From 1933, polyethylene became one of the most widely used plastics

And in the 1930s nylon took centre stage— a polymer designed to mimic silk, but with many times its strength. Starting in 1933, polyethylene became one of the most versatile plastics, still used today to make everything from grocery bags, to shampoo bottles, to bulletproof vests. New manufacturing technologies accompanied this explosion of materials. The invention of a technique called injection-moulding made it possible to insert melted plastics into molds of any shape, where they would rapidly harden. This created possibilities for products in new varieties and shapes—