17. Sep 2014
Will the claims of oxo-degradable plastics stand up to scientific lab scrutiny?
That’s precisely what OWS (Organic Waste Systems nv, Ghent, Belgium) and IKT (Institute of Polymer Technology, University Stuttgart, Germany) intend to find out. They are setting up a multi-client study to provide a definitive answer to the question: do oxo-degradable plastics biodegrade or do they not?
After all, biodegradable plastics, whether oil-based, such as BASF’s ecoflex, or derived 
from biomass, such as the PLA, PHA and TPS materials currently available on the market, all share one thing in common: they are certified as biodegradable. Simply put, these materials have been tested and proven to be capable of being “broken down especially into innocuous products by the action of living things, such as microorganisms,” as the Merriam-Webster dictionary defines it.
And this is the sticking point - the heart of the ongoing biodegradable – oxo-degradable controversy. Basically, scientifically based studies characterizing the microbial degradation of oxo-degradable plastics are lacking.
To remedy this situation, building on a desk research study conducted last year by OWS for Plastics Europe, a comprehensive laboratory-testing program is now planned, with the ultimate aim of delivering the necessary scientifically based proof of whether or not oxo-degradable products biodegrade.
What are oxo-degradable materials, anyway? They are simply conventional plastics, such as PE, PP, or PET, that are mixed with a small percentage of an additive, which subsequently accelerates free radical “degradation” of plastics. Proponents of these materials argue that by breaking down the long carbon-hydrogen bonds and reducing the plastic's molecular weight, the molecules become 'wettable' and able to sustain a biofilm on the surface supporting microorganisms, which then consume the molecules and reduce the plastic into water, carbon dioxide, and reusable biomass.
However, lacking proof from independent laboratories or certification bodies that this process actually occurs, critics of these materials doubt whether complete biodegradation takes place, and have dubbed these products oxo-fragmentable. Experts fear that these fragments will disperse into the environment, causing further problems with microplastic waste.
The fight is a fierce one. The controversy has already led the European Commission to consider a possible ban on oxo-degradable carrier bags. And in France, a group of MPs in the French National Assembly have called for a similar ban. Predictably, the oxo-degradable plastics industry has reacted furiously, calling this "a skillful lobbying attempt to take oxo-biodegradable plastics off the French market and leave the field clear for bio-based plastics which are not competitive with oxo-bio and have very limited usefulness."
Biodegradable materials offer advantages in certain functional biodegradation applications. These materials are particularly suitable for applications such as agricultural film, sod netting, and plant pots, or, closer to home, as bio-bags for organic household waste. Whether such biodegradable plastics are a solution against littering is a different discussion. Oxo-degradable plastics, however, are specifically being marketed as the solution to worldwide plastics refuse. It’s a message that’s being heard around the globe. As countries increasingly adopt the widespread use of oxo-degradable plastics, the time has come to establish once and for all, what happens to oxo-degradable plastics at the end of life.
The multi-client project aims to put the issue to rest by investigating the claims and by attempting to verify these in the laboratory. “To make this study as objective and neutral as possible, we are aiming at a broad participation including government agencies, consumer goods producers, NGO’s, oxo-degradable producers and the bioplastics industry,” said OWS.
In a first phase a number of oxo-degradable plastic products available in the market will be abiotically treated. In a second phase, the fragmented parts will be used for further biodegradation testing according to internationally accepted ISO and ASTM standards.
Throughout the project, interim results will be provided on a regular basis. These intermediate results will be sent to all project partners, enabling them to keep track of the progress made. At the end of each phase, a report will be published and distributed amongst the project partners; a final report will appear at the end of the study.(KL)
More information can be found in the official proposal:
http://bit.ly/1qWJvV2