I've been looking for silk pillowcases that don't cost 20$ a piece.
Jessicurl warns against using/buying polyster satin.
http://www.jessicurl.com/100-Silk-Pi...es-pr-641.html
I found this.....
"Charmeuse satin- It can be made of silk, or a synthetic lookalike such as polyester. Silk charmeuse is more expensive and delicate, but is softer and a better insulator. Polyester charmeuse is cheaper and can often withstand machine washing, but doesn't breath as well as silk."

Do you know which yours is?