The 7 Different Types of Plastic

Not all plastic is born equal. In fact, not only can plastic be found in a variety of different shapes and colors, but also in many different types. Each one is different from the other and has different uses. For example, some types of plastic are reusable and others aren’t because of the chemicals they contain; some can be recycled and others need to be disposed of in a different way.

In order to help you make better-informed decisions about the products that you buy, today we will go through the seven different types of plastic, how they differ, and their impact on the environment. So, keep reading!

WHY ARE THERE DIFFERENT TYPES OF PLASTIC?

In , the Society of the Plastics Industry introduced the Resin Identification Code (RIC) system which divided plastic resins into 7 different categories.

The purpose was to “provide a consistent national system to facilitate recycling of post-consumer plastics." Since then, after undergoing some minor variations, the RIC has been recognized as the worldwide standard plastic classification.

THE DIFFERENT PLASTIC TYPES

1 – PET

Plastics that belong to group number one are made out of polyethylene terephthalate or PET. It holds the number one spot because of its widespread utility.  It is mostly used for food and drink packaging purposes due to its strong ability to prevent oxygen from getting in and spoiling the product inside.

It’s usually picked up through most curbside recycling programs and has a tremendously positive track record! In fact, PET bottles are the most widely recycled plastic in the world!

2 – HDPE

Technical name - High-Density Polyethylene – it’s an incredible resistant resin used for grocery bags, milk jugs, recycling bins, agricultural pipe, but also playground equipment, lids, and shampoo bottles among others.  Because it’s made with long unbranched polymer chains it’s much stronger and thiicker than PET. Also, it is relatively hard and resistant to impact and can be subjected to temperatures of up to 120 °C  without being affected. As far as its disposal is concerned, HDPE is accepted at most recycling centers in the world, as it is one of the easiest plastic polymers to recycle. 

3 – PVC

Polyvinyl chloride is the world's third-most widely produced synthetic plastic polymer. It comes in two basic forms: rigid and flexible. In its rigid form, PVC is largely used in the building and construction industry to produce door and window profiles and pipes (drinking and wastewater). When mixed with other substances, It can be made softer and more flexible and applied to plumbing, wiring, and electrical cable insulation and flooring. 

Thanks to its versatile properties, such as lightness, durability, and easiness of processability, PVC is now replacing traditional building materials like wood, metal, concrete, rubber, ceramics, etc. in various applications.

Despite its many advantages and efforts made by the plastic industry to increase its reusability, PVC is still hardly recyclable and should therefore be avoided, whenever possible. 

4 – LDPE

Contrary to HDPE, LDPE is characterized by low-density molecules, giving this resin a thinner and more flexible design. It has the simplest structure of all the plastics, making it easy and cheap to produce. Used in plastic bags, six-pack rings, various containers, dispensing bottles, and most famously for plastic wraps, is not often recycled through curbside programs.

5-PP

Polypropylene is the second-most widely produced commodity plastic and its market is forecasted to grow even more in the following years. Hard and sturdy, it can withstand high temperatures and is found in tupperwares, car parts, thermal vests, yogurt containers, and even disposable diapers.

Fun fact: because it is VERY resistant to fatigue, PP is usually used for living hinges (the thin piece of plastic that allows a part of a product to fold or bend from 1 to 180 degrees).

6 – PS

Polystyrene is the sixth type of plastic on the list and it can be solid or foamed. It is a very inexpensive resin per unit weight and easy to create, for these reasons it can be found everywhere: from beverage cups, insulation, packing materials to egg cartons and disposable dinnerware. Perhaps better known by its commercial name – Styrofoam – it’s highly inflammable and dangerous as it can leach harmful chemicals, especially when heated (which often happens because, as it’s found in disposable take-out containers, people oftentimes microwave it to heat up the food inside it). 

Environmentally-speaking it’s among the worst types of plastic: first, it is regarded as not biodegradable. Second, polystyrene foam blows in the wind and floats on water, due to its low specific gravity. Animals do not recognize it as artificial and may mistake it for food causing serious effects on the health of birds or marine animals that might swallow it.

In addition, polystyrene is not accepted in curbside collection recycling programs and is not separated and recycled where it is accepted. To sum up, it’s a no-go.

7 – OTHER PLASTIC

If plastic cannot be identified in the six types above-mentioned, then it will be included in group number 7. The best-known plastics of this group are polycarbonates (PC) used to build strong, tough products. Polycarbonates are commonly used for eye protection in the creation of lenses for sunglasses, sport and safety goggles. But they can also be found on mobile phones and, more frequently, in compact-discs (CD).

In recent years, the use of these resins has been controversial: the basis of this controversy is their leaching that, occurring at high temperature, releases bisphenol A, a compound that is on the list of potential environmental hazardous chemicals. Moreover, the decomposition of BPA in landfills does not occur meaning that this chemical will be persistent in the ground and will eventually find its way into water bodies contributing to aquatic pollution. On top of this, plastics number 7 is almost never recycled.

