June 6, 2023

Recycling Plastic Types

The first fully synthetic plastic was invented in 1907 by Belgian chemist Leo Baekeland using heat, pressure and only two chemicals. Its main and sole purpose was to provide electrical insulation to developing US electrical infrastructure. Now, over 115 years later, plastic today has become an entirely different product than its two-part predecessor. Increased demand for the polymer in World War 2, NASA spacecrafts, and packaging supplies in all realms of business has turned plastic into an extremely versatile, dexterous, and abundant material with its own market and production line. Many modern plastics (today, made from crude oil) contain different chemicals that can affect its strength and determine its purpose in the world. Increasing diversification in plastic composition led to increasing confusion on how to identify these plastics, and as a result, RICs were created in the 1980s. Resin Identification Codes (RIC) help distinguish plastics from each other. They allow for plastic categorization for recycling and manufacturing purposes. These codes divide plastics into seven main categories based on what plastic resins were used to produce them. Additionally, the plastics are arranged in order of how recyclable they are (1 is most recyclable, 7 is least recyclable).

Number 1 Plastics are created using Polyethylene Terephthalate, or PET plastic. Typical examples of Number 1 Plastics are plastic beverage bottles, cooking oil bottles, peanut butter jars, and mouthwash bottles. Commercially, PETs are the most sought after plastic to recycle because they are less energy intensive and costly to repurpose, and virtually all PET plastic can be recycled.

Number 2 Plastics are created using High Density Polyethylene, or HDPE. Most food and beverage jugs (milk and water jugs, etc.) are made of HDPE in addition to cleaning containers and detergent bottles. HDPE is very strong and very easy to clean, and virtually all HDPE plastics can be recycled.

Polyvinyl Chloride (PVC) is the primary chemical used in creating Number 3 Plastic. The most notable example of PVC can be found in pipes (also known as PVC pipes). Thermal insulation, some furniture, and trays are also made of Number 3 Plastic. When PVC plastic is repurposed and heated, the process releases chemical byproducts that are dangerous for humans. Because of this, PVC plastic is harder to recycle and is usually not allowed in curbside recycling unless specialized facilities exist to handle the material.

All Number 4 Plastics are made with Low Density Polyethylene, or LDPE. These plastics are the bags and wraps of the world: the plastic shopping bags, grocery bags, or plastic wraps used in cooking and containing. The lower density of the material makes it lightweight, flexible, and therefore great for carrying items. Consequently, this is also the reason why it’s difficult to recycle: its flexibility often causes it to get caught in machinery, damaging equipment and making the recycling process more costly. Many grocery store chains have now implemented grocery bag recycling stations to collect plastic bags and repurpose the plastic for items such as park benches, decking material, or new bags.

Yogurt tubs, disposable cutlery, juice bottles, and straws are a few of the items that Number 5 Plastic, or Polypropylene (PP) can make. While PP plastics are recyclable, many are not allowed in curbside recycling programs. Additionally, some Number 5 Plastics are not manufactured to be recyclable, a perfect example being straws.

Polystyrene (PS), or Number 6 Plastic, is widely used for disposable, single use plastic products. Examples of Number 6 Plastics are food trays, plastic foam cups, packaging peanuts, and some egg cartons. Styrofoam is a form of Number 6 Plastic, and the material is notoriously used for packaging in shipping. PS plastic is very tough to recycle because of its structure and chemical composition. The rigid, porous structure of the resin makes it difficult to clean and repurpose into raw material. Additionally, the handling of PS plastic has the potential to release harmful chemicals such as carcinogens into the atmosphere and water.

Any products that are not made of Plastics #1 - 6 are labeled as Number 7 Plastics. They are the wildcard of the group - in terms of composition and purpose, Number 7 Plastics are both the most diverse and difficult plastics groups to recycle. Many hazardous plastics are placed in this category, such as plastics containing BPA, a known endocrine disruptor. More examples include nylon, acrylic materials, and some car parts. The diversity of these plastics makes it hard for local governments to recycle them curbside.

The first step in effectively recycling plastics is to identify what type of plastic you’re dealing with. Only then can you make the right decision on what plastics belong in a landfill or belong in the recycling stream. CIRT’s mission is to make the process of recycling easier for the consumer by informing them about what types of plastics are curbside recyclable in their area. This is why CIRT offers local curbside recycling information on all 7 types of plastics in use today.