The Different Types of Plastics

There are many different types of plastics and it’s important to know which one you are using before putting it in the recycling bin. Mixing the wrong kinds of plastics can jam recycling centers and even contaminate an entire batch of recycled materials. In 1988, the Society of the Plastics Industry introduced a Resin Identification Code system that divided plastic resins into 7 different categories.

Plastics are a group of polymers made up of long chains of repeating units, called monomers, linked together by oxygen, nitrogen or sulfur atoms. These chains may be completely rigid or flexible, depending on how the monomers are made. Plastics are also categorized by the type of additives that are mixed in to give them specific properties. The additives are known as Masterbatch and the concentrations of these granules can be varied to create plastics that have a variety of uses.

The most common types of plastics are made from polyethylene terephthalate (PET). This type of plastic is often used to make soda bottles, food storage containers and polyester film. It is also an excellent water and gas barrier. It is not as rigid as other types of plastics, but it is still very strong and can hold its shape well.

Polyvinyl chloride (PVC) is another very popular plastic. It is a bit harder than PET and more heat-resistant. It is also less rigid than other plastics, which makes it ideal for PVC pipes and vinyl tiles. It is also used to produce milk jugs, grocery bags and other packaging.

Other thermoplastics include polyethylene and polystyrene. These types of plastics are very versatile, which is why they are used to produce such a wide range of products, including CD and DVD cases, single-use disposable cutlery, trays and smoke detector housings.

These types of plastics are also used in manufacturing cellular phones, computers and television screens. They are much more durable than most other plastics and can withstand repeated bending without breaking.

Thermosets are hard and do not flex as easily as the other plastics in this category. They are typically used to manufacture automotive parts, tires and aircraft components. They are typically derived from phenols and epoxy resins.

Plastics with very high performance are generally referred to as engineering plastics and include polyacetal, polyamide (particularly those known by the trade name nylon) and polytetrafluoroethylene (trademark Teflon). They are expensive but have superior chemical resistance and temperature tolerance, which is why they are used in aerospace and military equipment.

Some of the most popular plastics have been around for a very long time, such as Bakelite, which was first created in the 1920s. Other, more recent, examples are the clear and colored polycarbonates used to make computer and laptop casings and the transparent, flexible thermoplastic elastomers like styrene acrylonitrile (PMMA or acrylic) that is commonly found in contact lenses and glazing, and marketed under such names as Perspex and Plexiglas. The ability to mold and remold these plastics has greatly increased their popularity.