It is strong, stiff, lightweight, renewable and can also absorb energy. The researchers at RISE and KTH call their Fibrillar nanocellulose (CNF) super-material one of the strongest bio-based material in the world. The material is stiffer than spider silk and can tolerate loads five times heavier than a strand of hair can withstand.
The raw material is available in almost unlimited quantities. Cellulose is present in the cell walls of plants and is therefore the most common organic substance in nature. Based on this, researchers at RISE and KTH have developed the world's strongest biomaterial.
The manufacturing of this strong fibre utilises the fibrils in wood fibre. The process takes place in a flow cell where two streams of water are quickly directed from each direction at a third stream of water. The movement of the water causes the fibrils to lie in the same direction. By simultaneously lowering the pH, you can get the fibrils to attach to each other and form a fibre in gel form.
– The result is a material with incredible strength and stiffness. Until recently, spider silk was regarded as the world's strongest biomaterial and everyone thought it was amazing that nature could produce something like that. But this is actually eight times stiffer, says Karl Håkansson, a researcher at RISE who in the autumn of 2018 was awarded the Blue Sky Young Researchers Innovation Award for his research in the field.
Stronger than a human hair
The material is five times stronger than a strand of human hair. A hair from a human is, on average, 100 microns thick and capable of supporting a load of approximately 2 hectograms or one tetra pack filled with two decilitres of cream without breaking. A thread of nanocellulose of the same thickness could support a one kilo carton of milk
– It is one of the world's absolute strongest and stiffest bio-based material. The fibrils are naturally strong and capable of keeping up large trees and keeping together man made items such as wooden furniture and cartons. But with our process where they orient themselves in the same direction and attach to each other, they form a material that becomes very much stronger, says Daniel Söderberg, director of Treesearch, where RISE is a partner.
Wide application area
Possible future areas of application are many and large. One example is protective clothing for people working in forestry, for example. This would help forestry workers to utilise in a new way the raw materials that they work with.
Another potential area is space rockets where the strong nanocellulose could in principle be used for all portable parts that are not exposed to weather and wind.
– The majority of the parts in a rocket of course burn up. So it is better to use renewable material and have a low weight than waste natural resources that are running out, says Karl Håkansson.
Won't cause inflammation
Nanocellulose can also be used in special composites for vehicles or sports equipment. Because the material is not broken down and does not cause inflammation, it could also be used for artificial tendons and ligaments (such as the cruciate ligament) that are surgically inserted into human bodies.
– We are looking for a suitable partner to be able to manufacture an initial product for a niche market. An artificial cruciate ligament would be suitable, says Daniel Söderberg.