Bioplastics: an ecological alternative
Why use PHA plastics?
For the health of the planet and its inhabitants, it is essential to produce biodegradable plastics in order to reduce our dependence on non-renewable petroleum resources. But what are they? According to the European Bioplastics organization, the types of bioplastics are :
- plastics of biological origin, but not biodegradable (polyethylene – PE)
- biodegradable plastics of biological origin (polylactic acid – PLA, polyhydroxyalkanol – PHA, polybutylene succinate – PBS)
- compostable fossil-based biodegradable plastics such as aliphatic polyester
The 3 environmental benefits of PHA
- Reduced plastic waste: PHAs are biodegradable and help reduce the amount of persistent plastic waste in the environment. They decompose naturally, leaving no trace behind.
- Reduced carbon footprint: the production of PHA from renewable sources generates fewer greenhouse gases than the manufacture of petroleum-based plastics.
- Organic waste recovery: some PHAs can be produced from agricultural or industrial waste. This circular method makes the most of by-products and residues.
PHA: a natural and (therefore) biodegradable product
PHA (Polyhydroxyalkanoate) is produced by certain bacteria as an energy source. It is by definition natural. Unlike traditional petroleum-based plastics, the various types of PHA are biosourced. They are produced from renewable raw materials such as sugars, vegetable oils or other biomasses. These bioplastics are also distinguished by their ability to biodegrade in a variety of environments. Whether in soil or water, they represent an ecological alternative to conventional plastics.
How is PHA produced?
A biosourced plastic thanks to mobilized bacteria
PHA production is based on a fermentation process. It involves specific microorganisms capable of synthesizing these polymers under certain conditions. Indeed, they set up a survival mechanism when :
- there is a lack of certain nutrients
- in the presence of excess carbon in their nutrient environment
PHAs are then accumulated in the form of microscopic inclusions (granules, as it were) that constitute an energy reserve for the bacteria. In other words, this defensive reflex produces matter.
The 5 main stages in the industrial manufacture of PHA
- Natural raw materials and micro-organisms. The process begins by sourcing renewable raw materials to feed the micro-organisms. Glucose, vegetable oils (such as canola or soybean oil) or other carbon sources derived from agricultural waste can be used. PHA-producing microorganisms are grown and multiplied in a fermentation reactor on an ideal nutrient medium. Temperature, oxygen pressure and pH are controlled.
- In the presence of nutrient stress (such as nitrogen or phosphorus limitation), the micro-organisms react. They begin to accumulate PHA granules inside their cells.
- Once the bacteria have produced sufficient PHA, they are harvested and lysed. Their cell walls are then broken down to extract the polymer. Extraction can be carried out by various methods (mechanical, chemical or enzymatic).
- After extraction, the raw PHA is purified to remove impurities. Once the material is clean and usable, it can be exploited by industry.
- The purified polymer can be transformed into various products by molding, extrusion or other conventional processes. PHA can be used in the same way as traditional plastics.
What are the properties and technical advantages of PHA?
PHA = biodegradable
First and foremost, PHA is biodegradable. This bioplastic deteriorates naturally in any environment. Whether in compost, soil or even seawater, PHA will disappear. This aspect sets it apart from its cousins, where micro-particles can persist for centuries.
PHA = biosourced
Being a biosourced material, PHA is (by default) biocompatible. Non-toxic to humans, it can be used for medical applications such as sutures, implants and drug capsules. For biomedical applications, PHA is the perfect choice.
PHA = strength
Depending on bacterial strains and production conditions, PHA can have a wide range of properties. From rigid, resistant materials to flexible, elastic films, this material can be adapted to specific uses. This mechanical variability is an asset for industry.
PHA = renewable
Unlike petrochemical plastics, PHA is produced from renewable raw materials. This eco-responsible aspect helps reduce the overall carbon footprint and also avoids drawing on natural resources. The important thing is to produce without using, but also without leaving…
PHA represents a promising innovation in the field of sustainable materials. Its biodegradability, biocompatibility and renewable origin make it an ecological alternative to traditional plastics. This bioplastic makes it possible to reduce the environmental footprint of many products, winning over the planet and its inhabitants alike.
