1
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Mols RHM, Vogiatzis GG, van Breemen LCA, Hütter M. Microscopic Carriers of Plasticity in Glassy Polystyrene. MACROMOL THEOR SIMUL 2021. [DOI: 10.1002/mats.202100021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Roy H. M. Mols
- Polymer Technology Department of Mechanical Engineering Eindhoven University of Technology P. O. Box 513 Eindhoven 5600 MB The Netherlands
- Dutch Polymer Institute PO Box 902 Eindhoven 5600 AX The Netherlands
| | - Georgios G. Vogiatzis
- Dutch Polymer Institute PO Box 902 Eindhoven 5600 AX The Netherlands
- School of Chemical Engineering National Technical University of Athens 9 Heroon Polytechniou Street, Zografou Campus Athens GR‐15780 Greece
| | - Lambèrt C. A. van Breemen
- Polymer Technology Department of Mechanical Engineering Eindhoven University of Technology P. O. Box 513 Eindhoven 5600 MB The Netherlands
| | - Markus Hütter
- Polymer Technology Department of Mechanical Engineering Eindhoven University of Technology P. O. Box 513 Eindhoven 5600 MB The Netherlands
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2
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Strickland DJ, Melchert DS, Hor JL, Ortiz CP, Lee D, Gianola DS. Microscopic origin of shear banding as a localized driven glass transition in compressed colloidal pillars. Phys Rev E 2020; 102:032605. [PMID: 33075911 DOI: 10.1103/physreve.102.032605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 07/21/2020] [Indexed: 06/11/2023]
Abstract
Here we report on compression experiments of colloidal pillars in which the evolution of a shear band can be followed at the particle level during deformation. Quasistatic deformation results in dilation and anisotropic changes in coordination in a localized band of material. Additionally, a transition from solid- to liquidlike mechanical response accompanies the structural change in the band, as evidenced by saturation of the packing fraction at the glass transition point, a diminishing ability to host anelastic strains, and a rapid decay in the long-range strain correlations. Overall, our results suggest that shear banding quantitatively resembles a localized, driven glass transition.
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Affiliation(s)
| | - Drew S Melchert
- University of California Santa Barbara, Santa Barbara, California 93106, USA
| | - Jyo Lyn Hor
- University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Carlos P Ortiz
- University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Daeyeon Lee
- University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Daniel S Gianola
- University of California Santa Barbara, Santa Barbara, California 93106, USA
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3
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Abstract
The time-dependent response of structural materials dominates our aging infrastructure's life expectancy and has important resilience implications. For calcium-silicate-hydrates, the glue of cement, nanoscale mechanisms underlying time-dependent phenomena are complex and remain poorly understood. This complexity originates in part from the inherent difficulty in studying nanoscale longtime phenomena in atomistic simulations. Herein, we propose a three-staged incremental stress-marching technique to overcome such limitations. The first stage unravels a stretched exponential relaxation, which is ubiquitous in glassy systems. When fully relaxed, the material behaves viscoelastically upon further loading, which is described by the standard solid model. By progressively increasing the interlayer water, the time-dependent response of calcium-silicate-hydrates exhibits a transition from viscoelastic to logarithmic creep. These findings bridge the gap between atomistic simulations and nanomechanical experimental measurements and pave the way for the design of reduced aging construction materials and other disordered systems such as metallic and oxide glasses.
