Sustainable Fashion: Would you Wear Birch?

(April 4th, 2014) Besides food, clothing our ever-increasing human population is going to be a major challenge in the near future. The need for sustainable clothing is felt today, more than ever. Finnish scientists developed a cool solution to this problem: birch cellulose-based fabric.

Birch trees are well known for their robust wood and their papery patterned bark. They provide high quality plywood, paper pulp and medicinal extracts. Representative of growth, stability and renewal in the Celtic culture, birch trees are very adaptable and can swiftly repopulate damaged land. In fact, how many trees have had a poem dedicated to them? Well, the birch did. The poet, Robert Frost, has beautifully immortalised the boyhood joy in climbing trees in his poem ‘Birches’.

The birch’s versatile nature has been confirmed yet again by an invention that is set to redefine our take on clothing. Named “Ioncell fibre” after the production method, this novel material is derived from birch wood pulp.

So, what makes it so special? Well, firstly it is sourced from trees that don’t rely on artificial irrigation, making it an environment friendlier option than say cotton. In addition, the Ioncell method is not limited to processing birch cellulose. Recycled paper and used cotton clothes could also be potential raw materials, making this method even more sustainable in the long run. The cherry on the cake is that the Ioncell fibre is mechanically much stronger than cotton and viscose.

The people behind this research are Herbert Sixta of Aalto University and Ilkka Kilpeläinen of the University of Helsinki. Sixta’s group developed the Ioncell method of fibre production and Kilpeläinen’s team developed the ionic liquid (liquid salt) on which this method is based. Lab Times caught up with both scientists to learn more about their experiences.

Kilpeläinen recalls how it all began, “We started working with ionic liquids in 2006 as we had some lignin samples, which were very difficult to dissolve. We finally found that ionic liquids (ILs) were able to dissolve these for NMR analysis. At about the same time, another group had published the dissolution of cellulose in the same type of ILs. Therefore, it was quite obvious to try the dissolution of wood. To our surprise wood dissolved, too. Since then, we have been working to find new structures for cellulose dissolution, modification and regeneration.”

Sixta started research in fibre production as R&D Director at the Austrian textile company Lenzing AG, where he focussed on finding a substituent solvent for commercial TENCEL® fibre production. In 2007, he joined Aalto University, but he could only continue this research in 2009, when the Forest Cluster Ltd (today FIBIC) launched a national programme on cellulose-related research.

It was a rocky start with the first years not yielding much. “Gradually, the process conditions were optimised so that at the end of 2012 the first fibre samples with properties comparable to viscose were produced. In the turn to 2013, we switched to the solvent developed by Ilkka,” he reminisces.

After 3 months of intensive testing, the scientists experienced the breakthrough they had been looking for and they proudly presented their results at an international conference. But their good fortune was short-lived. “Coming back, we continued the work. Even though the ‘same’ conditions were applied as during our successful run before the conference, we were not able to produce good fibres anymore. The team went through very hard times…we were confronted with the request from the management of the funding agency to produce a fabric to demonstrate the ‘capabilities’ of this ‘new process’,” Sixta recalls.

The team carried on with an unwavering resolve. “We accepted the challenge even though we were not able to produce one single fibre until June 2013. The team, consisting first of 3, later of 2 PhD students and a postdoc, started the experimental programme by the end of June. When I left for giving lectures at Graz University of Technology (Austria) on June 28, no single fibre had been produced. However, the first encouraging emails reached me already the next day. Since then, we were able to produce fibres of high quality again. The amount of fibres produced was steadily increased, so that by the end of August we had enough fibres for a scarf,” he shares. And last month, an elegant dress crafted out of the Ioncell fibre made its debut on the fashion runway of the Finnish design company Marimekko (see photos).

The makers believe that it will be another 3-5 years before the fibre can be produced industrially. How much would the dress cost, you wonder? Sixta elaborates, “The costs of producing fibres in our very small plant can, of course, be calculated, but these costs are irrelevant. Provided that the solvent can be recovered with a recovery rate equal or higher than that for commercial solvents (99.75%), the fibre costs in the long run should be lower than those made by the TENCEL® process. Otherwise the process will not be commercially feasible.” Keep watching this space to find out when you can get your hands on some birch apparel!

Latika Bhonsle

Photos: Marimekko

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