Micro-mechanical modeling of the stress softening in double-network hydrogels

Morovati, Vahid; Dargazany, Roozbeh

doi:10.1016/j.ijsolstr.2019.01.002

Cited by 52 publications

(8 citation statements)

References 45 publications

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“…[ 16 ] In the mechanical strength studies, some constitutive models for IPN hydrogels have been proposed such as Gent hyperelastic model, [ 39 ] Arruda‐Boyce eight‐chain model, [ 40 ] micromechanically based constitutive model, [ 41 ] phenomenological model, [ 42 ] and micromechanical model. [ 43 ] These models in a broad framework, it has been stated that the short chain mesh structures in these hydrogels exhibit an easy breaking behavior under low deformation force, while the long mesh structures carry and spread the force. Here, the fine balance between the proper brittleness of the short network and the ductility of the long network is very important.…”

Section: Introductionmentioning

confidence: 99%

Preparation of poly(acrylamide‐co‐2‐acrylamido‐2‐methylpropan sulfonic acid)‐g‐Carboxymethyl cellulose/Titanium dioxide hydrogels and modeling of their swelling capacity and mechanic strength behaviors by response surface method technique

Boztepe

Daskin

Erdoğan

et al. 2021

Polymer Engineering & Sci

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It is very important that new generation, unique, high mechanical strength, and biocompatible hydrogel composites are developed due to their potential to be used as biomaterials in the biomedical field. Modeling of the swelling capacity and mechanical strength behavior of hydrogels is a domain of steadily increasing academic and industrial importance. These behaviors are difficult to model accurately due to hydrogels show very complex behavior depending on the content. In this study, a series of poly(acrylamide‐co‐2‐acrylamido‐2‐methylpropan sulfonic acid)‐g‐carboxymethyl cellulose/TiO2 (poly(AAm‐co‐AMPS)‐g‐CMC/TiO2) superabsorbent hydrogel composites were prepared by free‐radical graft copolymerization in aqueous solution. Structural and surface morphology characterizations were conducted by using Fourier‐transform infrared spectroscopy and scanning electron microscope analysis techniques. For modeling the equilibrium swelling capacity and fracture strength behaviors of hydrogels, the composition parameters (such as mole ratio of AMPS/AAm, wt% of CMC, and wt% of TiO2) was proposed by response surface method (RSM) Design Expert‐10 software. Statistical parameters showed that the RSM model has good performance in modeling the swelling capacity and mechanic fracture strength behaviors of poly(AAm‐co‐AMPS)‐g‐CMC/TiO2 hydrogel composites. According to the RSM model results, the maximum swelling capacity and fracture strength values were calculated as 270.39 g water/g polymer and 159.23 kPa, respectively.

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Section: Introductionmentioning

confidence: 99%

Preparation of poly(acrylamide‐co‐2‐acrylamido‐2‐methylpropan sulfonic acid)‐g‐Carboxymethyl cellulose/Titanium dioxide hydrogels and modeling of their swelling capacity and mechanic strength behaviors by response surface method technique

Boztepe

Daskin

Erdoğan

et al. 2021

Polymer Engineering & Sci

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“…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%

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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“…All of the aforementioned constitutive models were only compared to uniaxial tests of double network hydrogels . For example, the damage evolution in the work of Wang and Hong was compared with uniaxial tension and compression .…”

Section: Introductionmentioning

confidence: 99%

A Multiaxial Theory of Double Network Hydrogels

et al. 2019

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The incorporation of a stiff and brittle phase into a soft and flexible polymer network makes double network hydrogels remarkably tougher than the conventional one. It also induces a stress softening in cyclic loading, which is seemingly identical to that of filled rubbers. Therefore, material models proposed for double network hydrogel are mostly based on continuum damage theories of filled elastomers. However, recent experimental studies clearly distinguish double network hydrogels from filled elastomers by the damage cross-effect in multiaxial deformation. In this paper, a micromechanical model for double network hydrogels under multiaxial deformation is proposed on the basis of the analytical network-averaging concept. Accordingly, the directional fracture of the first network results from cumulative damage in all directions. Furthermore, the strong interpenetration of the two networks is taken into account. The proposed analytical model includes very few physically motivated material constants and demonstrates excellent agreement with comprehensive experimental data of double network hydrogels under multiaxial loading conditions.

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Micro-mechanical modeling of the stress softening in double-network hydrogels

Cited by 52 publications

References 45 publications

Preparation of poly(acrylamide‐co‐2‐acrylamido‐2‐methylpropan sulfonic acid)‐g‐Carboxymethyl cellulose/Titanium dioxide hydrogels and modeling of their swelling capacity and mechanic strength behaviors by response surface method technique

Preparation of poly(acrylamide‐co‐2‐acrylamido‐2‐methylpropan sulfonic acid)‐g‐Carboxymethyl cellulose/Titanium dioxide hydrogels and modeling of their swelling capacity and mechanic strength behaviors by response surface method technique

Chain breaking in the statistical mechanical constitutive theory of polymer networks

A Multiaxial Theory of Double Network Hydrogels

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