One type of plastic, PET, is called polyethylene terephthalate. This plastic, high transparency, good water resistance, but also relatively hard, used to make water bottles is particularly good.
There is a chemical fiber, called polyester, the full name of the chemical fiber is "chemical fiber", different from the "natural fiber", such as cotton fiber, hemp fiber, wool fiber. Polyester fiber, straight, strong, beautiful clothes.
Interesting thing is coming, do bottle PET, and do clothes polyester, in fact, is the same substance of different forms, different names, they can be transformed into each other. PET bottles, remove the label, cap, clean, crushed, in the plastic extruder through the 280C high temperature melting into liquid, and then from a very small hole out of the jet, you get a very fine silk, about 2 microns in diameter, thinner than a hair. Dozens of filaments, twisted into a strand, is the line we see, these lines can be used to weave cloth, cloth can be dyed to become fabric, fabric can be made into clothes. Here is a video to see how PET bottles are turned into clothes, this process is generally called "plastic recycling".