I didn't have any PVC (which I recommend) but I did ask for a tube at my local hardware store. It worked as well as I could do with the size I had. This was 1 inch exterior and 5/8 inch interior. If the tube had been 1 inch interior, it would have gone over the whole handle. But this will work for a while.
I cut it 8" long with some cheap steak knives and it was a cinch to get over the handle. I probably didn't need the tape, but I figured it couldn't hurt!
It gives me just enough for my poor back to stop stooping just to sweep!
PS: This would work for mop too, but I would advise to do the PVC first. You tend to use the end of a mop with more force than a broom.