What are Plastics?
At the meeting on disposable plastics, the definition of plastics and the role of regenerated cellulose fibres in the application of the Directive (EU) 2019/904 (SUP Directive) were discussed (13 December 2019). In the guidance of REACH and ECHA, the Commission authorities had positions that cellulose fibres, such as viscose, cupro and also lyocell fibres, would be classified as ”plastics” on the grounds that the processes are chemical and the molecular weight of the cellulose is reduced.
In nature, cellulose is produced as a result of photosynthesis from carbon dioxide and water to produce oxygen. This cellulose, reinforcing plant cells e.g. in wood and leaves, is going through modification steps in order to reduce the molecular weight. This cellulose is also purified for paper and regenerated for viscose fibres. It is demonstrable that cellulose-based fibres are rapidly degraded in the oceans and produce glucose, either of which is part of the nourishment of marine plankton.
EDANA, the viscose fibre industry and all invited experts, including myself, and the Institutes (eg Nova) opposed this interpretation. According to that interpretation, paper should also be classified as ”plastic” because chemical processing of pulp uses chemicals and the molecular weight of cellulose is reduced. As an example of similar type of chemicals hydrochloric acid is actively digesting and degrading carbohydrates in our stommage.
Synthetic fibres are made from oil-based raw materials by polymer chemical processes. They also produce most of the marine micro-plastics that do not decompose in the sea.
It seems that when designing EU SUP (single-used-plastics) regulations, the left hand does not know what the right does. One of the driving forces behind the Horizon 2020 program, which is widely supported by the Commission, is the development of bio-based and circular economy based on natural raw materials. The development of the bioeconomy has been identified as of major importance for environmental and climate policy in most EU countries.
Man-made cellulose fibres, such as viscose, modal, lyocell, cupro, polynosic, ”fortisan” are regenerated, purified fibres made from wood and plant cellulose. Their polymer chain is not chemically changed. Their structural difference is related on physical differences in polymer crystallinity and orientation. Their chemical structure is close to bleached paper, and they show rapid biodegradation, as well. The chemicals used in the regeneration process are recycled in the process, and used for side-products, as well. In case pulp mill is integrated in the production of viscose fibers, the carbon dioxide warming potential could be negative (consuming carbon dioxide).
Cellulose exists naturally in different DP/PD values in wood and plants produced by photosynthesis and bacteria, and as glucose of zooplankton processes in marine environment, as well.
Cellulose is also depolymerized in natural conditions to lower molecular mass and finally to glucose.Cellulose exist naturally in different DP/PD and crystal values without any treatment, such as wood, cotton, linter, flax, sisal, hemp, bacterial etc. Natural celluloses are degraded in nature to lower DP values similar than in pulp, paper and viscose fibers. In viscose fibers, cellulose I is turned to cellulose II as the result of changed hydrogen bonds, which are secondary bonds. Secondary bonds do not share electrons and are not covalent chemical bonds. Thus, viscose is easily biodegradable and soluble compared with other forms of cellulose. As the conclusion, the definition of plastics in the Directive should not include viscose, cupro, lyocell and other regenerated cellulose fibers, which do not contain any chemically bonded substituent.
Pertti Nousiainen