Yeah, ditto on the "flour isn't explosive" thing - flour
burns really well if you light a dust-cloud of it, and you can get a fairly impressive fireball (for that matter any fine flammable particulate dust does the same - we got a better effect with custard powder), but it doesn't explode.
Mind you, we made a fairly nifty experiment to show the power behind the burning - you can explode the lid off a tin with a few grams of flour. Get an old custard tin, drill a hole in it and fit an old fashioned tobacco pipe into it. Connect up a plastic tube to where the pipe sticks through the outside (any old one - like the ones you can buy for winemaking) and either fit a big (and I mean 50-100ml, you can usually get them in your science dept at school) old plastic syringe to it like we did or else just blow through it. First put the lid on the tin and blow through the pipe - you might manage to blow the lid off, but it's not very impressive.
Then take the lid back off, and fill the bowl of the pipe (inside the tin) with flour or custard or something. Put a tealight into the tin and light it, then put the lid back on. Retire to a safe distance, and blow through the tube.
The custard will ignite into a fireball, and the sudden heat will blow the lid off the tin.
Just... don't do it indoors.
And don't stand too close for fear of flying lids.
(you can get a nifty little fireball if you do it without the lid on, too. Just ditto on the "don't do it indoors" malarky.)
For a technicality, "polymer" simply means "many units" - plastics are polymers, but starch is a polymer molecule as well. It's one of them ambiguous can-mean-what-it-likes sort of word. :b