The Rise of Polyhydroxyalkanoates (PHA) in Packaging: A Unique, Biobased Solution for Sustainability

Polyhydroxyalkanoates (PHAs) stand out as a promising alternative to conventional, fossil-based plastics like polyethylene and polypropylene. Image courtesy of CJ Biomaterials.

By Jerri DiRenzo, Senior Director of Applications and Development, CJ Biomaterials

As the global demand for sustainable packaging grows, brands and manufacturers are increasingly turning to biobased materials that can offer both environmental benefits and superior performance. Among these materials, polyhydroxyalkanoates (PHA) stand out as a promising alternative to conventional, fossil-based plastics like polyethylene and polypropylene. In this article, we explore the unique advantages of PHAs and how they are accelerating the transition to biomaterials in the packaging industry.

The Unique Benefits of PHA in Packaging

PHAs are a class of polyesters that are produced via microbial fermentation. Biobased PHAs use renewable feedstocks, such as sugarcane, as a sustainable sugar source for the fermentation process. What sets PHA apart from other biobased plastics is its versatility and environmental performance. Unlike fossil-based plastics, PHA has a low carbon footprint and is both biodegradable and compostable in all environments, making it an ideal candidate for packaging that needs to comply with evolving waste legislation and greenhouse gas emissions reporting.

While there are numerous PHA variations, today there are two primary forms that can and are being used to make plastic packaging more sustainable. There is a soft, rubbery form of PHA known as amorphous PHA (aPHA) that works well as a modifier to other polymers and biopolymers including polylactic acid (PLA) and semi-crystalline PHA (scPHA). The aPHA can be used to tailor the properties of both rigid and flexible packaging structures, while maintaining high levels of biobased content and compostability.

In rigid thermoforms for food packaging and food serviceware, adding aPHA to PLA will improve mechanical performance of neat PLA, improving impact strength and toughness to levels that meet the specifications required for use in automated food packaging lines, while still maintaining transparency. The blend also maintains high levels of certifiable biobased content and can accelerate the composting process for PLA giving packaging engineers a broader range of thicknesses when designing packaging, while providing dramatic improvements in tear propagation resistance, puncture toughness, and tensile elongation relative to neat PLA. In blends where aPHA is incorporated into PLA at levels exceeding 30%, results show that these films meet certifiable home composting conditions. Blown films using aPHA can be either transparent or opaque and are ideal candidates for snack food packaging, produce bags, frozen food bags, and other flexible packaging applications where compostability is a desired attribute.

PHA is commonly available as a semi-crystalline polymer that is suitable for applications requiring greater stiffness and high-heat stability. The scPHA can be used on its own or in combination with aPHA to better tune mechanical properties to a specific packaging or foodservice application. Injection molded cutlery and drinking straws are two examples currently making use of the unique mechanical properties enabled by a compound of aPHA and scPHA, while delivering on sustainability criteria for compostability and biobased content.

While these initial applications that incorporate blends of aPHA with PLA are promising, we are still at the beginning of our journey in developing blends of biopolymers that provide effective, sustainable alternatives to traditional packaging application. Traditional plastics have been available for over 60 years, providing manufacturers and supply chains multiple decades to optimize fossil-based polymer production and conversion into packaging. Alternatively, scPHA has been available for less than 20 years and aPHA has only been available for the past 2 years. New biopolymers and biopolymer blends are more frequently being introduced. Within the PHA family alone, there are over 150 types of PHAs that vary in structure and properties. This breadth opens a wide design window for packaging converters and brandowners.

Polyhydroxyalkanoates (PHAs) are a class of polyesters that are produced via microbial fermentation. Image courtesy of CJ Biomaterials.

Key Drivers for PHA Adoption

As consumers become more aware of the impact plastics have on the environment, climate, and even their health, there is an increasing demand for packaging solutions that are not only compostable but also free from harmful chemicals like PFAS (per- and polyfluoroalkyl substances) and phthalates. PHAs, in particular, have consistently shown that they are free from these chemicals of concern by obtaining not only food contact certification from the US Food & Drug Administration, but also undergoing ecotoxicity and PFAS-specific testing that is required when certifying a material for compostability with accredited 3^rd parties like the Biodegradable Products Institute (BPI) or TÜV Austria.

With the prevalence of new research identifying the presence of microplastics within environments and human tissues, concern regarding their impact is quickly growing. Increasing the use of materials, like PHA, that have the inherent ability to hydrolyze and biodegrade in soil and marine environments, will prevent the creation of more persistent microplastics in the environment.

The desire to make compostability faster and more flexible is also driving PHA adoption. Composting is a varied process with no universal industry standard beyond recommended best practices guiding compost site operations, nor a single composting technology that applies everywhere. Materials must be adaptable and capable of breaking down within a range of conditions.

