Biomimetic Bouligand structure assisted mechanical enhancement of highly particle-filled polymer composites

The limited mechanical properties of highly particle-filled polymer composites significantly hinder their practical application. Inspired by the Bouligand structure in the dactyl club of mantis shrimp, carbon fibers are implanted in a stereotactic manner in these composites to create a Bouligand structure with a controllable twisted angle, thereby improving their mechanical properties. This composite material, featuring a 15 degrees twisted Bouligand configuration, demonstrates remarkable toughness and strength. It exhibits a maximum toughness of 32 kJ/m(3), an ideal flexural strength of 8.86 MPa, and a flexural toughness of 472 kJ/m(3), representing enhancements of 170 %, 64 %, and 300 % compared to the raw composite, respectively. Additionally, the Bouligand structure improves the peak stress and total energy absorption (similar to 10.08 MJ/m(3)) of each composite in the impact tests. Furthermore, the crack morphology and finite element (FE) simulations reveal a synergistic strengthening mechanism involving effective stress transfer, and twisted crack extension mechanism. This study indicates that constructing biomimetic Bouligand structure is a promising strategy for reinforcing the highly particle-filled polymer composites.