It seems that most adhesives don't bond well to these kinds of plastics, kind of like trying to glue something to a Teflon frying pan. The last time I did this type of repair, I sandblasted the repair area first, using coarse sand. It really roughed up the surface, giving something for the glue to hang on to. Then I used a few layers of fiberglass cloth, thoroughly impregnated with J B weld. Been over ten years and still holding. BTW, I DO NOT recommend the "quick" version, just the good old let-it-cure-24hrs stuff.