Process may offer biodegradablity in petrochemical plastics

By Jane Byrne

- Last updated on GMT

Related tags Biodegradable plastic Biodegradation Polymer

A research group based at University College Dublin claims it can convert plastics such as polystyrene (PS), polyethylene terephthalate (PET) and mixed plastics into a biodegradable polymer.

Project leader Dr Kevin O’Connor claims that the research group is aiming 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.

The process will be of interest to food and drink manufacturers under increasing regulatory pressure to reduce packaging waste and meet EU targets on landfill.

O’Connor told that the team has successfully converted PS to a polyhydroxyalkanoate (PHA) that is flexible, heat stable and water resistant, using the bacterium Pseudomonas putida CA-3.

“We are unique in this ability to convert petrochemical plastics to biodegradable plastics,” ​he claims.

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

The research group said that it 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.


Understanding of the biochemical pathways utilised by bacteria for polymer synthesis, as well as the diversity of polymers accumulated, are key points of interest in the research, according to the project summary.

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, explained O’Connor.

He said that 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,”​ claims O’Connor

Bioplastics study

A recent study, published by UK-based market analysts Applied Market Information (AMI) earlier this year, claims that the market for bioplastics remains small, not least because of a lack of facilities to ensure that the packaging can be recycled or composted properly.

"Less than one per cent of global polymers are currently classified as compostable bioplastics according to the European EN 13432 standard,"​ AMI analyst Chris Noble told

"This means that plastics have to completely biodegrade into harmless microscopic fragments within 90 days. However, the standard allows for this to take place within ideal composting conditions, such as industrial composting facilities where the materials are heated to high temperatures in order to accelerate the composting process."

"Obviously, these materials will take much longer to compost in a home composting environment, and critics argue there isn't a sufficiently well developed network of industrial composting facilities in, for example, the UK to justify investment in these materials,"​ he added.

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