The researchers, led by associate professor Michelle Coote and PhD student Anya Gryn’ova from the ARC Centre of Excellence for Free Radical Chemistry and Biotechnology at ANU, modelled polymer degradation on the supercomputers to discover how to make better, more robust plastics.
Coote said: ’Although plastics have been manufactured for a long time, we have uncovered critical information that will enable longer-lasting plastics to be created, which is important if we want to reduce the amount of plastic waste entering landfill every year.’
Historically, scientists thought that plastics left out in the sun become brittle and fail due to a process called autoxidation, where exposure to light or heat generates free radicals, which are reactive species that attack the polymeric chains in the plastic causing them to rearrange and break. Crucially, each ’broken’ polymer chain was then thought to attack the next polymer chain, leading to a cascading failure that results in visible damage to the plastic.
However, the research led by Coote suggests that most types of plastics should actually be inherently resistant to this process, and the reason that damage occurs at all is because most polymer chains contain a small number of defect structures, formed during their manufacture.
’The good news is that if you can remove these defect structures you could greatly improve the stability of many plastics,’ said Gryn’ova.
The findings of the research have led to a number of recommendations to prolong the shelf life of plastics, including improving manufacturing reaction conditions. Conversely, the information will also assist in creating improved biodegradable plastics.