and plastic flexible adhesive. It also dries clear and resists water, in addition to being U/V-resistant. There's also Loctite's plastic bonder, an epoxy that, as the name implies, bonds plastics ...

Epoxy adhesives often come in a two-part arrangement, typically a resin and a hardener. Loctite has a product suited for a vinyl fence called Plastics Bonding System, which sells on Amazon for $27.38.