Viscous solvent effect on fracture of predamaged double-network gels examined by pre-notch and post-notch crack tests

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids Pub Date : 2024-10-29 DOI:10.1016/j.jmps.2024.105926

Yong Zheng , Jian Ping Gong

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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 Γ_bulk and Γ_tip, 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.

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通过缺口前和缺口后裂纹试验研究粘性溶剂对预破坏双网凝胶断裂的影响

双层网络（DN）凝胶由两种性质截然不同的互穿聚合物网络组成，自发明以来就因其对裂纹萌生和扩展的巨大阻力而备受关注。本研究通过对水溶胀和乙二醇（EG）溶胀的 DN 凝胶进行缺口前和缺口后裂纹测试，系统地研究了粘性溶剂对 DN 凝胶断裂行为的影响。断裂能分析表明，粘性溶剂 EG 所改变的链动力学会显著降低两个单独的断裂能贡献Γbulk 和Γtip，这两个断裂能贡献分别来自于体积和裂纹尖端附近的能量耗散。此外，我们还观察到链动力学会影响 DN 凝胶中裂纹尖端前的裂纹扩展行为和网络链的分子取向。通过研究裂纹尖端前方的延迟模式，可以分析网络链的分子取向。在 EG 膨胀的 DN 凝胶中观察到了不寻常的蝴蝶状延迟模式，这与水膨胀 DN 凝胶中的传统损伤区模式形成了鲜明对比。这表明，粘性溶剂 EG 引起的链动力学减缓导致了裂纹尖端前的显著粘弹性机械响应，从而控制了裂纹尖端的应力/应变场。这项研究为了解 DN 凝胶的基本增韧机制，特别是聚合物链动力学的影响提供了宝贵的见解。实验分析综合了缺口前和缺口后裂纹测试中的断裂能量贡献、裂纹扩展行为和延缓观察结果，可用于表征具有不同增韧机制的其他软材料，从而有助于未来软材料的设计和应用。

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来源期刊

Journal of The Mechanics and Physics of Solids 物理-材料科学：综合

CiteScore

9.80

自引率

9.40%

发文量

276

审稿时长

52 days

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.