PHAs are fully biodegradable

PHAs have the highest potential among all bioplastics due to their easy and well shown biodegradability. The biodegradability of PHAs has been studied for decades. But what does it mean “biodegradable”? We might imagine a plastic bag slowly disappearing in the ocean, but it is not the whole story. Let’s get more proper picture about the biodegradability.

What does “biodegradable” mean?

The principle of biodegradation is based on the activity of living organisms in the degradation process. The microorganisms are the actors of biodegradability in the most cases. Here we focus on the biodegradability of polymers.

If something is biodegradable, it does not mean it can be littered into the environment without regrets. No waste should get into free ecosystems.

The word “biodegradable” should never stand alone. It is meaningless, if not specified WHERE the material is biodegradable.

The biodegradability is influenced by the conditions of the environment and the properties of the polymer.

Environment

Fresh and waste water
Soil
Marine environment
Industrial composting
Home composting
Landfill
Aerobic
Anaerobic

Environmental Conditions

The microorganisms
Temperature
Moisture
pH
O2 content
Other carbon source availability
UV radiation
Salinity
etc.

Polymer Properties

Chemical formulation
Particle size
Surface properties
Shape of the particle
Porosity
Crystallinity
Molecular weight
Polymer processing
Impurities
Additives

Scheme 1: The biodegradability is influenced by the conditions of the environment and the properties of the polymer. 1-6

References

1 Volova, T., E. Shishatskaya, N. Zhila, et al., Eds. New Generation Formulations of Agrochemicals. New York: Apple Academic Press, 2020.

2 Fernandes, M., A. Salvador, M. M. Alves and A. A. Vicente. Factors affecting polyhydroxyalkanoates biodegradation in soil. Polymer Degradation and Stability. 2020, 182: 109408. doi: https://doi.org/10.1016/j.polymdegradstab.2020.109408.

3 Dilkes-Hoffman, L. S., P. A. Lant, B. Laycock and S. Pratt. The rate of biodegradation of PHA bioplastics in the marine environment: A meta-study. Marine Pollution Bulletin. 2019, 142: 15-24. doi: https://doi.org/10.1016/j.marpolbul.2019.03.020.

4 Manna, A. and A. K. Paul. Degradation of microbial polyester poly(3-hydroxybutyrate) in environmental samples and in culture. Biodegradation. 2000, 11(5): 323-329. doi: 10.1023/A:1011162624704.

5 Kim, M.-N., A.-R. Lee, J.-S. Yoon and I.-J. Chin. Biodegradation of poly(3-hydroxybutyrate), Sky-Green® and Mater-Bi® by fungi isolated from soils. European Polymer Journal. 2000, 36(8): 1677-1685. doi: https://doi.org/10.1016/S0014-3057(99)00219-0.

6 Šerá, J., L. Serbruyns, B. De Wilde and M. Koutný. Accelerated biodegradation testing of slowly degradable polyesters in soil. Polymer Degradation and Stability. 2020, 171: 109031. doi: https://doi.org/10.1016/j.polymdegradstab.2019.109031.