A Coupled Thermodynamic Model for Transport Properties of Thin Films during Physical Aging

Hu, Hongjiu; Fan, Xiaoming; He, Yaolong

doi:10.3390/polym11030387

Cited by 5 publications

(5 citation statements)

References 46 publications

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“…It is an inherent property that is temporary and variable, where the polymer′s physical state and density significantly affect its value. The mechanism of reducing the extra free volume of the membrane can be linked to physical aging, arising from the contraction of the lattice and the migration and diffusion of the free volume from the inside of the membrane to the surface [ 32 ]. These explanations reveal the importance of the polymer structure in the kinetics of the drug release.…”

Section: Resultsmentioning

confidence: 99%

Viscoelastic Behavior of Drug-Loaded Polyurethane

et al. 2021

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Drug-eluting stents are desirable platforms for local medicine delivery. However, the incorporation of drugs into polymers can influence the mechanical and physicochemical properties of said matrix, which is a topic that is still poorly understood. In fact, this is more noticeable since the apposition is most often accompanied by mechanical stresses on the polymer coating, which can induce therapeutic failure that can result in death. It is therefore necessary to better understand their behavior by examining their properties in conditions such as those in living beings. We studied polyurethane drug carriers made in-house. Diclofenac epolamine was chosen as a model hydrophilic medicine. We used thermal measurements (DMTA) and tensile tests. The aim was to establish the influence of the loading and release of the drug on the physicochemical properties of this polymer in the presence of a stagnant or circulating fluid medium, phosphate-buffered saline (PBS). For the two PU/drug loadings studied, the effect of the initial drug load was more marked. The free volume fraction and the number of pores in the samples increased with the increasing percent of the drug and with release time. The kinetic profiles were accelerated with the loading ratio and with the presence of flow. Young′s modulus and ultimate stress were not significantly influenced by the release time. A relevant relationship between the tensile properties and the viscoelastic behavior of the samples was developed. Our results have implications for optimizing the performance of drug coatings for stents.

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Section: Resultsmentioning

confidence: 99%

Viscoelastic Behavior of Drug-Loaded Polyurethane

et al. 2021

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“…For an ASSB with time-aging SPE, as the essence of the time-aging of SPE is the process of free volume escaping outward [ 18 , 19 , 20 ], it can be expected that the time-aging would result in not only the decline of ion migration in the electrolyte but also the decrease in bulk volume of SPE because of the polymer densification induced by the aging process. As a result, changes in cutoff time and contact area caused by aging may affect the electrochemical performance of the ASSB.…”

Section: Methodsmentioning

confidence: 99%

“…Tian and Qi have found that contact loss formed during cell fabrication resulted in degradation of the battery performance [ 17 ]. The imperfect contact may be worsened during the physical aging process, where excess free volumes progressively escape from the polymer-lithium salt system due to a naturally occurring densification of the polymer structure [ 18 , 19 , 20 ]. Although the physical aging-induced SPE volume decrease may reduce the contact area of electrolyte/electrode interface and correspond to the electrical properties, up to now, no previous studies have paid close attention to the effect of time-aging on the interfacial contact between the solid electrolyte and electrode.…”

Section: Introductionmentioning

confidence: 99%

Modeling and Simulation in Capacity Degradation and Control of All-Solid-State Lithium Battery Based on Time-Aging Polymer Electrolyte

Fang

Fan

et al. 2021

Polymers

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The prediction of electrochemical performance is the basis for long-term service of all-solid-state-battery (ASSB) regarding the time-aging of solid polymer electrolytes. To get insight into the influence mechanism of electrolyte aging on cell fading, we have established a continuum model for quantitatively analyzing the capacity evolution of the lithium battery during the time-aging process. The simulations have unveiled the phenomenon of electrolyte-aging-induced capacity degradation. The effects of discharge rate, operating temperature, and lithium-salt concentration in the electrolyte, as well as the electrolyte thickness, have also been explored in detail. The results have shown that capacity loss of ASSB is controlled by the decrease in the contact area of the electrolyte/electrode interface at the initial aging stage and is subsequently dominated by the mobilities of lithium-ion across the aging electrolyte. Moreover, reducing the discharge rate or increasing the operating temperature can weaken this cell deterioration. Besides, the thinner electrolyte film with acceptable lithium salt content benefits the durability of the ASSB. It has also been found that the negative effect of the aging electrolytes can be relieved if the electrolyte conductivity is kept being above a critical value under the storage and using conditions.

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“…However, due to a rapid solvent volatilization or the steep cooling from melting temperature in the process of solidification, all of above amorphous or semi-crystalline polymers are inevitably in the high nonequilibrium state. The electrolyte material with excess thermodynamic quantities would spontaneously evolve with time to equilibrium, which is referred to as physical aging [ 34 , 35 ], leading to pronounced variations in the microstructure and also macroscopic properties under storage and servicing operations. Accordingly, the physical aging process of SPEs and its effects on ASSB performance is a pivotal scientific problem to be solved.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Integrity Degradation and Control of All-Solid-State Lithium Battery with Physical Aging Poly (Vinyl Alcohol)-Based Electrolyte

Zhou

et al. 2020

Polymers

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Ensuring the material durability of an electrolyte is a prerequisite for the long-term service of all-solid-state batteries (ASSBs). Herein, to investigate the mechanical integrity of a solid polymer electrolyte (SPE) in an ASSB upon electrochemical operation, we have implemented a sequence of quasi-static uniaxial tension and stress relaxation tests on a lithium perchlorate-doped poly (vinyl alcohol) electrolyte, and then discussed the viscoelastic behavior as well as the strength of SPE film during the physical aging process. On this basis, a continuum electrochemical-mechanical model is established to evaluate the stress evolution and mechanical detriment of aging electrolytes in an ASSB at a discharge state. It is found that the measured elastic modulus, yield stress, and characteristic relaxation time boost with the prolonged aging time. Meanwhile, the shape factor for the classical time-decay equation and the tensile rupture strength are independent of the aging history. Accordingly, the momentary relaxation modulus can be predicted in terms of the time–aging time superposition principle. Furthermore, the peak tensile stress in SPE film for the full discharged ASSB will significantly increase as the aging proceeds due to the stiffening of the electrolyte composite. It may result in the structure failure of the cell system. However, this negative effect can be suppressed by the suggested method, which is given by a 2D map under different lithiation rates and relative thicknesses of the electrolyte. These findings can advance the knowledge of SPE degradation and provide insights into reliable all-solid-state electrochemical device applications.

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A Coupled Thermodynamic Model for Transport Properties of Thin Films during Physical Aging

Cited by 5 publications

References 46 publications

Viscoelastic Behavior of Drug-Loaded Polyurethane

Viscoelastic Behavior of Drug-Loaded Polyurethane

Modeling and Simulation in Capacity Degradation and Control of All-Solid-State Lithium Battery Based on Time-Aging Polymer Electrolyte

Mechanical Integrity Degradation and Control of All-Solid-State Lithium Battery with Physical Aging Poly (Vinyl Alcohol)-Based Electrolyte

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