Mycelium technology| Bioplastics – Are they the solutions we have been waiting for?

Green sources have been our saviour in the reduction of fossil fuel pollution. May be they can do it again here. Besides, they are birds of the same feathers; our conventional plastics are made by the polymerization of the carbon in fossil fuel. However, not all biodegradable plastics are made from green sources. They are majorly two types namely bio-plastics and petrochemical based plastics enhanced with biodegradable supplements.

To aid our understanding of these different classes of biodegradable plastic; it is germane to first address a popular misconception which has caused some ecologists to raise their eyebrows at the idea of biodegradable plastics especially the petrochemical based biodegradable ones.

Oblivious of the slight discrepancy between these two terms: biodegradable and compostable, one may have the wrong conclusion about these solutions that nature has brought to us.

A material is said to be biodegradable if it can be naturally decomposed by microorganisms but the end product may not be free of harmful chemical substance. On the other hand, a compostable material is that which is able to decompose at a reasonable amount of time and nourish the soil without releasing any harmful chemical substance/gas into it.

A compostable material is always biodegrable, but a biodegradable material may not necessarily be compostable.

In other words, a cardboard is biodegrable and at the same time compostable but oil based plastic will degrade over time but eventually it may be harmful to the soil.
Now, that you have an understanding of these two terms, let us come back to our discussion.

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Bioplastics

These are natural polymers produced from renewable sources such as vegetables, corn starch, cellulose, other sugar derivatives etc. They are biodegrable and compostable and unlike the traditional plastic, they release no carbon dioxide into the atmosphere.

Additionally, they break easily within few weeks and are of commensurate physical quality with the traditional oil based plastics. There are many types of bio plastics and their characteristics depends on the base material used for its production e.g. protein-based, sugar cane, polyesters, fermented feed stocks (polyethylene) etc.

A very common base polymer material for bioplastics is a polyester called Polylactic acid (PLA) derivable from mainly corn starch, sugar cane and cassava through chemical processes such as condensation, polymerization etc. It can be made into different forms/products by extrusion processes. You can read about extrusion in this post by @adetola. PLA is widely used due to its significant physical qualities like the traditional polyethylene terephthalate (PET) plastics coupled with its unique ability to maintain original properties when it is chemically recycled.
It is also worthy to note that not all bioplastics are biodegradable; mostly those that are obtained by blending other artificial chemicals with biological sources or from genetically modified crops.

Companies like Natureworks, Evercorn etc. have brought these ideas to life with their innovative products. Another example is the bioplastic bottle [Veganbottle] recently developed in 2017 by a French company named Vegan. The bottle is made from sugarcane and expectedly it is 100% compostable. The choice of sugar cane is stemmed from the fact that it is an easy to grow crop requiring little water and do not affect the growth of other farmland produce. The bottle can also been made with the combination of sugarcane and other green sources such as cocoa, and wood with the same results.
Reports comparing the energy costs per production of bio-plastics and conventional plastics have also shown that the energy/fossil fuel consumed in the production of many bio-plastics is lower than the oil based plastics.

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Petrochemical based biodegradable plastics

These are plastics made from petroleum residue but enhanced with biodegradable additives. As you would have guessed, the essence of the additives is to enable them biodegrade. These additives are derivable from natural sources as well as different synthetic chemical compositions. The idea is to break the long polymer chain so that they can be easily consumed by microorganism. Several additives achieve biodegradation in different ways.

A more prominent method is the use of additives known as oxo-biodegradable additives that promote the oxidation of plastics when buried in landfills due to heat or exposure to UV light or oxygen. Examples of such additives are transition metals salts. Two major advantages of oxo-biodegradable plastics is that they do not produce methane gas as their end product and the length of time for which degradation should begin can be factored-in from the composition of the additives. Similarly oxo-biodegradable plastics can decompose anywhere whether in sea or on land

As we all know that plastics somehow find their way to water bodies, some other plastics are specifically enhanced to degrade in a set time in the presence of a reasonable amount of moisture and so they are called hydro-biodegradable plastics.
In general, based on the type of additives used, biodegradable plastics can also be categorized into: oxo-biodegradable and hydro-biodegradable plastics.

