Plastic microparticles found in the environment have gotten a lot of attention lately. Many of the plastics are very durable and do not degrade in a reasonable time in the nature, although today there are also biodegradable plastics available. Small pieces of plastic can be found almost everywhere on the Earth and it is not fully understood what kind of consequences that could have for the human beings and environment. Therefore, replacing non-biodegradable plastics with biodegradable materials in packaging, clothes and cosmetics has high focus right now. Cellulose fibrils come from wood or other natural resources; are they biodegradable? Can they replace non-biodegradable plastic and reduce the amount of microplastics in the environment?
Biodegradability of cellulose
Cellulose, the building block of cellulose fibrils, is a very common material in the nature and present, for instance, in plant cell walls. Since cellulose is so common material, there are also a lot of microorganisms which are able to utilize cellulose for nutrition. Most of them are fungi or bacteria and they can use enzymes or radical generation for degradation of the cellulose chain. Since cellulose fibrils are made of the same material, there is a good chance that it is also biodegradable. However, also the physical form of cellulose matters, and solid particles (like cellulose fibrils) tend to be more stable than dissolved polymers. Is there any scientific data showing the biodegradability of cellulose fibrils? Let us have a look.
Biodegradability of cellulose fibrils
The researchers at VTT, Technical Research Centre in Finland, have studied the biodegradability of cellulose fibrils as concentrated suspension, film and in paper products in controlled composting test and pilot-scale composting test (find the original article here). These tests were based on EN standards which are used for evaluating the biodegradability of packaging materials. The tests showed that cellulose fibril films and concentrated suspension are biodegradable according to the EN 13432 standard, using cellulose powder or Whatman filter paper as a reference. Moreover, the researchers found out that 1.5% of cellulose fibrils in paper actually increased the biodegradability compared to reference paper. This might be related to the higher surface area of the fibrils compared to cellulose fibers.
In addition to biodegradation, it is important to know that the biodegradation products produced during the composting are not toxic. The above mentioned article studied also the degradation products by using V. fischeri bioluminescence test. Samples from the composting test were tested 7 days and 65 days after the starting point and no toxicity was observed. These tests together lead to the conclusion that the cellulose fibrils disintegrate during a composting process and does not produce any toxic biodegradation products.
New, compostable materials
Cellulose fibrils are made from natural raw material, cellulose, which is biodegradable by many microorganisms. This makes it an excellent alternative when designing new, fully biodegradable materials and avoiding microplastics. For example, the fibrils can be used for creating biodegradable packaging materials, cosmetic products without synthetic polymers or strong composites together with biodegradable plastics.