With the help of supercomputers, researchers at the Australian National University (ANU, Canberra; www.anu.edu.au) have discovered ways of making polymers more resistant to degradation through the sun’s rays and thus extend the shelf-life of plastic products. The team, led by associate professor Michelle Coote and Ph.D student Anya Gryn’ova of the university’s ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, developed their project using a simple clothes peg as a model.

Scientists have long thought that clothes pegs and other plastics left out in the sun become brittle and fail due to a process called autoxidation, the university explains. The principle is that exposure to light or heat generates free radicals that attack the polymeric chains in the plastic causing them to rearrange and break. “Each ‘broken’ polymer chain is then thought to attack the next polymer chain, leading to a cascading failure that results in visible damage to the plastic.”

The Australian team says its findings suggest that most types of plastics “should be inherently resistant to this process” and that damage occurs because most polymer chains contain a small number of defect structures, formed during their manufacture. Replacing the defective structures should greatly improve stability and reduce the amount of plastic waste entering landfill every year, says Coote.

ANU has made a number of recommendations to prolong the shelf-life of plastics, including using improved manufacturing reaction conditions and choosing more resistant polymers for long-term plastic design. By the reverse token, the information gained also should facilitate the creation of improved biodegradable plastics, the university scientists say.