Polylactic acid (PLA) is the most popular bioplastic. In 2023, it was the most produced bioplastic globally, accounting for 27% of the total share, and is expected to account for 43.6% of production capacity by 2028, according to European Bioplastics.
PLA is also the most popular bioplastics in the agricultural market segment, where it is used for products such as mulching films.
A drawback of PLA, however, is its limited biodegradability. It is industrially compostable, but it cannot be composted at home. And even under industrial conditions, it has been shown that it takes around 20 days before PLA films start to biodegrade, which means that they are only suitable for processing well-managed industrial composting facilities. Even there, if the prescribed process of turning and mixing is disturbed, the biodegradation process may not be completed by the end of the cycle, with as a result, poorer quality compost containing PLA fragments. An additional challenge relates to the polymer fragments at the compost pile surface - because they are not exposed to the same conditions, it can take them longer to biodegrade, especially relevant fragments that constantly resurface during pile turning due to their low density. The upshot is that not all composting facilities are equally willing to accept PLA.
For agricultural applications, it would be much more efficient if PLA-based products could biodegrade on site. Scientists have been working hard to find a way to accelerate the biodegradation process in industrial composting facilities and even to expand PLA’s biodegradation efficiency in home and backyard composting settings.
Now, a new research project at Wageningen University is making another effort in that direction. The UV-Light Triggered Rapid and Adjustable Degradable REnewAble Materials (ULTRA-DREAM) project aims to develop new technology for UV-light triggered biodegradation of bioplastics, such as PLA or poly(butylene succinate) (PBS), at their end-of-life (EoL).
To this end, the team is exploiting the UV susceptibility of furans, organic, highly volatile compounds with a boiling point close to room temperature (31 C). The team has recently shown that bio renewable furan building blocks, such as furandicarboxylic acid (FDCA) are sensitive to degradation under UV irradiation. Incorporation of furans into biobased polymers is expected to increase the rate of degradation of products such as agricultural mulching films or decorative and paper coatings by exposure to sunlight when emitted into the environment.
Both the furans and the original polymers come from agricultural side streams. “We convert low value non-food residues to high added value functional products,” explained project leader Ghazal Tavakoli. “This way we develop new classes of bio-renewable, biodegradable materials with an improved circular potential.”
The project started in summer 2023 and is expected to run until the end of 2026.