Just What Is A ‘Sustainable’ Plastic?

One of the interesting outcomes of Lego’s three-year-old effort to replace ABS in its iconic building block toys may be a new—and significantly more meaningful—definition of what constitutes a “sustainable” plastic.

In the past decade or so, the definition has largely been in the hands of suppliers, and the predictable result has been confusion, chaos and a loss of credibility for much of the global plastics industry.

720_LEGO_brickslooseFor a while, companies that produced photodegradable plastics pitched them as sustainable. It turned out that the material was just breaking into chunks that didn’t degrade. Also, the material junked up recycling streams. Companies that produced biodegradable plastics implied they would break down when tossed on the ground as litter. Then there were a lot of claims about plastics with some bio content and surely this must be helpful to the environment. Companies like MHG (formerly Meredian/Danimar Scientific) even advertise that their bioplastics are not plastics.

The situation became so confusing that responsible OEMs turned to a group of kosher rabbis of materials’ sustainability who had their own scorecards and made big bucks on their blessings.

Plastics trade groups like the SPI can’t do a good job in this area because they represent the good guys and the bad guys.

Increasingly, it strikes me that big users of plastics are developing excellent concepts of sustainability as part of meaningful corporate scorecards.

I am impressed for example with efforts at Lexmark, which were very quietly outlined and documented in an Antec paper this spring that received little public mention. Lexmark is not interested (at least for now) in biobased plastics and views a truly sustainable system as one that is closed loop. That is, if you generate the material, you have the responsibility to re-use it. Results are impressive and improving.

It, of course, would not be practical for Lego to recover the zillions of ABS bricks it molds, and besides, one of the beauties of the Lego system is that its bricks are meant to last—and last—and last. Sorry John Kenneth Galbraith, no planned obsolescence with this simple marvel of Danish engineering.

So the better route may be making plastic bricks out of a “sustainable” material.

Lego has already tackled what might be considered the “low-hanging” environmental fruit, by redesigning packaging and even building an offshore windfarm to generate power.

So the tougher battle seems to be finding a plastic that provides the durability and “locking” effect (clutching power) of ABS, while also making the planet a better place. So how can Lego’s material choice make the planet better?

Yes the feedstock matters. But how much energy is consumed producing that feedstock? Are harmful chemicals/fertilizers used that pollute water supplies? How much energy is used transporting the feedstock and then converting it into a polymer? What are the process pollutants? Is the feedstock a food source to someone in the world? Are there any potential health effects of the chemicals in the renewable plastic compound? What percentage of the compound is really renewable? What happens to the material when the kids grow up and someone finally throws the Lego bricks away? Can they be recovered and reused? Are they composted? Incinerated? What are the energy and health implications of any of those choices?

Is the end result a game changer, or just a feel-good PR story?

A Lego initiative to develop its own sustainable plastic was announced last month. If any company intends to do the right thing, I am sure it must be Lego.

Next: There are a lot of commercial bioplastics out in the marketplace. Why is Lego developing its own plastic?

About Doug Smock

Former Chief Editor at Plastics World and Senior Technical Editor Design News
Europe, Packaging ,

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