Abstract Double-network hydrogels (DN gels) with excellent mechanical properties have great application prospects as an innovative soft material. The Mullins effect originally discovered in rubber materials is also observed in this material. The network alteration theories have achieved many successes in capturing this stress-softening behavior of DN gels and exploring the underlying damage mechanisms. In this paper, we develop a network alteration theory to account for the softening behaviors of DN gels under both uniaxial tension and pure shear and simultaneously explore more about the damage origins. The advantage of the use of worm-like chain model for DN gels is illustrated. New network evolutions of the network alteration parameters are further developed on a basis of an existing network alteration theory. The model predictions of the new model for the experimental results of DN gels under both uniaxial tension and pure shear are compared with those of the old one. The results demonstrate that the new model is more physically sound and offers much better predictive capabilities. It is found that the dangling chains, chain disentanglements and the degradation of the interactions between the two networks during deformation play significant roles in the Mullins softening of DN gels. This paper gives new insights into the microdamage origins of DN gels and significantly improve the network alteration theory for DN gels.

中文翻译：

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双网络水凝胶Mullins软化的网络改变理论的发展

摘要 具有优异力学性能的双网络水凝胶（DN gels）作为一种创新的软材料具有广阔的应用前景。在这种材料中也观察到最初在橡胶材料中发现的穆林斯效应。网络改变理论在捕捉 DN 凝胶的这种应力软化行为和探索潜在的损伤机制方面取得了许多成功。在本文中，我们开发了一种网络改变理论来解释 DN 凝胶在单轴拉伸和纯剪切下的软化行为，同时探索更多关于损伤起源的信息。说明了使用蠕虫状链模型对 DN 凝胶的优势。网络变更参数的新网络演进是在现有网络变更理论的基础上进一步发展的。将新模型对 DN 凝胶在单轴拉伸和纯剪切下的实验结果的模型预测与旧模型进行了比较。结果表明，新模型在物理上更可靠，并提供了更好的预测能力。发现悬链、链解缠结和变形期间两个网络之间相互作用的退化在DN凝胶的Mullins软化中起重要作用。本文对DN凝胶的微损伤起源提供了新的见解，并显着改进了DN凝胶的网络改变理论。结果表明，新模型在物理上更可靠，并提供了更好的预测能力。发现悬链、链解缠结和变形期间两个网络之间相互作用的退化在DN凝胶的Mullins软化中起重要作用。本文对DN凝胶的微损伤起源提供了新的见解，并显着改进了DN凝胶的网络改变理论。结果表明，新模型在物理上更可靠，并提供了更好的预测能力。发现悬链、链解缠结和变形期间两个网络之间相互作用的退化在DN凝胶的Mullins软化中起重要作用。本文对DN凝胶的微损伤起源提供了新的见解，并显着改进了DN凝胶的网络改变理论。