Biodegradable – Back to nature 

Recycling is one approach to minimizing waste, but there are more options that protect soil, air, water from the tons of waste and even some of the toxic components. Materials that decompose or biodegrade in soil or in a landfill are already available. Some fibers can even biodegrade in marine water what is good news as the laundering process suspended tiny fiber particles that flow into the rivers and oceans.

Let’s get rid of the myths that all bio-based materials are biodegradable and all petro-based materials are not. Learn about polymers like Viscose, Tencel, Modal, Umorfil, Apexa, and Amni Soul Eco. Have a look at the overview about the global standards like worldwide ISO, European EN, or American ASTM. What is the Vincotte certificate and all the other related specifications? PERFORMANCE DAYS asked for you some of the important questions and collected the basic information about how much time it takes until materials biodegrade. Start to create a truly biodegradable line of clothing with the help of the April 2017 Focus Topic: “BIODEGRADABLE – Back To Nature”.

Definition: Biodegradable

The concept of biodegradable materials is to reduce the amount of (toxic) waste that is polluting the earth – whether after the textile’s useful life or while in use (abrasion and laundering). According to early definitions from 1961, biodegradable material degrades to carbon dioxide, biomass, hydrogen/water, oxygen and methane with microorganisms (i.e., bacteria & fungi) over a certain period of time. Moreover, certain factors such as water, oxygen, and temperature influence the degeneration time, meaning some materials decompose differently in compost, soil, landfill, fresh water or marine water and differently (fast) in customer or industrial disposal.

All compostable materials are biodegradable in compost (aerobic), but outside this particular surrounding, e.g. in soil (aerobic) or landfill (anerobic), they might not (bio-)degrade.

If 60 – 90% of the material (fabric and accessories) has broken down within this amount of time, it may be considered as biodegradable. However, in terms of durability, more research is required to evaluate the extent to which biodegradable materials may be less durable than non-biodegradable ones. As of the time this article was prepared, PERFORMANCE DAYS is not aware of any fiber that degrades while being worn.

Today, most biodegradabiltity tests measure the percentage of degration within the following time frames:

Home composting 12 months
Industrial composting 6   months
Soil 24 months
Fresh Water 2   months
Marine Water 6   months

Source: Bio-plastics comprised of biodegradable and bio-based plastics (taken from Tokiwa et al. 2009: available under the Creative Commons Attribution license) Seen in: Biodegradable plastic & marine litter. Misconceptions, concerns and impacts on marine environments, by United Nations Envrioment Programme (UNEP, 2015)


Standards & certificates

Industrial compostability: specifications
SO 17088 Specification for compostable plastics.
ISO 18606 Packaging and the environment – Organic recycling.
EN 14995 Plastics. Evaluation of compostability. Test scheme and specifications.
EN13432 Packaging – Requirements for packaging recoverable through composting and biodegradation – Test scheme and evaluation criteria for the final acceptance of packaging.
ASTM D6400 Standard specification for labelling of plastics designed to be aerobically com posted in municipal or industrial facilities.
ASTM D6868 Standard specification for labelling of end items that incorporate plastics and polymers as coatings for additives with paper and other substrates designed to be aerobically composted in municipal or industrial facilities.
AS 4736 Biodegradable plastics – Biodegradable plastics suitable for composting and other microbial treatment.

 

All of the above specification address the following four aspects:

  • Biodegradation under controlled composting conditions, requiring 90% biodegradation within  maximum 180 days.
  • Disintegration under industrial composting conditions, requiring 90% disintegration within  maximum 84 days.
  • Possible negative effects on the composting process, setting maximum levels for heavy metals  and Fluorine content.
  • Possible negative effects on the quality of the resulting compost, including harmful  components, requiring proof of no negative effects on plant germination and growth.

 

Test methods

Specifications also refer to one or more test methods. Some of the various test methods for determining the biodegradation of materials are listed below:

ISO 14855

  • Determination of the ultimate aerobic biodegradability of plastics under controlled composting conditions.
  • Simulates typical aerobic composting conditions wherein temperature, aeration & humidity are closely controlled.
  • ISO 14855 can be used to determine the biodegradation under industrial composting  conditions (58°C) as well as under home composting conditions (28°C).
  • EN 14046 is the EU-reference for biodegradation testing under controlled composting  conditions, ASTM D5338 is the US-reference.

ISO 16929

  • Determination of the degree of disintegration of plastics under defined composting conditions  in a pilot-scale test.
  • Simulates typical aerobic composting conditions wherein temperature, aeration & humidity are closely controlled.
  • ISO 16929 is a pilot-scale test, closely mimicking real-life conditions and hence more  representative to lab-scale testing (ISO 20200).

ISO 17556

  • Plastics – Determination of the ultimate aerobic biodegradability of plastics in soil by  measuring the oxygen demand in a respirometer or the amount of carbon dioxide evolved.
  • Simulates soil conditions wherein temperature and humidity are closely controlled.
  • ISO 17556 can be used to determine the biodegradation in soil.
  • ASTM D5988 is the US-reference for soil biodegradation testing.