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4
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Zhang M, Wang YM, Li FX, Jiang SQ, Li MZ, Liu L. Mechanical Relaxation-to-Rejuvenation Transition in a Zr-based Bulk Metallic Glass. Sci Rep 2017; 7:625. [PMID: 28377604 PMCID: PMC5429611 DOI: 10.1038/s41598-017-00768-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 03/13/2017] [Indexed: 11/19/2022] Open
Abstract
The relaxation of amorphous materials, i.e., aging, would largely endanger their performances in service. Here we report a mechanical relaxation-to-rejuvenation transition of a Zr35Ti30Be27.5Cu7.5 bulk metallic glass (BMG) in elastostatic compression at ambient temperature, thus provide an accessible way to tailor the mechanical properties of amorphous materials. To unravel the structural evolution underlying the observed transition, atomistic simulations parallel with the experimental tests on a typical model glass system Zr60Cu40 were performed, which successfully reproduced and thus upheld the experimentally observed mechanical relaxation-to-rejuvenation transition. The variations of coordination number and atomic volume during the transition are evaluated to indicate a de-mixing tendency of the constituent atoms in the rejuvenation stage. This de-mixing tendency largely explains the difference between mechanical rejuvenation and thermal rejuvenation and reveals a competitive relationship between activation enthalpy and activation entropy in the stress-driven temperature-assisted atomic dynamics of BMG, such as diffusion and plastic deformation etc.
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Affiliation(s)
- M Zhang
- School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Y M Wang
- School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - F X Li
- Department of Physics, Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing, 100872, China
| | - S Q Jiang
- Department of Physics, Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing, 100872, China
| | - M Z Li
- Department of Physics, Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing, 100872, China
| | - L Liu
- School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China.
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5
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Zhao Y, Liu J, Li X, Lu Y, Wang SQ. How and Why Polymer Glasses Lose Their Ductility Due to Plasticizers. Macromolecules 2017. [DOI: 10.1021/acs.macromol.6b02158] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yue Zhao
- Department of Polymer Science
and Institute of Polymer Science and Engineering, University of Akron, Akron, Ohio 44325-3909, United States
| | - Jianning Liu
- Department of Polymer Science
and Institute of Polymer Science and Engineering, University of Akron, Akron, Ohio 44325-3909, United States
| | - Xiaoxiao Li
- Department of Polymer Science
and Institute of Polymer Science and Engineering, University of Akron, Akron, Ohio 44325-3909, United States
| | - Yue Lu
- Department of Polymer Science
and Institute of Polymer Science and Engineering, University of Akron, Akron, Ohio 44325-3909, United States
| | - Shi-Qing Wang
- Department of Polymer Science
and Institute of Polymer Science and Engineering, University of Akron, Akron, Ohio 44325-3909, United States
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6
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Nonlinear stress relaxation behavior of ductile polymer glasses from large extension and compression. POLYMER 2015. [DOI: 10.1016/j.polymer.2015.11.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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7
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Li X, Wang SQ. Mapping Brittle and Ductile Behaviors of Polymeric Glasses under Large Extension. ACS Macro Lett 2015; 4:1110-1113. [PMID: 35614813 DOI: 10.1021/acsmacrolett.5b00554] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have carried out a series of tensile extension tests on the two most common polymer glasses to describe their generic mechanical responses as a function of deformation rate at different temperatures. The essentially defect-free polystyrene and poly(methyl methacrylate) both show remarkable re-entrant failure: being ductile at intermediate rates and showing diminishing toughness at both higher and lower rates. We draw phase diagrams to map out the relationship between brittle-like and yield-like states in terms of temperature, rate, and stress. A coherent understanding of the rich phenomenology requires us to describe in more detail the interplay between the chain network and the primary structure bonded by intersegmental van der Waals forces.
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Affiliation(s)
- Xiaoxiao Li
- Morton Institutes of Polymer
Science and Engineering, University of Akron, Akron, Ohio 44325, United States
| | - Shi-Qing Wang
- Morton Institutes of Polymer
Science and Engineering, University of Akron, Akron, Ohio 44325, United States
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8
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Fiocco D, Foffi G, Sastry S. Memory effects in schematic models of glasses subjected to oscillatory deformation. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:194130. [PMID: 25923880 DOI: 10.1088/0953-8984/27/19/194130] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We consider two schematic models of glasses subjected to oscillatory shear deformation, motivated by the observations, in computer simulations of a model glass, of a nonequilibrium transition from a localized to a diffusive regime as the shear amplitude is increased, and of persistent memory effects in the localized regime. The first of these schematic models is the NK model, a spin model with disordered multi-spin interactions previously studied as a model for sheared amorphous solids. The second model, a transition matrix model, is an abstract formulation of the manner in which occupancy of local energy minima evolves under oscillatory deformation cycles. In both of these models, we find a behavior similar to that of an atomic model glass studied earlier. We discuss possible further extensions of the approaches outlined.
