Converting Petrochemical Plastics Into Biodegradable Polymers

Researchers at University College in Dublin have developed a new process to convert petrochemical plastics such as polystyrene (PS), polyethylene terephthalate (PET) and mixed plastics into a biodegradable polymer.

In a recent interview with FoodProductionDaily.com project leader Dr Kevin O’Connor revealed that his research group had successfully converted PS to a polyhydroxyalkanoate (PHA) that is flexible, heat stable and water resistant, using the bacterium Pseudomonas putida CA-3.

The new process aims to reduce the amount of waste being sent to landfills through a process of biodegradable plastic synthesis, that recycles the materials into a new biodegradable product.

Dr O’Connor believes the new process will be of interest to food and drink manufacturers under increasing regulatory pressure to reduce packaging waste and meet EU targets on landfill.

The process involves heat-treating the plastic in the absence of air, which breaks the bonds in the plastic and converts it back to the single chemicals that were used to make the polymer in the first place. These chemicals (an oil product in the case of PS and a solid product in the case of PET) are then fed to bacteria, which digest the products fully and, in doing so, start to form a different polymer inside themselves (much like squirrels storing nuts). This polymer is then extracted from the bacteria.

“The polymer is an elastic plastic that is resistant to heat (up to 270 °C) and it is biodegradable as the bacteria that make it can also degrade it,” says Dr O’Connor, who adds that his research team is unique in their ability to convert petrochemical plastics to biodegradable plastics.

Dr O’Connor’s research group has applied for patents in relation to the conversion of PET and mixed plastic using the technology and it is hoping to form partnerships with waste and packaging companies to commercialise the project.

“We are collaborating with other scientists who will start to process our polymer with a view to developing products for packaging and other applications,” says Dr O’Connor.