WARREN, Mich. — Wearing a lab coat, Eve Vitale asked a chemistry class at Warren Mott High School if anyone had heard anything bad about plastics. Hands shot up. It doesn’t degrade, said one student.

For 40 years, plastic and petrochemical companies have tried to convince the public that plastics can be recycled. But they’ve known for just as long that plastics recycling would never work. A report ...