This is a great starter article about plastic, available from Pebble Go.
This is a large book, only available online through National Georgraphic Databases. You'll need to use the search tool on the right hand side to find the plastics part of the book. It'll tell you about how plastic is made, and what materials are made of plastic.
This link will show you in steps how plastics are made.
If you've ever wondered what our world would be like without plastic, without compact discs, Silly Putty, lightweight laptops, and so many more everyday items, you'll find answers to your musings through the courtesy of the Nobel Foundation. Discover exactly what plastics are, the major impact they've had on the world, and the polymerization process. A colorful, informative graph shows the characteristics, uses, and recycling implications of the thermoplastic and thermoset groups of plastic, using everyday items as analogies to help illustrate the differences. After you've finished learning about plastics, have fun playing the Heating Plastics online game.