Can you put polystyrene in the microwave oven
Well, I can tell you with absolute authority that polystyrene melts in the microwave.

Here's a chunk of polystyrene cut from a foam shipping container. I double checked with the website (Propak), and the stuff is polystyrene.



I placed a random chunk of chicken on the cube, and microwaved on high for 1 minute.

 

So yeah, it melts. Is it toxic if it melts into your food a few times? Probably not. Should you do it? Probably not.