According to this particular survey, it seems like an epoxy is the best:
http://info.craftechind.com/blog/bid...ue-for-Plastic
I always plump for a cyanoacrylte (super glue) type as a starter, but depends on whether you can afford several shots at it. Cyanoacrylate will discolour some plastics without any adhesion, but others it will stick like fury. If you can't afford mistakes, my advice is to always Google for the best info before experimenting. The best adhesives for all the different plastics are well established.
TC