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Affiliation(s)
- Davide Fiocco
- Institute of Theoretical Physics (ITP), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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9
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Cugini AV, Lesser AJ. Aspects of physical aging, mechanical rejuvenation, and thermal annealing in a new copolyester. POLYM ENG SCI 2014. [DOI: 10.1002/pen.24035] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Angela V. Cugini
- Department of Polymer Science and Engineering; University of Massachusetts; Amherst Massachusetts
| | - Alan J. Lesser
- Department of Polymer Science and Engineering; University of Massachusetts; Amherst Massachusetts
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10
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Fiocco D, Foffi G, Sastry S. Encoding of memory in sheared amorphous solids. PHYSICAL REVIEW LETTERS 2014; 112:025702. [PMID: 24484027 DOI: 10.1103/physrevlett.112.025702] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Indexed: 06/03/2023]
Abstract
We show that memory can be encoded in a model amorphous solid subjected to athermal oscillatory shear deformations, and in an analogous spin model with disordered interactions, sharing the feature of a deformable energy landscape. When these systems are subjected to oscillatory shear deformation, they retain memory of the deformation amplitude imposed in the training phase, when the amplitude is below a "localization" threshold. Remarkably, multiple persistent memories can be stored using such an athermal, noise-free, protocol. The possibility of such memory is shown to be linked to the presence of plastic deformations and associated limit cycles traversed by the system, which exhibit avalanche statistics also seen in related contexts.
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Affiliation(s)
- Davide Fiocco
- Institute of Theoretical Physics (ITP), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Giuseppe Foffi
- Institute of Theoretical Physics (ITP), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland and Laboratoire de Physique de Solides, UMR 8502, Bât. 510, Université Paris-Sud, F-91405 Orsay, France
| | - Srikanth Sastry
- TIFR Centre for Interdisciplinary Sciences, 21 Brundavan Colony, Narsingi, 500075 Hyderabad, India and Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur Campus, 560064 Bangalore, India
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11
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Lempesis N, Vogiatzis GG, Boulougouris GC, van Breemen LC, Hütter M, Theodorou DN. Tracking a glassy polymer on its energy landscape in the course of elastic deformation. Mol Phys 2013. [DOI: 10.1080/00268976.2013.825018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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12
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Kaushal M, Joshi YM. Tailoring relaxation time spectrum in soft glassy materials. J Chem Phys 2013; 139:024904. [PMID: 23862962 DOI: 10.1063/1.4812838] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Physical properties of out of equilibrium soft materials depend on time as well as deformation history. In this work we propose to transform this major shortcoming into gain by applying controlled deformation field to tailor the rheological properties. We take advantage of the fact that deformation field of a certain magnitude can prevent particles in an aging soft glassy material from occupying energy wells up to a certain depth, thereby populating only the deeper wells. We employ two soft glassy materials with dissimilar microstructures and demonstrate that increase in strength of deformation field while aging leads to narrowing of spectrum of relaxation times. We believe that, in principle, this philosophy can be universally applied to different kinds of glassy materials by changing nature and strength of impetus.
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Affiliation(s)
- Manish Kaushal
- Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India
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13
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14
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Singh S, Ediger MD, de Pablo JJ. Ultrastable glasses from in silico vapour deposition. NATURE MATERIALS 2013; 12:139-144. [PMID: 23291708 DOI: 10.1038/nmat3521] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Accepted: 11/13/2012] [Indexed: 06/01/2023]
Abstract
Glasses are generally prepared by cooling from the liquid phase, and their properties depend on their thermal history. Recent experiments indicate that glasses prepared by vapour deposition onto a substrate can exhibit remarkable stability, and might correspond to equilibrium states that could hitherto be reached only by glasses aged for thousands of years. Here we create ultrastable glasses by means of a computer-simulation process that mimics physical vapour deposition. These stable glasses have, far below the conventional glass-transition temperature, the properties expected for the equilibrium supercooled liquid state, and optimal stability is attained when deposition occurs at the Kauzmann temperature. We also show that the glasses' extraordinary stability is associated with distinct structural motifs, in particular the abundance of regular Voronoi polyhedra and the relative lack of irregular polyhedra.
