A statistical mechanics framework for polymer chain scission, based on the concepts of distorted bond potential and asymptotic matching

Mulderrig, Jason; Talamini, Brandon; Bouklas, Nikolaos

doi:10.1016/j.jmps.2023.105244

Cited by 15 publications

(3 citation statements)

References 122 publications

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“…The task of relating chain tension to nominal strain imposed on the network is impossible to carry out without detailed information on the network structure. Discussion of other treatments, ,,− often single-chain based, is beyond the scope of the present work. Through eq , illustrated in Figure , our modeling aims to describe overall network response in terms of bond tension buildup toward values for dissociation.…”

Section: Elastomersmentioning

confidence: 99%

Fracture Behavior of Polymers in Plastic and Elastomeric States

Wang,

Fan,

Gupta

et al. 2024

Macromolecules

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Our recent studies departed from the conventional description of polymer fracture behavior while maintaining consistency with the principles of material mechanics including linear elastic fracture mechanics (LEFM). In traditional fracture mechanics of brittle materials, crack resistance is quantified in terms of toughness G c , which represents the critical energy release per unit fracture surface area. This perspective suggests that high G c involved high energy dissipation. A new perspective has surfaced, proposing a fundamental yet underexplored, seemingly universal fracture mechanism and explaining the origin of high G c within an alternative framework. According to this view, for unfilled plastics and elastomers, f racture initiates when local tensile stress surpasses the polymer's f racture strength σ F(inh) , and high toughness is a consequence of high fracture strength. Remarkably, for polymers in both plastic and elastomeric states, their inherent strength σ F(inh) appears to be of a comparable magnitude to the nominal tensile strength σ b . Spatial−temporal resolved polarized optical microscopic (str-POM) measurements have started to provide insight into the fracture mechanism and unveil a concealed length scale (P) representing the size of a stress saturation zone at the crack tip. The two-parameter theoretical framework shows (a) toughness of brittle plastics increases quadratically with its strength σ F(inh) and linearly with P and (b) elastomers exhibit significantly greater toughness and higher tensile strength at lower temperatures due to the increased stability of covalent bonds given the lower thermal energy and plausible frictional effect on bond vibration frequency. Embracing this emerging paradigm where we recognize polymer strength to be time-dependent, we anticipate new advancements in polymer design and a clearer understanding of the fracture behavior of polymeric materials.

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Section: Elastomersmentioning

confidence: 99%

Fracture Behavior of Polymers in Plastic and Elastomeric States

Wang,

Fan,

Gupta

et al. 2024

Macromolecules

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“…Building on this theory, many studies have utilized the statistical chain models and have characterized chain scission at the microscale. [76][77][78] Notably, a fracture initiation criterion was introduced based on the critical energy needed to rupture molecular bonds. 79 Building on this foundation, the eight-chain network model was integrated into the phase field framework, 80 positing that fracture propagation in polymers is primarily driven by internal molecular distortional energy.…”

Section: Introductionmentioning

confidence: 99%

“…In the realm of fracture studies considering microscale properties, pioneering work by Lake and Thomas 26 related the critical energy release rate of rubber materials to the binding energy between monomer units. Building on this theory, many studies have utilized the statistical chain models and have characterized chain scission at the microscale 76–78 . Notably, a fracture initiation criterion was introduced based on the critical energy needed to rupture molecular bonds 79 .…”

Section: Introductionmentioning

confidence: 99%

A multiscale anisotropic polymer network model coupled with phase field fracture

Arunachala,

Abrari Vajari,

Neuner

et al. 2024

Numerical Meth Engineering

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The study of polymers has continued to gain substantial attention due to their expanding range of applications, spanning essential engineering fields to emerging domains like stretchable electronics, soft robotics, and implantable sensors. These materials exhibit remarkable properties, primarily stemming from their intricate polymer chain network, which, in turn, increases the complexity of precisely modeling their behavior. Especially for modeling elastomers and their fracture behavior, accurately accounting for the deformations of the polymer chains is vital for predicting the rupture in highly stretched chains. Despite the importance, many robust multiscale continuum frameworks for modeling elastomer fracture tend to simplify network deformations by assuming uniform behavior among chains in all directions. Recognizing this limitation, our study proposes a multiscale fracture model that accounts for the anisotropic nature of elastomer network responses. At the microscale, damage in the chains is assumed to be driven by both the chain's entropy and the internal energy due to molecular bond distortions. In order to bridge the stretching in the chains to the macroscale deformation, we employ the maximal advance path constraint network model, inherently accommodating anisotropic network responses. As a result, chains oriented differently can be predicted to exhibit varying stretch and, consequently, different damage levels. To drive macroscale fracture based on damages in these chains, we utilize the micromorphic regularization theory, which involves the introduction of dual local‐global damage variables at the macroscale. The macroscale local damage variable is obtained through the homogenization of the chain damage values, resulting in the prediction of an isotropic material response. The macroscale global damage variable is subjected to nonlocal effects and boundary conditions in a thermodynamically consistent phase field continuum formulation. Moreover, the total dissipation in the system is considered to be mainly due to the breaking of the molecular bonds at the microscale. To validate our model, we employ the double‐edge notched tensile test as a benchmark, comparing simulation predictions with existing experimental data. Additionally, to enhance our understanding of the fracturing process, we conduct uniaxial tensile experiments on a square film made up of polydimethylsiloxane (PDMS) rubber embedded with a hole and notches and then compare our simulation predictions with the experimental observations. Furthermore, we visualize the evolution of stretch and damage values in chains oriented along different directions to assess the predictive capacity of the model. The results are also compared with another existing model to evaluate the utility of our model in accurately simulating the fracture behavior of rubber‐like materials.

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Mechanochemical Recycling of Highly Cross‐Linked Thermosets: Economic‐Friendly and Pollution‐Free

Shi,

Wang

2024

Adv Funct Materials

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Highly cross‐linked thermosets possess superior mechanical properties and have found broad applications in engineering. However, due to the dense cross‐links, it is extremely challenging to recycle highly cross‐linked thermosets, causing serious environmental and sustainable concerns. Herein, a mechanochemical recycling strategy is proposed for highly cross‐linked thermosets via the synergy of mechanics and chemistry, which is economic‐friendly and pollution‐free. To demonstrate the strategy, diverse metal‐complex catalysts are employed to recycle highly cross‐linked epoxy incorporated with switchable covalent bonds at certain pressure, temperature, and time. The effect of each catalyst on the efficiency of recycling is evaluated, which follows a descending order: Zr4+ > Mn3+ > Co3+ > Fe3+ > Co2+ > Zn2+ > OTi4+ > Ni2+. The results show that the mechanical properties, such as Young's modulus, ultimate strength, peak strain, impact strength, flexural modulus and strength, as well as thermal stability of the recycled samples are almost identical to those of as‐synthesized ones. The effectiveness of the method is further confirmed via micromorphology.

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A statistical mechanics framework for polymer chain scission, based on the concepts of distorted bond potential and asymptotic matching

Cited by 15 publications

References 122 publications

Fracture Behavior of Polymers in Plastic and Elastomeric States

Fracture Behavior of Polymers in Plastic and Elastomeric States

A multiscale anisotropic polymer network model coupled with phase field fracture

Mechanochemical Recycling of Highly Cross‐Linked Thermosets: Economic‐Friendly and Pollution‐Free

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