An insight into the toughness modulus enhancement of high-performance knotted microfibers through the correspondence analysis

Abstract

A variety of applications, spanning from structural or biomedical engineering to flexible electronics, require the development of materials able to withstand high load and, at the same time, accommodate high strain before failure. While strength and toughness are often self-excluding properties in man-made materials, they can be efficiently combined by nature, which provides source of inspiration for novel materials design. Herein this paper, we pursue a bio-inspired approach, based on the introduction of a mechanical sink, such as a running knot, to improve the toughness modulus of high-performance polymeric microfibres. These are then enriched with additional smart features, such as a viscoelastic coating, surface roughening or a combination of those, to amplify the beneficial effect of the knot introduction. The role played by all such features on the mechanical performances of the prepared fibre samples, namely load at failure and toughness modulus increase, is then evaluated through a statistical technique, known as correspondence analysis (CA). While this exploratory analysis is widely adopted in biology, ecology, neuroscience or genetics, applications in structural or mechanical engineering are still rare. Here, we show that CA can be a powerful tool for the design of materials provided with enhanced toughness without losing strength.

Cellulose Nanocrystal Composites with Enhanced Mechanical Properties for Robust Transparent Thin Films

“…Interestingly, the addition of TOCNCs to CMC produces nanocomposite films with significantly improved mechanical properties, not only in terms of strength (145.8 ± 19.4 MPa vs 74.0 ± 10.8 MPa for pure CMC films) and Young’s modulus (11.4 ± 3.1 GPa vs 4.9 ± 0.9 GPa for pure CMC films) but also toughness (4.0 ± 2.1 MJ·m –3 vs 1.8 ± 2.1 MJ·m –3 for CMC films). Although strength and toughness are usually at odds with each other, in the case of our composite films, the presence of TOCNCs allows them to withstand more load but not at the expense of the deformation capability characterizing the CMC matrix, which is basically preserved. This result demonstrates that an efficient stress transfer mechanism is achieved from the matrix to the nanocrystal reinforcements, favored by the hydrogen bonds that are established between them.…”