Is there cotton in polyester?

Update: 01-07-2021
Abst: No there isn't. Polyester is a synthetic polymer made from coal tar, and in fact polyester is actually Polyethylene terephthalate polyester film fibe...
No there isn't.
Polyester is a synthetic polymer made from coal tar, and in fact polyester is actually Polyethylene terephthalate polyester film fiber
(PET) which is a thermoplastic polymer used commonly for other purposes besides clothing. Water bottles and film canisters are both PET.
To make polyester thread, pellets of PET are melted and forced through a die creating threads. Once these threads cool they can be woven into fabric like natural fibers. They can also be mixed with natural fibers to make a blended fabric (50% polyester 50% cotton).