Sign up for the PlasticsToday NewsFeed newsletter.
Sponsored By
Bioplastics: New Developments Expand Use of PLA; Study Confirms No Microplastics Left Behind
Researchers make inroads in replacing petroleum-based low-density polyethylene with polylactic acid (PLA) film. Meanwhile, a meta-study claims that, under the right conditions, PLA will fully degrade into biomass, CO2, and water.
Norbert Sparrow
July 1, 2024
3 Min Read
Image courtesy of Fraunhofer IAP
At a Glance
- Flexible PLA developed by Fraunhofer researchers is devoid of migrating plasticizers.
- PLA can be processed into plastic film using conventional equipment.
- Study shows PLA will fully biodegrade into biomass, water, and carbon dioxide when exposed to moisture and humidity.
DuPont scientist Wallace Carothers is generally credited with synthesizing polylactic acid (PLA) in 1932 — admittedly, he is best known for his research that led to the development of nylon — but it wasn’t until late in the last century that PLA started to be used in an appreciable way, especially in medical applications. Its biocompatibility and bioresorption properties have made it an essential polymer for drug-eluting stents and implants.
PLA is also one of the most popular biopolymers in the race to replace petroleum-based plastics precisely because of its degradation properties. It continues to make headlines as researchers hone the material’s properties and further its environmental benefits, as illustrated by two recent developments — a PLA-based flexible and recyclable plastic film and a study showing that PLA will fully biodegrade under the right conditions and not leave behind microplastics.
PLA-based flexible film earns researchers prestigious prize.
Researchers at Germany’s Fraunhofer Institute for Applied Polymer Research (IAP) that developed a flexible and recyclable plastic film based on PLA and paved the way for its commercialization have received the 2024 Joseph von Fraunhofer Prize. The annual prize recognizes outstanding scientific achievements by Fraunhofer employees, rewarding research teams with €50,000 and substantial bragging rights.
Fraunhofer IAP researchers (left to right): Dr. Antje Lieske, Dr. Benjamín Rodríguez, and André Gomoll. Image courtesy of Fraunhofer IAP.
The research at IAP involved replacing petroleum-based low-density polyethylene (LDPE) with a biopolymer to reduce the carbon footprint of single-use shopping and garbage bags. PLA showed promise — it is bio-based, biodegradable, and easy to recycle, said the researchers — but its high stiffness made the polymer unsuitable for flexible packaging applications. They found a solution by coupling polyether plasticizers directly with the polymer chain, making the material more flexible over time.
“Until now, plasticizers have been mixed into PLA as additives. However, the plasticizer molecules migrate out of the material over time, making the PLA stiff and rigid again,” explained researcher Dr. Benjamín Rodríguez. “To prevent this migration, we anchored the polyether to the polymer. To achieve this, we synthesized PLA-based block copolymers in which the polyether chain segment is covalently linked to PLA chain segments at both ends.”
The discovery results in several advantages:
The flexible PLA does not contain any migrating plasticizers and, unlike LDPE, is at least 80% bio-based.
The material can be produced cost-efficiently from commercially available raw materials.
The process does not require large-volume synthesis plants but can be implemented locally by medium-sized companies.
The PLA material can be processed into plastic films using conventional processing equipment in a similar way to LDPE.
It can be chemically recycled with considerably less energy input than LDPE.
The material is being commercialized under the Plactid name by the Polymer-Group, and its subsidiary SoBiCo GmbH has commissioned a production plant in Pferdsfeld, Germany. Ultimately, the company plans to produce 10,000 tons of the material annually.
Study concludes that bio-based PLA does not produce microplastics.
A recently released meta-study commissioned by Holland Bioplastics, a Netherlands-based association promoting biopolymers, claims to show that PLA will hydrolyze — break down chemically using water as a reactant — into increasingly smaller molecules and eventually fully biodegrade.
Research laboratory Hydra Marine Sciences conducted a systematic review of published scientific literature beginning with an initial scan of more than 30,000 reports, 500 of which were identified as relevant for deeper review. The research confirmed that the environmental degradation of PLA is mainly driven by hydrolysis. As long as the PLA is exposed to moisture and humidity, it will degrade at a rate determined by temperature until the polymer chains are so short that the material becomes soluble in water and will biodegrade into biomass, water, and carbon dioxide, according to the report.
“The meta-study shows that in contrast to non-biodegradable plastic, which will persist and permanently accumulate as micro- and nano-plastics in the environment, PLA in the environment will not leave persistent pollution as long as humidity and water are present,” said Christian Lott, managing director, Hydra Marine Sciences.
About the Author(s)
You May Also Like
