Additives accelerate degradation of bioplastics

Newsletter 02/2020

Short cycle times in composting plants often prevent the degradation of plastics that are in themselves compostable. Therefore, the Fraunhofer LBF develops additive systems that accelerate degradation and reduce the necessary composting time. The result: greater acceptance of biodegradable plastics.

© Fraunhofer UMSICHT
Non-additive comparative sample (left) and additive sample (right) during storage under industrial composting conditions.

© Fraunhofer LBF
Remaining average molecular weight in % after two weeks of composting under industrial conditions

Polylactide (PLA) consists of lactic acid and can be biologically degraded by microorganisms. In order to be able to use this advantage optimally, it is important that the biodegradation can be controlled and accelerated. Tests in a laboratory composting plant, which were carried out in cooperation with the Fraunhofer UMSICHT, now show that this can be achieved with additives. Industrially produced PLA was compounded with special additives at the Fraunhofer LBF and test bars were manufactured by injection molding. The degradation was investigated both optically and chromatographically.

Composting tests confirm the effectiveness of the developed additive systems

The experiments carried out under industrial composting conditions confirm the effect of the additive systems already observed in laboratory studies, which we reported on in the April 2020 newsletter. The test samples with the corresponding additives disintegrate faster and have a lower mean chain length. These results are an important milestone in the development of additive systems for controlled accelerated biodegradability of bioplastics, in particular the PLA, which is well established in the bioplastics market.

Processing stability and service life

By using a suitable stabilizer, processing stability is guaranteed and long-term stability can be controlled depending on the composition.

Additive formulations for every application

Research at the Fraunhofer LBF is not only focused on accelerating the biodegradation of plastics by additives, but also on stabilization during processing and in long-term applications. The focus is on sustainable solutions based on biogenic resources and replacing environmentally critical substances.