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Affiliation(s)
- Sadanand Singh
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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15
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Hudzinskyy D, Michels MAJ, Lyulin AV. Rejuvenation, Aging, and Confinement Effects in Atactic-Polystyrene Films Subjected to Oscillatory Shear. MACROMOL THEOR SIMUL 2012. [DOI: 10.1002/mats.201200050] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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16
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Senden DJA, van Dommelen JAW, Govaert LE. Physical aging and deformation kinetics of polycarbonate. ACTA ACUST UNITED AC 2012. [DOI: 10.1002/polb.23161] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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17
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Chung YG, Lacks DJ. Atomic mobility in strained glassy polymers: The role of fold catastrophes on the potential energy surface. ACTA ACUST UNITED AC 2012. [DOI: 10.1002/polb.23166] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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18
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Bandyopadhyay A, Odegard GM. Molecular modeling of physical aging in epoxy polymers. J Appl Polym Sci 2012. [DOI: 10.1002/app.38245] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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19
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Lacks DJ. Sheared polymer glass and the question of mechanical rejuvenation. J Chem Phys 2012; 136:124907. [DOI: 10.1063/1.3698473] [Citation(s) in RCA: 13] [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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20
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Odegard GM, Bandyopadhyay A. Physical aging of epoxy polymers and their composites. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/polb.22384] [Citation(s) in RCA: 224] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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21
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Lee HN, Ediger MD. Interaction between physical aging, deformation, and segmental mobility in poly(methyl methacrylate) glasses. J Chem Phys 2010; 133:014901. [DOI: 10.1063/1.3450318] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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22
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Lee HN, Ediger MD. Mechanical Rejuvenation in Poly(methyl methacrylate) Glasses? Molecular Mobility after Deformation. Macromolecules 2010. [DOI: 10.1021/ma1006649] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Hau-Nan Lee
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - M. D. Ediger
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
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23
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Gao GJ, Blawzdziewicz J, O'Hern CS. Geometrical families of mechanically stable granular packings. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 80:061303. [PMID: 20365164 DOI: 10.1103/physreve.80.061303] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Indexed: 05/29/2023]
Abstract
We enumerate and classify nearly all of the possible mechanically stable (MS) packings of bidipserse mixtures of frictionless disks in small sheared systems. We find that MS packings form continuous geometrical families, where each family is defined by its particular network of particle contacts. We also monitor the dynamics of MS packings along geometrical families by applying quasistatic simple shear strain at zero pressure. For small numbers of particles (N<16), we find that the dynamics is deterministic and highly contracting. That is, if the system is initialized in a MS packing at a given shear strain, it will quickly lock into a periodic orbit at subsequent shear strain, and therefore sample only a very small fraction of the possible MS packings in steady state. In studies with N>16, we observe an increase in the period and random splittings of the trajectories caused by bifurcations in configuration space. We argue that the ratio of the splitting and contraction rates in large systems will determine the distribution of MS-packing geometrical families visited in steady state. This work is part of our long-term research program to develop a master-equation formalism to describe macroscopic slowly driven granular systems in terms of collections of small subsystems.
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Affiliation(s)
- Guo-Jie Gao
- Department of Mechanical Engineering, Yale University, New Haven, Connecticut 06520-8284, USA
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24
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Rottler J. Fracture in glassy polymers: a molecular modeling perspective. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:463101. [PMID: 21715863 DOI: 10.1088/0953-8984/21/46/463101] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Over the past 25 years, molecular modeling and simulations have provided important insights into the physics of deformation and fracture of glassy polymers. This review presents an overview of key results discussed in the context of experimentally observed polymer behavior. Both atomistic and coarse-grained polymer models have been used in different deformation protocols to study elastic properties, shear yielding, creep, physical aging, strain hardening and crazing. Simulations reproduce most of the macroscopic features of plasticity in polymer glasses such as stress-strain relations and creep response, and reveal information about the underlying atomistic processes. Trends of the shear yield stress with loading conditions, temperature and strain rate, and the atomistic dynamics under load have been systematically explored. Most polymers undergo physical aging, which leads to a history-dependent mechanical response. Simulations of strain hardening and crazing demonstrate the nature of polymer entanglements in the glassy state and the role of local plasticity and provide insight into the origin of fracture toughness of amorphous polymers.
