Plastics are pernicious.
Some thermo plastics can not be bonded with adhesives (glue / cement) but an auto body shop can use a thermal (heated melted plastic) process to do repairs for plastics like those on car bumpers. A similar thermal type of process is used for my X-ski base with a P-tex stick and for repairing Coleman and Pelican canoes made of plastic. A delicate touch is required so the item does not become a blob of melted plastic.
PVC and ABS (as found in plumbing supplies and electrical conduit) and other types of plastic items have special adhesives that often include solvents to partial dissolve the bonding parts to create exceptionally strong bonds. Some adhesives will bond two different types of plastics but the magnitude of difficulty is very high for success. Plexi-glass "adhesive" is pure solvent which bonds the pieces into one contiguous seamless (if done correctly) solid piece with no joint.
Successful use of these adhesives can often be discovered by testing on a piece of scrap material to see if they "work".
Mechanical joining with rivets, screws or nuts and bolts is often the only recourse.
Ekiom
June 2011