An Extreme Toughening Mechanism for Soft Materials

• Main Authors: Lin, Shaoting, Londono, Camilo Duque, Zheng, Dongchang, Zhao, Xuanhe
• Format: Journal Article
• Language: English
• Published: 12-02-2022
• Subjects: Physics - Applied Physics; Physics - Soft Condensed Matter
• DOI: 10.48550/arxiv.2202.06186

Soft yet tough materials are ubiquitous in nature and everyday life. The
ratio between fracture toughness and intrinsic fracture energy of a soft
material defines its toughness enhancement. Soft materials' toughness
enhancement has been long attributed to their bulk stress-stretch hysteresis
induced by dissipation mechanisms such as Mullins effect and viscoelasticity.
With a combination of experiments and theory, here we show that the bulk
dissipation mechanisms significantly underestimate the toughness enhancement of
soft tough materials. We propose a new mechanism and scaling law to account for
the extreme toughening of diverse soft materials. We show that the toughness
enhancement of soft materials relies on both bulk hysteric dissipation, and
near-crack dissipation due to mechanisms such as polymer-chain entanglement.
Unlike the bulk hysteric dissipation, the near-crack dissipation does not
necessarily induce large stress-stretch hysteresis of the bulk material. The
extreme toughening mechanism can be universally applied to various soft tough
materials, ranging from double-network hydrogels, interpenetrating-network
hydrogels, entangled-network hydrogels and slide-ring hydrogels, to unfilled
and filled rubbers.