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Affiliation(s)
- Jörg Rottler
- Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC, V6T 1Z1, Canada
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25
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Vorselaars B, Lyulin AV, Michels MAJ. Deforming glassy polystyrene: Influence of pressure, thermal history, and deformation mode on yielding and hardening. J Chem Phys 2009; 130:074905. [DOI: 10.1063/1.3077859] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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26
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Pan P, Zhu B, Dong T, Yazawa K, Shimizu T, Tansho M, Inoue Y. Conformational and microstructural characteristics of poly(L-lactide) during glass transition and physical aging. J Chem Phys 2009; 129:184902. [PMID: 19045426 DOI: 10.1063/1.3010368] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The glass transition and physical aging processes of poly(L-lactide) (PLLA) were studied by variable-temperature Fourier transform infrared (FTIR) spectroscopy and (13)C solid-state NMR spectroscopy. The glass transition temperature (T(g)) of PLLA can be well determined from the temperature-dependent FTIR intensity. Nearby T(g), a distinct change in the slope of spectral intensity versus temperature plot is detected. FTIR results suggest that the energy-favorable gauche-trans (gt) conformers rearrange into the less energy-favorable gauche-gauche (gg) counterparts with heating over the glass transition region, which becomes more distinct at temperature above T(g). Besides, the 1267 cm(-1) band, which shows different trends of variation from the other bands upon heating, was assigned to be more sensitive to the nu(as)(C-O-C)+delta(CH) vibration mode of the less energy-favorable gg conformers in PLLA. By comparing the FTIR spectra of the aged and deaged PLLA, it was demonstrated that the rearrangement from the high- to low-energy conformers, i.e., gg to gt, occurs with physical aging. (13)C spin-lattice relaxation measurements indicate that the relaxation rate distribution broadens with aging, which agrees with the previous suggestion that the locally ordered domains are formed during physical aging. Because of the larger variation in the conformational state and microstructure, the FTIR intensities vary much more abruptly for the aged sample with heating to nearby T(g).
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Affiliation(s)
- Pengju Pan
- Department of Biomolecular Engineering, Tokyo Institute of Technology, 4259-B-55 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan
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27
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Mulder T, Harmandaris VA, Lyulin AV, van der Vegt NFA, Kremer K, Michels MAJ. Structural Properties of Atactic Polystyrene of Different Thermal History Obtained from a Multiscale Simulation. Macromolecules 2008. [DOI: 10.1021/ma800873z] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Tim Mulder
- Group Polymer Physics, Eindhoven Polymer Laboratories, Technische Universiteit Eindhoven, P.O. Box 513, 5600 MB Eindhoven, The Netherlands; Dutch Polymer Institute, P.O. Box 902, 5600 AX Eindhoven, The Netherlands; and Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - V. A. Harmandaris
- Group Polymer Physics, Eindhoven Polymer Laboratories, Technische Universiteit Eindhoven, P.O. Box 513, 5600 MB Eindhoven, The Netherlands; Dutch Polymer Institute, P.O. Box 902, 5600 AX Eindhoven, The Netherlands; and Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Alexey V. Lyulin
- Group Polymer Physics, Eindhoven Polymer Laboratories, Technische Universiteit Eindhoven, P.O. Box 513, 5600 MB Eindhoven, The Netherlands; Dutch Polymer Institute, P.O. Box 902, 5600 AX Eindhoven, The Netherlands; and Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - N. F. A. van der Vegt
- Group Polymer Physics, Eindhoven Polymer Laboratories, Technische Universiteit Eindhoven, P.O. Box 513, 5600 MB Eindhoven, The Netherlands; Dutch Polymer Institute, P.O. Box 902, 5600 AX Eindhoven, The Netherlands; and Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - K. Kremer
- Group Polymer Physics, Eindhoven Polymer Laboratories, Technische Universiteit Eindhoven, P.O. Box 513, 5600 MB Eindhoven, The Netherlands; Dutch Polymer Institute, P.O. Box 902, 5600 AX Eindhoven, The Netherlands; and Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - M. A. J. Michels
