I have a Dometic fridge in my motorhome. It has a door shelf that I carry full of soft drinks (6) as I motor down the highways. The third shelf down broke on the door hinge end. Too much weight, I guess.
I'm always asked in hardware stores, Lowes, etc "what kind of plastic is it?" Well, I have no idea. If it was metal I could tell the asking person if it's either cast iron, aluminum, steel, copper, pot metal, etc.
I had an old tube of Testor's plastic model airplane cement in my shop. I put a few drops on the broken end, pressed it together and then used some masking tape to hold it firmly in place, let it set up overnight, and "walla"-- it's together now. A little white spray paint and it's as good as new. I think the glue "melts the pieces together", similiar to what welding does to metal.
I've driven over 800 miles now (with 6 full soda cans on the shelf) and the shelf is still intact.
I had tried "JB Weld". It didn't hold.
You can buy this plastic model cement in any "Hobby Shop". You might want to carry a small tube of this in your rig "just in case"
Good luck and happy, safe travels,