A New Solution in the Plastic Pollution Crisis
Amorphous PHA Could Be an Answer
By Max Senechal, Chief Commercial Officer and Senior Vice President, CJ Biomaterials
More than 300 million tons of plastic are produced every year, and at least 14 million tons of that plastic end up in the ocean, making up 80% of all marine debris found from surface waters to deep-sea sediments according to a 2021 report by the International Union for Conservation. The concept of reduce/reuse/recycle is a very good, ambitious idea to help solve the problem of plastic waste, but given the amount of recycling that is performed, it is not practical as a stand-alone solution. According to a 2022 report released by the Science X Network, only 5%-6% of the plastic waste generated in the United States annually is ever actually recycled. It is clear that the growth of plastic use is increasing faster than the ability to recycle it. To truly address the challenge of plastic waste, advanced technology must be used to help provide an easier, more responsible end-of-life management solution. Polyhydroxyalkanoate (PHA) holds the potential to replace plastics’ linear use and disposal practices with a fully circular life cycle for plastics.
Why is it critical to address plastic pollution now?
In addition to the data shared above, the amount of plastic waste generated annually is expected to almost triple by 2060, from 460 million tons in 2019 to 1.23 billion tons, according to the Organization for Economic Co-operation and Development (OECD). That same report predicts that plastic leakage to the environment will double to 44 million tons per year, and that the buildup of plastics in lakes, rivers and oceans will also increase from 353 million tons in 2019 to more than one billion tons by 2060. All of this is expected to happen, despite the increased use of recycled plastics.
What are PHAs?
In 1926, the first polyhydroxyalkanoate (PHA), poly(3-hydroxybutyrate) was discovered by the French scientist Maurice Lemoigne during his work with the bacterium Bacillus megaterium. PHAs are polyesters usually produced by various bacteria and archaea as a form of carbon and energy storage. It is important to note that PHAs are natural products, much like wood.
During the past 50 years, much research and many development projects have been dedicated to the ever-growing class of PHAs. To date, the number of known PHA monomers has increased to more than 150, including unsaturated and aromatic monomers.
Amorphous PHA is a softer, more rubbery material that offers fundamentally different performance characteristics than crystalline or semi-crystalline forms of PHA that currently dominate the market. Amorphous PHA is a thermoplastic material that can be compounded with other biopolymers and processed into various shapes and forms including fibers, films, tubes, foams, textiles, microspheres, and molded constructs using standard processing techniques.
Amorphous PHA is a tough, ductile, pliable, and thermoplastic biomaterial. This biopolymer has excellent thermal processability and, in combination with other polymers, can be converted into various structures including fibers, films, tubes, and microspheres.
The material (amorphous PHA) works well as a modifier to other polymers or biopolymers and can be used to increase bio-based content, accelerate biodegradation and improve functional properties of resins and finished products.
PHAs are readily biodegradable and ultimately, the products of their degradation are carbon dioxide and water, and methane when it occurs aerobically and anaerobically, respectively. Environmental conditions, such as temperature and pH, and PHA properties, likewise monomer type, molecular weight, crystallinity, and surface area, directly influence the degradation rate. In the environment, PHAs are observed to have a relatively fast degradation mostly via microbial activity. This is why PHAs offer a better circular solution to the issue of plastic waste, because the plants that are used as feedstock are pulling CO2 out of the air, and products made with PHA-modified biopolymers biodegrade into CO2 and water, which are ultimately used by plants to grow and thrive (See Chart 1).
How are biomaterials changing?
Significant progress has been made over the last 10 years in using biodegradable polymers to address plastic waste. Polylactic acid (PLA), in particular, has made significant inroads, and it is the biomaterial of choice for the plastics industry. The challenge PLA faces is that it is very brittle and can be difficult to process, limiting its usefulness for certain applications. Modifying PLA with aPHA increases its flexibility as well as its toughness, making it a viable solution for numerous end products including snack bags, food packaging and countless others.
What is more, aPHA increases the rate of composting of PLA and other biobased polymers. Like PLA, aPHA is Technischer Überwachungsverein (TÜV) certified OK biodegradable under industrial compost. But, unlike PLA, it is also TÜV OK-certified biodegradable in soil and marine environments and also certified for home compost, meaning that it does not require specialized equipment or elevated temperatures to fully degrade.
Introducing aPHA as a modifier can make an immediate impact on the market. Global production capacity of PLA was approximately 335,000 tons in 2020, and that is not enough capacity to meet demand. A conservative estimate is that half a million tons of PLA needs to be produced to satisfy market demand. Looking beyond PLA to all biopolymers (PBAT, PBS, PBST, etc.), European Bioplastics estimates that total global production capacity of bioplastics will eclipse 7.5 million tons by 2026. aPHA can play a role across the entire spectrum serving as a modifier to improve functionality and biodegradability for bioplastics.
What are the packaging applications for aPHA?
There are applications for aPHA in the snack food, agricultural, organic waste, coatings and adhesives, personal care and healthcare markets. When considering the packaging industry, aPHA is a viable option to modify films for packaging. In fact, it is already being used in Korea to package a popular brand of tofu.
Packaging made with pure PLA films can be too rigid, and tear easily. If that same PLA film contains approximately 20% aPHA, it becomes more flexible, and at the same time it improves its toughness, making the package more tear resistant. Moreover, the inclusion of aPHA, can improve the rate of biodegradation, making it a valuable material for applications where the biodegradability of the product itself brings value. This includes compost bags and bins. Certain compost bags on the market today break or tear too easily, before the bags are taken away. Adding aPHA can correct this problem. Meanwhile, using the right mixture of aPHA in single-use food packaging could help make it compostable, allowing consumers to throw all their waste into the same bin when they are finished with it.
In the past, the holy grail for packaging was to increase bio-content and to have it be biodegradable, but today it is the ability to include on the package that it is ‘home compostable’ without having to include any caveats for specific conditions. aPHA is TUV OK-certified home compostable and can act in synergy with many other biopolymers, enhancing the biodegradable profile. It is sourced from renewable material and can be responsibly disposed of after its use, making it possible for manufacturers to develop a truly circular packaging solution.
About the Author
Max Senechal is Chief Commercial Officer and Senior Vice President of the Biomaterials Business at CJ Biomaterials. For information on CJ Biomaterials, visit www.cjbiomaterials.com