- Group Polymer Physics, Eindhoven Polymer Laboratories, Technische Universiteit Eindhoven, P.O. Box 513, 5600 MB Eindhoven, The Netherlands; Dutch Polymer Institute, P.O. Box 902, 5600 AX Eindhoven, The Netherlands; and Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
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28
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Warren M, Rottler J. Mechanical rejuvenation and overaging in the soft glassy rheology model. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 78:041502. [PMID: 18999430 DOI: 10.1103/physreve.78.041502] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2008] [Indexed: 05/27/2023]
Abstract
Mechanical rejuvenation and overaging of glasses is investigated through stochastic simulations of the soft glassy rheology (SGR) model. Strain- and stress-controlled deformation cycles for a wide range of loading conditions are analyzed and compared to molecular dynamics simulations of a model polymer glass. Results indicate that deformation causes predominantly rejuvenation, whereas overaging occurs only at very low temperatures, small strains, and for high initial energy states. Although the creep compliance in the SGR model exhibits full aging independent of applied load, large stresses in the nonlinear creep regime cause configurational changes leading to rejuvenation of the relaxation time spectrum probed after a stress cycle. During recovery, however, the rejuvenated state rapidly returns to the original aging trajectory due to collective relaxations of the internal strain.
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Affiliation(s)
- Mya Warren
- Department of Physics and Astronomy, The University of British Columbia, 6224 Agricultural Road, Vancouver, BC, V6T 1Z1, Canada.
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29
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Affiliation(s)
- Robert A. Riggleman
- Department of Chemical and Biological Engineering, University of Wisconsin, Madison, Wisconsin, 53706, and Departments of Materials Science and Chemistry, University of Illinois, Urbana, Illinois, 61801
| | - Kenneth S. Schweizer
- Department of Chemical and Biological Engineering, University of Wisconsin, Madison, Wisconsin, 53706, and Departments of Materials Science and Chemistry, University of Illinois, Urbana, Illinois, 61801
| | - Juan J. de Pablo
- Department of Chemical and Biological Engineering, University of Wisconsin, Madison, Wisconsin, 53706, and Departments of Materials Science and Chemistry, University of Illinois, Urbana, Illinois, 61801
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30
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Kierkels JTA, Dona CL, Tervoort TA, Govaert LE. Kinetics of re-embrittlement of (anti)plasticized glassy polymers after mechanical rejuvenation. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/polb.21349] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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31
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Boulougouris GC, Theodorou DN. Dynamical integration of a Markovian web: A first passage time approach. J Chem Phys 2007; 127:084903. [PMID: 17764290 DOI: 10.1063/1.2753153] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
In this work we address the dynamics of Markovian systems by tracking the evolution of the probability distribution, utilizing mean first passage time theory to augment the set of states considered. The method is validated on a lattice system and is applied, in conjunction with landscape analysis (saddle point searches) and multidimensional transition-state theory, to an atomistic model of glassy atactic polystyrene, in order to follow its time evolution over more than ten orders of magnitude on the time scale, from less than 10(-15) up to 10(-5) s. Frequencies extracted from the eigenvalues of the rate constant matrix are in favorable agreement with experimental measurements of subglass relaxation transitions at 250 K.
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Affiliation(s)
- Georgios C Boulougouris
- School of Chemical Engineering, National Technical University of Athens, Zografou Campus, GR-15780 Athens, Greece.
