Bioplastics are often promoted as an alternative to "conventional" (petro-sourced) plastics. We speak of biosourced plastics, biodegradable plastics and compostable plastics.
What concepts lie behind these names? What exactly do they mean? Are these alternatives better for the environment? Do they meet the environmental challenges of pollution control and waste management? Do they offer an opportunity for the plastics industry to redefine its business model and make it part of a circular economy?
Bioplastics
Bioplastics are in fact biosourced and/or biodegradable materials. Bioplastics are not necessarily synonymous with reduced environmental impact. In fact, they can sometimes raise new issues.
Bioplastics refer to two types of materials:
Biosourced plastics
Biobased plastics are plastics whose raw material comes from biomass (plants such as wheat, corn, beet, potatoes, algae, etc.). These plastics are not necessarily biodegradable, and the biomass used in their production is not usually organically grown.
For their manufacture, biomass can be mixed with other materials. These bio-based plastics therefore often contain a greater or lesser quantity of biomass, expressed as a percentage. The aim of this alternative is to diversify raw materials and reduce dependence on oil.
Biodegradable plastics
Biodegradable plastics, on the other hand, are supposed to break down by a natural chemical process (degradation by micro-organisms) into simple elements (carbon, hydrogen...). European standards define biodegradable plastics and govern their use. These include NF EN 13432: 2000, which designates plastics suitable for composting in an industrial environment, and NF T 51-800: 2015, which concerns plastics suitable for home composting.
Indeed, for a plastic to be considered compostable in an industrial environment, it must degrade 90% over a period of less than 6 months. However, industrial composting conditions require the material to be exposed to heat of between 50 and 70°C during this period. These conditions are difficult to achieve in the natural environment.
When these plastics end up in the oceans, for example, they do not degrade. There may also be partial degradation of the material, resulting in the production of micro-plastics that accumulate in soil and marine environments. They can then degrade into nano-plastics and inhibit the growth of certain green algae or the reproduction of crustaceans.
For a plastic to be considered suitable for home composting, it must be 90% degradable when exposed to heat between 20 and 30°C for a period of less than 12 months. Even then, the conditions for degradation are not always met.
Whether compostable in an industrial or domestic environment, ADEME recommends that these plastics be processed by industrial composting platforms.
To conclude, let's take a look at the ADEME website: (https://www.ademe.fr/expertises/produire-autrement/produits-biosources/passer-a-laction/dossier/valorisation-
fin-vie/options-fin-vie)
Received ideas: notions to be clarified
Biosourced and biodegradable are often mistakenly confused. The former refers to the origin of the raw material (biomass), while the latter refers to a product's end-of-life. The majority of biodegradable products are also biosourced (polylactic acid - PLA - for example), but some are of fossil origin (polycaprolactone - PCL - for example).
The vast majority of biodegradable and/or compostable materials (PLA, for example) can only be biodegraded industrially (standard EN13432, which governs the biodegradability of packaging in an industrial environment), in dedicated composting platforms and under precise conditions (temperature, humidity...) that cannot be found in an individual composter or in nature. Under no circumstances, therefore, should a biodegradable product be disposed of in the natural environment.
Ok compost labels for industrial and domestic composting:
Labels for products made from biobased materials:
