Answer:
Plastics are made of natural gas and oil.
They repel water.
Explanation:
Plastics usually man made i.e synthetic are basically long chain of hydrocarbon chain of polymers developed from petrochemicals. Since plastics are produced from polymers, polymers which are a chain of monomers are produced from crude oil, petroleum, natural gas or coal. Due to the absence of free mobile electrons , plastics are poor conductors of heat and electricity.
Since Plastics are made up of sticky materials like crude oil which act as poisons and repel water to get attached with plastic debris and are often harmful for the petroleum based objects in sea.