Fatigue-induced stress-softening in cross-linked multi-network elastomers: Effect of damage accumulation

Morovati, Vahid; Bahrololoumi, Amir; Dargazany, Roozbeh

doi:10.1016/j.ijplas.2021.102993

Cited by 40 publications

(18 citation statements)

References 53 publications

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“…CPEs with 500 nm particles (Figure B) exhibit a 23% reduction in average ionic conductivity after cycling (1.4 × 10 –7 ± 2.3 × 10 –8 vs 1.1 × 10 –7 ± 2.0 × 10 –8 S/cm, mean ± standard deviation), and the difference based on a one-sided t -test assuming unequal variances is statistically significant ( p = 0.042). Ionic conductivity has been observed to change based on tensile strain applied to PEO electrolytes, and irreversible chain detachment and decomposition have been identified as a major contributor to fatigue softening of elastomers . To our knowledge, similar studies have not been reported for cyclic mechanical compression of CPEs.…”

Section: Resultsmentioning

confidence: 95%

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Softening of PEO–LiTFSI/LLZTO Composite Polymer Electrolytes for Solid-State Batteries under Cyclic Compression

Yoon,

Mulay,

Baltazar

et al. 2023

ACS Appl. Energy Mater.

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Composite polymer electrolytes (CPEs) strike an effective balance between ionic conductivity and mechanical flexibility for lithium-ion solid-state batteries. Long-term performance, however, is limited by capacity fading after hundreds of charge and discharge cycles. The causes of performance degradation include multiple contributing factors such as dendrite formation, physicochemical changes in electrolytes, and structural remodeling of porous electrodes. Among the many factors that contribute to performance degradation, the effect of stress specifically on the composite electrolyte is not well understood. This study examines the mechanical changes in a poly(ethylene oxide) electrolyte with bis(trifluoromethane) sulfonimide. Two different sizes of Li6.4La3Zr1.4Ta0.6O12 particles (500 nm and 5 μm) are compared to evaluate the effect of the surface-to-volume ratio of the ion-conducting fillers within the composite. Cyclic compression was applied to mimic stress cycling in the electrolyte, which would be caused by asymmetric volume changes that occur during charging and discharging cycles. The electrolytes exhibited fatigue softening, whereby the compressive modulus gradually decreased with an increase in the number of cycles. When the electrolyte was tested for 500 cycles at 30% compressive strain, the compressive modulus of the electrolyte was reduced to approximately 80% of the modulus before cycling. While the extent of softening was similar regardless of particle size, CPEs with 500 nm particles exhibited a significant reduction in ionic conductivity after cyclic compression (1.4 × 10–7 ± 2.3 × 10–8 vs 1.1 × 10–7 ± 2.0 × 10–8 S/cm, mean ± standard deviation, n = 4), whereas there was no significant change in ionic conductivity for CPEs with 5 μm particles. These observations performed deliberately in the absence of charge–discharge cycles show that repetitive mechanical stresses can play a significant role in altering the performance of CPEs, thereby revealing another possible mechanism for performance degradation in all-solid-state batteries.

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Section: Resultsmentioning

confidence: 95%

“…Figure shows the accumulated effect of cyclic compression over the entire duration of 500 cycles for the two different particle sizes. The power-law dependence is consistent with Basquin’s law of fatigue and progressive stress softening that is also observed in elastomers …”

Section: Resultsmentioning

confidence: 99%

Softening of PEO–LiTFSI/LLZTO Composite Polymer Electrolytes for Solid-State Batteries under Cyclic Compression

Yoon,

Mulay,

Baltazar

et al. 2023

ACS Appl. Energy Mater.

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“…Under cyclic loading with increasing stresses and strains, elastomers show significant strain progressive softening (also known as the Mullins effect). − Characterizing these effects is especially relevant for materials that are subjected to multiple loads at large stretch amplitudes during their application. To do so, we performed two types of tests: repetitive cyclic loading at a low strain (10 cycles until 30% strain, Figure S14) and a cyclic test increasing the applied strain from 10 to 150% (Figure h–j).…”

Section: Results and Discussionmentioning

confidence: 99%

Self-Healing, Recyclable, and Degradable Castor Oil-Based Elastomers for Sustainable Soft Robotics

Cornellà

Tabrizian

Ferrentino

et al. 2023

ACS Sustainable Chem. Eng.