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32
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Lyulin AV, Michels MAJ. Time scales and mechanisms of relaxation in the energy landscape of polymer glass under deformation: direct atomistic modeling. PHYSICAL REVIEW LETTERS 2007; 99:085504. [PMID: 17930956 DOI: 10.1103/physrevlett.99.085504] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2006] [Indexed: 05/25/2023]
Abstract
Molecular-dynamics simulation is used to explore the influence of thermal and mechanical history of typical glassy polymers on their deformation. Polymer stress-strain and energy-strain developments have been followed for different deformation velocities, also in closed extension-recompression loops. The latter simulate for the first time the experimentally observed mechanical rejuvenation and overaging of polymers, and energy partitioning reveals essential differences between mechanical and thermal rejuvenation. All results can be qualitatively interpreted by considering the ratios of the relevant time scales: for cooling down, for deformation, and for segmental relaxation.
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Affiliation(s)
- Alexey V Lyulin
- Group Polymer Physics, Eindhoven Polymer Laboratories, Technische Universiteit Eindhoven, 5600 MB, Eindhoven, The Netherlands.
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33
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Guo H, Wilking JN, Liang D, Mason TG, Harden JL, Leheny RL. Slow, nondiffusive dynamics in concentrated nanoemulsions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 75:041401. [PMID: 17500888 DOI: 10.1103/physreve.75.041401] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2006] [Indexed: 05/15/2023]
Abstract
Using multispeckle x-ray photon correlation spectroscopy, we have measured the slow, wave-vector-dependent dynamics of concentrated, disordered nanoemulsions composed of silicone oil droplets in water. The intermediate scattering function possesses a compressed exponential line shape and a relaxation time that varies inversely with wave vector. We interpret this dynamics as strain in response to local stress relaxation. The motion includes a transient component whose characteristic velocity decays exponentially with time following a mechanical perturbation of the nanoemulsions and a second component whose characteristic velocity is essentially independent of time. The steady-state characteristic velocity is surprisingly insensitive to the droplet volume fraction in the concentrated regime, indicating that the strain motion is only weakly dependent on the droplet-droplet interactions.
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Affiliation(s)
- H Guo
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA
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34
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Duff N, Lacks DJ. Shear-induced crystallization in jammed systems. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 75:031501. [PMID: 17500700 DOI: 10.1103/physreve.75.031501] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Revised: 11/17/2006] [Indexed: 05/15/2023]
Abstract
Simulations are used to address the effects of oscillating shear strain on jammed systems composed of spherical particles. The simulations show that shear oscillations with amplitudes of more than a few percent lead to substantial crystallization of the system. To ensure that the conclusions are independent of the simulation methodology, a range of simulations are carried out that use both molecular dynamics and athermal dynamics methods, soft and hard potentials, potentials with and without attractive forces, and systems with and without surrounding walls. The extent of crystallization is monitored primarily by the Q(6) order parameter, but also in some simulations by the potential energy and the radial distribution function, and by direct visual inspection. A mechanism is proposed for shear-induced crystallization of jammed systems, based on fold catastrophes of the free-energy landscape.
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Affiliation(s)
- Nathan Duff
- Department of Chemical Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA
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35
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Chung B, Ramakrishnan S, Bandyopadhyay R, Liang D, Zukoski CF, Harden JL, Leheny RL. Microscopic dynamics of recovery in sheared depletion gels. PHYSICAL REVIEW LETTERS 2006; 96:228301. [PMID: 16803351 DOI: 10.1103/physrevlett.96.228301] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2005] [Indexed: 05/10/2023]
Abstract
We report x-ray photon correlation spectroscopy and diffusing wave spectroscopy studies of depletion gels formed from nanoscale silica colloids in solutions of nonabsorbing polymer following the cessation of shear. The two techniques provide a quantitatively coherent picture of the dynamics as ballistic or convective motion of colloidal clusters whose internal motion is arrested. While the dynamics possesses features characteristic of nonergodic soft solids, including a relaxation time that grows linearly with the time since shear, comparison with behavior of quenched supercooled liquids indicates that this evolution is not directly related to traditional aging phenomena in glasses.
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Affiliation(s)
- B Chung
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
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