ISO 14851

  • Determination of the ultimate aerobic biodegradability of plastic materials in an aqueous  medium.
  • When using fresh water and 21°C, the method simulates conditions in rivers, lakes, wastewater treatment plants, etc. When using seawater and 30°C, the method simulates marine conditions.
  • ASTM D6691 is the US-reference for biodegradation testing in marine waters.

ISO 15985

  • Plastics – Determination of the ultimate anaerobic biodegradation and disintegration under high-solids anaerobic digestion conditions.
  • Simulates dry anaerobic digestion conditions, covering both mesophilic (37°C) as well as thermophilic (52°C) conditions. If run at 37°C, the method can also be used to mimic landfill conditions.
  • ASTM D5511 is the US-reference for biodegradation testing in anaerobic conditions.


Biodegradable Fibres

100% Natural

Asked to name a biodegradable fibre, most people think first of all of the bio-based (often cellulose) fibres such as cotton or linen (flax) AND other natural (often protein) fibres such as cashmere, silk or (merino) wool. These examples are indeed biodegradable as compost but, unfortunately, they are not always suitable for sportswear. A specific example would be a cotton running shirt that stores water like a sponge. In this case a functinal fabric with moisture management and quick dry is needed.

100% Synthetic

Besides the natural fibres, some synthetic fibres are biodegradeble as well. The current list is not long, but very interesting. Hopefully, it will get longer in the future with the increasing awareness of the limited resources on our unique planet earth. The information about some very promising materials based on spider proteins or seaweed is not yet complete and has not been widely marketed. Nevertheless, it indicates that more development is already in the pipeline. PERFORMANCE DAYS takes this opportunity to thank Camangi Corp, DuPont, Lenzing and Solvay for their pioneering work in the field of biodegradable fabrics and for their great support in preparing the chart above.

Blends

It is generally true that blending a biodegradable natural fibre with a biodegradable synthetic fiber leads to a biodegradable blend. However, combining biodegradable fibres (like coffee or kapok) and non-biodegradable fibres (such as normal polyester) will not lead to a 100% bio- degradable fabric. Most of the biodegradable blends that are currently available on the market are blends of purely natural fibres, whereas blends of natural and synthetic fibres are less often to be found. The following overview might be an inspiration:

Biodegradation in microbial active soil within 7 weeks*

* Source: AATCC „New Approaches Towards a Sustainable Textile Industry of Tomorrow“ PERFORMANCE DAYS thanks Christin Glöckner, Hohenstein Institute for her support!


Conclusion

Demand a specific definition

Unfortunately, the term “biodegradable” is not used correctly by everyone as it is generally undefined and is not legally protected (at least not everywhere). There is a huge difference between degrading and biodegrading. What is the difference? Cotton degrades to biomass i.e., it biodegrades. Plastics (PE, PP, P) degrade too, but only some plastics also biodegrade to biomass. Even radioactive waste degrades, but it takes up to millions of years. So, lots of materials need much longer to degrade than a human being lives! What a reasonable time is for something to decompose is left to your individual choice.

Some useful questions might be 
How to know... which material bio-degrades and which does not-biodegrade?
What materials... inside of your fabric are biodegradable? Everything?
Into what substance(s)... does this fabric degrade? Completely? Is it really biomass?
What happens, for example, with the color dyes in the fabrics?
What percentage is... biodegradable?
How fast... does it decompose (in months)?
How long... can the consumer use the product before it is destroyed?
Is this considered to be a disadvantage or an advantage?*
What environment... causes the material to degrade (Industrial composting, soil, landfill, water,  or marine)? Does it really end up in this environment?
How is it collected... and who tracks the product life cycle to ensure a closed loop from the  raw material to the finished textile and back to raw material.
Which data... is required about the product by the collector and where is data to be  found?
Where/How... does the user dispose of the textile?**
Who informs... the consumer and takes care that the textile can biodegrade?

* PERFORMANCE DAYS has no knowledge of any fiber that degrades while being worn. Possible advantage: Apparel that degrades directly after one-time-use, don‘t need to be washed. Right now the market demands garments that last, but maybe it is worth to follow this vision for the future? Possible disadvantage: E.g., biodegradable motorcycle pants might decompose over time so they might be less durable, less protective and therefore less save especially when needed most. ** Household vs. industrial composting? Home disposal could have the advantage of decreased transport costs and a smaller CO² footprint. Whereas, industrial disposal could possibly generate additional energy (e.g. gas) besides the biomass.

Take into consideration what happens with
  • Fabrics?
  • Accessories (buttons, zippers, labels, yarns, print...)?
  • Packaging materials?
  • Chemicals – such as color/dye or treatments?

Is this an eco-friendly solution?

Biodegrading in a marine environment

In a marine environment, material is broken down into microscopic sized parts, but these parts are not necessarily biomass (i.e., not necessarily nutrients that benefit the eco-system) and can still do harm to the environment (compost, soil, landfill, fresh water, marine life, etc.). This detail substantially influences the decomposition time and the final result.

Think about the following chart:

Source: Wikipedia „Approximate time for compounds to biodegrade in a marine environment“

Disclaimer: Despite the Focus Topic being prepared with great care, no guarantee or warranty of accuracy, completeness, or timeliness of the content is provided. Design & Development GmbH Textile Consult disclaims any and all liability in respect of this information.


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