHEN ◽  
RUI GUO ◽  
CHUNGUANG MA ◽  
TINGYANG DAI ◽  
SUNJIE YE ◽  
...  
Keyword(s):  
Casting Process ◽  
Core Shell ◽  
Solution Casting ◽  
Polymer Dielectric ◽  
Self Assembled

scholarly journals Interface Characteristics of Neat Melts and Binary Mixtures of Polyethylenes from Atomistic Molecular Dynamics Simulations

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1059
Author(s):  
Sanghun Lee ◽  
Curtis W. Frank ◽  
Do Y. Yoon
Keyword(s):  
Molecular Dynamics ◽  
Surface Tension ◽  
Molecular Dynamics Simulations ◽  
Binary Mixtures ◽  
Surface Segregation ◽  
Surface Region ◽  
Polymer Chains ◽  
Methyl Groups ◽  
Free Standing ◽  
Dynamics Simulations

Molecular dynamics simulations of free-standing thin films of neat melts of polyethylene (PE) chains up to C150H302 and their binary mixtures with n-C13H28 are performed employing a united atom model. We estimate the surface tension values of PE melts from the atomic virial tensor over a range of temperatures, which are in good agreement with experimental results. Compared with short n-alkane systems, there is an enhanced surface segregation of methyl chain ends in longer PE chains. Moreover, the methyl groups become more segregated in the surface region with decreasing temperature, leading to the conclusion that the surface-segregation of methyl chain ends mainly arises from the enthalpic origin attributed to the lower cohesive energy density of terminal methyl groups. In the mixtures of two different chain lengths, the shorter chains are more likely to be found in the surface region, and this molecular segregation in moderately asymmetric mixtures in the chain length (C13H28 + C44H90) is dominated by the enthalpic effect of methyl chain ends. Such molecular segregation is further enhanced and dominated by the entropic effect of conformational constraints in the surface for the highly asymmetric mixtures containing long polymer chains (C13H28 + C150H3020). The estimated surface tension values of the mixtures are consistent with the observed molecular segregation characteristics. Despite this molecular segregation, the normalized density of methyl chain ends of the longer chain is more strongly enhanced, as compared with the all-segment density of the longer chain itself, in the surface region of melt mixtures. In addition, the molecular segregation results in higher order parameter of the shorter-chain segments at the surface and deeper persistence of surface-induced segmental order into the film for the longer chains, as compared with those in neat melt films.

Molecular Dynamics and Crystallization Behavior of Chiral Isooctyloxycyanobiphenyl as Studied by Dielectric Relaxation Spectroscopy

1999 ◽  
Vol 103 (20) ◽  
pp. 4197-4205 ◽  
Author(s):  
Maria Massalska-Arodz ◽  
Graham Williams ◽  
Dale K. Thomas ◽  
W. Jeremy Jones ◽  
Roman Dabrowski
Keyword(s):  
Molecular Dynamics ◽  
Dielectric Relaxation ◽  
Crystallization Behavior ◽  
Dielectric Relaxation Spectroscopy

A cluster approach to the structure of imperfect materials and their relaxation spectroscopy

1983 ◽  
Vol 390 (1798) ◽  
pp. 131-180 ◽  
Keyword(s):  
Steady State ◽  
Power Law ◽  
Structural Organization ◽  
Configurational Entropy ◽  
Binding Energies ◽  
Coarse Grained ◽  
Dielectric Relaxation Spectroscopy ◽  
Relaxation Dynamics ◽  
Steady State Distribution ◽  
State Distribution

A new theory is proposed for the explanation of observed relaxation phenomena, which differs significantly from theories suggested by the authors before. The theory is based on a model of structural organization of macroscopically sized samples of imperfectly structured materials, both solids and liquids, and is intermediate in character. In terms of the model, a microscopic structure is maintained over a cluster containing a number of microscopic units, with an array of clusters described by a steady-state distribution completing the macroscopic picture. The structural regularity of each level of morphological organization is precisely defined by a coarse-grained index, which is given a thermodynamic interpretation in terms of binding energies and configurational entropy. The limiting cases of an ideal liquid and a perfect crystal are recovered as asymptotic extremes in terms of this definition. The consequences of this model for the relaxation dynamics of the structure are examined and it is shown that prepared fluctuations decay in a time-power law manner as coupled zero-point motions evolve either within clusters or between clusters, with a power determined by the relevant regularity index. As a result, the origin of power law noise in materials is explained in terms of configurational entropy, and its relation with gaussian and white noise, which appear as asymptotic limits, outlined. The shape of the steady-state distribution of the array of clusters is also determined without any a priori assumptions, and it is shown to range from an unbounded form to a δ function as the regularity of the array superstructure increases. Experimental examples of dielectric relaxation spectroscopy have been used to illustrate these structural concepts and outline the way in which this technique can be used to deduce the structural organization of the sample. Finally, a short description is given of some commonly observed forms of response and their structural interpretation.

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