scholarly journals Non-Markovian Methods in Glass Transition

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1997
Author(s):  
Constantino Torregrosa Cabanilles ◽  
José Molina-Mateo ◽  
Roser Sabater i Serra ◽  
José María Meseguer-Dueñas ◽  
José Luis Gómez Ribelles
Keyword(s):  
Glass Transition ◽  
Complex Dynamics ◽  
Open Cluster ◽  
Relaxation Times ◽  
Dynamic Heterogeneity ◽  
Slowing Down ◽  
Markovian Dynamics ◽  
Glass Forming Materials ◽  
Dynamics Simulations ◽  
The Relationship

A model for the heterogeneity of local dynamics in polymer and other glass-forming materials is provided here. The fundamental characteristics of the glass transition phenomenology emerge when simulating a condensed matter open cluster that has a strong interaction with its heterogeneous environment. General glass transition features, such as non-exponential structural relaxations, the slowing down of relaxation times with temperature and specific off-equilibrium glassy dynamics can be reproduced by non-Markovian dynamics simulations with the minimum computer resources. Non-Markovian models are shown to be useful tools for obtaining insights into the complex dynamics involved in the glass transition phenomenon, including whether or not there is a need for a growing correlation length or the relationship between the non-exponentiality of structural relaxations and dynamic heterogeneity.

scholarly journals Testing the paradigm of an ideal glass transition: Dynamics of an ultrastable polymeric glass

2018 ◽  
Vol 4 (12) ◽  
pp. eaau5423 ◽  
Author(s):  
Heedong Yoon ◽  
Gregory B. McKenna
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glassy State ◽  
Relaxation Times ◽  
Fictive Temperature ◽  
Transition Dynamics ◽  
Kauzmann Temperature ◽  
Glass Forming ◽  
Equilibrium Data ◽  
Glass Forming Materials

A major challenge to understanding glass-forming materials is obtaining equilibrium data far below the laboratory glass transition temperatureTg. The challenge arises because it takes geologic aging times to achieve the equilibrium glassy state when temperatures are well belowTg. Here, we finesse this problem through measurements on an ultrastable amorphous Teflon with fictive temperatureTfnear to its Kauzmann temperatureTK. In the window betweenTfandTg, the material has a lower molecular mobility than the equilibrium state because of its low specific volume and enthalpy. Our measurements show that the determined scaled relaxation times deviate strongly from the classical expectation of divergence of time scales at a finite temperature. The results challenge the view of an ideal glass transition at or near toTK.

Effects of dynamic heterogeneity and density scaling of molecular dynamics on the relationship among thermodynamic coefficients at the glass transition

2015 ◽  
Vol 143 (2) ◽  
pp. 024502 ◽  
Author(s):  
K. Koperwas ◽  
A. Grzybowski ◽  
K. Grzybowska ◽  
Z. Wojnarowska ◽  
M. Paluch
Keyword(s):  
Molecular Dynamics ◽  
Glass Transition ◽  
Dynamic Heterogeneity ◽  
The Relationship

A study on the progress of mutarotation above and below the Tg and the relationship between constant rates and structural relaxation times

2017 ◽  
Vol 19 (31) ◽  
pp. 20949-20958 ◽  
Author(s):  
K. Wolnica ◽  
M. Dulski ◽  
E. Kaminska ◽  
A. Cecotka ◽  
M. Tarnacka ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Structural Relaxation ◽  
Relaxation Times ◽  
Ftir Studies ◽  
Wide Range ◽  
The Relationship

Comprehensive FTIR studies on the progress of mutarotation in d-fructose mixed with maltitol have been carried out over a wide range of temperatures, both above and below the glass transition temperature Tg.

Slow Dynamics and the Glass Transition in Confining Systems

2003 ◽  
Vol 790 ◽  
Author(s):  
Li-Min Wang ◽  
Fang He ◽  
Ranko Richert
Keyword(s):  
Glass Transition ◽  
Structural Relaxation ◽  
Relaxation Times ◽  
Porous Solids ◽  
Solvation Dynamics ◽  
Slow Dynamics ◽  
Free Standing ◽  
Interfacial Conditions ◽  
Fluid Environment ◽  
Glass Forming Materials

ABSTRACTThe slow dynamics associated with the structural relaxation of glass forming materials near the glass transition is very sensitive to the effects of small confining geometries. Based upon the experimental results of triplet state solvation dynamics, we explore the extent to which confinement effects can be rationalized solely in terms of interfacial dynamics which are modified relative to the bulk situation. The importance of the interfacial conditions is emphasized by observing the changes due to the surface chemistry, by comparing relaxation times at and further away from the surface, and by studying the effects of ‘soft’ versus ‘hard’ confining materials. While ‘hard’ confinement by porous solids is observed to result in slower dynamics and an increased glass transition temperature Tg for propylene glycol, our 4.6 nm nanodroplets suspended in a more fluid environment display faster structural relaxation, equivalent to a reduction of Tg as observed in free standing polymer films.

