Engineers and the fate of all plastics ever made

Leland Teschler – Executive Editor

lteschler@wtwhmedia.com

On Twitter @ DW—LeeTeschler

A research paper made headlines recently when it claimed 79% of all plastics made since the invention of polymer resins now reside in landfills or are scattered around the landscape. All in all, the researchers figure that we’ll be sitting on roughly 12,000 metric tons of plastic waste by 2050.

Engineers, of course, design the products made from plastics. So it is disconcerting to realize LTeschlerthat engineers could be put in the role of fall-guys for unleashing a plague of plastics on humankind.

To see whether this is a fair criticism, we need to take a closer look at the research findings. The paper appeared in the peer-review journal Science Advances. Authored by researchers from UC Santa Barbara, the University of Georgia, and the Sea Education Association at Woods Hole, it looks at all mass-produced plastics but focuses primarily on those used as packaging materials.

Most analyses of waste are annoying in that they are generally preachy and often have a thinly veiled agenda of non-materialism. Thankfully, this one is not in that camp. The authors don’t judge anyone for the mountain of plastics in landfills but only point out that we’d best think about “the environmental challenges posed by the enormous and sustained global growth in plastics production and use.”

The plastic packaging that authors concern themselves with includes polyethylene (PE), low-density and linear low-density PE, polypropylene (PP), polystyrene (PS), polyvinylchloride (PVC), polyethylene terephthalate (PET), and polyester, polyamide, and acrylic (PP&A) fibers. They say these seven groups account for 92% of all plastics ever made. Approximately 42% of all non-fiber plastics have been used for packaging, which is predominantly composed of PE, PP, and PET. The building and construction sector is the next-biggest consumer, using 69% of all PVC.

One point to note is that the vast majority of plastics in landfills aren’t the ones most design engineers work with. Engineers are more likely to use engineering plastics that go into products to replace wood or metal. They include Nylon 6, polyamides, polycarbonates, polyimides, polyphenylene sulfide, and similar compounds. The researchers note that engineering plastics are in use far longer than those that go into packaging. Plastics for industrial machinery have an average lifetime of about 20 years; plastics for packaging may be discarded less than a year after they’re made.

Of course, some plastics used in packaging get recycled. Researchers estimate the highest recycling rates in 2014 were in Europe (30%) and China (25%). In the U.S. plastic recycling has remained steady at 9% since 2012. But researchers point out that plastics recycling delays, rather than avoids, their final disposal. And it is difficult to figure out how much manufacturing of primary plastic we avoid by recycling old stuff.

In a nutshell, the problem these researchers highlight is that there is currently no economical way to break down plastics into something usable that isn’t itself a plastic. However, there is one possibility the authors don’t consider: A review of history shows that for technology, where there is a will, there’s usually a way.

So we should never discount the idea that landfills may eventually be viewed as storehouses of useful plastic material rather than as problems to be dealt with.

Comments

  1. Niall Lazenby says:

    Looking for an engineering plastics company based in the UK to use. I’ve found a company called Westley Plastics who look to be good, has anyone got any prior knowledge or know if they are a good company to go through? Any comments would be greatly received. Thanks. http://www.plasticsuk.com/

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