{"title":"Viscous solvent effect on fracture of predamaged double-network gels examined by pre-notch and post-notch crack tests","authors":"Yong Zheng , Jian Ping Gong","doi":"10.1016/j.jmps.2024.105926","DOIUrl":null,"url":null,"abstract":"<div><div>Double network (DN) gels, composed of two interpenetrating polymer networks with contrasting properties, garnered considerable attention since their invention due to large resistances to crack initiation and propagation. This study systematically investigates the effect of viscous solvent on the fracture behavior of DN gels through pre-notch and post-notch crack tests conducted on both water-swollen and ethylene glycol (EG)-swollen DN gels. Fracture energy analysis reveals that the chain dynamics changed by viscous solvent EG would remarkably reduce the two individual fracture energy contributions Γ<sub>bulk</sub> and Γ<sub>tip</sub>, originating from the energy dissipation in the bulk and in the crack tip vicinity, respectively. Furthermore, we observed that chain dynamics influence crack propagation behaviors and the molecular orientation of network strands ahead of crack tips in DN gels. Examination of the retardation patterns ahead of propagating crack tips allows for the analysis of the molecular orientation of network strands. Unusual butterfly-like retardation patterns were observed for the EG-swollen DN gels, in stark contrast to the conventional damage zone patterns seen in water-swollen DN gels. This suggests that the slowed chain dynamics induced by the viscous solvent EG lead to significant viscoelastic mechanical responses ahead of crack tips, which governs the stress/strain fields at the crack tip. This study offers valuable insights into the underlying toughening mechanism of DN gels, particularly regarding the effect of polymer chain dynamics. The experimental analysis, integrating findings on fracture energy contributions, crack propagation behaviors, and retardation observations from both pre-notch and post-notch crack tests, could be applied to characterize other soft materials with diverse toughening mechanisms, thereby aiding in the design and application of future soft materials.</div></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":null,"pages":null},"PeriodicalIF":5.0000,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of The Mechanics and Physics of Solids","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0022509624003922","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Double network (DN) gels, composed of two interpenetrating polymer networks with contrasting properties, garnered considerable attention since their invention due to large resistances to crack initiation and propagation. This study systematically investigates the effect of viscous solvent on the fracture behavior of DN gels through pre-notch and post-notch crack tests conducted on both water-swollen and ethylene glycol (EG)-swollen DN gels. Fracture energy analysis reveals that the chain dynamics changed by viscous solvent EG would remarkably reduce the two individual fracture energy contributions Γbulk and Γtip, originating from the energy dissipation in the bulk and in the crack tip vicinity, respectively. Furthermore, we observed that chain dynamics influence crack propagation behaviors and the molecular orientation of network strands ahead of crack tips in DN gels. Examination of the retardation patterns ahead of propagating crack tips allows for the analysis of the molecular orientation of network strands. Unusual butterfly-like retardation patterns were observed for the EG-swollen DN gels, in stark contrast to the conventional damage zone patterns seen in water-swollen DN gels. This suggests that the slowed chain dynamics induced by the viscous solvent EG lead to significant viscoelastic mechanical responses ahead of crack tips, which governs the stress/strain fields at the crack tip. This study offers valuable insights into the underlying toughening mechanism of DN gels, particularly regarding the effect of polymer chain dynamics. The experimental analysis, integrating findings on fracture energy contributions, crack propagation behaviors, and retardation observations from both pre-notch and post-notch crack tests, could be applied to characterize other soft materials with diverse toughening mechanisms, thereby aiding in the design and application of future soft materials.
期刊介绍：
The aim of Journal of The Mechanics and Physics of Solids is to publish research of the highest quality and of lasting significance on the mechanics of solids. The scope is broad, from fundamental concepts in mechanics to the analysis of novel phenomena and applications. Solids are interpreted broadly to include both hard and soft materials as well as natural and synthetic structures. The approach can be theoretical, experimental or computational.This research activity sits within engineering science and the allied areas of applied mathematics, materials science, bio-mechanics, applied physics, and geophysics.
The Journal was founded in 1952 by Rodney Hill, who was its Editor-in-Chief until 1968. The topics of interest to the Journal evolve with developments in the subject but its basic ethos remains the same: to publish research of the highest quality relating to the mechanics of solids. Thus, emphasis is placed on the development of fundamental concepts of mechanics and novel applications of these concepts based on theoretical, experimental or computational approaches, drawing upon the various branches of engineering science and the allied areas within applied mathematics, materials science, structural engineering, applied physics, and geophysics.
The main purpose of the Journal is to foster scientific understanding of the processes of deformation and mechanical failure of all solid materials, both technological and natural, and the connections between these processes and their underlying physical mechanisms. In this sense, the content of the Journal should reflect the current state of the discipline in analysis, experimental observation, and numerical simulation. In the interest of achieving this goal, authors are encouraged to consider the significance of their contributions for the field of mechanics and the implications of their results, in addition to describing the details of their work.
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