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Comment by plosticks | Hacker News Reader

Polyethylene is a wonderful material for subtractive manufacturing, especially parts that you might otherwise 3D-print or make out of wood.

It's easy to make "bricks" by melting and pressing chips and shredded material in a mold, and those bricks make excellent machine stock.

You can't use it as a building material, but I like the idea of mixing in sand and using them as paving stones. After all, we frequently pave playgrounds with flammable material made out of shredded tires.

I do wonder about microplastics flaking off of them, though. PE is pretty remeltable, but like most plastics it gets a bit more brittle with every cycle. Most recycling outfits mix some virgin plastics in with the recycled stuff for that reason.

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After all, we frequently pave playgrounds with fl\ammable material made out of shredded tires. Wait,really? Could you point me to some material about it? I know it was tried several times in many countries but IIRC everyone returned to just pure alsphalt, but I don't remember what was the actual reason.

Rubber covered playgrounds are considered safer for falls.[0] However, it's not just for kids, recycled substrates for athletic facilities are very popular. This shoe manufacturer recycles some of its products just for that purpose.[1]

[0]https://www.calrecycle.ca.gov/Tires/Products/Types/Playgroun... [1]https://www.nikegrind.com/

Thank you. I realized my mistake, I totally skipped the word playgrounds. Now everything make sense :)

>I do wonder about microplastics flaking off of them

especially under strong light/UV of equatorial Sun. While the story looks great at first, i wonder whether it can succeed under more strong environmental review.

The article says the factory has been running since 2017. That's going on 4 years of stuff from the factory being in the sun. I have seen plastic items last less than one Texas summer in the sun. Either they've done a brilliant PR campaign to keep the "sun kills this product" stories, or it is less of an issue than HN wants it to be.

There are UV inhibitors that are added to plastic. They give you more time in the sun, though eventually you are done.

Or nobody really cares about these bricks except for puffy PR pieces and questions about material lifespan aren't really interesting to the reporter printing about bricks stronger than concrete.

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