What glue works the best on plastics?

I am trying to glue 2 plastic pieces together Ethylene-Vinyl-Copolymer and Polypropylene. What glue or adhesive works best to adhere these 2 together? I have already tried Gorilla Glue, Gorilla Glue Supper Glue and Epoxy. I have heard Chloroform works well. Please advise. Thanks!