I'm planning a chimney demo and planning to hang plastic from floor to ceiling to section where I'm working from the rest of the house. What millimeter thick plastic would be best? I want something thick enough to work but not so heavy I can't tape it up with 2 inch blue painters tape.
I can comment, from tons of experience, that trying to secure the plastic with blue painters tape is highly likely to lead to a great disappointment in performance. Taping up even the thinnest plastic sheeting is so easily torn down by any pulls and tugs on the plastic. Heavier plastic is even worse.
My recommendation, if you have to use tape, is to use something a lot more aggressive such as Gorilla Tape.
Even better is to drape the top edge of the plastic over a thin board strip such as a 1x2 and prop that up against the ceiling with additional 1x2s that are cut to the proper length to wedge in from floor to ceiling. Then run painters tape along the edge to seal the plastic to the ceiling if needed.
Note that professionals use a product that has adjustable spring loaded posts to hold up plastic in the same manner that I described with the 1x2s above. One such system is described here.
Any thickness of plastic will stop dust from going through it. The only reason to use thicker plastic as opposed to thinner is that the thicker plastic holds up a little better to punctures and tears (which can then let some dust through). If it's far enough away from your work area that you aren't worried about debris falling against it, you can go as thin as you're comfortable with and tape it. If you can't avoid debris falling against it, go with heavier plastic (or preferably a plastic tarp) and use something more substantial to secure it.
We use pre-taped painter's plastic sheeting all the time for dust management. It comes on a dispenser roll with a built in cutter (like cling film) and tape on one edge. Simply stick the tape to the ceiling (or wherever) and then pull down the folded thin polythene sheet (we use a 10 foot or 3m version).
The polythene is very light so you should put it out of the workspace (better to work anyway) and place something on the bottom edge as pressure (hot/ cool air/doors opening etc. will billow the plastic).
It's brilliant for covering up kitchens etc. just tape it to the cornice/coving etc. near the ceiling and then drape it over the whole thing down to the floor.
Never had a problem with it pulling paint but then we have a lot of wooden ceilings here so it's not very often an issue...
p.s. the film is so thin it seems to hold the dust via static so the clean up is marvellously easy.