Researchers at KTH Royal Institute of Technology in Stockholm have managed to produce a bio-based material based on wood that supposedly surpasses the strength of all known bio-based materials, fabricated or natural, including spider silk. Source: Wired UK
This new lightweight material could in theory be used not only to create new kinds of super-strong furniture, but new airplanes, cars, buildings and other products.
Working with cellulose nanofibres, the fibres that coat the cell walls of wood which are the essential building block of wood and other plant life, the KTH team managed to translate the incredible mechanical properties of these nanofibres into larger, lightweight materials. The findings were published in the journal ACS Nano.
The development process included controlling the flow of these nanofibres suspended in water in a 1mm wide channel milled in stainless steel. Connecting flows of deionised water and low-pH water then aligned the nanofibres in the right direction which then let the cellulose nanofibres self-organise into a well-packed state where they could be joined together.
KTH then densified this material to make it into a “super wood” that has a tensile strength nearly four times greater than steel.
Material scientists have tried to replicate the properties of spider silk on an industrial scale for decades. The naturally occurring material is stronger than steel, remarkably light and extremely elastic. This gives it immense potential, not only for clothing but also engineering and medical uses.
Labs are using genetically altered E. coli or yeast to produce the silk proteins through fermentation. The resulting silk is then spun by mimicking a spider’s spinneret.
“The bio-based nanocellulose fibres fabricated are eight times stiffer and have strengths higher than natural dragline spider silk fibres, generally considered to be the strongest bio-based material,” said Daniel Söderberg, researcher at KTH. “The specific strength is exceeding that of metals, alloys, ceramics and E-glass fibres.”
Söderberg says the study opens the way for developing nanofibre material that can be used for larger structures while retaining the nanofibres’ tensile strength and ability to withstand mechanical load. The process can also be used to control nanoscale assembly of carbon tubes and other nano-sized fibres.
