Flexible plastic films from PLA

Innovative film material made from the bioplastic PLA

Dr. Benjamín Rodríguez, Dr. Antje Lieske and Dipl.-Ing. (FH) André Gomoll of the Fraunhofer IAP received the Joseph von Fraunhofer Prize 2024 on 12 June 2024 for outstanding scientific achievements in solving application-oriented problems.

The packaging market is currently dominated by the plastic polyethylene (LDPE, low density polyethylene). However, this is petroleum-based, non-biodegradable and can only be mechanically recycled with a loss of properties.

The polyester polylactide (PLA), on the other hand, is bio-based, biodegradable and can be chemically recycled into new plastics with comparatively little energy input. Due to its high brittleness, however, it is not suitable in its conventional form for the production of flexible disposable packaging such as carrier bags or bin liners, which are among the main sources of single-use plastic waste. In addition, PLA can only be produced profitably in continuous large-scale plants, which has so far excluded smaller companies as manufacturers.

Our research team has succeeded in developing a flexible and recyclable material for film applications based on PLA and enabling the commercialization of these so-called PLA block copolymers for medium-sized companies. This provides the packaging market with an alternative, sustainable material.

Project movie (German)

Interview with our award winners

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Why is the development of new types of bioplastics necessary?

© Fraunhofer, Photo: Piotr Banczerowski
Dr. Antje Lieske studied synthetic chemistry at the HU Berlin. She completed her doctorate at the TU Berlin and at the Fraunhofer IAP, where she has been working since 1993. She has been head of the "Polymer Synthesis" department since 2004.

"Our motivation to develop innovative bioplastics lies on the one hand in the urgency of defossilizing the economy. After all, dependence on petroleum-based raw materials is not only problematic from an ecological point of view, but also in terms of the finite resources and geopolitical dependencies that go hand in hand with it.

Another key aspect is the circular economy. In an ideal circular system, as much material as possible is recycled, but in practice there are always unavoidable losses. To compensate for these losses, we need sustainable sources of carbon. However, this is a challenge because there are usually no bio-based analogs for fossil plastics with the same material properties.

This is where our development work comes in: PLA can play a key role in both aspects - i.e. defossilization and circular economy. We are developing new types of PLA materials that are bio-based and biodegradable and at the same time have the material properties of petroleum-based plastics."
What makes the new PLA material so special?

© Fraunhofer, Photo: Piotr Banczerowski
Dr. Benjamín Rodríguez studied chemical engineering at ITESM, Monterrey, Mexico (Bachelor). He completed his master's thesis and doctorate at TU Berlin and Fraunhofer IAP. He has been a post-doc in the "Polymer Synthesis" department since 2022.

"PLA has one of the strongest market potentials in the bioplastics sector. It is bio-based, biodegradable and easily recyclable. Due to its high rigidity, PLA is predestined for rigid packaging, e.g. the trays in which tomatoes are sold. However, it is too brittle for flexible film applications such as plastic wrap.

To make PLA more flexible, plasticizers are usually mixed in as an additive. However, the plasticizer molecules migrate out of the material over time, causing the PLA to become stiff and hard again.

To prevent this migration, we have chemically anchored plasticizers, so-called polyethers, directly in the PLA. Polyethers are non-toxic, commercially available and can also be produced biobased. This means that the plasticizer cannot migrate in the synthesized PLA block copolymers and the material remains permanently flexible.

In addition, the new film material is at least 80 percent bio-based. We will increase this figure to almost 100 percent in the future.

We will also integrate a process step for the chemical recycling of PLA into the existing process.

This new class of bioplastics therefore has unique material properties and will make an important contribution to making plastic packaging more sustainable in the future."
Can the flexible PLA film material already be used industrially?

© Fraunhofer, Photo: Piotr Banczerowski
Dipl.-Ing. (FH) André Gomoll studied "Packaging Technology" at the Berlin University of Applied Sciences. He completed his diploma thesis at the Fraunhofer IAP in 2007, where he has been head of the synthesis technology center since 2008.

"Our material can be produced cost-effectively from commercial raw materials in a simple synthesis process.

While PLA could previously only be produced profitably in continuous large-scale plants, the new PLA material can also be produced by small and medium-sized companies on smaller continuous plants. Similar to LDPE, the product can be processed into films on conventional processing plants, but can be chemically recycled with considerably less energy input than LDPE.

These unique material properties prompted the Polymer Group to commercialize this technology. In 2023, a production plant for the new PLA block copolymers was put into operation in Pferdsfeld by our partner SoBiCo GmbH, a subsidiary of the Polymer Group. It produces 2,000 tons of the new bioplastics per year under the brand name Plactid®. In the long term, 10,000 tons of the new flexible PLA material are to be produced there each year."

Acknowledgement of the research team

A big thank you goes to our funding bodies - the Agency for Renewable Resources FNR, the Federal Ministry of Food and Agriculture and the Federal Office for Agriculture and Food - as well as our industrial partner SoBiCo GmbH.

We would also like to thank our colleagues from the "Polymer Synthesis" department and the teams from the "Processing Technology Center Biopolymers Schwarzheide" and "Materials Testing" at the Fraunhofer IAP.