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Stevenson CS, Curro JG, McCoy JD. The glass transition temperature of thin films: A molecular dynamics study for a bead-spring model. J Chem Phys 2017; 146:203322. [DOI: 10.1063/1.4977521] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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Puosi F, Chulkin O, Bernini S, Capaccioli S, Leporini D. Thermodynamic scaling of vibrational dynamics and relaxation. J Chem Phys 2016; 145:234904. [DOI: 10.1063/1.4971297] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- F. Puosi
- Dipartimento di Fisica “Enrico Fermi,” Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
| | - O. Chulkin
- Dipartimento di Fisica “Enrico Fermi,” Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
| | - S. Bernini
- Dipartimento di Fisica “Enrico Fermi,” Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
| | - S. Capaccioli
- Dipartimento di Fisica “Enrico Fermi,” Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
- IPCF-CNR, UOS, Pisa, Italy
| | - D. Leporini
- Dipartimento di Fisica “Enrico Fermi,” Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
- IPCF-CNR, UOS, Pisa, Italy
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Budzien J, Heffernan JV, McCoy JD. Effect of chain flexibility on master curve behavior for diffusion coefficient. J Chem Phys 2013; 139:244501. [DOI: 10.1063/1.4851437] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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Brown JR, McCoy JD. Nonlinear dynamic heat capacity of a bead-spring polymeric glass former. J Chem Phys 2012; 137:244504. [DOI: 10.1063/1.4772467] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Brown JR, McCoy JD. The potential energy landscape contribution to the dynamic heat capacity. J Chem Phys 2011; 134:194503. [PMID: 21599069 DOI: 10.1063/1.3590107] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The dynamic heat capacity of a simple polymeric, model glassformer was computed using molecular dynamics simulations by sinusoidally driving the temperature and recording the resultant energy. The underlying potential energy landscape of the system was probed by taking a time series of particle positions and quenching them. The resulting dynamic heat capacity demonstrates that the long time relaxation is the direct result of dynamics resulting from the potential energy landscape. Moreover, the equilibrium (low frequency) portion of the potential energy landscape contribution to the heat capacity is found to increase rapidly at low temperatures and at high packing fractions. This increase in the heat capacity is explained by a statistical mechanical model based on the distribution of minima in the potential energy landscape.
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Affiliation(s)
- Jonathan R Brown
- Department of Materials and Metallurgical Engineering, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801, USA
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Adolf DB, Chambers RS, Elisberg B, Stavig M, Ruff M. Predicting cohesive failure in thermosets. J Appl Polym Sci 2010. [DOI: 10.1002/app.32938] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Adolf DB, Chambers RS, Hammerand DC, Tang MY, Westgate K, Gillick J, Skrypnyk I. Modeling the response of monofilament nylon cords with the nonlinear viscoelastic, simplified potential energy clock model. POLYMER 2010. [DOI: 10.1016/j.polymer.2010.01.030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Dotson TC, Budzien J, McCoy JD, Adolf DB. Cole–Davidson dynamics of simple chain models. J Chem Phys 2009; 130:024903. [DOI: 10.1063/1.3050105] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Coslovich D, Roland CM. Pressure-energy correlations and thermodynamic scaling in viscous Lennard-Jones liquids. J Chem Phys 2009; 130:014508. [DOI: 10.1063/1.3054635] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Roland CM, Bogoslovov RB, Casalini R, Ellis AR, Bair S, Rzoska SJ, Czuprynski K, Urban S. Thermodynamic scaling and the characteristic relaxation time at the phase transition of liquid crystals. J Chem Phys 2008; 128:224506. [DOI: 10.1063/1.2931541] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Dotson TC, Heffernan JV, Budzien J, Dotson KT, Avila F, Limmer DT, McCoy DT, McCoy JD, Adolf DB. Rheological complexity in simple chain models. J Chem Phys 2008; 128:184905. [DOI: 10.1063/1.2912054] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Coslovich D, Roland CM. Thermodynamic Scaling of Diffusion in Supercooled Lennard-Jones Liquids. J Phys Chem B 2008; 112:1329-32. [DOI: 10.1021/jp710457e] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- D. Coslovich
- Dipartimento di Fisica Teorica, Università di Trieste, Strada Costiera 11, 34100 Trieste, Italy, and Naval Research Laboratory, Code 6120, Washington, District of Columbia 20375-5342
| | - C. M. Roland
- Dipartimento di Fisica Teorica, Università di Trieste, Strada Costiera 11, 34100 Trieste, Italy, and Naval Research Laboratory, Code 6120, Washington, District of Columbia 20375-5342
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Heffernan JV, Budzien J, Avila F, Dotson TC, Aston VJ, McCoy JD, Adolf DB. Rotational relaxation in simple chain models. J Chem Phys 2007; 127:214902. [DOI: 10.1063/1.2798755] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Heffernan JV, Budzien J, Wilson AT, Baca RJ, Aston VJ, Avila F, McCoy JD, Adolf DB. Molecular flexibility effects upon liquid dynamics. J Chem Phys 2007; 126:184904. [PMID: 17508829 DOI: 10.1063/1.2730502] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Simulation results for the diffusive behavior of polymer chain/penetrant systems are analyzed. The attractive range and flexibility of simple chain molecules were varied in order to gauge the effect on dynamics. In all cases, the dimensionless diffusion coefficient, D*, is found to be a smooth, single-valued function of the packing fraction, eta. The functions D*(eta) are found to be power laws with exponents that are sensitive to both chain stiffness and particle type. For a specific system type, the D*'s for both penetrant and chain-center-of-mass extrapolate to zero at the same packing fraction, eta0. This limiting packing fraction is interpreted to be the location of the glass transition, and (eta0-eta), the distance to the glass transition.
