Bioplastics : magic or another trick ?

Bioplastics, biosourced plastics, biodegradability, what is the reality behind these magic words?

Bio means life, Bio makes us at ease, and it sounds so good. These two little syllables comfort us and whisper in our ears that everything will be fine. As our society slowly becomes aware of the ravages of its addiction to single-use plastic on the Ocean, on biodiversity, on the planet and on ourselves, new words have appeared on our shelves.

Bioplastic, biosourced plastics, biodegradable… The SeaCleaners looks at the scientific realities behind these appealing keywords.

Bioplastics, an ecological headache

Bioplastic is a rather vague term, it can include the best and the worst, and many producers are waiting for this name to be regulated.    According to the definition given by Wikipedia: “bioplastics include a large number of materials and products that are biosourced, biodegradable/compostable, or both”.

Bioplastics therefore include both biobased plastics containing materials of animal or plant origin and petroleum-based plastics that can degrade under very specific industrial conditions (often creating even more serious problems).   

As 60% of the biosourced plastics on the market¹ are not biodegradable, it is clear that bioplastics are an ecological headache.   

To see more clearly in bioplastics, it is necessary to explore biosourced plastics on the one hand and biodegradable plastics on the other.  

Bio-based plastics, the polymer would melt in its mouth

Biosourced plastics are therefore produced in part or in full from materials of plant or animal origin. Corn, soya, palm, sugar cane, castor oil, algae, mushrooms, etc. Numerous are the origins of plastics. 

For the record, bio-based plastics are not new: for example, milk protein, casein, reacted with formaldehyde to produce galalith, a plastic widely used in the manufacture of buttons, electrical equipment and jewellery at the beginning of the 20th century.   

Beyond casein, various protein sources have been tested… But more expensive than petroleum-based plastics, biosourced plastics are still rarely preferred by manufacturers.  

Very few biobased plastics are 100% biobased. The reason is simple: As the major constituents of plastic materials are polymers (of natural or non-natural origin), fillers and additives.  

While polymers and fillers can be synthesised from naturally occurring elements, it is more difficult to reproduce the requirements of the additives that give the plastic its technical properties in the same way.  

Thus, today, the vast majority of biobased plastics also contain petroleum derivatives.   

While some producers play on the ambiguity and are comfortable with this situation, others are working hard to solve this problem and create products without petrochemical additives.  

Finally, biobased plastics can pose an ethical problem.   

We know that global agriculture is under stress, that water resources are dwindling, that agricultural soils are in increasing demand, leading to the destruction of ecosystems and the habitat of many species. It doesn’t seem like a very good idea to rely on corn, soy or palm to feed our addiction to plastic.  This is an element to be taken into account in the choice of the origin of bioplastics by the manufacturers.  

Biodegradables, a lie by omission ?

Ah, the famous biodegradable wipes that block the pipes and are the scourge of wastewater treatment plants (3/4 of the interventions on the ground, for an annual cost of up to 1 billion euros for the European Union), or the biodegradable bags found intact 3 years after being buried… They have become symbols of the vagueness surrounding the term biodegradable.   

In fact, this term refers to the ability of a product to decompose and be effectively “bio-assimilated” by the environment under the action of micro-organisms and factors such as humidity, heat or the presence of water.   

Virtually everything is biodegradable… A plastic bag is biodegradable… It just takes 450 years to decompose.   

As you will have understood, the term biodegradable does not give any information such as the speed of this degradation or the particular conditions under which the material in question can degrade.   

Since 1 January 2022, the use of vague terms such as “biodegradable” or “environmentally friendly” on a product or packaging is prohibited in France.  

Did you know? From 1 January 2022, products and packaging that can be composted in industrial composting will no longer be allowed to have the word “compostable” on their packaging. Those that can be composted in domestic conditions will have to be labelled “Do not throw away in nature”.  

Indeed, to be degraded, these materials must respect very precise conditions (burial, temperature rise), as industrial composting cannot be reproduced in domestic compost, and domestic composting does not allow this plastic to become wild waste. 

To solve the plastic crisis, the magic material will not be enough: the entire value chain must be reconsidered 

In spite of this, we are also dreaming of a perfect bioplastic, 100% biosourced and made from waste, a carbon sensor, with all the properties of plastic, biodegradable under all conditions and without toxic residues, and competitive with traditional plastic.  

Perhaps one day this magical material will become widespread. But for it to be truly virtuous, the entire value chain will have to be rethought.  

Today, most compostable bioplastics are not recycled at their true value because the recycling chain is not yet fully developed.   

Today, the life cycle of a bioplastic such as PLA, a bioplastic generally made from corn or rice, makes it more polluting than a traditional recycled plastic.   

Its manufacture requires more energy and water resources.   

Although it is officially compostable in industrial conditions, its decomposition time is 12 weeks (compared to 4 weeks for organic waste), which is too long for a traditional composting process, and it is sometimes redirected towards the incinerator.   

This is the conclusion reached by the market gardener Agricool when they carried out a life cycle analysis of their products. They abandoned PLA, and instead adopted R-PET (recycled PET), which is less water-intensive, less CO2-intensive and well recycled.   

And Agricool concludes: “We are just one link in the recycling chain and changes must be made at all levels: by brands, by consumers (in the way they sort and consume) and by waste recovery centres.

Conclusion : The superhero is still far to be the magic bio-plastics. Instead YOU have the superpowers ! Control your plastic consumption. Apply the five Rs: refuse, reduce, reuse, recycle and return to the earth.

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Sources 

Atiwesh, A. Mikhael, C.C. Parrish, et al.
Environmental impact of bioplastic use: a review
Heliyon, 7 (2021), p. E07918
 

Biodegradability of Plastics: Challenges and Misconceptions
Stephan Kubowicz and Andy M. Booth
Environmental Science & Technology 2017 51 (21), 12058-12060

 

Shen, J. Haufe, M.K. Patel, Product overview and market projection of emerging bio-based plastics – PRO-BIP 2009, 2009.

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