PHA vs PLA: What’s the Difference?

PHA and PLA are often grouped together under the term bioplastics, but they are very different materials. Both can be made from renewable resources and both are used as alternatives to conventional fossil-based plastics, but their production routes, material properties, processing behaviour and end-of-life options are not the same.

PLA is already well established in applications such as packaging, disposable products and 3D printing. PHA, on the other hand, is gaining more attention in applications where true circularity, biodegradability and the risk of persistent microplastics are important considerations.

Understanding the differences between PHA and PLA is important when selecting a material for a new product. The right choice depends on what the application needs to do, how it will be processed and what should happen to the material after use.

What is PLA?

PLA stands for Polylactic Acid. It is a thermoplastic polyester that is commonly produced from renewable feedstocks such as corn starch, sugar cane or sugar beet.

The process typically starts with the fermentation of sugars to produce lactic acid. This lactic acid is then converted into lactide and polymerized to produce PLA, by direct polycondensation or ring opening polymerization. 

PLA has become one of the most widely used bioplastics because it is relatively easy to process, commercially available at scale and suitable for many established production methods. It is commonly used in rigid packaging, cups, trays, films and especially in 3D printing.

PLA is generally known for being relatively stiff and transparent, although its properties can vary depending on the grade and formulation.

What is PHA?

PHA is short for PolyHydroxyAlkanoates. Unlike PLA, PHA is not one single polymer, but a broad family of polyesters naturally produced by microorganism through fermentation.

Under suitable conditions, microorganisms accumulate PHA inside their cells as a way of storing carbon and energy. The polymer is then recovered, purified and further processed into a usable thermoplastic material.

Different PHA types can have very different properties. Some are relatively rigid and highly crystalline, while others can be amorphous and thus much softer and flexible. This makes PHA a versatile material family that can be adapted for many different processing methods and applications.

At Helian Polymers, this diversity is an important part of how we work with PHA.
Material selection is not simply about choosing “PHA”, but about selecting the right type, grade or formulation for the intended application.

PHA is a family, PLA is a specific polymer.
This is one of the most important differences between the two materials.

How are PHA and PLA produced?

The production routes of PHA and PLA are fundamentally different.

PLA is typically produced by first fermenting renewable sugars into lactic acid.
This lactic acid is then chemically converted and polymerized into PLA.

PHA is produced directly by microorganisms. During fermentation, bacteria accumulate the polymer inside their cells. The PHA is then recovered and purified before it can be used as a raw material.

Both materials can therefore be produced using renewable carbon sources, but the biological process behind PHA is different from the chemical polymerization route used for PLA.

PLA:
Renewable feedstock → sugar → lactic acid → polymerization → PLA

PHA:
Renewable feedstock → fermentation → extraction → purification → PHA

Biodegradability and end-of-life

One of the biggest differences between PHA and PLA is how the materials behave at the end of their useful life.

PLA is commonly described as compostable, but in practice it generally requires industrial composting conditions with controlled (elevated) temperature and humidity to break down efficiently. Under normal environmental conditions, PLA can remain present for a long time.

Many PHA materials can biodegrade in a wider range of environments, because naturally occurring microorganisms are able to metabolize and digest the polymer. Depending on the specific PHA type, formulation and conditions, this can include environments such as soil, compost and aquatic systems.

This difference is particularly relevant in applications where there is a risk that material may accidentally, or intentionally enter the natural environment. In those situations, the ability of a material to biodegrade without leaving behind persistent plastic particles can become an important design consideration.

It is still important to look at the specific material and certification rather than assuming that every PHA or PLA grade behaves in exactly the same way.

How do the material properties compare?

PLA and PHA can both be used as thermoplastics, but their mechanical behaviour can differ significantly.

PLA is typically relatively stiff and has good dimensional stability, which makes it suitable for rigid products and structures. However, it can also be brittle in certain applications unless modified or blended with other materials.

PHA covers a much broader range of mechanical properties because it includes many different polymer types. Depending on the specific PHA, the material can range from rigid and crystalline to much more flexible and elastic.

This broader property range gives developers more possibilities when designing materials for a specific application. Instead of starting with one fixed polymer profile, different PHA types and compounds can be selected or formulated to achieve the required balance between stiffness, flexibility, toughness and processing behaviour.

How are PHA and PLA processed?

Both PHA and PLA can be processed using common plastics technologies.

PLA is widely used in extrusion, thermoforming, injection moulding and 3D printing. Its established processing behaviour and commercial availability have helped it become popular in many applications.

PHA can also be processed using familiar techniques such as injection moulding, extrusion, blow-moulding, film processing, thermoforming, coating and fibre processing.

The main difference is that PHA processing depends strongly on the specific type and formulation being used. Different grades can behave very differently during processing, which makes material selection and application testing especially important.

This is where practical development support can make a major difference.
At Helian Polymers, we do not only supply raw PHA materials, but also support customers with material selection, formulation, compounding, testing and processing trials.

Where are PHA and PLA used?

PLA is already widely used in applications where stiffness, transparency and established processing are important. Typical examples include food packaging, cups, trays, disposable items and 3D printing filaments.

PHA is being used and developed across a growing range of applications. These include packaging, consumer products, coatings, films, fibres, agriculture, adhesives, biomedical applications and material research.

New PHA grades and formulations continue to broaden the range of possible applications. In many cases, the material is being considered for products where end-of-life behaviour and the reduction of persistent plastic particles are important.

The choice between PHA and PLA therefore depends less on which material is “better” in general and more on what the product needs to achieve.

Which material should you choose?

There is no single answer to whether PHA or PLA is the right material. The best choice depends on the application.

PLA can be a strong option for products that require rigidity, transparency and a widely available biobased polymer. Its established supply chain and processing knowledge also make it attractive for many conventional applications.

PHA becomes particularly interesting when a wider range of material properties is needed or when biodegradation behaviour plays a more important role in the product design.

Questions around processing method, mechanical performance, product lifetime, end-of-life and the environment in which the product will be used all influence the decision.

For that reason, material selection should always start with the application rather than the polymer name.

From material choice to application

Choosing between PHA and PLA is only the first step in product development. Once a material family has been selected, the right grade, formulation and processing conditions still need to be determined.

At Helian Polymers, our focus is specifically on PHA. We work with raw PHA building blocks, existing PHA compounds and bespoke material development. This allows us to support companies and research teams from the first material selection through to processing trials and final application development.

The goal is not simply to supply a polymer, but to help develop a material and the converting process that works in the intended product.

PHA or PLA?

Both PHA and PLA have an important role in the transition towards new material systems.

PLA is already widely established and offers a practical biobased alternative for many rigid applications. PHA offers a broader polymer family with different material properties and an end-of-life pathway that can be particularly interesting for applications where biodegradation is important.

The right choice depends on what the material needs to do.