Can you recommend a sealent that sticks to polypropylene? Silicone lifts right off. Sikaflex 221 apparently is also not suitable.
Today I attached a polycarbonat window. The silicone might seal, but only because its under compression by screws.
I got hot glue to work by roughing up the texture with a chissel. This is only a mechanical interlock. Its not waterproof.