I know that plastics (polyurethane, polystyrene, polyethylene, etc) are very different from one another.
What I’ve been thinking about is, would it be possible to make some sort of powder with a mix of all these plastics, that could then be mixed with a binding agent to make bricks, plates and other, well, plastic things?
For anyone wondering “why”, this is a recycling idea, one that, if simply mixing in some binding agent (glue) works, or some glue + another plentiful material (dirt? sand?), wouldn’t need heat to give reuse to the plastics, thus eliminating a possible source of toxic fumes and allowing PVC to be thrown into the mix.
I know it is possible to do something like this with heat. You need to heat the mixture, usually to ~300º C, so once the molten plastic cools, most everything is stuck together. Such examples are plentiful around the internet. That’s why I wanna know if there’s a way to do it without using heat
This reminds me of recycled glass countertops which have bits of glass mixed with concrete.
With plastics I suppose you could use epoxy resins or cement. Here’s a research paper exploring mixing HDPE into cement.
The hard part is finding the specific mix of ingredients to make your finished product to work well in a particular application. For example, many plastics degrade from UV exposure so you won’t want them outdoors for extended periods. Other plastic products are made with chemical additives like colorants, lubricants, or fire retardants that may affect the long-term stability of your mixture.
Makes me wonder the quantity of chemicals that could leech from HDPE embedded cement
My understanding is that polyethylene is relatively stable and inert. That’s why it’s commonly used in food packaging, medical implants, and other applications where you really do not want things leaching out. So it’s probably not a bad choice as a filler material.
I would be more worried about the really cheap plastics used in low-end consumer products. Plastics used in electronics also often have fire retardants to meet fire safety regulations, and those can definitely leach out over time. The soft grip materials on things like toothbrushes and screwdrivers are gross, too; sometimes that stuff degrades into sticky goo and starts releasing oily compounds.