What is the difference between silk and polyester?

Why is polyester so cheap? Have you ever wondered? Why would I buy a wrap for over 20 dollars when I can get one for 3 dollars at Wal-Mart? Simply put silk is natural and polyester is not.

Polyester is a synthetic fiber which is synthesized using by products of petroleum.

This fibre is completely hydrophopbic and strong. Has a crispy surface, used for party wear garments (women), and has various other technical uses. Melts with a plastic burning smell. Can be heat set. Non biodegradable. The cross section can vary according to the requirements. Can be cut into staple fiber and be blended. Delustering agents ( titanium dioxide) are added in order to reduce the luster.

Silk is a natural animal spun fibre, has a serrated surface due to serecin present(gummy layer) over the fiber. Has a traingular cross section with subdued luster. Spun by silk worms which are mainly categorized into 2 of which one is bombyx (cultivated) and the other is tussah(wild).  Silk is expensive. Made of protein called fibroin. Silk naturally is spun with two filaments together, however it is degummed and separated.