Simulation of high-density water: Its glass transition for various water models

2014 ◽  
Vol 140 (13) ◽  
pp. 134504 ◽  
Author(s):  
Martin Jehser ◽  
Markus Seidl ◽  
Clemens Rauer ◽  
Thomas Loerting ◽  
Gerhard Zifferer
Keyword(s):  
Glass Transition ◽  
High Density ◽  
Water Models

scholarly journals Cluster Glass Transition of Ultrasoft-Potential Fluids at High Density

2016 ◽  
Vol 117 (16) ◽  
Author(s):  
Ryoji Miyazaki ◽  
Takeshi Kawasaki ◽  
Kunimasa Miyazaki
Keyword(s):  
Glass Transition ◽  
High Density

scholarly journals Origin of the emergent fragile-to-strong transition in supercooled water

2018 ◽  
Vol 115 (38) ◽  
pp. 9444-9449 ◽  
Author(s):  
Rui Shi ◽  
John Russo ◽  
Hajime Tanaka
Keyword(s):  
Experimental Data ◽  
Glass Transition ◽  
Supercooled Water ◽  
Arrhenius Law ◽  
Widom Line ◽  
Slowing Down ◽  
Strong Transition ◽  
Dynamical Properties ◽  
Water Models ◽  
Insight Into

Liquids can be broadly classified into two categories, fragile and strong ones, depending on how their dynamical properties change with temperature. The dynamics of a strong liquid obey the Arrhenius law, whereas the fragile one displays a super-Arrhenius law, with a much steeper slowing down upon cooling. Recently, however, it was discovered that many materials such as water, oxides, and metals do not obey this simple classification, apparently exhibiting a fragile-to-strong transition far above Tg. Such a transition is particularly well known for water, and it is now regarded as one of water’s most important anomalies. This phenomenon has been attributed to either an unusual glass transition behavior or the crossing of a Widom line emanating from a liquid–liquid critical point. Here by computer simulations of two popular water models and through analyses of experimental data, we show that the emergent fragile-to-strong transition is actually a crossover between two Arrhenius regimes with different activation energies, which can be naturally explained by a two-state description of the dynamics. Our finding provides insight into the fragile-to-strong transition observed in a wide class of materials.

scholarly journals Effects of Expandable Graphite at Moderate and Heavy Loadings on the Thermal and Electrical Conductivity of Amorphous Polystyrene and Semicrystalline High-Density Polyethylene

Applied Nano ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 31-45
Author(s):  
Panagiotis A. Klonos ◽  
Lazaros Papadopoulos ◽  
Dimitra Kourtidou ◽  
Konstantinos Chrissafis ◽  
Vasileios Peoglos ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Glass Transition ◽  
High Density Polyethylene ◽  
Laser Flash ◽  
Filler Loading ◽  
High Density ◽  
Heat Capacity Change ◽  
Expandable Graphite ◽  
Thermal Transitions ◽  
Scanning Calorimetry

In this work, we prepared and investigated two series of polymer composites, wherein the matrix was either an amorphous polystyrene (PS) or a semicrystalline high-density polyethylene (HDPE) filled with expandable graphite (EGr) at relatively high loadings within the range 5–55 wt %. For the investigation we employed a thermogravimetric analysis and differential scanning calorimetry to assess the thermal transitions and evaluate the various polymer fractions (crystalline (CF), mobile (MAF) and rigid amorphous (RAF)) in addition to broadband dielectric spectroscopy and a laser flash analysis to evaluate the EGr effects on electrical conductivity, σ, and thermal conductivity, λ, respectively. In PS, EGr was found to impose an increase of the glass transition temperature and a systematic decrease of the corresponding heat capacity change. The latter was rationalized in terms of the formation of an interfacial RAF. No glass transition was recorded for HDPE whereas the fillers increased the CF moderately. As expected, σ increased with the filler loading for both matrices, up to 10−3–10−2 S/cm, resulting in a conductive percolation threshold for electrons at > 8 wt % EGr. Simultaneously, the λ of PS and HDPE were strongly increased, from 0.13 and 0.38 W·K–1·m–1 up to 0.55 and ~2 W·K–1·m–1, respectively. λ demonstrated an almost linear EGr loading dependence whereas the semicrystalline composites exhibited a systematically higher λ.

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