Symphony claims that if sent to landfill, d2w plastics will degrade in aerobic conditions. In anaerobic conditions they become inert and like conventional plastics will not emit methane.
The company literature expressly states that d2w plastics are not currently intended for composting.
“Additionally, if hydro-degradable material is mixed with conventional plastics in a normal recycling chain, where plastics recovery is the objective, it will contaminate the batch and ruin the process,” Bobroff added. “I must say that hydro-degradable sacks are the right product for municipal composting schemes. But not for shopping bags or general packaging.”
When asked about the Loughborough report, Bobroff noted that Symphony has independent test reports that prove its d2w products do degrade into fragments, which are no longer plastic, and that they then biodegrade.
Symphony refers to CEN TR15351, where oxo-degradation is defined as ‘degradation resulting from oxidative cleavage of macromolecules’, and oxo biodegradation is defined as ‘degradation resulting from oxidative and cell-mediated phenomena, either simultaneously or successively’.
The company claims its d2w products comply with the above definition, and refers to independent tests conducted by Smithers Rapra Technology Ltd: “Polyolefin products made with d2w additive will abiotically degrade in the presence of oxygen. Degradation has been proven in accordance with the requirements of ASTM 6954-04 by passing ASTM 5510 (RAPRA Report 46095).”
When asked about the industrial composting standards (EN13432 and ASTM D6400) that require 90 per cent conversion to carbon dioxide within 180 days, Bobroff suggested that the EN and ASTM industrial composting standards were drawn up by the plant-based plastics sector, and specifically for their type of plastic. These are designed only for industrial composting systems within a specified time-frame. “Composting is conducted as a business, where time is money” says Bobroff.
“The Oxo-biodegradable Plastics Association countered all of the accusations of ‘unfounded claims’ about end-of-life options for oxo-degradables by listing all the test reports we had,” said Bobroff. “The situation was similar in the US, which is very interested in compostable packaging, even though they have very few industrial composting facilities. We’re doing a lot over there to get them to realise that it is not necessarily the right thing. We have answered everything.”
Bobroff acknowledged the long time scale of two to five years for d2w plastics to biodegrade is an issue, but explained, “We could speed biodegradation up but if we did that, it would shorten the shelf life of the product – so you can’t do one thing and not affect the other.
“The issue we have to address to begin with is what shelf life the customer wants. We have to ensure a package fulfils the basic functions first, for example to protect the product from contamination and damage.”
In the final analysis, the entire debate is a question of semantics: about ‘ownership’ of the word ‘biodegradable’ – the bioplastics sector’s efforts to discredit the oxo-degradable manufacturers’ use of the term, and Bobroff’s careful use of the term hydro-degradable when referring to the bioplastic/PLA product appear to deny them both exclusivity in the field of biodegradable plastics.
However, according to Bobroff’s description of the two-stage process quoted above, after the first degradation stage, what biodegrades is not plastic; it is ‘material’. Therefore, the oxo-detractors would appear justified in disputing the oxo-degradable claims that their product is biodegradable plastics, as it is clearly not plastic any longer.
The bioplastics sector has its own semantic demons to contend with. During the 2008 Interpack show, the industry held an open forum debate to address the confusion over the term ‘compostable’, which the public generally interpreted as meaning able to biodegrade in a hole dug in the back garden.
Bioplastics are industrially compostable, but emit greenhouse gas and require a separate waste stream to avoid batch contamination - inappropriate in countries which do not have the infrastructure.
Oxo-degradable plastic does not compost, nor is it intended to, but the structure breaks down to the point where microbes can attack it which, although this does not happen within the 180 days set by composting standards, may be more appropriate in the developing world where landfills are little more than an open dump on the edge of town.
“It really isn’t easy to address all that,” said Bobroff. “But isn’t it much better to get the plastics to degrade even in two to five years than for it to be lying or floating around for decades?”
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