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Götz T. Gresser: “A sustainable textile requires the entire process chain to be sustainable”

The DITF - German Institutes of Textile and Fibre Research Denkendorf - form the largest textile research centre in Europe. The development of sustainable products and processes has been on the DITF’s agenda for years and is one of the institutes’ research priorities. Prof. Dr.-Ing. Götz T. Gresser, the director and spokesman of the DITF, talked with BIOPRO about the background to the textile developments.

Glossary

  • Cellulose is a insoluble polysaccharide and the main part of the cell wall of plants. The single component of cellulose is glucose.
Prof. Dr.-Ing. Götz T. Gresser has been the director of the DITF and head of the Institute for Textile and Fibre Technologies (ITFT) at the University of Stuttgart since 2013. © DITF

What do you think makes a textile particularly sustainable, what qualities must it have? 

For me, sustainable textiles need to have a biobased origin. However, I’d rather use the term renewable resources. A biobased origin on its own is not enough. In my opinion, the raw materials used for sustainable textiles also need to be processed in a sustainable way, including for example during the dyeing and finishing processes. We want to move away from using fluorocarbons, which are thought to be harmful to human health. In addition, textile filters ensure the environmentally friendly and resource-saving cleaning and recovery of process water in the industry, and textile separation and dehumidification systems ensure clean air during production. 

 

At present, cotton is the dominant natural resource as far as textiles are concerned. It accounts for around 25 percent of the 100 million tons of fibre material produced worldwide every year. Cellulose and lignin are also spun into fibre materials. For example, the sustainable production of carbon fibres from cellulose or lignin is a major area of research at the DITF. The production of fibre materials from cellulose consumes significantly less resources, such as water, than cotton. It is therefore more sustainable to produce fibre using cellulose than cotton.

What motivated DITF to make sustainable textiles a priority in its research and development processes?

We’ve always processed natural fibres. Expertise in the use of renewable resources has been an integral part of our research and development processes since the research centre was established in 1921. Some decades later, Germany's textile industry underwent a change. Raw material only plays a minor role in producing modern textiles for making clothes, at least as far as manufacturing costs are concerned. Sewing is the main factor, accounting for around 50 percent of manufacturing costs. So it’s no surprise that the manufacture of clothes has been relocated to countries with lower wages.

 

Nowadays, the textile machinery industry is a high-tech industry. While one in four textile machines in the world today comes from Germany, only one in ten cars is built here. The German textile industry has become highly specialized and is a European leader in technical textiles. Today, approximately 70 percent of the revenues in the textile industry in Germany are achieved with technical textiles. As Germany transitions into a bioeconomy, it stands to reason that the development of sustainable fibres and textiles, with a special focus on technical textiles, is also becoming a priority here in Denkendorf. 

 

Innovative textile structures made from sheathed fibre bundles ensure that irrigation is tailored to plant requirements without the need for sensors or control technology. The system was developed by the DITF, the wick manufacturer WEDO and the Weihenstephan-Triesdorf University of Applied Sciences and tested in this raised bed for energy self-sufficiency. © DITF

How is this implemented in practice, and which aspects do you think are particularly important?

If we want to achieve an entirely circular economy in terms of sustainability, this can only be done with sustainably processed raw materials. Denkendorf is unique in Europe in that our research and development work focuses on all stages of production and processes along the entire fibre and textile value creation chains – including implementation of sustainable solutions. I think it is extremely important to master the entire process chain. But it is just as important to think sustainably. Employees who can do both are incredibly important in our search for sustainability. They help us create the platform we need to develop sustainable solutions for the industry.

The Denkendorf Institutes are located at the interface between research and application. They work closely with industry, have joint projects and also carry out contract research for companies. What is your assessment of the demand and requirements for sustainable solutions in the textile industry?

I think the whole industry is highly aware of the issue. Nevertheless, revolutionary changes rarely occur in the textile industry. Here, we are more concerned with evolving towards sustainability. We need to grow our expertise. A car maker, for example, does not have the know-how to work with sustainable textile materials. Therefore, he initially uses sustainable material for producing relatively small components. Then, of course, the question arises as to what he should do with his capacity and expertise in sheet metal processing if the entire production is suddenly changed. Nevertheless, demand for lightweight constructions has risen quite quickly in the mobility sector as a whole - triggered, amongst other things, by the transition to renewable energies. Textile materials are generally well-suited for lightweight constructions, and the demand for sustainable solutions is growing. In addition to use in cars, sustainable textile solutions are becoming increasingly important in construction and architecture. Examples include thermal insulation, solar thermal energy and energy-efficient façade shading.

 

Customer requirements also play a part in all sectors. Manufacturers are finding that sustainable products are selling well, which in turn reinforces the demand for sustainable products. This development is also supported by the start-up sector. A lot is going on here. Start-ups tend to specialize in sustainable products right from the word go and develop special manufacturing processes. Here at the DITF, we are the point of contact for all types of companies and provide support in the form of expertise in sustainable textile products.

 

Sustainability also includes long usage cycles of materials, which is a key element of circular economies. How can recycling be achieved with textile composites, and is this also possible with smart textiles, for example with a sensor function?

Sensor fibres, for example conductive fibers, can now be largely recycled in their entirety. This is more difficult with composite materials. Here at the DITF, we work on solutions for recycling recovered materials. That is, we start from separate precursor materials. For example, we are developing techniques for processing recovered carbon fibres from fibre composites into yarn and then a textile. This can then be reprocessed into automotive industry products.

The solar collector and heat accumulator are housed in one unit in the knitted latent heat accumulators from DITF's development forge. The textile solar collector is light and flexible. © DITF

How economical is the production and use of sustainable textiles today and what needs to be improved in the future to make such products competitive? 

I see great potential in the sustainable production of new fibre materials by reducing the number of process steps involved in producing textiles. For example, methods are being developed that produce yarns and knit a textile with a single machine. Overall, this can make production more sustainable. Process optimization is also about using fewer resources, such as water and energy, to maintain the same product quality. And there is quite a bit of flexibility as far as the utilization of materials is concerned. Every yarn has a certain strength. One of our research goals is to obtain the same strength with the recylate. If we achieve this, it would be a major competitive advantage. Digitization is also a sustainability aspect that pays off. Pattern fabrics can be produced virtually. The more simulations are used, the less waste and scrap is produced. We examine how we can link processes to avoid waste and second choice materials. As a Mittelstand 4.0 centre of competence we show small- and medium-sized companies what is digitally possible today.

 

All in all, I think that sustainable textiles are a megatrend. I believe that, especially in the field of technical textiles, there will be a variety of new materials and new processing methods that will enable us to meet demand. It also opens up completely new applications and markets. Textile moss walls are an example in which only textiles offer the possibility of efficient use. The textile matrix ensures that the plants are supplied with the right amount of moisture; this is a basic prerequisite for moss walls to act as fine dust filters.

 

I should add that new markets only arise if customers have the necessary mindset. Thanks to our purchasing power in Germany, I think we are prepared to spend more on a product that is produced fairly and sustainably. There is also a move towards this direction worldwide. However, a product’s sustainability must become even more verifiable and understandable. We need to further boost the credibility of sustainable products.

Website address: https://www.biooekonomie-bw.de/en/articles/news/goetz-t-gresser-a-sustainable-textile-requires-the-entire-process-chain-to-be-sustainable/