How long can I keep HDPE plastic in an oven for before it starts to burn?

I am recycling HDPE plastic (chips) in an oven. I left it in the oven for 10 mins and it melted the outside layer of the plastic fine. When I cut into the plastic with a saw after it cooled, there was a layer that hadn't melted.


I think 180 degrees Celcius is about the right temperature (it's round about the minimum melt temperature for HDPE), but I would like how long I can keep it in the oven for before it combusts?


My thinking is if I leave it in the oven longer than 10 mins, it will also melt the inside. But I especially don't want to leave it in the oven long enough to make nasty combustion fumes.


Any help with time I should leave it in the oven would be appreciated ('practical' answers preferred).


[![Chips](https://i.stack.imgur.com/hhoI8.jpg)](https://i.stack.imgur.com/hhoI8.jpg)
[![Bricks](https://i.stack.imgur.com/xL9Oy.jpg)](https://i.stack.imgur.com/xL9Oy.jpg)




I highly recomend going to a trift store and picking up a cheap panini press, or a toaster oven. On the panini press, theres usually no ability to change temperatures, but I find its extremely hard to melt it unless you walk away for like 20 minutes. On the toaster oven, 160° should be perfect and i've never had it burn at that temperature. I hope this helps :)


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