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Affiliation(s)
- Julieanne V Heffernan
- Department of Materials and Metallurgical Engineering, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801, USA
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Roland CM, Bair S, Casalini R. Thermodynamic scaling of the viscosity of van der Waals, H-bonded, and ionic liquids. J Chem Phys 2006; 125:124508. [PMID: 17014192 DOI: 10.1063/1.2346679] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Viscosities eta and their temperature T and volume V dependences are reported for seven molecular liquids and polymers. In combination with literature viscosity data for five other liquids, we show that the superpositioning of relaxation times for various glass-forming materials when expressed as a function of TV(gamma), where the exponent gamma is a material constant, can be extended to the viscosity. The latter is usually measured to higher temperatures than the corresponding relaxation times, demonstrating the validity of the thermodynamic scaling throughout the supercooled and higher T regimes. The value of gamma for a given liquid principally reflects the magnitude of the intermolecular forces (e.g., steepness of the repulsive potential); thus, we find decreasing gamma in going from van der Waals fluids to ionic liquids. For some strongly H-bonded materials, such as low molecular weight polypropylene glycol and water, the superpositioning fails, due to the nontrivial change of chemical structure (degree of H bonding) with thermodynamic conditions.
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Affiliation(s)
- C M Roland
- Chemistry Division, Naval Research Laboratory, Code 6120, Washington, DC 20375-5342, USA.
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Casalini R, Capaccioli S, Roland CM. What Can We Learn by Squeezing a Liquid? J Phys Chem B 2006; 110:11491-5. [PMID: 16771424 DOI: 10.1021/jp062356o] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Relaxation times tau(T,upsilon) for different temperatures, T, and specific volumes, upsilon, collapse to a master curve vs Tupsilon(gamma), with gamma a material constant. The isochoric fragility, mV, is also a material constant, inversely correlated with gamma. From these experimental facts, we obtain a three-parameter function that accurately fits tau(T,upsilon) data for several glass-formers over the supercooled regime, without any divergence of tau below Tg. Although the values of the three parameters depend on the material, only gamma significantly varies; thus, by normalizing material-specific quantities related to gamma, a universal power law for the dynamics is obtained.
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Affiliation(s)
- R Casalini
- Naval Research Laboratory, Code 6120, Washington, D.C. 20375-5342, George Mason University, Fairfax Virginia 22030, USA.
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Casalini R, Roland CM. Why liquids are fragile. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2005; 72:031503. [PMID: 16241440 DOI: 10.1103/physreve.72.031503] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2005] [Indexed: 05/05/2023]
Abstract
The fragilities (T(g)-normalized temperature dependence of alpha-relaxation times) of 33 glass-forming liquids and polymers are compared for isobaric, mP, and isochoric, mV, conditions. We find that the two quantities are linearly correlated: mP = (37+/-3) + (0.84+/-0.05)mV. This result has obvious and important consequences, since the ratio mV/mP is a measure of the relative degree to which temperature and density control the dynamics. Moreover, we show that the fragility itself is a consequence of the relative interplay of temperature and density effects near T(g). Specifically, strong behavior reflects a substantial contribution from density (jammed dynamics), while the relaxation of fragile liquids is more thermally activated. Drawing on the scaling law log(tau) = I(T upsilon(gamma)), a physical interpretation of this result in terms of the intermolecular potential is offered.
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Affiliation(s)
- R Casalini
- Naval Research Laboratory, Code 6120, Washington, DC 20375-5342, USA.
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