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Self-healing polymers render their life cycle more sustainable by recovering their properties upon healing. Intrinsic self-healing polymers can be recycled, which further reduces waste production. Yet, despite these intrinsic benefits, several sustainability issues remain largely neglected, including the use of fossilderived materials, hazardous chemicals, and material management at the end of its life. Herein, we report a series of castor oil-based self-healing elastomers that account for these challenges and show improved mechanical and self-healing capabilities compared to the other bio-based self-healing materials. Castor oil was functionalized using a simple, one-pot, solventless synthesis from renewable resources and cross-linked by Diels−Alder cycloaddition. They can be reprocessed and recycled or hydrolytically degraded at the end of their service life. The mechanical properties of the materials can be tuned (Young's modulus 0.5−20 MPa), with a fracture strain of up to 487%. A fracture strain of 100% could already be recovered after just 60 s at room temperature and 75% of the mechanical properties after just 24 h. By taking advantage of these properties, a soft pneumatic gripper has been developed, capable of healing autonomously, which is fully recyclable and degradable. Hence, we provide a sustainable alternative for soft robotic applications and for self-healing elastomers in general.

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“…78 Further, the shape of the peak stress in the stress-life curve suggests that the Rabinowitz-Beardmore model curve 9 may be general enough to apply to all polymers, not just thermoplastics, provided that the model is adapted to account for elastomeric phenomena such as cross-link density, polymer chain debonding, polymer chain rearrangement, and cross-link breakdown. 19,20 In broad terms, nano-to microstructurally small crack incubation may begin with the initial monotonic overload and transition stages, and continue until long crack propagation results in failure of the material 5,9,79 but, as Opp et al 7 have noted, these results may depend on the polymer being tested, and more studies assessing the effect of fatigue on the microstructure of the dielectric elastomer sensors is needed to determine the times needed to incubate and propagate the cracks.…”

Section: Discussionmentioning

confidence: 99%

“…19 The increases in the cross-link density and the elastic modulus generally allows for increased cycling of elastomers in comparison to thermoplastics; however, repeated cycling of elastomers can result in polymer chain debonding and rearrangements and breakdown of the cross-links resulting in failure of the elastomer. 20 Stretch sensors have many potential applications especially in the medical, pharmaceutical, and athletic fields, 10, and interest in the use of not only stretch sensors, but wearable technologies in general, has continued to grow because of their potential use in telehealth applications. 10,[46][47][48][49][50][51][52][53][54] Despite the increased interest in the use of stretch sensors, fatigue testing standards for stretch sensors do not currently exist, 10,55 leading to the employment of variable methodologies in fatigue studies of stretch sensors.…”

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confidence: 99%

Electromechanical Fatigue Properties of Dielectric Elastomer Capacitive Sensors Based on Plantarflexion of the Human Ankle Joint

et al. 2023

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Wearable stretch sensors have potential applications across many fields including medicine and sports, but the accuracy of the data produced by the sensors over repeated uses is largely unknown due to a paucity of high-cycle fatigue (HCF) studies on both the materials comprising the sensors and the signal produced by the sensors. To overcome these limitations, using human physiologically-based parameters, stretch sensors were subjected to quasi-static testing and HCF with simultaneous capture of the signal. The strain produced by the sensor was then compared to the strain produced by the testing instrument, and the results suggest that the outputs are strongly correlated under quasi-static conditions. However, this correlation deteriorates under fatigue conditions. Such deterioration may be the result of several factors, including a mismatch between the material response to fatiguing and the signal response to fatiguing. From a materials perspective, the shape of the stress-life curve for the polymers comprising the sensors conforms to the Rabinowitz-Beardmore model of polymer fatigue. Based on these results, consideration of the material properties of a stretch sensor are necessary to determine how accurate the output from the sensor will be for a given application.

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Fatigue-induced stress-softening in cross-linked multi-network elastomers: Effect of damage accumulation

Cited by 40 publications

References 53 publications

Softening of PEO–LiTFSI/LLZTO Composite Polymer Electrolytes for Solid-State Batteries under Cyclic Compression

Softening of PEO–LiTFSI/LLZTO Composite Polymer Electrolytes for Solid-State Batteries under Cyclic Compression

Self-Healing, Recyclable, and Degradable Castor Oil-Based Elastomers for Sustainable Soft Robotics

Electromechanical Fatigue Properties of Dielectric Elastomer Capacitive Sensors Based on Plantarflexion of the Human Ankle Joint

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