Nano paper stronger than cast iron
Paper grocery bags that don´t tear? That may not be too far off thanks to the new nano paper, developed at KTH Royal Institute of Technology and STFI-Packforsk (A Swedish R&D company in the fields of pulp, paper, the graphics media, packaging and logistics). The material, which is tougher than cast iron, is made from nanosized whiskers of cellulose. Furthermore, it is lighter than conventional paper and could provide sturdy scaffolds for growing replacement tissues and organs. The new material recently got a news flash at Science´s online news section ScienceNOW, and has also got attention in The New York Times and New Scientist.
Conventional paper is made from cellulose, a crystalline polymer of glucose that is the primary component of plant cell walls. At the nanoscale level cellulose can be extremely strong, and the individual fibers are capable of withstanding more stress than glass fibers or steel wire.
“But paper processing generates relatively large cellulose microfibers riddled with defects that can break apart under stress. That leaves most commercial paper with a tensile strength that tops out at about 30 megapascals (MPa),” says Lars Berglund, a lightweight structures engineering expert at KTH Royal Institute of Technology, to ScienceNOW.
In order to make the paper tougher, Berglund and his colleagues kept the cellulose fibers small, according to ScienceNOW. They managed to do so by breaking down wood pulp in water with a combination of enzymes and mechanically beating it further. The result – pulished in the current issue of the American Chemical Society´s magazine Biomacromolecules – is a paper with a tensile strength double than that of cast iron.
Håkan Soold