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100% biobased textile not a matter of course
Wool, linen, cotton: the textile industry has traditionally used natural materials. And yet precisely this industry embraced the use of synthetic petroleum-based fibres after the Second World War. What is more, textile is full of property-improving additives such as plasticizers, fire retardants, pigments, stabilizers, adhesives and nucleating agents. It is time for a sustainable alternative.
That is the objective of the Interreg project ‘Pure nature: 100% biobased’: to provide sustainable, non-toxic, biodegradable alternatives based on renewable raw materials. This should enable the carpet and clothing industries in Flanders and southern Netherlands to use up to 50% biobased materials in their products by 2030. High-quality fibres and yarns that are made entirely from biobased materials are needed for this purpose. The significant size of these markets means there is a potentially huge impact on the environmental footprint.
The business sector and knowledge institutes are working together in this project on research into biopolymers for textile, new biobased additives and methods for measuring the sustainability. Participants include Centexbel (Belgian technical and scientific centre for the textile industry), the Centre of Expertise Biobased Economy (Avans and HZ Universities of Applied Sciences) and the Flemish textile company De Saedeleir Textile Platform. The Aachen-Maastricht Institute for Biobased Materials (AMIBM) is the consortium leader. Three of its departments are researching new fibres as well as additives and the improvement of the sustainability of production in a more general sense.
‘Textiles are used for a wide range of applications, for instance clothing and carpet, but also in technical applications,’ says Benjamin Weise, project leader textile processing at AMIBM. ‘Depending on the application, the fibre needs to have specific properties. For instance, in the production process we can modify the toughness of the fibre to produce fibres that have a certain flexibility. We are also investigating the usefulness of the fibre for a range of processing methods for woven or knitted fabrics, or for non-wovens, for example for use in carpet.’
The extrusion process used to make the fibres or yarns does require high requirements on the polymer material. ‘For instance, it is quite a challenge to find sufficiently biobased materials with properties that are just as good as those of the usual polyamides and PET. PET in particular has extremely high tenacity with low residual stress. No good biobased alternative exists for this as yet.
Additives are therefore needed to spin yarn from biopolymers. Karel Wilsens, researcher in active components at AMIBM: ‘This means that biobased textile ends up with a content of only 70% polymer and 30% of additives to give the fibre its required properties.’
Not for the washing machine
No fully biobased alternative is currently available for any of these additives. Wilsens: ‘There have been some attempts to develop them, but the results were not very successful. The main challenge is to get the performance to the required level for your application. For example, nature provides more than enough pigments, but the question is how we can isolate them in a sustainable way and put them in a fibre. Natural materials were not designed for the washing machine.’
Reason enough for work on new additives to take place at three locations: at Centexbel on fire retardants and plasticizers, at Avans and HZ Universities of Applied Sciences on colouring agents and pigments and at AMIBM on nucleating agents and coatings. Tests are carried out in the laboratory on the additives developed. Different combinations are applied through compounding (mixing melted components), extrusion (spinning the melted substance into fibres), coating, refining and painting. The compounds and textile fibres thus obtained are analysed to determine the most suitable chemical technology for fully (100%) biobased textile products.
Success depends not only on the additives actually functioning, but also on their production on a sufficiently large scale and on their being produced cheaply. The processes are investigated on pilot scale for this purpose. Various companies will use these to further develop tufted carpet, clothing, bedding and non-woven carpet backing.
During the different development stages, the environmental impact of the biobased additives, fibres and applications is also examined by means of a life cycle analysis (LCA). Yvonne van der Meer, LCA researcher at AMIBM: ‘That is new as well. These days most life cycle analyses of textiles ignore additives, although they can be responsible for almost a third of the greenhouse gas emissions. But to really prove the sustainability benefits of biobased alternatives we need to do a complete assessment, of fossil-based materials as well. Subsequently we hope that we can reduce the emissions using biobased additives. We do come up against barriers, because we cannot choose only the most sustainable options. That is because the technical properties remain the guiding principle. They determine the usability.’
The Pure Nature project started in January 2018 and will run until 31 December 2020. If everything goes successfully, the market should see new additives within two years.