I'm often asked by people "can any plastic be used to repair a kayak?" the short answer is, no!! , most plastics with the exception of a few will only stick to themselves.
This is a LDPE weld rod welded to a HDPE kayak hull, looks good doesn't it? when the test weld is cold, I try to pull it off with pliers and most of the time can't.
Test weld fail, this weld had good penetration however it detached with just a light pull, imagine that happening out at sea in rough water, I cannot stress enough the importance of compatible materials for repair and done by someone that knows how to do the repair properly.