system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do certain types of thermoplastics or rubber (i.e. used for soft buttons of a tv remote or the insulation of cheap headphone cables) turn sticky or even gooey after they haven't been used in a long while?
gpt
The have a plasticiser in them which given time and environmental conditions leaches out.

Not a perfect analogy, but think of it like an oily rag where the oil will over time flow out.  The rag will end up dry and there will be a pool of oil.