why is there static with polyester blanket?

Answer 1

Two reasons: dis-similar materials and it is an insulator.

Here's how: When you drag a plastic comb through your hair, or rub a ballon against your hair or take a nylon coat off while wearing a polyester sweater, you are rubbing two different materials together.

One material has a slightly greater affinity for electrons and picks up some from the surface of the other material. So one item ends up being negatively charged and the other ends up being positively charged. This enables you to stick the charged ballon to the ceiling, but it also gives you a static spark when you touch something grounded like a light switch.

Just like rubbing your feet (while wearing shoes) on the carpet to zap another kid back in school. You can build up 1,000-2,000 volts of static electricity (at a very, very low amperage!).

If the material were a conductor, the charge would be carried away. So it does not happen with metals.

It only happens on dry days because humid air bleeds off the charge. So we mostly notice the effect inside during winter when our heating systems create dry indoor air.

There are anti-static sprays sold for computer users for carpets and clothes that make them a little bit conductive. "Anti-cling" sheets to add to the clothes dryer do the same thing.