What is plastic made of?
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From the brains behind Brains On, this is the Moment of Um. Moment of Um comes to you from APM Studios. I'm Ruby Guthrie. I don't know about you, but I'm always trying my best to reduce the amount of garbage I produce. I compost my food scraps.

I buy dry goods in bulk from the co-op and then put them in glass jars. I try to bike or take the bus instead of drive. I carry my reusable water bottle so I don't have to rely on plastic ones. In fact, the less plastic I can use, the better. It's wild how much plastic we produce and then toss away. And I'm trying everything I can do to cut down on that.

In fact, I don't even really understand what plastic is. And neither does Julian, who asked this question. Hi, my name is Julian and I'm from Winnipeg, Canada. And my question is, what is plastic made of? It's a good question, but it's a pretty complicated one. Plastic is made out of many different kinds of plastic. That's like asking, what is food made out of?

I'm Frank Bates and I'm a Regents Professor at the University of Minnesota. There are different categories of plastic. The big ones are polyethylene, polypropylene,

polystyrene, polyvinyl chloride, polyethylene terephthalate. Those are the five big ones. That's about 90% of all plastics. And they're made from relatively simple chemical compounds, but they each have their own unique properties. So a water bottle made out of PET

which is a big plastic, has properties that you appreciate are different than the properties of the Tupperware that goes in your, maybe your refrigerator. And the PET is a particularly interesting one because you can take those plastic bottles and you can actually turn them back into the chemicals that they came from and then remake the plastic over again.

So it's kind of like what you do with an aluminum can. So in principle, PET can be recycled quite nicely. But plastic bags, which are made out of polyethylene, it's harder. Plastic is a hugely controversial subject now. They're extremely important for society. You know, if you think about food packaging, you think about transportation vehicles, windmills,

You consider what happens with medical devices, artificial hips. There's so many places they're important, but as you probably know, they cause pollution and litter. And we have to figure out how to fix that. So we have a big center at the University of Minnesota that's working on that. And that's a topic I work on. It's a non-trivial set of things you have to do, but one would be if we could recycle.

And it's complicated for the very reason I just gave you, because there's so many different kinds of plastic. So you can't just pick them up, collect them, melt them and put them together and use them again. But if we designed them to start with so that they were easy to collect and recycle, we could do that. That would require probably government regulation, which there's so much resistance to.

So we need to get companies to embrace the idea that if they're going to have marketable products, they have to do this. So that's one thing. Another direction is to make plastic that you can decompose and it just falls apart and makes innocuous products when you're done with it.

And there are ways to do that. But it becomes complicated quickly, mostly because people like the fact that plastic is cheap. It's so cheap. So I could make a really good environmentally sound plastic. But if it's $200 a pound, nobody's going to buy it.

So we have this dilemma and it's a combination of factors, which for young people, people coming into science and engineering, this is the kind of challenge that you want. This is an immensely important topic and whoever asks a question about plastic is onto something important. And I will say one more thing, the business side of it is huge.

We sell, we make almost a trillion dollars a year of plastic. It's hard to get your arms around that, but it's just a huge business. And as I said, it feeds into so many different products that we have. So we have to learn how to do it better, but they're not going away. We need them. But this is a big problem. It's both a problem and an opportunity. This is what comes with technology almost always.

I recently found out that a plastic cup can take between 50 and 80 years to decompose.

80 years? That's older than my mom. And my grandma. That's too long. And only 9% of all plastic produced is recycled. So if you're not recycling on a regular basis, this is your reminder. Please recycle. And if you can avoid using single-use plastic in the first place, even better.

If you like this episode, take a second to subscribe wherever you listen to podcasts. And if you want to learn even more about this subject, check out the Brains On podcast, where we have two whole episodes all about trash. If you have a moment of um question, we'd love to help you answer it. Drop us a line by going to brainson.org slash contact. See you next time and the next day and every weekday. And don't forget to recite. I'm I'm I'm I'm I'm

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