Plastics are a group of materials that come from using polymers or long chains of molecules made up of many repeating parts. These polymers can be designed to be hard, soft, transparent, flexible, or anything in between. Plastic is most commonly used for packaging and food containers because it is inexpensive and easy to mold into different shapes.
Typically a plastic product will have a number in front indicating what type it is. The following list shows the common plastic types you might see on products:
A polymer called styrene also has uses in the petrochemical industry. It is very hard plastic and is most commonly used to make things like bottled drinks, refrigerators, plastic bags, gas canisters, insulation, and packaging. Although styrene is toxic to humans and can cause severe allergic reactions if ingested, it does not release the same amount of dioxin into the air when it decomposes as other plastics. It is more difficult for animals to eat than many other types.
This plastic is used in insulation and packaging commonly shaped into a disposable drinking cup called a ‘brillo’ and rice sachets. It is a very hard plastic, but it can still be melted if it gets hot enough. It should not be eaten and has to be disposed of properly in the right way. It can even cause accidental poisoning if it is swallowed. The problem is that because it is so hard and cannot be melted down easily, recycling facilities can often only make one use of it before discarding it as waste.
3. High-Density Polyethylene (HDPE)
Polyethylene is another plastic that is hard, strong, and cheap to make. It is used to make many different kinds of packaging for food, such as milk bottles, juice cartons, detergent tubs, and shampoo bottles. It can also be used to make rope or carpets.
4. Low-Density Polyethylene (LDPE)
This is a less hard version that HDPE, but still very strong and tough. It has the same uses as HDPE but has more flexibility, so it makes softer packaging that can be folded over more than HDPE could be without breaking.
5. Polypropylene (PP)
This plastic is made from a polymer called propylene. It is very hard and strong but can be melted down and reused. PP is used to make things like milk bottles, water bottles, yogurt pots, and straws.
6. Styrene-Acrylonitrile (SAN)
This plastic is very hard and made from acrylonitrile and styrene (like polystyrene). However, it does not tend to contain as many dioxin byproducts as other plastics do when it degrades in the environment. It can be used to make packaging and other plastic products.
This is tough, strong plastic used to make cases for mobile phones and laptops and reusable bags that use less energy than a normal plastic bag.
Scientists are also trying to create a new group of plastic that will degrade easily in the environment, but so far, it has only been possible to do this by making the plastic liable to break down into lots of small pieces. So far, scientists have created a material that would decompose in a matter of months rather than withstand our weather for hundreds of years like most plastic does now.