Polyhydroxyalkanoates (PHAs)

Definition of PHA:

Polyhydroxyalkanoates (PHAs) are polymers produced in nature, mainly as a result of bacterial fermentation.

What are PHAs?

PHAs are a family of naturally occurring polymers that can be produced from organic waste streams, biogas, sugars and fat-rich, plant-based feedstock. To date, there are over 150 known types of PHAs.

PHAs are synthsised through a fermentation process where small molecules bond together within a microorganism to produce a chain-like structure. These structures, known as polymers, are extracted, cleaned and in some cases pelletised, ready to be used in a myriad of applications.

What are the benefits of PHAs?

PHAs are best known for their high melting temperature, tensile strength and modulus. However, their chemical composition can be adjusted to form a soft and elastic material, making them ideal for flexible substrate applications such as PE, PET and paper for packaging and PVC for fabrics.

PHAs are a renewable alternative to fossil-based plastics, which help to reduce carbon emissions and harm to people and the planet through contamination or additives. In a world where single-use products are increasingly present in our lifestyles, a bio-based formulation can help to keep plastic pollution from our land and seas for centuries to come.

As well as being bio-based, they are also biodegradable, taking as little as days to break down in soil or water, compared to centuries for fossil-based plastics. As the energy storage element of bacteria, they contain the right enzymes to convert PHAs back to monomers and CO2, making them biodegradable by nature.

Therefore, PHAs are a circular solution as they can be reused, recycled or composted for future feedstocks.

What are the challenges associated with PHAs?

Although PHAs have the potential to replace single-use plastic products, further scaling and investment are necessary to make them a cost-effective alternative, as petroleum-based plastics remain cheaper and more widely produced.

Furthermore, due to being sourced from natural feedstocks, factors such as land use, food prices and environmental conditions must also be considered in the supply chain. Fortunately, there are several PHA manufacturers that are using waste and side stream carbon sources to avoid these issues, and are coming on line with larger scale production.

Finally, the benefits naturally found in PHAs may not be suitable for all applications, therefore some augmentation is required in the production process to ensure optimum performance.

What is the future of PHAs?

In response to increasing regulation and consumer demand, more organisations are reducing their use of petroleum-based plastics and exploring bio-based alternatives. With more widespread adoption and testing, there is the potential to benefit from efficiencies of scale to bring down costs and reap the benefits of bioplastics.

Stahl is currently testing potential PHA-based applications across our entire portfolio, and to support this transition, we have joined the Global Organization for PHA (GO! PHA), a non-profit platform that advocates and advances the use of PHAs. As a member of the network, we will join forces with the wider value chain to help move PHAs beyond the testing phase and accelerate their potential application in the coatings market.

Find out more about GO!PHA in our press release.

Not done, learning today?

No worries, we’ve got you covered. At Stahl, we are committed to transitioning toward a circular economy: increasing the biodegradability of our products will play a key role in that endeavor.
You can find out more about how Stahl is increasing our use of biodegradable chemicals check out these articles here: