What are bioplastics?
Today there is still no clear and precise definition of the term “bioplastics”. This is due to the fact that the world of polymeric materials is constantly expanding and evolving, leading to the need for continuous updating of the definitions provided. However, an official definition can be that provided by European bioplastics, an association representing the interests of the bioplastics industry in Europe.
According to this definition, bioplastics are not a single material. They comprise a whole family of materials with different properties and applications. However, a plastic material can be defined as bioplastic if it is bio-based or biodegradable, or if it has both.
More precisely, the term “bio-based” means that the material is derived (partly) from biomass (plants), i.e. from a renewable source. In particular, biomass for the production of bio-based plastics can be derived from sugar cane, maize, etc.
Specifically, however, the term “biodegradable” refers to the fact that the material is able to undergo the biodegradation process. This is a chemical process during which naturally occurring microorganisms convert the material into a substance of natural origin (e.g. water, carbon dioxide, etc.). The process depends not only on environmental conditions but also on the type of material: as mentioned above, not all materials are biodegradable.
The definition provided by European bioplastics reports an important difference, often confused. The property of biodegradability, in fact, differs greatly from being a bio-based material. In other words, it is not automatic that a bio-based plastic material is also biodegradable, contrary to common thinking! The capacity of biodegradation, in fact, does not depend on the origin of the basic constituent element of the material, but is closely linked to its chemical structure. Therefore, taking the concept to extremes, 100% of bio-based plastics may not be biodegradable; while 100% of plastics of fossil origin may be biodegradable.
Types of bioplastics
From the combination of the two conditions that define a plastic as a bioplastic, three different categories can be identified:
- bio-based and biodegradable plastics (e.g. PLA, PHAs, etc.);
- bio-based and non-biodegradable plastics (e.g. PE-biobased, PP-biobased, etc.);
- non-bio-based (i.e. produced from fossil resources) and biodegradable plastics (e.g. PBAT, PCL, etc.).