PHA’s flexibility makes it well-suited for this challenge. By varying the use of aPHA and scPHA, or adding aPHA to PLA, packaging applications can be designed for various composting environments, helping to create solutions that work in both commercial and home composting systems. Additionally, advancements in PHA formulations allow for the development of thicker, stronger parts that still degrade within certifiable composting timelines, addressing the misconception that compostable materials must be fragile or lack durability.

The fast-evolving regulatory and legislative landscape is also playing an important role. Across the US, five states have passed extended producer responsibility (EPR) laws focused on packaging. The growing trend is to allow for packaging that is either recyclable or compostable with reduced fees for packaging that can be processed through these pathways. As a result, PHAs are being used to drive new developments in compostable food packaging and formats that are not accepted or processed in the current recycling infrastructure.

As these drivers are creating opportunities for the adoption of PHA-based packaging and food serviceware, 3^rd party certification of sustainable attributes like biobased content or compostability is presenting both an opportunity and a challenge. Right now, there is no certification for testing the physical recyclability of each new plastic package or item that comes to the market. Comparatively, each new packaging or product seeking compostability certification must be evaluated or tested according to international standards. For biobased content or compostability, there are many required certifications that verify accurate, standardized testing has been conducted to back up the claims.

Within the U.S. alone there are several relevant certifications that have been built around international test standards and specifications:

• BPI (Biodegradable Products Institute) certification for industrial compostability
• TÜV Austria OK compost HOME, OK compost INDUSTRIAL, OK biodegradable SOIL, and OK biodegradable MARINE
• USDA Biopreferred for biobased content
• OK Biobased for biobased content

The bar for materials that want to claim biobased content or compostability is high. It should be. However, it is important to recognize that the cost of certification is a very real challenge for rapid material innovation and new materials and applications that are entering the market. The time and expense of testing each new formulation or packaging design is considerable. When packaging destined for recycling does not require similar rigor in its claims or efficacy, the unintended consequence is the creation of an imbalance for how quickly innovation can happen.

PHA has a low carbon footprint and is both biodegradable and compostable in all environments. Image courtesy of CJ Biomaterials.

Composting or Recycling?

It is important to note that compostability does not need to compete with recycling — the two approaches can and should coexist. Certain types of packaging, particularly food-contaminated items like condiment packets and takeout containers, are unlikely to be recycled due to challenges with the materials and the food scraps.

For items containing food or small format flexible packaging, composting provides an optimal end-of-life solution. When diverting food-bearing packaging and serviceware to compost, it helps keep food scraps out of landfills where they emit methane. In fact, due to food scrap degradation, landfills are the third largest source of methane emissions in the U.S. according to the Environmental Protection Agency (EPA). By using compostable packaging for these hard to recycle and food-related applications, biopolymers like PHA can have an impact on both reducing plastic waste in landfills and reducing potent greenhouse gas emissions. At the same time, recyclable materials still play a critical role in circular packaging systems, especially where beverage bottles are considered.

Ultimately, as brands work toward sustainability goals, the conversation must shift beyond just “compostable vs. recyclable” and toward a broader strategy that incorporates both approaches in a way that provides the best sustainable solution for the specific package and product.

Looking Ahead

PHA holds significant promise, but realizing its full potential requires a concerted effort from all stakeholders. Transparency across the supply chain, from raw material sourcing to product manufacturing, is critical for building consumer trust in the performance and sustainability attributes of PHA-based packaging and food serviceware.

Industry collaboration is equally essential. Material producers, converters, brands, certifiers, and composters must all work together to address technical challenges, optimize production processes, and develop innovative applications for PHA. This includes working together to grow composting infrastructure and other end-of-life solutions for PHA-based products.

Cost competitiveness also remains a key hurdle, and collaborative efforts to improve production efficiencies, and achieve economies of scale will be vital for PHA to become a mainstream material. This will require significant investment from brands willing to champion these new materials and support the development of the necessary infrastructure. Just as early adopters of previous plastic technologies helped drive down costs and expand applications, brand leadership will be essential for PHA to reach its full potential.

The success of PHA hinges on a shared vision and a commitment to working together so that we can benefit from the use of bioplastics and minimize the negative environmental or safety impacts found with some traditional plastics. As the PHA industry grows, it’s essential to remember that when one succeeds, we all succeed. A thriving PHA market benefits everyone involved; producers, brand owners, and consumers. A collaborative approach, coupled with strategic brand investment, will be key to unlocking the full potential of this promising biomaterial.

About the Author

Jerri DiRenzo is the Senior Director of Applications and Development with CJ Biomaterials. Two PHA variations produced by CJ Biomaterials are certified via USDA Biopreferred for biobased content and the Biodegradable Products Institute (BPI) for industrial compostability. They are additionally certified by TÜV Austria as OK compost HOME, OK compost INDUSTRIAL, OK biodegradable SOIL, and OK biodegradable MARINE.Visit: https://cjbiomaterials.com