I did some research looking for an adhesive to properly glue (once and for all) the front bumper cover to the metal bumper on my XR.
I found a product line called Duramix by Polymer Engineering
Corporation. They manufacture a complete line of adhesives and
fillers, including their number
4036 THERMOPLASTIC OLEFIN (T.P.O.) REPAIR. (4035 in the smaller 20cc cartridges)
This stuff is a urethane based two-part epoxy, that comes in a dual tube syringe with a mixing tip. I used it to repair some small gouges on my bumper covers before I painted them. Works like a dream. Working time of 50 seconds. Sand in 15 minutes.
The adhesive for the bumper is 4125 in the 50cc size, with a working time of 10 minutes, bond in 30 minutes, cure 4 hours.
You can see them here:
About $7 for the 20cc 4036, and $18 for the 50cc 4125 adhesive. I highly recommend.