#Research & Development

2021-11-25

Environmentally-friendly reforestation: Biodegradable tree covers made from renewable raw materials

Stephan Baz (Head of Staple Fiber Technologies) with the environmentally friendly tree cover in original size and as a demonstrator on a red maple. In the foreground: hybrid yarn variants made from flax or cotton. Photo: DITF

In reforestation projects, the seedlings must be protected. So-called growth covers prevent game from feeding on the young plants and help to ensure that they are not prevented from growing by other plants. Previously used sheaths made of plastic and metal are often not removed in time and pollute the environment. The German Institutes of Textile and Fiber Research Denkendorf (DITF) have developed a biodegradable yarn for growth covers from renewable raw materials.

Reforestation is not only necessary after storms and fires. In general, the forest must be prepared for climate change through mixed stands and rare tree species. Growth envelopes are an important component of forest management in the early years.

Covers available on the market must be removed and collected after three to five years. This is often not dealt with due to lack of personnel or is no longer possible due to overgrowth, or because the cover has grown into the tree. As a result, numerous growth covers remain in German forests every year until they rust or are shredded into environmentally-harmful plastic components by external influences. Although currently available variants made of bioplastics are based on renewable raw materials, they are not biodegradable, decompose already during the use phase and pollute nature with small and microplastics.

Tree cover made of yarn developed at the DITF in use. Photo: Buck GmbH & Co. KG

The company Buck GmbH & Co. KG therefore commissioned the DITF to develop a yarn from renewable raw materials that is also biodegradable. This yarn should be able to be processed into a tube using a knitting machine and then consolidated into a stiff but at the same time pliable tube.

Renewable natural fibers and polylactide (PLA), which Trevira provided free of charge for the research, were used as starting materials for the development of a hybrid yarn. PLA consists of chemically bonded lactic acid molecules and is currently the only biodegradable thermoplastic available on an industrial scale. Particular attention was paid to ensuring that PLA was particularly pure in order to avoid environmental damage from plasticizers or other ingredients.

Flax fibers were initially used as renewable natural fibers. In several successive processes of spinning preparation, they were opened with the PLA staple fibers, mixed and processed into a fiber sliver. Subsequently, preliminary investigations were carried out to determine a suitable yarn structure for the biobased hybrid yarn. A simple, widely used spinning process was sought that would ensure rapid implementation on an industrial scale. Spinning trials were carried out on a rotor spinning machine, on the roving frame, a process upstream of ring spinning, and on a spiral covering spinning tester developed at the DITF. Finally, roving production by means of a roving frame was selected, since this process produces a voluminous as well as at the same time strong hybrid yarn with sufficiently flexible setting parameters and, moreover, is widely used by many spinning mills. The hybrid yarn was then processed into a knitted fabric at Buck GmbH & Co. KG to produce a knitted fabric from which a beam cover was made.

For material and economic reasons, the flax fibers were replaced by cotton fibers to optimize the hybrid yarn. The cotton fiber is more flexible across the longitudinal fiber axis than the flax fiber. As a result, it is more flexible in the knitted fabric and in the subsequent application as a tree cover in relation to external forces such as animals or wind. Cotton fibers are available in cotton spinning mills compared to flax fibers, which increases the number of potential suppliers for the hybrid yarn.

“Production is a product”

From technical textiles and AI-driven robotics to the limitations of textile circularity: Professor Dr Thomas Gries looks back on more than two decades of development at ITA Aachen. In the interview, he explains why production technology remains a decisive success factor, discusses international collaborations and innovation ecosystems, and shares his views on the transformation of production landscapes and the challenges facing an increasingly regulated industry.

“We need to move away from the price trap and return to a value-driven mindset.”

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“Innovation, resilience and international experience remain the great strengths of the Swiss textile machinery industry”

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Meadow Grove Research joins ITMF as Corporate Member

Meadow Grove Research is a commodity research firm specializing in supply, demand, and trade analysis in cotton and other soft commodities. Providing clarity to the complex nature of the global fiber supply chain is one of its most formidable services. The firm thrives on customer engagement and providing the best framework for critical decisions.

ALADIN paves the way for circular and demand-driven textile production in Europe

Textile production can be organized sustainably by utilizing short supply chains and preventing overproduction. This can already be achieved today by intelligently connecting and efficiently utilizing existing infrastructure. At the same time, production becomes circular when innovative technologies and materials are used that enable high-quality recycling. The ALADIN research project, launched in May 2026 and co-funded with five million euros under the EU Horizon Europe program, is creating the conditions for this.

TERIS reaches milestone: Fraunhofer consortium develops new standards for tire analysis

In the “TERIS” project, the Fraunhofer institutes ICT, IGD, and IWM—led by the Fraunhofer Institute for Structural Durability and System Reliability LBF—have reached a decisive milestone. For the first time, the teams aim to generate, analyse, and predict tire wear in the laboratory in a standardized and practical manner. As part of this milestone, results are now available on reference abrasion, particle analysis, tribological models, AI-based surface analysis, a test bench concept, and methods for accelerated aging and VOC detection. The tire industry, testing services, and environmental agencies will in future benefit from reliable, rapid laboratory procedures for emissions assessment.

Geotextiles made from recycled materials: GREEN leads the way into the industry

For the industry, recycled materials are creating new opportunities in geotextile production. In the GREEN project, the Fraunhofer Cluster of Excellence Circular Plastics Economy CCPE demonstrates that recycled polypro-pylene (PP), polyethylene terephthalate (PET), and high-density polyeth-ylene (HDPE) can be processed into nonwovens, fibers, and membranes that meet industrial requirements. This creates opportunities for use in existing production lines and new value chains in the geotextile market.

Rieter sees Barmag integration on track as orders and sales rise

The first half of 2026 was shaped by the successful completion of the largest acquisition in Rieter’s history. The Man-Made Fiber Division enables entry into the growth segment of man-made fibers and sustainably strengthens Rieter’s market position in the Asia region. The expanded Group is now the world’s leading system supplier for the processing of natural and man-made fibers. In the first half of the year, initial cost savings in material costs and operating expenses have already been realized. The targeted synergies are expected to amount to at least CHF 20 million by the end of the 2028 financial year. Due to the completion of the acquisition on February 2, 2026, the first half of the year for the Man-Made Fiber Division only amounts to five months.