How long does it take for plastic to rot?

Answer 1

Biodegradable plastics can break apart into tiny pieces within a year, from weathering and ultraviolet solar radiation. Some non biodegradable plastics, like water bottles, buried in the earth, could survive largely intact for several billion years.

Plastic foam cigarette butts typically last twenty to thirty years, if they are on the surface, exposed to the sun and elements.

There is very wide variation.

Answer 2

That'd depend on the type of plastic and the environment its kept in. Some plastics will break down rather quickly when exposed to UV-light(sun light), while some stuff that looks like plastic is actually based on starch, and will break down rather quickly. Others will remain stable for years and years.

Answer 3

The decomposition starts after 50 years, and it takes 400 years to be completely decomposed.