I know epoxy and bondo/polyester resins won't stick - I use the cutting boards to mix on. A few years back, I tried "gluing" a water tank - some sort of poly product in my buddy's RV. It held for a while then started leaking again. So then I welded it together. Held since - and thats over 3 years!
The glue I tried was similar to this stuff: http://cyberfixusa.com/_wsn/page2.html
I see they have a primer now too, so maybe that would help - pretty expensive stuff.
If you want to buy a plastic welder there is this one: http://www.autobodydepot.net/scripts...stweldgate.bbx
But you could experiment using a small torch and try welding it together - Careful - its Hot--and runny. Don't let it get brown - burnt and won't stick as well.