Sustainable tree protection
For many years, growth covers have been used in forestry. The tubular cover protects young tree trunks from wildlife bites and competing vegetation. The growth aids play an important role in reforestation, but are usually made of plastic or metal - if they are not removed by hand in time after three to five years or if they grow together with the plants, they can pollute the environment. The German Institutes for Textile and Fiber Research (DITF) have therefore developed a more sustainable solution: Researchers at the innBW institute have spun a strong and biodegradable hybrid yarn from renewable cotton fibers. The company Buck GmbH & Co. KG, which commissioned the project, has processed the yarn into a knitted fabric and now uses it to make a tree cover.
Flax fibers were initially used as renewable natural fibers. In several successive processes of spinning preparation, they were opened with polylactide staple fibers, blended and processed into a 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 wrap-around spinning tester developed at DITF. Finally, roving production using a roving frame was selected, since this process produces a voluminous as well as strong hybrid yarn with sufficiently flexible setting parameters and is also widely used by many spinning mills.
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.
About the DITF
The German Institutes for Textile and Fiber Research (DITF) are the largest textile research center in Europe with more than 300 scientific and technical staff. They are the only textile research institution worldwide to cover the entire production and value chain of textiles on an area of more than 25,000 square meters. Since 1921, the DITF have been working on all important textile topics. The DITF are among the world's leading research institutions in this field.