First, talk to you about the little stars polypropylene with polyester.

Polypropylene is the trade name of polypropylene fiber, which is made by polymerization of propylene as raw material, obtained by melt spinning fiber. Polypropylene industrial production started in 1957, is a rising star in the synthetic fiber. Because of polypropylene with the production process is simple, inexpensive products, high strength, relative density of light, etc., so the polypropylene developed rapidly. Polypropylene is currently the fourth largest varieties of synthetic fibers.

Polyester is a synthetic fiber is an important species, is the trade name of polyester fiber. It is purified terephthalic acid (PTA) or dimethyl terephthalate (DMT) and ethylene glycol (EG) as raw material by esterification or transesterification and polycondensation fiber-forming polymer obtained - - polyethylene terephthalate, fibers made ​​by spinning and after-treatment of the ester (PET).

What is the difference between the two it? In this little star to teach you a simple way - burning identification method.
Polyester: combustion fiber curling, side burner, side smoke, yellow flame, a faint sweetness, leaving a dark brown lumps after combustion.
PP: side curled, side melting burning bright flame, blue, there is a little like the smell of burning asphalt, after the burning ashes into a fawn.
In addition, polypropylene is lighter than water, floats on water; polyester heavier than water, submerged in water.