It's hard to find glues to use on Polyethylene. Here's a list starter for things that work and those that don't.
Glues that work:
-- Scotch Weld DP 8010 by 3 M
-- Scotch Weld DP 8010 NS (same epoxy but with fillers)
Outstanding bonding. These glues are not the easiest to find, and not cheap. Price for small container is about $20; available through some R.S. Hughes, Graingers, Fastenal, and perhaps other industrial suppliers.
Tip: you can save the added expense of an applicator and dispenser if you're willing to push it out of the unequal cylinders and mix it. Five minute working time.
Glues that don't stick:
-- JB Weld
-- Super Glue epoxies (all -- verified w/ manufacturer)
-- Gorilla Glue (according to manufacturer -- didn't try it personally)
-- PVC glue, even w/ primer
Anybody got something to add to the list?