Necking of double-network gels: Constitutive modeling with microstructural insight

Morovati, Vahid; Saadat, Mohammad Ali; Dargazany, Roozbeh

doi:10.1103/physreve.102.062501

Cited by 25 publications

(10 citation statements)

References 58 publications

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“…Second, the assumption that the distribution of chains in the first network swell isotropically as the filler network is introduced could be invalid for this large degree of swelling. Third, the breaking of chains in the first network could induce a more complicated damage mechanism that involves the filler networks (Morovati et al, 2020). Fourth, the discrepancy could be related to transfer reactions that create additional crosslinks during synthesis (Ducrot et al, 2014).…”

Section: Rate-independent Irreversible Breakingmentioning

confidence: 99%

“…This approach has been successfully applied when modeling the irreversible damage or fracture of polymer networks (Talamini et al, 2018;Tehrani and Sarvestani, 2017;Li and Bouklas, 2020). Additionally, irreversible breaking has been incorporated into many models for multinetwork elastomers and gels (Lavoie et al, 2016;Bacca et al, 2017;Morovati and Dargazany, 2019;Lavoie et al, 2019b;Zhong et al, 2020), sometimes addressing a particular phenomenon such as necking instability (Zhao, 2012;Vernerey et al, 2018;Morovati et al, 2020). Another portion of these physicallybased constitutive models tends to be specialized for transient networks enabled by highly dynamic bonds.…”

Section: Introductionmentioning

confidence: 99%

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Chain breaking in the statistical mechanical constitutive theory of polymer networks

Buche,

Silberstein

2021

Preprint

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Elastomers are used in a wide range of applications because of their large strain to failure, low density, and tailorable stiffness and toughness. The mechanical behavior of elastomers derives mainly from the entropic elasticity of the underlying network of polymer chains. Elastomers under large deformation experience bonds breaking within the backbone chains that constitute the polymer network. This breaking of chains damages the network, can lead to material failure, and can be utilized as an energy dissipation mechanism. In the case of reversible bonds, broken chains may reform and heal the damage in the network. If the reversible bonds are dynamic, chains constantly break and reform and create a transient network. A fundamental constitutive theory is developed to model the mechanics of these polymer networks. A statistical mechanical derivation is conducted to yield a framework that takes in an arbitrary single-chain model (a Hamiltonian) and outputs the following: the single-chain mechanical response, the breaking and reforming kinetics, the equilibrium distribution of chains in the network, and the partial differential equations governing the deformationcoupled network evolution. This statistical mechanical framework is then brought into the continuum scale by using macroscopic thermodynamic constitutive theory to obtain a constitutive relation for the Cauchy stress. The potential-supplemented freely jointed chain (uFJC) model is introduced, and a parametric study of its mechanical response and breaking kinetics is provided. This single-chain model is then implemented within the constitutive framework, which we specialize and apply in two exemplary cases: the mechanical response and irreversible breakdown of a multinetwork elastomer, and the mechanical response of a dual crosslink gel. After providing a parametric study of the general constitutive model, we apply it to a hydrogel with reversible metal-coordination crosslinks. In several cases, we find that the breakdown of the network causes secondary physical mechanisms to become important and inhibit the accuracy of our model. We then discuss these mechanisms and indicate how our existing framework can be adjusted to incorporate them in the future.

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Section: Rate-independent Irreversible Breakingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chain breaking in the statistical mechanical constitutive theory of polymer networks

Buche,

Silberstein

2021

Preprint

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“…Several constitutive models have been put forward that provide a connection between the evolution of damage and the global stress response of a DN. − These models can be fitted to experimental data and are also used in the interpretation of the output of mechanophores, i.e., molecular probes that report on the rupture of bonds locally . Some of these models, − referred to as statistical damage mechanics models, predict the global response from the evolution of chain-stretch with respect to an initial stretch distribution, assuming affine deformation and breaking of overstretched chains. As a result, the global mechanical response of a DN predicted by these models is the sum of the responses of two (or more) independent and affinely deforming networks.…”

Section: Introductionmentioning

confidence: 99%

Sharing the Load: Stress Redistribution Governs Fracture of Polymer Double Networks

et al. 2021

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The stress response of polymer double networks depends not only on the properties of the constituent networks but also on the interactions arising between them. Here, we demonstrate, via coarse-grained simulations, that both their global stress response and their microscopic fracture mechanics are governed by load sharing through these internetwork interactions. By comparing our results with affine predictions, where stress redistribution is by definition homogeneous, we show that stress redistribution is highly inhomogeneous. In particular, the affine prediction overestimates the fraction of broken chains by almost an order of magnitude. Furthermore, homogeneous stress distribution predicts a single fracture process, while in our simulations, fracture of sacrificial chains takes place in two steps governed by load sharing within a network and between networks, respectively. Our results thus provide a detailed microscopic picture of how inhomogeneous stress redistribution after rupture of chains governs the fracture of polymer double networks.

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“…Several constitutive models have been put forward that provide a connection between the evolution of damage and the global stress response of a DN. [23][24][25][26][27] These models can be fitted to experimental data and are also used in the interpretation of the output of mechanophores, i.e. molecular probes that report on the rupture of bonds locally.…”

Section: Introductionmentioning

confidence: 99%

“…molecular probes that report on the rupture of bonds locally. 18 Some of these models, [25][26][27] referred to as statistical damage mechanics models, predict the global response from the evolution of chain-stretch with respect to an initial stretch distribution, assuming affine deformation and breaking of over-stretched chains. As a result, the global mechanical response of a DN predicted by these models is the sum of the response of two (or more) independent and affinely deforming networks.…”

Section: Introductionmentioning

confidence: 99%

Sharing the load: stress redistribution governs fracture of polymer double networks

Tauber,

Rovigatti,

Dussi

et al. 2021

Preprint

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The stress response of polymer double networks depends not only on the properties of the constituent networks, but also on the interactions arising between them. Here we demonstrate, via coarse-grained simulations, that both their global stress response and their microscopic fracture mechanics are governed by load sharing through these inter-network interactions. By comparing our results with affine predictions, where stress redistribution is by definition homogeneous, we show that stress redistribution is highly inhomogeneous. In particular, the affine prediction overestimates the fraction of broken chains by almost an order of magnitude. Furthermore, homogeneous stress distribution predicts a single fracture process, while in our simulations fracture of sacrificial chains takes place in two steps governed by load sharing within a network

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Necking of double-network gels: Constitutive modeling with microstructural insight

Cited by 25 publications

References 58 publications

Chain breaking in the statistical mechanical constitutive theory of polymer networks

Chain breaking in the statistical mechanical constitutive theory of polymer networks

Sharing the Load: Stress Redistribution Governs Fracture of Polymer Double Networks

Sharing the load: stress redistribution governs fracture of polymer double networks

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