SUBI2MA - Characterization and Modification of PET Fibers for Accelerated Degradation

Improved Biodegradability of Petroleum-Based Plastics Through Additives

As part of the Fraunhofer flagship project SUBI2MA, the Fraunhofer LBF is investigating the functionalization of polyethylene terephthalate (PET) through the addition of additives. The additives used are intended to accelerate the hydrolytic degradation of the polymer chain, thereby enabling the biodegradation of PET. This ensures that PET fibers released unintentionally are biodegraded and do not remain in the environment. This development is supported by various chemical and chromatographic analytical methods that provide information on the specific degradation mechanisms of the polymer chains.

Microplastics are released into the natural environment not only through improper disposal but also through the daily use of plastic products. Synthetic fibers made of polyester are particularly prone to unintentional release during everyday use. Due to their chemical structure, they are not easily degraded under ambient conditions and remain in the environment for long periods of time.

subi2ma - beschleunigter Abbau von PET-Fasern, alterung, additive
Even after short aging periods, accelerated degradation (increase in MVR) can be observed in the samples containing additives.

Additive Systems for Accelerated Hydrolysis

In previous projects, we were able to demonstrate for bioplastics that the addition of a customized additive formulation accelerates hydrolytic degradation.

This system is now to be adapted for petro-based plastics such as PET. This would accelerate hydrolytic degradation in the environment and enable biodegradation. Initial studies show that the addition of various additives accelerates the hydrolytic degradation of PET. To test this, the PET containing additives was subjected to water immersion, and its melt flow rate - as an indicator of viscosity and thus polymer chain length - was measured over time. The results show that degradation can be accelerated by adding additives.

Stackplot der LAC-Chromatogramme einer unbekannten PBT/PET-Probe und eines PBT als Referenz
Stack plot of the LAC chromatograms of an unknown PBT/PET sample and a PBT reference sample

Chromatography for PET Characterization

Chromatography can be used for separation based on molecular weight (gel permeation chromatography, GPC) or chemical structure (adsorption chromatography, LAC). GPC confirmed the chain degradation accelerated by additives, while optimization of LAC enabled the separation of PBT and PET. Building on these results, chromatography will be further developed to chromatographically differentiate between various terminal groups in PET, thereby enabling conclusions to be drawn about degradation mechanisms.