What glue works best with polyethylene?

To bond polypropylene surfaces, first prepare the surfaces by treating them with a primer. Then apply the proper bonding agent. The process is fairly similar to bonding PVC.

(Note: to further enhance the bond, light surface abrasion can be used before priming)

ANS 2 - You glue polypropylene with 3M DP 8005. -BUT it's not cheap !