Toughening elastomers via microstructured thermoplastic fibers with sacrificial bonds and hidden lengths

TL;DR

This paper introduces a novel toughening strategy for elastomers by embedding microstructured thermoplastic fibers with sacrificial bonds and hidden lengths, significantly enhancing their stiffness and energy dissipation capabilities.

Contribution

It demonstrates a new method of toughening elastomers using microstructured fibers with sacrificial bonds, inspired by biological materials, fabricated via 3D printing and infiltration techniques.

Findings

17-fold increase in stiffness

7-fold increase in energy to failure

Multiple fracture events enhance energy dissipation

Abstract

Soft materials capable of large inelastic deformation play an essential role in high-performance nacre-inspired architectured materials with a combination of stiffness, strength and toughness. The rigid "building blocks" made from glass or ceramic in these architectured materials lack inelastic deformation capabilities and thus rely on the soft interface material that bonds together these building blocks to achieve large deformation and high toughness. Here, we demonstrate the concept of achieving large inelastic deformation and high energy dissipation in soft materials by embedding microstructured thermoplastic fibers with sacrificial bonds and hidden lengths in a widely used elastomer. The microstructured fibers are fabricated by harnessing the fluid-mechanical instability of a molten polycarbonate (PC) thread on a commercial 3D printer. Polydimethylsiloxane (PDMS) resin is infiltrated around the fibers, creating a soft composite after curing. The failure mechanism and damage tolerance of the composite are analyzed through fracture tests. The high energy dissipation is found to be related to the multiple fracture events of both the sacrificial bonds and elastomer matrix. Combining the microstructured fibers and straight fibers in the elastomer composite results in a ~ 17 times increase in stiffness and a ~ 7 times increase in total energy to failure compared to the neat elastomer. Our findings in applying the sacrificial bonds and hidden lengths toughening mechanism in soft materials at the microscopic scale will facilitate the development of novel bioinspired laminated composite materials with high mechanical performance.