|MLA Citation:||Bloomfield, Louis A. "Question 831"|
How Everything Works 19 Jan 2018. 19 Jan 2018 <http://howeverythingworks.org/print1.php?QNum=831>.
Most common plastic items are made from thermoplastics because these meltable plastics can reshaped easily. But different thermoplastics melt at different temperatures, depending on how strongly their long molecules cling to one another. The plastic in an Oven Cooking Bag is almost certainly a thermoplastic form of Nylon, but one that melts at such a high temperature that it doesn't change shape in the oven. It's possible that the Nylon has been cross-linked to form a thermoset, so that it can't melt at all, but I wouldn't expect this to be the case.