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”.

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:

Industrial compostability: specifications

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.
  
  

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*

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 

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:

*Postscript:

In November 2018, PERFORMANCE DAYS received information that might become relevant for this FOCUS TOPIC:

The German Parliament/Bundestag has worked on sheet WD8-028-15 entitled "Ausarbeitung: Biologisch abbaubare Kunststoffe" (biodegradable man-made materials). It says that drop-in-solutions like Bio-PET (Polyethylenterephthalat) and Bio-PVC (Polyvinylchlorid) are chemically identical with normal PET or PVC. Those are not biodegradable. Possible additive on those materials do support the (faster) oxo-degration - which leads to a fragmentation into microplastic. Whereas biodegration shall be defined as fragmentation into: water, CO², methane and biomass/minerals only.