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Mycelium technology

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This technology is taking a different approach from the status quo. The idea here is to produce ecofriendly substitutes for plastic packaging materials from agricultural waste using the root-structure of mushroom called mycelium as living glue. This idea is scalable and has also been used to produce durable wood-like materials for furniture, buildings from hemp, mycelium and starch without falling any tree. Amazing, right? Yeah.

Let’s quickly talk about mycelium. Mycelium is an essential part of a fungus through which it absorbs nutrients. It is white natural glue that powerfully binds the structure of fungi in whatever form. Fungi can exist as an organism with just one cell e.g. yeast or having many cells as in the case of mushroom. Mushrooms are like fruits on the tree called fungi but the larger parts of the organism are underground. Fungi are produced from dead or decaying organic or inorganic materials and so they can be cultured. A common example is the growth of molds (fungi) on stale bread. Mycelium grows in fungus like a tree having many branching networks with every branch firmly connected together. This is why the largest living organism on earth is found to be a honey fungus 3.8km wide.

While this idea still sounds like science fiction, a company known as Ecovative has set the ball in motion. The company has developed and productized a mycelium based material that can replace the popular polystyrene packaging material called Styrofoam. The processes involved in the manufacture of materials through this means are quite simple. Mycelium is added to the pallet form of agricultural wastes such as husks, corn stalks after the waste have been pasteurized. This composition is then placed in container to bring out the shape desired. The mycelium is allowed to grow in the container for about four-five days after which its growth is stopped by pasteurization and then the product becomes solid. So, it would not be wrong to say that the product is practically grown.

Interestingly, such materials are durable, lightweight, safe, biodegradable and can be composted even in homes. The strength of products derived through this means is a function of mycelium

So, do we have the solution we need?

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We are getting closer to victory but there are still setbacks associated with these solutions. Making petrochemical plastics biodegrade is a nice development that will lower the rate of plastic pollutions but the fact that most of their end products (methane gas) will still be dangerous to the environment is what makes bio plastic a better solution.

In the words of Malinconico et al. in one of their papers about the natural polymers and additives

biodegradability, although important cannot be the only driving force for the market acceptance of so called “green” plastics and chemicals.

This is the main reason why ecologists and other scientists have considered the idea of using additives with oil based plastics a false solution

Bioplastics on the other hand obviously eliminates this shortcoming as it leaves no trail behind but there are concerns that the production of bioplastics from plants in large quantity could result in increment in the price of agricultural products as farm crops that should be grown for consumption purposes may now be used for bioplastics

Also, some bioplastics bottles are said to have similar physical features with the traditional plastics which is a problem because they cannot be recycled together due to their different chemical compositions. In other words, this similarity will make collection and recycling of plastic bottles a tedious job.

Despite the importance and features of mycelium based products, there are already disapprovals stemmed from the fact that they are produced from fungus. This is actually a misinformed view and the discovery of penicillin for example should change the heart of anyone thinking in that direction. Similarly, the production of mycelium based material takes time compared to the conventional plastics and presently, only few products can be manufactured through this means.

Final thought

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Some of these solutions may not look like it yet but they are definitely good steps in the right direction and it is safe to conclude that we are getting closer to the end of this long battle. The inability of plastics to biodegrade is big issue but the bigger picture even seems to be what comes after decomposition.

Fortunately, bioplastics can handle both problems. Mycelium technology on the other hand may not be our immediate answer, but it looks very promising. Similarly, if recycling could be wholly deployed in every corners of the world, this issue would soon be long forgotten.

I hope you enjoyed the ride. Hopefully this article has brought you up to date about the happenings near and far in the world of plastics. Let’s do this again. Thank you for reading.

References

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• A whopping 91% of plastic isn’t recycled
• Biodegradable plastics
• Biodegradable and compostable alternatives to conventional plastics
• Bioplastic
• Enhancing Biopolymers: Additives Are Needed for Toughness, Heat Resistance & Processability
• Bioplastics and biodegradable plastics
• Mushrooms: An ecological alternative to plastics?
• The technology that will build our future may be found in mushrooms
• Malinconico, M., Cerruti, P., Santagata, G., Immirzi,B. Natural polymers and additives in commodity and specialty applications: A challenge for the chemistry of future.

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