Additives to biodegrade plastics don’t work

A new study from Michigan State University shows that several additives that claim to break down polyethylene (i.e., plastic bags) and polyethylene terephthalate (i.e., soda bottles) simply don’t work in common disposal situations such as landfills or composting.

“Making improper or unsubstantiated claims can produce consumer backlash, fill the environment with unwanted polymer debris and expose companies to legal penalties,” said Susan Selke, co-author of the study and MSU packaging professor.

The results, featured in the current issue of Environmental Science and Technology, are a culmination of a three-year study that focused on five additives and three categories of biodegradation, which cover the majority of methods available on the market today.

The team studied biodegradation with oxygen, such as in composting; biodegradation without oxygen, such as in an anaerobic digester or a landfill; and simply burying plastics.

“There was no difference between the plastics mixed with the additives we tested and the ones without,” said Rafael Auras, co-author and MSU packaging professor. “The claim is that, with the additives, the plastics will break down to a level in which microorganisms can use the decomposed material as food. That simply did not happen.”

3-D printing gets a way to instantly recycle plastic waste into new 3-D ‘ink’

3-D printers are getting cheaper and faster – this week the company CarbonD announced a 3-D printer that the company claims is 25 times faster than the average starting at around $2,500; meanwhile the Xyz home-oriented printer can be had for about $500.

As with regular printers, however, so with the 3-D versions – supplies are another story.  The spools of plastic “ink” used in 3-printers are not so cheap – about $30 a spool – and depending on what the printer is printing, could end up as nothing more than an expensive blob of waste plastic.

Three students at the University of British Columbia – Dennon Oosterman, Alex Kay and David Joyce – have come up with a way to reduce the waste as well as the cost of 3-D printing. The three have designed an instant plastic recycling machine for home and small-business 3-D printers. The unique feature of this consumer-oriented extruder is that it has a built-in function to grind and pound plastic waste – like pieces of the lids from coffee cups – into small pellets. The machine, called a ProtoCycler, accepts ABS and PLA plastic waste, though each batch of waste for making into new “ink” filaments must come from the same type of plastic.

The ProtoCycler can then extrude new plastic filaments from the pellets at a rate of 5 to 10 feet per minute. That’s faster than traditional extruders. The ProtoCycler machine also uses less energy than typical plastic filament-producing equipment, so it is more efficient. Colors will be able to be added to the filaments.

There are still issues to resolve. The recycling system has different settings to handle different types of plastic waste – currently just ABS and PLA plastic – though the designers say configurations for new kinds of plastic will be able to be downloaded over the Internet.

The three student designers have formed a company called ReDeTec, to sell the machines; and they are planning for the first recycling+extruders to be ready for market within a year. A successful Indiegogo campaign netted over $100,000 for the company; ReDeTec plans to sell the ProtoCycler for $699.

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PHILIPPINES, Manila : A father and son (L) on a makeshift boat made from styrofoam paddle through a garbage filled river as they collect plastic bottles that they can sell in junkshops in Manila on March 19, 2015. They earn three US dollars a day. The Philippines will be observing World Water day on March 22, a global event that focuses on finding access to clean and safe water. AFP PHOTO / NOEL CELIS

Sooo, About That “Biodegradable Plastic”


A recently published study found that plastics imbued with chemicals to aid in biodegradability really didn’t do anything, and that the plastics persist just as long as regular ol’ polluting plastics. (x)

Of course, the plastics industry blasted the study, and says it was a flawed design (x). Their major complaint is that the additives are supposed to help with “oxo-biodegradation” - that is, degrading when exposed to oxygen - which the study didn’t take into account.

The problem is that when plastics aren’t exposed to oxygen - e.g. in landfills - it doesn’t help at all. Furthermore, there didn’t seem to be much biodegradation; as the plastics.com article notes, quoting the study authors, “We got oxidative degradation. That happened. What we did not find after oxidative degradation—equal to several weeks of sunshine exposure—was biodegradation,” she said. “That didn’t happen.”

I don’t pretend to be an expert on this stuff, but I suspect that many of us will be disheartened to hear about all this. We love plastics, but we also love the planet. We should keep in mind that ‘eco-plastic’ (or any ‘eco-product’) isn’t always what we hope (e.g. “greenwashing”), and continue to push materials researchers to make further advances. We’re not there yet, but we can continue to make progress (particularly with public pressure).

In the meantime, keep being a smart consumer and recycling as much as possible.

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