Cellulosic fibers
Cellulose is a major component of plant biomass and one of the most abundant polymers produced in nature. It forms part of a closed natural material cycle that the ecosystems of the planet are well equipped to deal with. This cellulose cycle builds the basis for Lenzing’s business model and provides opportunities to address some of the most challenging issues facing society, such as climate change or emerging circular economy options. Even if the carbon from the materials is released at the end of their life, it is renewable carbon and part of the natural cycle, ensuring that no additional fossil carbon enters the atmosphere.
Standard fibers from Lenzing are produced from cellulose in an industrial process. The final fiber product consists of the chemically unmodified natural polymer cellulose. Figure “Fiber types on the world market” below shows that two groups of fibers consist of unmodified natural polymers: natural fibers, and regenerated/wood-based cellulosic fibers. Both groups of fibers are inherently biodegradable. Other fiber types can be difficult to biodegrade, such as conventional fossil-based synthetics, some of the biosynthetic fibers, and some semi-synthetic fibers made from chemically modified natural polymers. For a systematic overview of fiber biodegradation, see the “Biodegradable Polymers in Various Environments” chart compiled by the Nova Institute.
Fiber types on the world marketa
End of life of Lenzing’s fibers
Looking at the end-of-life stage for products manufactured from Lenzing’s fibers including clothing, home textiles, technical products, hygiene products and personal care products, there are several processing options:
- Recycling: Products made from wood-based fibers can in principle be recycled and used again for fiber production at Lenzing. This is shown by the example of Lenzing’s fibers leveraging recycled post-industrial and post-consumer cotton waste within REFIBRA™ or Eco Cycle technologies on a commercial scale.
- Compostability: If recycling is not possible, some textile and nonwoven applications can be composted if all constituents are biodegradable. The BioSinn report (funded by the German Federal Ministry of Food and Agriculture) from the Nova-Institute lists such applications – including wet wipes or binding yarns. All LENZING™ fibers are compostable, fulfilling the requirements for compostability in terms of biodegradability, disintegration and absence of eco-toxicity.7
- Anaerobic digestion: Alternatively, for certain products it may be appropriate to use anaerobic digestion with energy recovery (biomethane production) in waste treatment. LENZING™ fibers are fully degradable in controlled anaerobic waste treatment conditions.
- Incineration: If composting is not an option, the final products can be incinerated and the embedded energy recovered. Since the fibers consist of natural polymers, they are climate-neutral in terms of incineration, which means that only the amount of CO2 initially stored in the plant is released. Either way, both composted materials and CO2 provide input for plant growth, thereby closing the natural carbon cycle.
- Landfill: The least preferable option for materials’ end-of-life is landfill, which is still a regular practice in many countries. While this option has to be phased out as soon as possible, Lenzing’s cellulosic fibers can biodegrade without releasing microplastics or toxic substances if conditions in the landfill favor biodegradation.
Biodegradability
The ability of a material to be broken down by micro-organisms (bacteria, fungi) into carbon dioxide, water, and biomass, or compost, so that it can be consumed by the environment.
Compostability
Capability of being biodegraded at certain temperatures (industrial: 58°C; home: 28°C) in soil under specified conditions and time scales.
External scientific approval of biodegradability
Results of experiments conducted by the University of California’s prestigious Scripps Institution of Oceanography (SIO) in San Diego provide scientific proof that wood-based cellulosic fibers offer an effective, biodegradable substitute to fossil-based synthetic fibers. SIO has a global reputation for being one of the oldest, largest and most important marine research centers worldwide. In a study published in October 2021, scientists from the SIO confirmed that wood-based cellulosic fibers biodegrade in the ocean within a short period of time at the end of their life cycle. The research was the result of an independent project aimed at understanding the end-of-life scenarios for textiles and nonwovens discarded in the environment. The study compared the degradation processes of nonwovens made from fossil-based synthetic materials, such as polyester, with those of cellulosic materials, such as Lenzing’s wood-based lyocell, modal and viscose fibers in specific scenarios – under various real oceanic conditions and controlled aquaria conditions. The results of these experiments are striking: while wood-based cellulosic fibers fully biodegraded within 30 days, the fossil-based fibers tested were practically unchanged after more than 200 days.
“Our goal is to raise widespread awareness of major challenges such as plastic pollution and persuade the industry to make the transition to wood-based, biodegradable TENCEL™, LENZING™ ECOVERO™ and VEOCEL™ fibers.”
Microplastics
Small plastic particles of 5 mm or less in size – known as “microplastics” – are perceived to be a major pollution problem in freshwater bodies and the sea. While recent industry initiatives and legislation aim to promote the development of less polluting alternatives, Lenzing, as a producer of wood-based cellulosic fibers, laid the foundations for biodegradable products more than 80 years ago.
European Union Single Use Plastics Directive
According to the Directive (EU) 2019/904 (SUPD – single use plastics directive), which aims to reduce the impact of plastic products on the environment, natural polymers that have not been chemically modified do not fall under the “plastic” definition. The Commission guidelines on single-use plastic products in accordance with Directive (EU) 2019/904 clearly state that viscose and lyocell are not considered to be chemically modified and are therefore not classified as plastic. Also, the proven biodegradability of LENZING™ fibers shares the same aim of this Directive, i.e. avoiding plastic pollution. Consequently, the SUPD is a potential catalyst for nonwoven applications of LENZING™ fibers.
The Lenzing Group collaborates in industry and multi-stakeholder initiatives – including the Microfiber Consortium of the European Outdoor Group, the Cross Industry Agreement of the textile and detergent industries, and the “Textile Mission” project within the German research program on plastics in the environment (“Plastik in der Umwelt”). Lenzing provides fiber and textile intermediate materials for testing and developing new textile constructions, and gives feedback on drafts of reports and guidance documents.
The biodegradability of Lenzing’s fibers was tested at the independent research laboratory Organic Waste Systems (OWS) in Belgium, one of the world’s leading biodegradability and compostability testing companies. The assessment was performed in accordance with existing and applicable international standards, reflecting all relevant natural and artificial environments where biodegradation can take place (figure “Biodegradation of LENZING™ fibers in various environments”). Certificates from the certification organization TÜV Austria show that LENZING™ standard fibers biodegrade relatively rapidly in all natural environments, and in industrial waste treatment targeting biodegradation. This should not be seen as a means of waste disposal or as an excuse for littering, but as an additional safeguard to avoid pollution. Lenzing’s fibers thus offer a sustainable solution to the plastics pollution problem. More details and components of testing and certificates as well as on biodegradability in general can be found in the “End of product use” focus paper.
Biodegradation of LENZING™ fibers in various environmentsa
7) Ellen MacArthur Foundation, 2017. A new textiles economy: Redesigning fashion’s future, http://www.ellenmacarthurfoundation.org/publications, p. 21