Here’s a brief recap of what we have learned so far:

The Basics On 7 Common Types of Plastic

In our continuing effort to provide educational resources on plastic pollution and sustainability, we thought we would address one of the most common questions we receive: Isn’t plastic all the same? In short … no. 

However, it’s understandable that many people make the assumption that it’s one material, all the same from top to bottom. In fact, there are hundreds of types of plastic (also called polymers), but only a handful that we interact with on a regular basis. 

While we believe that plastic alternatives are a must, and support initiatives to develop them, the reality is that plastic is here and will be for some time. Therefore, I say let’s try to better understand it, rather than ignore it or simply bash it. In the end, not all plastic is bad. Humanity has certainly benefited from it in some ways and you can even make arguments that support that it’s also been beneficial to the environment – although in very specific examples. 

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Having knowledge of the different types of plastic is critical to understanding the complexity of recycling, upcycling and the health factors associated with plastic. But the key word there is “complexity.” It’s a huge topic, so this article is just a starting point, meant to be a basic introduction for those that have little to no knowledge, not a comprehensive look for those already in the know. 

The first step is to simply know the core basics for the types of plastic that we most encounter, numbered according to their recycling codes. Here’s a short guide:

1) Polyethylene Terephthalate (PET or PETE)

This is one of the most commonly used plastics. It’s lightweight, strong, typically transparent and is often used in food packaging and fabrics (polyester). 

Examples: Beverage bottles, Food bottles/jars (salad dressing, peanut butter, honey, etc.) and polyester clothing or rope. 

2) High-Density Polyethylene (HDPE)

Collectively, Polyethylene is the most common plastics in the world, but it’s classified into three types: High-Density, Low-Density and Linear Low-Density. High-Density Polyethylene is strong and resistant to moisture and chemicals, which makes it ideal for cartons, containers, pipes and other building materials. 

Examples: Milk cartons, detergent bottles, cereal box liners, toys, buckets, park benches and rigid pipes.

3) Polyvinyl Chloride (PVC or Vinyl)

This hard and rigid plastic is resistant to chemicals and weathering, making it desired for building and construction applications; while the fact that it doesn’t conduct electricity makes it common for high-tech applications, such as wires and cable. It’s also widely used in medical applications because it’s impermeable to germs, is easily disinfected and provides single-use applications that reduce infections in healthcare. On the flip side, we must note that PVC is the most dangerous plastic to human health, known to leach dangerous toxins throughout its entire lifecycle (eg: lead, dioxins, vinyl chloride).  

Examples: Plumbing pipes, credit cards, human and pet toys, rain gutters, teething rings, IV fluid bags and medical tubing and oxygen masks.

4) Low-Density Polyethylene (LDPE)

A softer, clearer, and more flexible version of HDPE. It’s often used as a liner inside beverage cartons, and in corrosion-resistant work surfaces and other products. 

Examples: Plastic/cling wrap, sandwich and bread bags, bubble wrap, garbage bags, grocery bags and beverage cups.

5) Polypropylene (PP)

This is one of the most durable types of plastic. It is more heat resistant than some others, which makes it ideal for such things as food packaging and food storage that’s made to hold hot items or be heated itself. It’s flexible enough to allow for mild bending, but it retains its shape and strength for a long time.

Examples: Straws, bottle caps, prescription bottles, hot food containers, packaging tape, disposable diapers and DVD/CD boxes (remember those!).

6) Polystyrene (PS or Styrofoam)

Better known as Styrofoam, this rigid plastic is low-cost and insulates very well, which has made it a staple in the food, packaging and construction industries. Like PVC, polystyrene is considered to be a dangerous plastic. It can easily leach harmful toxins such as styrene (a neurotoxin), which can easily then be absorbed by food and thus ingested by humans.

Examples: Cups, takeout food containers, shipping and product packaging, egg cartons, cutlery and building insulation.

7) Other

Ah yes, the infamous “other” option! This category is a catch-all for other types of plastic that don’t belong in any of the other six categories or are combinations of multiple types. We include it because you might occasionally come across the #7 recycling code, so it’s important to know what it means. The most important thing here is that these plastics aren’t typically recyclable. 

Examples: Eyeglasses, baby and sports bottles, electronics, CD/DVDs, lighting fixtures and clear plastic cutlery.

There you go … the most common types of plastic that we encounter. This is obviously very basic information on a topic that one could spend months on researching. Plastic is a complex material, just as its production, distribution and consumption are. We encourage you to dive in deeper in order to understand all these complexities, such as plastic properties, recyclability, health hazards and alternatives, including the pros and cons of bioplastics. 

Below you’ll find links to some great resources that will help get you started. Enjoy!