Combination of wood fibers and spider silk could rival plastic

20.09.2019 Achieving strength and extensibility at the same time has so far been a great challenge in material engineering: increasing strength has meant losing extensibility and vice versa. Now Aalto University, Aalto/Finland, and VTT Technical Research Centre of Finland, Espoo/Finland, have succeeded in overcoming this challenge.

© Photo: Photo: Eeva Suorlahti
The researchers created a truly new bio-based material by gluing together wood cellulose fibers and the silk protein found in spider web threads. Birch tree pulp was broken down to cellulose nanofibrils and aligned into a stiff scaffold. At the same time, the cellulosic network was infiltrated with a soft and energy dissipating spider silk adhesive matrix. The result is a very firm and resilient material which could be used in the future as a possible replacement for plastic, as part of bio-based composites and in medical applications, surgical fibers, the textile industry and packaging.
Silk is a natural protein which is excreted by animals like silkworms and also found in spider web threads. The spider web silk used by Aalto researchers, however, is not actually taken from spider webs but is instead produced by the researchers using bacteria with synthetic DNA.
In the future, it will be possible to manufacture similar composites with slightly different building blocks and achieve a different set of characteristics for other applications. Currently, work is being carried out on making new composite materials as implants, impact resistance objects and other products.