scholarly journals COOLING RATE DEPENDENCE AND DYNAMIC HETEROGENEITY BELOW THE GLASS TRANSITION IN A LENNARD–JONES GLASS

1999 ◽  
Vol 10 (08) ◽  
pp. 1443-1451 ◽  
Author(s):  
K. VOLLMAYR-LEE ◽  
W. KOB ◽  
K. BINDER ◽  
A. ZIPPELIUS
Keyword(s):  
Molecular Dynamics ◽  
Glass Transition ◽  
Cooling Rate ◽  
Melting Process ◽  
Rate Dependence ◽  
Local Order ◽  
Average Particle ◽  
Dynamic Heterogeneity ◽  
Lennard Jones ◽  
Dynamics Simulations

We investigate a binary Lennard–Jones mixture with molecular dynamics simulations. We consider first a system cooled linearly in time with the cooling rate γ. By varying γ over almost four decades we study the influence of the cooling rate on the glass transition and on the resulting glass. We find for all investigated quantities a cooling rate dependence; with decreasing cooling rate the system falls out of equilibrium at decreasing temperatures, reaches lower enthalpies and obtains increasing local order. Next we study the dynamics of the melting process by investigating the most immobile and most mobile particles in the glass. We find that their spatial distribution is heterogeneous and that the immobile/mobile particles are surrounded by denser/less dense cages than an average particle.

scholarly journals Configuration correlation governs slow dynamics of supercooled metallic liquids

2018 ◽  
Vol 115 (25) ◽  
pp. 6375-6380 ◽  
Author(s):  
Yuan-Chao Hu ◽  
Yan-Wei Li ◽  
Yong Yang ◽  
Peng-Fei Guan ◽  
Hai-Yang Bai ◽  
...  
Keyword(s):  
Glass Transition ◽  
Slow Dynamics ◽  
Theoretical Understanding ◽  
Correlation Lengths ◽  
Dynamic Correlation ◽  
Slowing Down ◽  
Metallic Liquids ◽  
Intrinsic Correlation ◽  
Scaling Analyses ◽  
Dynamics Simulations

The origin of dramatic slowing down of dynamics in metallic glass-forming liquids toward their glass transition temperatures is a fundamental but unresolved issue. Through extensive molecular dynamics simulations, here we show that, contrary to the previous beliefs, it is not local geometrical orderings extracted from instantaneous configurations but the intrinsic correlation between configurations that captures the structural origin governing slow dynamics. More significantly, it is demonstrated by scaling analyses that it is the correlation length extracted from configuration correlation rather than dynamic correlation lengths that is the key to determine the drastic slowdown of supercooled metallic liquids. The key role of the configuration correlation established here sheds important light on the structural origin of the mysterious glass transition and provides an essential piece of the puzzle for the development of a universal theoretical understanding of glass transition in glasses.

scholarly journals Predicting glass transition of amorphous polymers by application of cheminformatics and molecular dynamics simulations

Polymer ◽  
2021 ◽  
Vol 218 ◽  
pp. 123495
Author(s):  
Anas Karuth ◽  
Amirhadi Alesadi ◽  
Wenjie Xia ◽  
Bakhtiyor Rasulev
Keyword(s):  
Molecular Dynamics ◽  
Glass Transition ◽  
Molecular Dynamics Simulations ◽  
Amorphous Polymers ◽  
Dynamics Simulations

scholarly journals Sicily Before the Greeks. The Interaction with Aegean and the Levant in the Pre-colonial Era

2020 ◽  
Vol 6 (1) ◽  
pp. 172-205
Author(s):  
Davide Tanasi
Keyword(s):  
Material Culture ◽  
Complex Dynamics ◽  
Eastern Mediterranean ◽  
Colonial Era ◽  
Local Material ◽  
Gradual Process ◽  
Multiple Variables ◽  
New Perspective ◽  
First Time ◽  
The Relationship

AbstractThe relationship between Sicily and the eastern Mediterranean – namely Aegean, Cyprus and the Levant – represents one of the most intriguing facets of the prehistory of the island. The frequent and periodical contact with foreign cultures were a trigger for a gradual process of socio-political evolution of the indigenous community. Such relationship, already in inception during the Neolithic and the Copper Age, grew into a cultural phenomenon ruled by complex dynamics and multiple variables that ranged from the Mid-3rd to the end of the 2nd millennium BCE. In over 1,500 years, a very large quantity of Aegean and Levantine type materials have been identified in Sicily alongside with example of unusual local material culture traditionally interpreted as resulting from external influence. To summarize all the evidence during such long period and critically address it in order to attempt historical reconstructions is a Herculean labor.Twenty years after Sebastiano Tusa embraced this challenge for the first time, this paper takes stock on two decades of new discoveries and research reassessing a vast amount of literature, mostly published in Italian and in regional journals, while also address the outcomes of new archaeometric studies. The in-depth survey offers a new perspective of general trends in this East-West relationship which conditioned the subsequent events of the Greek and Phoenician colonization of Sicily.

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