To glue polypropylene, use a combination of a liquid plastic primer and adhesive or a two-component adhesive, and apply them on cleaned polypropylene surfaces. Press the polypropylene pieces against each other tightly and allow the glue to dry overnight.
The liquid plastic primer and adhesive or a two-component adhesive are available in home improvement or hardware shops. For the glue to be effective, flatten the polypropylene surfaces and clean them with a damp rag to remove grease, dirt and any protrusions. If the surfaces are too smooth, sand them with emery cloth or sandpaper.
Apply a coat of the plastic primer on both the surfaces and wait for approximately one minute to allow the primer to become dry and sticky. Now, apply a coat of the plastic adhesive evenly on both the surfaces. Alternatively, use a dispenser gun to dispense the two components of the polypropylene adhesive uniformly together on the surfaces.
After adhesive application, press the two surfaces together immediately and hold them tightly against each other for a minimum of 30 seconds. If required, clamp the two polypropylene pieces together. Clean any excess glue with a rag or scrape it with a knife if the glue dries fast. For the glue to work effectively, it must dry overnight.