Companies around the world are working to produce nanocellulose in commercial quantities, paving the way to a vast array of products based on materials derived from trees, as they attempt to end our dependence on petrochemicals.
“I think it will give us the opportunity to produce, for example, fat free mayonnaise based on forest products that we don’t believe in today,” said Mikael Hannus, head of research and innovation at Finnish pulp mill operator Stora Enso. “I think nanocellulose, microcellulose will end up in many, many different applications as an enhancement or experience improvement agent.”
Producing nanocellulose has traditionally been too costly for mass production, but Europe’s largest paper manufacturer is exploring the development of a variety of new products using wood as a renewable resource.
Stora Enso has set up a large wood research centre, a sizeable part of which is dedicated to finding environmentally friendly alternatives to fossil-based materials on which the packaging industry currently depends.
Stora Enso has seen a downturn in its traditional paper making business, so has turned its hand to developing recyclable packaging materials using nanocellulose and lignin, both found in wood.
“The tree consists of cellulose, hemicellulose – which are close to the cellulose – and lignins,” said Hannus. “About 50 per cent of the tree is cellulose that is produced starting from this chips that are digested to produce pulp in a pulp mill.”
The pulp is then further refined and sometimes bleached to make white paper or board and also made into textile fibres, a raw material for viscose, which is used to manufacture fibres.
Nanocellulose fibrils can be isolated from the wood-based fibres by ripping the larger wood-fibres apart in a high-pressure homogenizer.
Stora Enso research and development manager Heidi Saxell explained that their nanocellulose is made from bleached pulp and processed using newly developed technology into a fibrillated material.
“It’s produced into this highly fibrillated material which has a very large surface area and this surface area in addition to the other properties – long fibril length – gives an opportunity to develop many different new materials out of it,” she said.
Saxell said a whole range of packaging materials, including foams and films could be developed.
Stora Enso is at the forefront in lignin research and is in the process of finalizing commercial-scale tests of its first lignin application in glue; replacing phenols, which are mainly obtained from crude petroleum.
Lignin makes up about a quarter of wood and is removed in pulp production, to be mostly disposed of or burnt as fuel in pulp mills. It is now increasingly seen as a potential green rival to many fossil-based materials.
According to Stora Enso research project manager Niklas Garoff, “in the tree lignin is the bio glue that is holding together the wood fibres and it is possible to extract the lignin in pulp mills. What you get is a brownish powder… and out of this lignin you can make a number of different, very interesting, applications and products and we, the research community, are just in the beginning of understanding the potential of lignin.”
He said that in the long term, scientists are looking at making high value products out of lignin, such as carbon fibre for making high performance composite materials where low weight and strong mechanical performance is needed; e.g. for airplanes, cars, and rotor blades for turbine wind mills.
The company says that currently all carbon fibre is made from oil-based materials and that it is exploring the possibilities of using lignin as a natural, ecological, raw material replacement.
According to Hannus, the cost of nanocellulose production has been prohibitive, but this is about to change. He believes that in the future, nanocellulose will enhance the way we feel and even taste things.
Stora Enso believes nanocellulose and lignin products will become widespread within ten years.