Bioplastics — Dreams and Reality
Bioplastics look like the universal solution for all the world’s pollution problems. How far is it from reality?
It is no exaggeration to say that the concept of materials coming from nature is very attractive to the consumers and to the industry. The future looks bright if we’ll move someday to a world where plastics will be biodegradable and made without fossil resources. Potentially bioplastics could become an eco-friendly and economically successful new group of materials with manifold applications and beneficial properties.
On the other hand, there are some issues that have to be deal with before that dream comes true.
What are bioplastics?
Bioplastics are a broad family of materials (polymers) consisting of small molecules (monomers) linked together in a repetitive formation. Bioplastics are materials that could be biodegradable, bio-based or both.
Biobased plastics are derived from biomass that is used as raw material instead of petrochemicals.
Many people have a wrong idea that if something is delivered from biomass then it must also be biodegradable.
It is important to make a clear that not all bio-based polymers are biodegradable and that not all biodegradable plastics are bio-based.
Biodegradable plastics are created from molecules, which are recognized by enzymes present in nature. This materials can break down into smaller molecules, such as carbon dioxide, methane and water by microorganisms. They could be manufactured from plants, animals, microorganisms, or could be purely synthetic (man-made). The biodegradability of plastics depends on the raw materials and specific chemical and physical properties of the final product, as well as on the environment under which the product is expected to biodegrade.
Today less than 40% of bio-based plastics are designed to be biodegradable
Bioplastic can be 100% fossil based. Bioplastic can be 0% biodegradable.
Confused? Picture below will help you to navigate in the universe of biobased and petrochemical based plastics including their degradabilities.
For instance, polycaprolactone and poly(butylene succinate) are delivered from petroleum, but they can be degraded by microorganisms. Despite the fact that polyethylene and nylon can be produced from biomass or renewable resources, they are non-biodegradable.
What can bioplastics be made of?
The first bioplastics were made by using traditional agricultural and renewable resources such as cellulose, casein and soybeans. These materials were partially forgotten after discovering petroleum and natural gas plastics. Second-generation sources moved to non-food renewable sources such as switch grass, sawdust, hemp, castor beans, as well as the agricultural byproducts, including peels and husks.
Research continues on developing new resources for bioplastics; third generation sources include algae and modified methanobacteria.
The list goes on and on but I don’t want to keep you here all day!
Can bioplastics be the real solution to the plastic problem?
The Bioplastic Feedstock Alliance stated, “Biobased products represent an opportunity for positive change, but that does not mean that they are free of environmental impacts.”
Although the vision for green technology is inspiring,…
“BIO” does not automatically means “GREEN”
* due to intensified farming, extensive use of fertilizers, deforestation and grassland conversion;
** a portion of the biomass should remain on agricultural land to secure soil quality and natural habitats for animals;
** biodegradation is slowed down in dry climates and does not occur in absence of water and oxygen. The majority of biodegradable polymers do not instantaneously degrade, producing exclusively carbon dioxide and water. Degradation renders polymers brittle, thus their degrading dust-like invisible particles are still present and float around in the air;
**** the biodegradation takes place in different environments; some polymers need industrial composting, others work in-home composting and a limited number also in soil, sweet or even salt water. It is difficult to separate recycled biodegradable and conventional plastics by existing recycling facilities;
***** physical and chemical properties may include disadvantages, thus several modifications during the processing steps are necessary to modulate the final performances of bioplastics.
It is obvious, that not all bioplastics are created equally. Therefore, instead of looking at the distinction between plastic and bioplastic, we have to expand functional properties of bioplastics, explore its recycling procedures and clarify potential health and environmental hazards. We need real calculations and clarification instead of commercial tricks “bio, sustainability…”. We need to share information and make the right decisions regarding the future of our planet’s well being.
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Plastic Market Watch: Bioplastics. Released Summer 2016. Issue VI. Plastics Industry Association
