Naturally-occurring nanofibres known as fibrils could be used to create a new generation of reinforced plastics and packaging materials, say Norwegian researchers.
Fibrils are 50-nm thick strings of cellulose that, when gathered into bundles, give stiffness to tree trunks and other plant stems. These tough fibres could, in principle, be used to reinforce plastics to a level required for automobile components. But the process is energy intensive and expensive, and controlling the size distribution of fibrils once they have been separated out from wood cells is a challenge.
Kristin Syverud of the privately-owned Paper and Fibre Research Institute (PFI) in Trondheim, together with colleagues at the independent research organisation SINTEF and the Norwegian University of Science and Technology (NTNU), is now looking to make fibril extraction more cost-effective. A group of Swedish researchers working for the PFI’s parent company is also tackling the problem, and recently published a patent on the industrial production of microfibrillated cellulose (MFC).
Synthesis of fibrils is not a realistic option, says Syverud: “Cellulose can be synthesised from bacteria, but the production volume is a problem, and I do not believe that this can be done on a large scale. Another approach is to dissolve cellulose and produce fibrils by electro-spinning.”
Dissolving cellulose is not straightforward, but Syverud believes that in the future this will be possible on an industrial scale, even though electro-spinning would limit production volumes achievable. “I think that decomposition of wood and plant fibres will be the profitable way to produce MFC,” she says.
Possible near-term applications of MFC are in high-strength papers, environmentally-friendly packaging with strong barrier properties, the stabilisation of emulsions, antimicrobial papers and nanocomposites.
For Syverud the primary driver is the environment: “[Fibrils] are a renewable resource that is being created by nature around us every day. And they are certainly cheap.”
Figure: These cellulose nanofibres known as fibrils, which are extracted from cells in pine timber, could be used to reinforce plastics and packaging materials. The scale bar on the left image represents 1 μm; on the right 200 nm (source: Norges Teknisk-Naturvitenskapelige Universitet).
Article first published in Nanomaterials News.