Things made of plastic, from credit cards to spoons to bags, have become so common in our lives that we can hardly think of life without them. Yet all plastics are made from petroleum, which will run out in a few decades. What do we do next?
How plastics are made
All plastics are polymers, that is they are made of a molecule which is itself made of hundreds of small molecules. These units are called monomers. Polyethylene (used in plastic bags) is made from a monomer unit called ethylene. Similarly styrofoam (used in disposable cups and plates) is made from a unit called styrene. PVC, which is used to make things like buckets and even plastic doors, is made from units of vinyl chloride linked to each other by chemical bonds. All these units ultimately come from petroleum. But the reserves of petroleum are quite rare, and will run out in our lifetime.
Plastic from potatoes
Potatoes contain a lot of starch (cellulose), which can be used to make a plastic-like material quite easily and cheaply. This plastic is not very strong or long-lasting. It is also very easily broken down by bacteria (see an article about eco-friendly plastic here). But that makes it the ideal material for making disposable spoons, cups, plates etc. In fact many companies have already begun to do so, and they have given it a nice name too – Spudware!
Plastic from chicken feathers and soybeans
The circuit board you see on electronic devices is made of a light but durable plastic, on which tiny electronic circuits are soldered on. As computers, mobile phones and other electronic gadgets spread through the world, we’ll need millions of these feather-bean boards!
A team from Cornell University found another way to make plastic. They used orange peels, and another material that is becoming increasingly common in our atmosphere – carbon dioxide. Orange peels contain a chemical called limonene (the same thing that gives the orange-y smell). The team found that you can convert it to limonene carbonate, which could then be polymerised into a useful plastic called poly-limonene carbonate (PLC). This is in fact a de-polluting plastic, because to make it you need to remove CO2 from the air, rather than add to it.
We hope that you’ll be inspired to make something equally clever from materials lying around the house too!