A toughening design for stretchable composite embedded with strain-rate stiffening elastomer

Abstract

Herein, a macroscopic double-network (DN) design for stretchable composite is proposed by embedding strain-rate stiffening elastomer (SSE) reinforced bars into the Ecoflex matrix. Due to the complementarity of mechanical properties between the soft-phase Ecoflex and hard-phase SSE as well as the strong interfacial bond strength, the Ecoflex/SSE composite achieves higher toughness and fatigue threshold than traditional single-network elastomers. Besides, based on the crack propagation characterization, strain-field evolution investigation, and finite element analysis, the fracture toughness of the Ecoflex/SSE composite is proved to be enhanced with the increase of the external strain rates. Interestingly, a sideway crack-arrest morphology is observed above 0.1 s−1, displaying a better anti-crack ability of the Ecoflex/SSE composite at the higher strain rate. As a fundamental research in macroscopic DN composite, the method in this work provides a new idea for the toughening optimization of the strain-rate stiffening material. With the high fracture toughness, fatigue threshold, and flexibility, the Ecoflex/SSE composite has broad application prospects in designing high-performance stretchable elastomers.